System and method for measuring intracranial pressure

Abstract

A method for measuring and communicating ICP using an implant and an external device includes measuring an absolute ICP by the implant, and comparing the measured absolute ICP to a predetermined threshold using the implant. The method also includes wirelessly transmitting the measured absolute ICP to the external device at a predetermined recurring interval, or in response to the comparison, and determining a gauge ICP based on the measured absolute ICP and an ambient pressure using the external device.

Description

US PATENT APPLICATION Inventor: Michael Nagy Docket No.: 53560-00020TITLE SYSTEM AND METHOD FOR MEASURING INTRACRANIAL PRESSURE CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The application claims priority to and benefit of U.S. Provisional Patent Application No. 63 / 749,734, filed on January 27, 2025, entitled “SYSTEM AND METHOD FOR MEASURING INTRACRANIAL PRESSURE”, which is incorporated herein by reference.TECHNICAL FIELD

[0002] The present teachings relate to methods, systems, and components thereof for measuring intracranial pressure (ICP), and more particularly to a diagnostic system, method, and sensor assembly employed to support long term continuous ICP measurement.BACKGROUND

[0003] Intracranial pressure (ICP) is the pressure inside the cranium. Its normal range is 7-15 mmHg in an adult, 3-7 mmHg in children, and 1.4-6 mmHg in infants. Accurate measurement of ICP is a key diagnostic used in the treatment of certain conditions, including, without limitation, hydrocephalus, hemorrhagic stroke, brain injury, swelling of the brain, brain tumors, or in assessing patients in a comatose state. Long-term measurement of ICP is particularly important for patients with permanently implanted shunts, such as hydrocephalus shunts, as these shunts are prone to failure, putting the patient at risk until a revision surgery can be performed. Current ICP measurement devices such as the Codman Camino are intended for short-term hospital use only, with the patient confined to a bed. These sensors are respectively inserted into a burr hole in the patient’s skull, and the sensor’s wires are attached to a bedside34294085.237408693.1monitor. Other versions place a fluid tube into the burr hole and connect it to a liquid pressure sensor at bedside.

[0004] ICP sensing can also be combined with fluid drainage in an external ventricular drain (EVD) device, such as the ev3 Navien by Medtronic. Here, a simple manometer scale may indicate the ICP, or an electronic ICP measurement device may be connected bedside. More recent ICP systems, such as the Neurovent P-Tel by Raumedic, and the M.Scio by Miethke are permanently implanted ICP measurement devices that can provide on-demand readings, using an external reader unit. These devices are permanently implanted in the patient, with a short electronic probe or fluid catheter entering a burr hole in the skull, and the scalp closed over the device. The rated lifetime of P-Tel is 30 days and that of M.Scio is 5 years. Both devices require a neurosurgeon to operate their reader device, which is held over the implant site to obtain each ICP reading. A clinical phase device, the Kitea ICP Monitor by Kitea Health, allows the patient to record ICP from a permanently implanted pressure sensor in the cranium. The P-Tel, M.Scio, and Kitea devices have no internal power source and can measure ICP only when powered by a large external device held against the patient’s head.

[0005] Many patients, however, require continuous, long-term monitoring of ICP throughout their daily activities, in a way that will not restrict those activities. These include patients with hydrocephalus shunts that are prone to failure; patients who are at risk of subarachnoid hemorrhage due to brain injury, stroke, etc.; patients with brain tumors; and patients who are comatose, among others. Therefore, there is a need for a wireless medical implant that can continuously and autonomously monitor and log ICP for periods of years without requiring action from human users.

[0006] Thus, it is desirable to provide a pressure sensor assembly, system, and method to reliably detect ICP in a manner that alleviates the foregoing limitations.237408693.1SUMMARY

[0007] The following presents a summary of this disclosure to provide a basic understanding of some aspects. This summary is intended to neither identify key or critical elements nor define any limitations of embodiments or claims. Furthermore, this summary may provide a simplified overview of some aspects that may be described in greater detail in other portions of this disclosure. This summary is intended to include various combinations of described aspects.

[0008] In accordance with an embodiment, an implantable intracranial pressure (ICP) sensor has a pressure sensor assembly including a capsule. The capsule includes the appropriate electrical components and includes a pressure sensing surface.

[0009] In accordance with another embodiment, the pressure sensor assembly includes a surface on the housing or a conduit or catheter defining a cavity therein. An incompressible liquid or gel is disposed in the cavity and fluidly contacts and exerts pressure against an exposed surface of a pressure sensor in the implant. In some versions of this embodiment, only the conduit or catheter penetrates the skull and enters the cranium; all electronics are outside the cranium in an enclosure coupled to the catheter or conduit.

[0010] In accordance with another embodiment, the pressure sensor assembly includes a plurality of conduits respectively configured to measure a plurality of ICP values. The pressure sensor assembly may be implantable into a cranium of a patient, or may have a plurality of fluid catheters or conduits as described above.

[0011] In accordance with another embodiment, a method of transmitting data includes measuring ICP, comparing the ICP relative to a predetermined ICP threshold value, and transmitting ICP data to an external device at a recurring time interval. The data transmit time interval may be fixed, may depend on whether the measured ICP is below, above or at the predetermined ICP threshold value, or may be triggered by another event such as a user request.337408693.1

[0012] In accordance with another embodiment, a method for measuring and communicating ICP using an implant and an external device includes measuring an absolute ICP by the implant, and comparing the measured absolute ICP to a predetermined threshold using the implant. The method also includes wirelessly transmitting the measured absolute ICP to the external device at a predetermined recurring interval, or in response to the comparison, and determining a gauge ICP based on the measured absolute ICP and an ambient pressure using the external device.

[0013] An ICP monitoring system includes a shunt that conveys cerebrospinal fluid (CSF) within a cranium, and a valve disposed in the shunt, controlling flow of the CSF through the shunt. The system also includes a first pressure sensor upstream from the valve with respect to CSF flow through the shunt, where the first pressure sensor performs a first ICP measurement. The system also includes a second pressure sensor downstream from the valve with respect to CSF flow through the shunt, where the second pressure sensor performs a second ICP measurement. The system also includes at least one processor operatively connected to the valve, the first pressure sensor, the second pressure sensor, and an external device, where the at least one processor determines a differential CSF pressure in the shunt, across the valve, based on the first ICP measurement and the second ICP measurement. The at least one processor also generates at least one of a control signal to the valve and an alert at the external device based on the determined differential CSF pressure.

[0014] In all embodiments, the pressure sensor device may be combined with a hydrocephalus shunt, may be placed in line with the shunt, in parallel with the shunt, or may be standalone without a shunt.DESCRIPTION OF THE DRAWINGS

[0015] The present teachings may be better understood by reference to the following detailed description taken in connection with the following illustrations, wherein:437408693.1

[0016] FIG. 1 is a block diagram of an example diagnostic system for measuring intracranial pressure (ICP) according to an embodiment.

[0017] FIG. 2 is a perspective view of an example implantable pressure sensor assembly according to an embodiment.

[0018] FIG. 3 is a perspective view of an example implantable pressure sensor assembly according to an embodiment.

[0019] FIG. 4 is a perspective view of an example implantable pressure sensor assembly according to an embodiment.

[0020] FIG. 5 is a flow chart of an example methodology for transmitting a measured ICP.

[0021] FIG. 6 is a block diagram of another example diagnostic system for measuring ICP according to another embodiment.

[0022] FIG. 7 is a perspective view of an ICP sensor according to another embodiment.

[0023] FIG. 8 is a is a block diagram of an example diagnostic system for measuring physiological or environmental parameters of an abdominal location.

[0024] The innovation disclosed herein may be embodied in several forms without departing from its spirit or essential characteristics.DETAILED DESCRIPTION

[0025] The present disclosure may be embodied in several forms without departing from its spirit or essential characteristics. The scope of the disclosure is defined in the appended claims, rather than in the specific description preceding them. All embodiments that fall within the meaning and range of equivalency of the claims are therefore intended to be embraced by the claims.

[0026] Reference will now be made in detail to embodiments of the present teachings, examples of which are illustrated in the accompanying drawings. It is to be understood that other embodiments may be utilized, and structural and functional changes may be made without537408693.1departing from the scope of the present teachings. Moreover, features of the embodiments may be combined, switched, or altered without departing from the scope of the present teachings, e.g., features of each disclosed embodiment may be combined, switched, or replaced with features of the other disclosed embodiments. In this disclosure, numerous specific details provide a thorough understanding of the subject disclosure. It should be understood that aspects of this disclosure may be practiced with other embodiments not necessarily including all aspects described herein, etc. As such, the following description is presented by way of illustration and does not limit the various alternatives and modifications that may be made to the illustrated embodiments and still be within the spirit and scope of the present teachings.

[0027] As used herein, the words “example” and “exemplary” mean an instance, or illustration. The words “example” or “exemplary” do not indicate a key or preferred aspect or embodiment. The word “or” is intended to be inclusive rather than exclusive unless context suggests otherw ise. As an example, the phrase “A employs B or C,” includes any inclusive permutation (e.g., A employs B; A employs C; or A employs both B and C). As another matter, the articles “a” and “an” are generally intended to mean “one or more” unless context suggests otherwise.

[0028] Throughout this disclosure, “proximal” means toward the brain, and “distal” means away from the brain. In an embodiment, a proximal catheter may drain cerebrospinal fluid (CSF) from the ventricle and a distal catheter empties the CSF into an abdominal peritoneum of a patient. However, other configurations, such as drainage from the subarachnoid space, or discharge into the right atrium or pleural sac, are also possible based on the present teachings. The present disclosure is not limited to the location of discharge. What is described herein is exemplary and any appropriate location of discharge within or even outside of the body may be utilized without departing from the present teachings. Further, some embodiments of the present disclosure may not provide drainage at all, and may not include the distal catheter, or may not include any fluid catheters.637408693.1

[0029] “Logic,” synonymous with “circuit” as used herein, includes but is not limited to hardware, firmware, software and / or combinations of each to perform a function(s) or an action(s). For example, based on a desired application or needs, logic may include a software-controlled microprocessor, discrete logic such as an application specific integrated circuit (ASIC), or other programmed logic device and / or controller. Logic may also be fully embodied as software.

[0030] “Software”, as used herein, includes but is not limited to one or more computer readable and / or executable instructions that cause a computer, logic, or other electronic device to perform functions, actions, and / or behave in a desired manner. The instructions may be embodied in various forms such as routines, algorithms, modules or programs including separate applications or code from dynamically linked libraries. Software may also be implemented in various forms such as a stand-alone program, a function call, a servlet, an app, instructions stored in a memory, part of an operating system or other type of executable instructions. It will be appreciated by one of ordinary skill in the art that the form of software is dependent on, for example, requirements of a desired application, the environment it runs on, and / or the desires of a designer / programmer or the like.

[0031] Referring to FIG. 1, an example system 100 for measuring intracranial pressure (TCP) within the cranium of a patient, which includes an implant 110, and one or more external devices 140 communicatively coupled to the implant 110 via a wireless communications link 160. To facilitate communication, the implant 110 may include a communications device 165 for sending and receiving data from the external devices 140, and an external battery charger 170 that charges the power supply 134. In some examples, the communications device 165 may include one or more controllers for standards -based networks (e.g., 2G, 3G, 6G, 4G LTE, 5G. GSM, UMTS. LTE. CDMA, WiMAX, Bluetooth Low Energy (BLE). Bluetooth Classic. Bluetooth 5, etc.), satellite communication networks, and / or wireless local area networks (e.g..737408693.1Wi-Fi®, Wireless Gigabit, etc.), etc. In some examples, the communications device 165 may include controllers for personal area networks (e.g., ZigBee® (“IEEE 802.15.4”), Near Field Communication (NFC), etc.) to communicatively couple the implant 110 to the external device 140. In some embodiments, the communications device 165 may include a Bluetooth device (e.g., antenna and transceiver), or facilitate Wi-Fi-based communication such as via frequencies defined by the IEEE 802.11 standards, short-range wireless frequencies such as Bluetooth®, or any suitable wired or wireless communications protocol that facilitates communication between the implant 110 and the external device 140. In some embodiments, the communications device 165 may include an RF antenna to wirelessly communicate with the external devices 140. It is also contemplated that the components of the implant 110 may wirelessly communicate with each other via RFID technology'.

[0032] In some embodiments, the system further supports patient identification and data access control without reliance on personally identifiable information. For example, a clinician-facing system, such as one of the external devices 140, may utilize a patient-specific key, token, or identifier that is associated with the implant 110 or a corresponding patient record. The patientspecific key may be exchanged wirelessly, for instance using Bluetooth®, BLE, NFC, or another short-range wireless protocol, when the implant 110 or an associated patient device is within a defined proximity of a clinician reader. Using such a key-based approach, the clinician reader may retrieve or access patient data associated with the implant 110 without requiring entry or transmission of the patient’s name or other personal identifiers. This proximity-based key exchange may facilitate secure and efficient access to implant data while reducing exposure of sensitive patient information.

[0033] With continued reference to FIG. 1, the implant 110 may include a controller 120 and a sensor assembly 132 including one or more sensors operatively connected to the controller 120. The controller 120 may embody a microcontroller that can send or receive data from the837408693.1one or more sensors. The controller 120 may include a processor 122 and a storage device 124. The processor 122 may embody any suitable processing device or set of processing devices such as, but not limited to: a microprocessor, a microcontroller-based platform, a suitable integrated circuit, one or more field programmable gate arrays (FPGAs), and / or one or more application-specific integrated circuits (ASICs). The storage device 124 may be volatile memoiy (e.g., RAM, which can include non-volatile RAM, magnetic RAM, ferroelectric RAM, and any other suitable forms); non-volatile memoiy (e.g., disk memoiy, FLASH memory, EPROMs, EEPROMs, non-volatile solid-state memory, etc.), unalterable memory (e.g., EPROMs), read-only memoi ', etc.). In some examples, the storage device 124 may include multiple kinds of memory, particularly volatile memory7and non-volatile memory. The storage device 124 may also embody a computer readable medium on which one or more sets of instructions are embedded, including, without limitation, a non-transitory computer readable medium. The instructions may embody one or more of the methods or logic as described herein. In a particular embodiment, the instructions may reside completely, or at least partially, within any one or more of the storage devices 124, the computer readable medium, and / or within the processor 122 during execution of the instructions.

[0034] The sensor assembly 132 may include environment sensors (e.g., temperature sensors, humidity sensors, pressure sensors, accelerometers, chemical sensors, light sensors, etc ). In an embodiment, the sensor assembly 132 may include a pressure sensor 132a that measures and transmits ICP (e.g., absolute ICP) in real time, a temperature sensor 132b that measures and transmits a temperature of the patient at the implant 110, and an accelerometer 132c or other inertial sensor that measures acceleration, where acceleration data output from the accelerometer 132c or other inertial sensor may be used by the controller 120 or the external device 140 to determine a position, posture, or orientation of the patient at the implant 110.937408693.1

[0035] In some embodiments, the sensor assembly 132 may embody a pressure sensor assembly. For example, referring to FIG. 2, a pressure sensor assembly 250, according to a first embodiment, may include a capsule 240 and a flexible conduit 270 (containing at least one wire) extending between an ICP sensor housing 243 and the capsule 240. The capsule 240 may¬ be shaped and dimensioned such that it may be deployed into the brain tissue via a small bunhole formed in the skull surface. For example, in some embodiments, the capsule 240 may include a length that is between about 3 and 8 cm, and a diameter that is between about 3 and 6 mm. In some embodiments, the capsule 240 may be made of a suitable biocompatible material, for example, alumina, cobalt-chromium, medical-grade silicon, titanium, silicone, PEEK, glass, sapphire, or fused silica.

[0036] In the embodiment shown, the capsule 240 defines an opening or window 241 for enabling CSF to enter the capsule 240. A proximal end 271 of the conduit 270 (disposed in the capsule 240) may be formed to terminate in a pressure sensor that exposes a pressure-sensing surface to measure ICP based on fluid entering the capsule 240 via the window 241. Beneficially, the capsule 240 protects the pressure sensing surface of the sensor (disposed therein) from inadvertently making contact with surrounding brain tissue, scar tissue, fibrotic growth, or other biofouling material which could hinder the accuracy of the ICP measurements.

[0037] In some embodiments, the sensor at the proximal end 271 of the conduit 270 (within the capsule) will be sensitive to changes in resistance corresponding to a force applied to the sensor via CSF flowing into the capsule 240 via the window 241. In such embodiments, such changes in resistance may be utilized to measure ICP. For instance, the controller 120 (FIG. 1) in the ICP sensor housing 243 may include circuitry or software to convert changes in resistance to a measured ICP in real time. In some embodiments, the controller 120 (FIG. 1) may be configured to convert the measured resistance to an electrical signal corresponding to a measured ICP value, e.g., the controller 120 includes an encoder.1037408693.1

[0038] In some embodiments, one or more wires or cables may act as a conduit 270 that transmits electrical signals to and from the pressure sensor, which has piezo-resistive strain gauges therein. The piezo-resistive strain gauges exhibit electrical resistance changes with pressure applied thereto. In some embodiments, the pressure sensor assembly 250 may include a diaphragm at a proximal end of the wire or cable with a strain gauge attached thereto configured to deflect via force applied thereto (e.g., via surrounding CSF). In such embodiments, the controller 120 (FIG. 1) may include circuitry or software to convert the deflection of the diaphragm to a measured ICP value. In other embodiments, the pressure sensor assembly 250 may include a diaphragm that is at least one plate of a capacitor, causing capacitance to change in proportion to diaphragm deflection caused by pressure. In other embodiments, pressure sensor assembly 250 may include a diaphragm that moves in proportion to pressure and is fixedly connected to an inductor, causing inductance to change in proportion to diaphragm deflection caused by pressure. Other embodiments may include a diaphragm that moves in proportion to pressure that changes optical properties of a light beam or beams. In all embodiments, appropriate circuitry for measuring the sensor’s response to pressure is included in assembly 250.

[0039] Referring to FIG. 3, another example of a pressure sensor assembly 350 is shown. In this embodiment, the pressure sensor assembly 350 includes a catheter or conduit 370 that is deployed into the brain tissue via a burr hole in the skull. In particular, the conduit 370 may define a space or channel therein for containing an incompressible liquid or gel 374, including, without limitation, a silicone gel, saline, CSF, or an inert oil. The conduit 370 may expose the incompressible liquid or gel 374 to surrounding CSF via an opening 372 formed through a proximal end 371 of the conduit 370, although it is contemplated that the opening 372 may be disposed in a different location, for example, in a side wall of the conduit 370 (e.g., proximate the proximal end 371), and that conduit 370 may have more than one opening. In some1137408693.1embodiments, the pressure sensor assembly 350 may include a pressure sensor 332 disposed in the ICP sensor housing 243. The pressure sensor 332 may include a flexible diaphragm or membrane 333 with a surface that is exposed to the incompressible liquid or gel 374 contained in the conduit 370. In other embodiments, conduit 370 may have no openings and have walls designed to flex at a known amount in proportion to external pressure, communicating that pressure through the conduit walls, into the internal fluid inside the conduit 370, and ultimately to pressure sensor assembly 350.

[0040] In this manner, as shown in FIG. 3, force applied to the incompressible liquid or gel 374 (via CSF contained in the conduit 370, e.g., upward as shown) will cause the incompressible liquid or gel 374 to communicate the force upward in the conduit 370, whereupon it will contact and exert force against the exposed surface of the membrane 333. In this manner, the force exerted against the membrane 333 by the incompressible liquid or gel may be converted to a measured ICP, e.g., via a controller 120 (FIG. 1) in the ICP sensor housing 243. The membrane may be an integral part of a pressure sensor or transducer, or it may transfer the force exerted on it to one or more other incompressible liquids or gels and membranes that ultimately transduce the exerted force into a pressure measurement. In some embodiments, the conduit 370 is a flexible conduit made of silicone, PTFE, or other biocompatible materials. It is contemplated that the conduit 370 may embody a rigid tube made of titanium, stainless steel, rigid plastic such as PEEK, or ceramics such as fused silica or glass. Further still, in another embodiment, the ICP sensor housing 243 may include the pressure sensor assembly 350 and its components formed therein. Specifically, the ICP sensor housing 243 may include the pressure sensor assembly 350, the conduit 370, which may expose the incompressible liquid or gel 374 to surrounding CSF via an opening 372 formed through a proximal end 371 of the conduit 370. In another embodiment, the pressure sensor 332 may be1237408693.1positioned in the proximal end 371 of the conduit 370. In this embodiment, the pressure sensor 332 would operate as described above.

[0041] The pressure sensor assembly 350 is arranged in an in-line configuration with respect to CSF flow defined by the conduit 370. In this regard, the conduit 370 defines a CSF shunt such that CSF flowing through the conduit 370 encounters the pressure sensing interface defined by the incompressible liquid or gel 374 before reaching a downstream flow-regulating component, such as a valve 380. With this construction, the pressure sensor 332 disposed in the ICP sensor housing 243 is positioned in-line along the CSF flow, downstream of a proximal end 371 of the conduit 370 and upstream of the valve 380, enabling pressure measurement at an in-line location without requiring the pressure sensor 332 to be disposed directly within a CSF flow? lumen or within the valve 380. With this construction, the conduit 370, the pressure sensor assembly 350, and the ICP sensor housing 243 collectively form an in-line pressure sensing structure.

[0042] In further embodiments, the valve 380 may be positioned at an intermediate location along a total length of a proximal catheter portion defined between the burr hole and the proximal end 371 of the conduit 370. In such embodiments, the valve 380 is spaced apart from the burr hole and from the proximal end 371 of the conduit 370, such that a first segment of the conduit 370 extends between the burr hole and the valve 380 and a second segment of the conduit 370 extends between the valve 380 and the proximal end 371. In one example, the valve 380 may be located approximately halfway along the total distance defined between the burr hole and the proximal end 371 of the conduit 370. With this arrangement, the pressure sensing interface defined by the incompressible liquid or gel 374 remains positioned upstream of the valve 380 with respect to CSF flow, while allowing the valve 380 to be located at a desired extracranial or subcutaneous location along the proximal catheter portion, enhancing mechanical stability and pressure measurement fidelity.1337408693.1

[0043] With continued reference to FIG. 3, in some embodiments, the pressure sensor 332 may include a MEMS piezo-resistive sensor integrated into the ICP sensor housing 243. The sensor component may be contained in a titanium, metal, or ceramic housing that may be hermetic. The sensor component may be an absolute, half-bridge or quarter-bridge sensor that measures incident pressure with respect to an internal vacuum or other fixed reference pressure. The sensor connections may exit the housing via a hermetically sealed feedthrough port, which may require at least one bridge completion resistor outside the sensor housing to complete the bridge. The sensor component may require a barometric pressure sensor external thereto in order to correct for changes in atmospheric pressure. The ICP sensor housing 243 may be filled with silicone oil or gel which communicates pressure from a thin membrane in the front face. All body contacting portions may be constructed from titanium. The pins from the feedthrough may be platinum-iridium, and the wires attached to the pins may also be of platinum-iridium.

[0044] In some embodiments, the implant 110 integrates with a CSF shunt defined by the conduit 370, which conveys CSF through the patient, where the valve 380 regulates CSF flow. The valve 380 is operatively coupled to the controller 120 such that the controller 120 monitors a valve operating state of the valve 380 that may be between a fully opened condition and a fully closed condition, and generates a control signal to actuate the valve 380 between a relatively open state, a relatively closed state, or an intermediate valve operating state.

[0045] Referring to FIG. 4, a pressure sensor assembly 450 according to another embodiment is shown. In this embodiment, the pressure sensor assembly 450 includes a plurality of conduits 470 extending downward from the ICP sensor housing 243. In the embodiment shown, all of the conduits 470 are extended into brain tissue via a single burr hole. It is contemplated that the conduits 470 may extend into the brain tissue via more than one bun hole, for example, a plurality of burr holes disposed at different locations on the skull. It should be noted that while a single pressure sensor assembly 250 / 350 / 450 is shown, the depicted embodiments may1437408693.1likewise include a plurality of pressure sensor assemblies that may be positioned in various burr holes around the skull of a patient so as to measure ICP at different locations within the cranium. In these embodiments, a single ICP sensor housing 243 may be utilized to limit the amount of hardware extending outside of the cranium of the patient. The ICP sensor housing 243 may contain all electronic components that are shared by the plurality of conduits 470 each of which terminates in a pressure capsule 440 containing a transducer or sensor element that transduces pressure into another parameter that can be measured and recorded by the common electronics in the ICP sensor housing 243. The locations may be selected based on the patient’s diagnostic requirements, for example in cases where regions of different pressures may exist in the brain due to stroke, tumor, brain injury, stenosis, or other complications. In some embodiments, the conduits 470 may include flexible conduits or rigid conduits, for instance, any suitable example of a flexible or rigid conduit, catheter, or tube disclosed herein. A plurality of capsules 440 may be disposed at proximal ends 471 of the conduits 470, respectively. The capsules 440 may take on any suitable example of a capsule disclosed herein. In some embodiments, the conduits 470 may be devoid of capsules 440 at distal ends thereof, for instance, where the conduits 470 embody fluid-filled conduits like the conduits 370 described with reference to FIG. 3.

[0046] With continued reference to FIG. 4, in some embodiments of the pressure sensor assembly 450, the implant 110 integrates with a CSF shunt that includes a valve 460 disposed in a conduit 470, along a CSF flow path. In such embodiments, one or more of the pressure capsules 440 define a first pressure sensor associated with one of the conduits 470 and positioned upstream of the valve 460 with respect to CSF flow through the shunt. With reference to FIG. 3, the pressure sensor 332 in the housing 243 or a pressure sensor downstream of the valve 460 defines a second pressure sensor fluidly coupled to the conduit 370, as the shunt, downstream of the valve 460.1537408693.1

[0047] In such embodiments, the controller 120 (see FIG. 1) may evaluate the determined differential CSF pressure across the valve 460 to assess operation of the shunt. When the differential CSF pressure across the valve 460 exceeds a predetermined differential pressure threshold for a predetermined period of time, the controller 120 determines the presence of an obstruction of the conduit 370 or an under-drainage condition at the valve 460. When the differential CSF pressure across the valve 460 falls below the predetermined differential pressure threshold for the predetermined period of time, the controller 120 determines the presence of an over-drainage condition at the valve 460.

[0048] In further embodiments, the first pressure sensor and the second pressure sensor together define a flow rate sensing configuration. In such embodiments, the controller 120 may determine a flow rate of cerebrospinal fluid through the conduit 470 based on the differential CSF pressure across the valve 460 or another flow restricting portion of the conduit 470. For example, when the valve 460 or a portion of the conduit 470 defines a known flow resistance, the controller 120 may estimate an instantaneous CSF flow rate using the determined differential CSF pressure and one or more stored pressure flow relationships. The controller 120 may further integrate the estimated flow rate over time to determine an amount of CSF drained through the shunt. Such flow rate and volume determinations may be used in assessing shunt performance, monitoring drainage over time, or supporting management of conditions such as normal pressure hydrocephalus, in which controlled CSF drainage may facilitate removal of metabolic waste products from the brain via CSF turnover.

[0049] In such embodiments, the controller 120 may determine a trend in the differential CSF pressure across the valve 460 over time based on a plurality of successive measurement cycles using the first pressure sensor and the second pressure sensor. The controller 120 evaluates whether the determined trend remains above a predetermined differential pressure threshold or increases across the plurality of successive measurement cycles. In response to the determined1637408693.1trend, the controller 120 generates an alert communicated to the external device 140 or a remote gateway, or generates a control signal to the valve 460.

[0050] In such embodiments, the controller 120 may periodically compare ICP measurements obtained from the first pressure sensor and the second pressure sensor when the valve 460 is in a closed state. Based on the comparison, the controller 120 determines an amount of drift between the first pressure sensor and the second pressure sensor. The controller 120 adjusts the first ICP measurement or the second ICP measurement by the determined amount of drift and determines the differential CSF pressure across the valve 460 based on the adjusted first ICP measurement or the adjusted second ICP measurement.

[0051] In some embodiments, after the controller 120 generates a control signal to actuate the valve 460, the controller 120 evaluates changes in ICP measured by the first pressure sensor and the second pressure sensor. In this regard, when the differential CSF pressure across the valve 460 remains elevated or increases after the valve actuation, and a difference betw een a subsequent ICP measurement and a prior ICP measurement at the first pressure sensor is greater than a difference between a subsequent ICP measurement and a prior ICP measurement at the second pressure sensor, the controller 120 determines the presence of an obstruction or blockage upstream of the valve 460. In response, the controller 120 generates a notification communicated to the external device 140 or a remote gateway indicating the detected obstruction or blockage.

[0052] With continued reference to FIG. 4, in some embodiments, the valve 460 operates at a valve operating state positioned between a fully open state and a fully closed state, and the controller 120 associates an expected differential CSF pressure across the valve 460 with the valve operating state. When the controller 120 determines that the differential CSF pressure across the valve 460 deviates from the expected differential CSF pressure by at least a predetermined threshold, the controller 120 maintains the valve 460 at the valve operating state1737408693.1or sets the valve 460 to a predetermined operating state that may be associated with a failsafe mode. In response to the detected deviation, the controller 120 generates a notification communicated to one of the external devices 140 or a remote gateway indicating the deviation between the first pressure sensor and the second pressure sensor.

[0053] In such embodiments, the controller 120 in the ICP sensor housing 243 receives a first ICP measurement from the first pressure sensor and a second ICP measurement from the second pressure sensor and determines a differential CSF pressure across the valve 460 based on a difference between the first ICP measurement and the second ICP measurement. The controller 120 uses the determined differential CSF pressure across the valve 460 to generate at least one of a control signal to the valve 460 or an alert communicated to the external devices 140.

[0054] While, as depicted, the valve 460 is located extracranially, one or more of the pressure sensors described herein may be positioned within the cranium, including within brain tissue. In particular, one or more of the pressure capsules 440 coupled to respective conduits 470 may be deployed through the burr hole such that the pressure sensor contained therein is disposed in the subarachnoid space or within brain parenchyma, directly measuring absolute ICP at a location within the brain while remaining operatively coupled to the extracranial valve 460 and controller 120 via the conduit 470.

[0055] In embodiments, the pressure sensing architecture include parallel structures that separately support ICP sensing and CSF communication within the implant 110. In such embodiments, a first structure, for example a conduit 470 that conveys CSF as part of a shunt and may include the valve 460 defines a CSF flow path, while a second structure defines a pressure communication path that is distinct from the CSF flow path. The first structure forming the pressure communication path may include a conduit 470 that contains a substantially static and incompressible fluid or gel, such as the incompressible liquid or gel 3741837408693.1described with reference to FIG. 3, and that terminates at a corresponding pressure capsule 440 or other pressure sensing interface disposed within the cranium. With this arrangement. CSF flow and pressure sensing are implemented in parallel using separate conduits 470 or lumens, such that ICP is communicated to a pressure sensor without requiring active CSF flow through the pressure communication path. This parallel configuration may reduce flow-induced artifacts, isolate pressure sensing from shunt dynamics, and permit independent optimization of CSF drainage and pressure measurement structures within the implant 110.

[0056] The conduits 470 shown in FIG. 4, which may be fluid conduits or electrical conduits containing multiple wires, are shown in a parallel configuration. How ever, in an alternative embodiment the conduits 470 may be placed in a series formation, where a single conduit would run from the housing 243 and each of the sensor capsules would attach to the single conduit either from a “T” branch or with the conduit 470 running through the capsule.

[0057] Referring to FIG. 1, the implant 110 may be configured to send measured ICP data to the one or more external devices 140 communicatively coupled with the implant 110, for example, a smartphone, a tablet, or a notebook, a wearable device worn by the user (e.g., a smartw atch or other suitable device including a processor, a pressure sensor, and a transceiver (e.g., a BLE transceiver circuit)) for receiving or sending data from / to the implant 110. For example, the wearable device may embody a necklace, a bracelet, a clip, a ring, a pin, a belt buckle (or attachment therefor), or a puck-shaped device (e.g., that may be stored in the user’s pocket), each including a processor, a sensor, and a transceiver, e.g., a wearable device, a smart phone, etc. Several of the external devices 140 may w ork in tandem.

[0058] In an embodiment, the controller 120 of the implant 110 may include circuitry or software to send data to the external devices 140, for example, measured ICP data derived via the sensor assembly 132 or other examples of data, for instance, motion or acceleration data (e.g., measured via an accelerometer in the implant 110), tilt angle data (e.g., measured via a1937408693.1suitable tilt angle sensor), temperature data (e.g., measured via a temperature sensor of the implant 110), or system health data such as implant battery level or self-test information.

[0059] In some embodiments, the controller 120 may include circuitry or software to send the data to the external devices 140 based on a timed sequence, e.g., every day, every hour, or every week. In some embodiments, the timed sequence may be set such that the data is transmitted to the external devices 140 at elongated, reoccurring time intervals (e.g., once per week instead of once per hour) to conserve battery life, e.g., in such embodiments where the pow er supply 134 is a rechargeable batten'.

[0060] For instance, referring to FIG. 5, the controller 120 may include logic to execute a method of transmitting the ICP to one of the external devices 140 based on a predetermined TCP threshold value. For instance, at step 502, one or more sensors (e.g., any example of an implant 110 disclosed herein) may measure ICP and transmit the ICP to the controller 120. At step 504, the controller 120 may transmit the measured ICP (step 502) to the external devices 140 (e.g., in real time or at predetermined intervals). The external device 140 may compare the measured ICP relative to a predetermined threshold value (e.g., 10 mmHg gauge). At step 506, if the measured ICP exceeds the predetermined ICP threshold value, then a notification may be provided to the user that ICP is above the preset threshold. The external device 140 may further instruct the user to take action to respond to the high ICP event; example actions may include contacting the physician’s office, changing posture to recumbent or to an upright position, taking medication, or going to a medical facility immediately. Transmitting data to the external device 140 only when the ICP threshold is exceeded may be more power efficient than transmitting on a timed basis, possibly allowing for a smaller device due to smaller battery capacity required. In embodiments, the implant 110 wirelessly transmits the measured absolute ICP upon determining that the measured absolute ICP satisfies a predetermined condition, such2037408693.1as exceeding the predetermined threshold value, independent of the predetermined recurring time interval.

[0061] Conversely, if the measured ICP is equal to or below the predetermined threshold value, then the external device 140 may record the measured ICP in a local memory the Cloud Database, or a remote server over a network (step 508). For instance, the external device 140 may include logic to wake up the communications device 165 to transmit data at a pre-selected time (e.g., every Friday at 8 am) based on the recurring time interval and transmit accumulated ICP data (time stamped) at the pre-selected time. As such, in response to comparing the determined gauge ICP to the predetermined threshold value, the external device 140 selectively performs one or more actions based on an outcome of the comparison, including recording the determined gauge ICP when the gauge ICP does not exceed the predetermined threshold value, or generating and transmitting an alert when the gauge ICP exceeds the predetermined threshold value.

[0062] In some embodiments, the sensor assembly 132 or pressure sensor assembly 250 / 350 / 450 may transmit ICP data to the controller 120, and the controller 120 may include logic to detect other patient medical conditions, for example, to determine brain compliance (e.g., the brain’s pres sure- volume response), idiopathic intracranial hypertension (i.e., pseudotumor), subarachnoid hemorrhage (e g., based on an increased ICP), etc. For example, the controller 120 may receive the measured ICP (e.g., an ICP waveform defining a changing amplitude value over time) and determine a brain compliance value. Any of the external devices 140 or databases mentioned may include software to analyze the ratio of the second echo pulse to the first arterial pressure pulse in each cycle of the ICP waveform, to estimate relative or absolute brain compliance using methods known in the art. For example, a high amplitude ratio between the first and second ICP waveform pulses may indicate high brain compliance, and a low ratio may indicate low compliance. Longitudinal brain compliance2137408693.1measurements over time can indicate trends in a patient’s brain compliance, which may be helpful in assessing neural health of the patient. Such software may include learning or artificial intelligence algorithms.

[0063] In further embodiments, pressure waveform characteristics derived from measured ICP may be used to assess CSF pathway characteristics and to identify obstruction conditions. In such embodiments, the controller 120 or one of the external devices 140 may analyze temporal features of an ICP waveform, including waveform presence, amplitude, morphology, pulsatility, or changes therein over time, in response to a known valve operating state or a known change in the valve operating state. For example, when the valve 460 is actuated from a relatively closed state toward a more open state, an expected change in the ICP waveform may include a reduction in mean pressure, a change in pulsatile amplitude, or a redistribution of waveform components over one or more cardiac cycles. If the expected waveform response is not observed, or if the waveform remains substantially unchanged following valve actuation, the controller 120 may determine the presence of an obstruction or impaired CSF flow. Conversely, the appearance, enhancement, or normalization of pulsatile waveform features following valve actuation may indicate an unobstructed CSF pathway. Such waveform-based assessments may be combined with absolute pressure measurements, differential pressure measurements, or valve state information, enhancing reliability of obstruction detection by the implant 110.

[0064] In some embodiments the controller 120 or one or more of the external devices 140 may perform automated waveform-based assessment or may present waveform data for clinician review to aid in determining the presence of an obstruction or impaired CSF flow. For example, the controller 120 or one or more of the external devices 140 may automatically analyze ICP waveform data using one or more criteria as described and generate an indication or alert when waveform characteristics are consistent with an obstruction condition. In other2237408693.1embodiments, the system transmits raw or processed ICP waveform data to an external device 140 or a remote database such as the Cloud Database, allowing a physician or other clinician to visually inspect waveform characteristics and make a clinical determination.

[0065] In further embodiments, waveform data may be acquired periodically, such as each time the implant 110 wakes from a low-power state to perform an ICP measurement. The controller 120 or one or more of the external devices 140 may store, transmit, or aggregate individual waveform measurements to generate an average waveform representation over a defined time window, such as a time window selected to span multiple respiratory' cycles. In embodiments, the defined time window spans a duration sufficient to capture multiple respiratory' cycles, for example and without limitation on the order of approximately eighteen seconds, during w hich most patients complete several breaths, reducing respiration-induced variability and enabling computation of a representative average ICP waveform with greater accuracy to a true value. In other embodiments, w aveform measurements may be aggregated over longer intervals, such as over successive cardiac cycles within a fifteen-minute interval, supporting longer-term trend analysis. The external device 140, the Remote Gateway, or a remote interface may present the averaged waveform data in a chart or graphical format, while also permitting access to individual waveform recordings corresponding to specific time stamps. This approach may reduce data volume while preserving clinically relevant waveform information and enabling both trend analysis and review' of discrete waveform events.

[0066] The external device 140, the Remote Gateway, or a remote interface may present the averaged waveform data in a chart or graphical format, while also permitting access to individual waveform recordings corresponding to specific time stamps. This approach may reduce data volume while preserving clinically relevant waveform information and enabling both trend analysis and review of discrete waveform events.2337408693.1

[0067] In some embodiments, the external device 140 determines that a trend of the gauge ICP lasts longer than a predetermined period of time when the trend persists across multiple successive measurement inter als, and generates an alert or notification when the trend exceeds the predetermined period of time. In some embodiments, determining the trend includes identifying an increase or a decrease across the plurality of gauge ICP values over time based on the comparison of the gauge ICP values with each other. In further embodiments, the external device 140 compares the determined trend of the plurality of gauge ICP values to a predetermined threshold and generates an alert or notification when the determined trend meets the predetermined threshold. In this regard, the predetermined threshold may include at least one of a magnitude threshold, a duration threshold, or a rate-of-change threshold associated w ith the plurality7of gauge ICP values.

[0068] For example, a brain compliance value corresponding with low- brain compliance may indicate that the patient is dehydrated, causing the brain tissue to be more rigid, causing a stronger echo pulse in the ICP waveform, w ereas a brain compliance value corresponding with high brain compliance may indicate that the brain tissue is softer and may manifest a weaker echo pulse in the ICP waveform. In this manner, the measured ICP may be particularly advantageous to determine other potential medical conditions or symptoms, including, without limitation, those associated with hydrocephalus.

[0069] In some embodiments, the external device 140 includes an ambient pressure sensor referred to herein as ‘’Pamb Sensor” that measures an ambient atmospheric pressure of an environment surrounding the patient. Ambient pressure data generated by the Pamb Sensor may be used by the external device 140 to determine the gauge ICP by compensating an absolute ICP measurement received from the implant 110 for ambient atmospheric pressure. The ambient pressure data may be time-stamped, stored in association with corresponding ICP2437408693.1measurements, and used to support trend analysis, alert generation, or post-processing, in a manner similar to other environmental or contextual data described herein.

[0070] For all measured and logged data, including ICP and brain compliance, the sy stem of FIG. 1 may be used to build a large “Cloud Database” containing data from all patients who use the device. The Cloud Database may anony mize this data and calculate various averages and trends, providing each physician user w ith access to general data trends for different patent demographics through the “Remote Gateway” shown in FIG. 1. For example, an authorized physician may query' the Cloud Database via the Remote Gateway to determine the average ICP and waveform pulse ratio for all patients in the database who are male and between the ages of 60 and 75. This quety capability may be useful for researchers as w ell as for physicians who wish to know how a particular patient’ s metrics compare with the rest of their demographic population.

[0071] Turning to FIG. 6, another example sy stem 200 is provided. The system 200 may include similar features as system 100, for example, an ICP sensor that is an implant 210, and may include one or more external devices 242 communicatively coupled therewith via a communications network 260. The implant 210 and external devices 242 may include similar features to the implant 110 and external devices 140 discussed above. A description of similar features has been omitted for brevity7.

[0072] In the embodiment shown, the external device(s) 242 may receive the measured ICP (absolute ICP) from the implant 210 to determine a gauge ICP (based on atmospheric pressure measured by an ambient pressure sensor in the external device 242). In some embodiments, the external devices 242 may receive the measured ICP to determine other medical conditions. For example, an external device 242 may embody a remote server 246 including a processor 247 and a storage device 249, for example, any suitable example of a processor and storage device described herein. The remote server 246 may include logic to execute a set of instructions (e.g..2537408693.1residing in the storage device 249) to determine a gauge ICP based on the absolute, measured ICP (from the implant 110) and atmospheric pressure (detected via the external device 242). In other embodiments, the remote server 246 may include logic to determine brain compliance or any other example medical condition or symptom thereof disclosed herein based on ICP and other data transmitted thereto (e.g., transmitted from the implant 210 and other implanted sensors). In some embodiments, the ICP data may be used to train a machine-learning model configured to predict a diagnosable medical event, for example, a severe headache or other symptoms attributed to an increase in ICP within the cranium. In some embodiments, the external device 242 may include an input device 245 (e.g., a physical button or touch screen button, an audio input device (e.g., a microphone, a voice response system, etc.)) that may be select ed / operated by the user (e.g., depressed or touched) to denote a symptom, e.g., a headache, nausea, or light-headedness associated with hydrocephalus or another potential medical condition. The corresponding signal (transmitted via the input device) may be sent to a host device (e.g., the implanted patient’s physician’s smartphone) for further investigation and diagnosis.

[0073] With continued reference to FIG. 6, in some embodiments, the external device 242 may include a battery charging function for charging the implant power supply (e.g., 134 in FIG.1). The external device 242 may be configured to recharge the implant power supply via any suitable example of wired or wireless charging (e g., inductive, radiofrequency energy (e.g., electromagnetic waves)). In some embodiments, the implant 210 may include a speaker 213 that emits an audible warning (e.g., a beep) if, for example, the measured ICP exceeds a predetermined threshold value. Alternatively, the external device 242 may include a speaker that emits an audible warning if the measured ICP exceeds a predetermined threshold. In some embodiments, an implanted patient may desire to add additional or secondary external devices 244 to the system 200, for example, to communicatively couple a smartphone with another2637408693.1device (e g., for a spouse, relative, friend, caretaker, teacher, nurse, or co-worker) to the implant 210. In some embodiments, the external device 242 may emit an audible alert, which may be different from other external device 242 audible alerts, indicating that the external device 242 has not contacted the implant 110 for an unacceptably long period of time, for example 30 minutes. The audible alert may be intended to motivate the user to bring the device 242 to within BLE range of the implant 110, for example within 10 feet.

[0074] In a further embodiment shown in FIG. 7, an ICP sensor 610 may include a housing 641 of a defined shape, such as rectangular, triangular, cuboid, circular, oval or the like or a combination of the foregoing. The housing 641 may be of any material that is biocompatible, including, without limitation, ceramics such as glass, sapphire, fused silica, alumina, etc., or metals such as titanium, or stainless steel. In the case of conductive housings, the housing 641 may be sufficiently thin to allow RF communication or may include a non-metal window over the communication antenna, or the antenna may be mounted on the outside of the metal enclosure. The housing 641 may include microelectronics 644, which may include one or more pressure sensors 647. The pressure sensor 647 may include a capacitive pressure sensor. The capacitive pressure sensor may include a diaphragm. The diaphragm may be constructed from materials such as plastic, glass, silicon or ceramic, which are biocompatible. The stiffness and strength of the material can be chosen to provide a range of sensitivities and operating pressures for the sensor depending on its use. The materials for the capacitor plate or plates may have a low coefficient of thermal expansion, so as to have a low sensitivity to temperature change. The sensor may also have low hysteresis to ensure accuracy and repeatability of measurements.

[0075] The sensor may be constructed directly on a silicon chip. This allows very small sensing elements to be constructed and combined with the electronics for signal conditioning and reporting.2737408693.1

[0076] In the sensor, the change in capacitance may be measured by connecting the sensor in a frequency-dependent circuit such as an oscillator or an LC tank circuit. In both cases, the resonant frequency of the circuit will change as the capacitance changes with pressure.

[0077] An oscillator requires some extra electronic components and a power supply. A resonant LC circuit can be used as a passive sensor, without its own source of power. This system, however, may be powered by an internal power source, e.g. a battery', or it may obtain power from one of the external devices 242.

[0078] In the case of passive sensors an external antenna may be used to provide a signal to stimulate the tuned circuit and so measure the change in resonance frequency. The external antenna may be of any appropriate configuration. In some embodiments, the external antenna may be incorporated into a hat or similar such device that w ill sit on the patient’s head to make the appropriate reading.

[0079] The ICP sensor may be fully implantable within another medical device, such as a shunt, or w'ithin the body directly. ’lire ICP sensor may be implanted directly virtually anywhere within the cranium to measure ICP. For example, in cases of traumatic brain injury' where patients undergo craniotomy for hematoma drainage, the ICP sensor may be placed below' the dura for continuous monitoring of the patient's ICP.

[0080] There are several interfaces for the integration of the ICP sensor with the hydrocephalus shunts. The ICP sensor can be placed within the proximal metal or rigid plastic connector piece of the shunt that interfaces with one of the catheters that goes into a patient's ventricle. The ICP sensor may also include a wireless data transceiver, power receiver, a rechargeable or non rechargeable battery, and an application specific integrated circuit (ASIC) chip that manages power and data. The ICP sensor may also contain external passive components like resistors and capacitors, and a memory chip such as an electronically erasable programmable read-only memory (EEPROM). The electronics may be programmable to accommodate rate of sampling.2837408693.1times when to sample, such as only during the day, or 24 hours a day. The device may be programmable to change its behavior depending on multiple factors, including rate of change of measurement, time since last measurement, time since last stored measurement, time of day and battery life remaining, and patient / clinician input.

[0081] The ICP sensor may uplink data from its data bank to a data repository on a server, through communicating through a personal electronic device, or an application on smartphones. The data may be time-stamped. The records for each patient may be stored cumulatively and may be updated routinely and accessed by clinician without seeing the patient. The ICP sensor may be powered by other methods, and any or some combination of the following: photovoltaic cells, radiofrequency (near field inductive coupling, mid-field, or far-field) using an on-chip or off-chip antenna, a battery, electrostatic induction by either keeping fixed voltage or fixed charge, capacitive charge transfer for energy storing, optical power transfer, an ultrasonic energy harvester such as transduction by micro-electromechanical system (MEMS) cantilevers or PIT, energy' harvested from other vibrations or temperatures generated by the body, energy from ambient temperature gradients or infrared radiation, electrochemical or fuel cell based energy harvesting.

[0082] With reference to FIG. 6, in the case of inductive coupling, power may be provided by a coil outside the enclosure. In addition, the energy harvesting could also be achieved by employing metamaterials. The coil of the external device 242 that couples with the coil of the implant 110 may reside on something worn, like a hat, a mask, for sleeping or as an attachment to glasses, or may be held or fixed to recharge for a period of time. The coil may be integrated into a pillow or device which charges the implant 110 when the patient is laying on a bed. In these embodiments, other forms of antenna may be used in place of a '‘coif’ form.

[0083] Further, the ICP sensor may utilize machine learning or artificial intelligence to make predictions for patients in which the implant 110 is implanted. In these embodiments, the ICP2937408693.1sensor may be wirelessly coupled with a computer network or the ICP sensor may be wirelessly coupled with one of the external devices 242 whereby the ICP sensor wirelessly communicates with the external device 242. In either embodiment, a computing system may be wirelessly in communication with the implant 110 or the external device 242, as applicable. The implant 110 may communicate directly or indirectly through the external device 242 to the computing system. The implant 110 may communicate its pressure readings over a defined period of time. Once this information is communicated, the computing system may utilize machine learning or artificial intelligence and make health outcome determinations based on the readings received. The computing system may also be operatively coupled with other sensors and all of this information may be fed into the computing system. This additional information along with the ICP sensor information may be utilized by the computing system to make predictions regarding the health or health outcomes of the applicable patient utilizing machine learning or artificial intelligence, including large learning models using data provided by all similar devices in the field.

[0084] For example, the ICP sensor may send readings on ICP readings taken over specific time periods. These time periods may correlate to certain life events or situations, e.g., headache, exercise, sleep, eating, etc. Separate sensors or sensing devices (such as aw-earable or the like) may be utilized to provide this additional information. The computing system may then take the data from the various sources, including, the ICP sensor, to determine or create correlations between a specific life event and the ICP of the patient. One example could provide that during eating ICP increases. This correlation may then alert a patient that while his or her ICP reading is higher than normal, it is expected because the patient is eating. Creating these correlations may prevent false negative events from arising. This may mean that the patient does not need to seek medical care despite an elevated ICP reading.3037408693.1

[0085] Further, the computing system may provide notifications to the patient and / or to a clinician based upon readings from the ICP sensor alone or based on additional information from other sensors or devices. In one example, the computing system may provide a notification of an anticipated event based on artificial intelligence or machine learning. The computing system may obtain the data from the ICP sensor along with data from other sources and make a determination of a potential health incident in advance of the health incident actually occurring. This may help a patient get treatment in a timely manner to mitigate against the health incident and prevent permanent negative implications from such health incident.

[0086] The computing system may include any kind of computer, tablet, smartphone, wearable or the like or a combination of the foregoing. The computing system may be configured to communicate wirelessly with the ICP sensor and any other sensor or device. These other sensors may include an accelerometer, a tilt sensor, motion sensor, temperature sensor, chemical sensor, electrical sensor (to measure brain signals), or a combination of any of the prior-mentioned sensors. The devices may include a smartwatch, fitness tracker, mobile ECG, blood pressure sensor, or any combination of the foregoing. These devices may communicate wirelessly with the computing system providing data in a continuous manner or over a predefined period of time. Once received, the computing system may use artificial intelligence or machine learning to analyze the data. This analysis can provide prognostication of health incidents, recommendation regarding treatment, actions a patient can take to mitigate against a negative health incident or the like. The computing system may send a notification directly to the patient, such as through a smartwatch, tablet, or smart phone. In addition, the computing system may send a notification to a clinician to alert him or her regarding a potential health incident for one of his or her patients.

[0087] In an embodiment, ICP sensor may be part of the system 100 of devices as shown in FIG. 1. In this embodiment the implant 110 may be battery operated, optionally by the power3137408693.1supply 134. The implant 110 may contain two antennas: one for communications and the other for wireless charging. The implant 110 may be powered on wirelessly by an RF signal coming from an external battery7charger 170 when the external battery7charger 170 is switched on and held near the implant 110. On wakeup, the controller 120 of the implant 110 may boot up and initialize all onboard peripheral devices and circuitry7. The implant 110 may then take readings from its onboard sensor components, including an ICP sensor component such as one of the pressure sensor assemblies 250, 350, 450.

[0088] The implant 110 may take a temperature reading and use the temperature reading as a basis for calibrating at least one of the other on-board sensor components, based on calibration coefficients, formulas, or lookup tables resident in nonvolatile memory7of the implant 110. In some embodiments, prior to implantation, the ICP sensor component may be exposed to a liquid environment at or near body temperature, such as water or another liquid maintained at approximately physiological temperature, to stabilize thermal conditions and facilitate calibration of the pressure sensor component. Calibration may be performed before, during, or after such exposure by acquiring pressure measurements in the liquid environment and storing corresponding calibration data in the implant 110 or an associated external device. Shortly before, during, or shortly after taking readings the implant 110 may advertise on BLE or a similar wireless communications protocol.

[0089] In some embodiments, the implant 110 further includes a temperature sensor positioned proximate to the ICP sensor component. Locating the temperature sensor near the ICP sensor component may improve accuracy of temperature compensation by ensuring that the measured temperature closely corresponds to the local thermal environment of the pressure sensing elements. The controller 120 may use the measured temperature to compensate for temperature-dependent drift or sensitivity variations of the ICP sensor component by applying stored calibration coefficients, mathematical correction functions, or lookup tables resident in3237408693.1nonvolatile memory. In embodiments where the pressure sensor component is disposed within or proximate to brain tissue, positioning the temperature sensor near the brain may further improve calibration accuracy by reducing thermal gradients between the pressure sensor component and surrounding tissue.

[0090] In some embodiments, the implant 110 is configured to calibrate or correct ICP measurements independent of patient posture or orientation. For example, the implant 110 may include at least one accelerometer or inertial sensor that detects patient position, orientation, or movement at the head or chest of the patient. The controller 120 may use information from the at least one accelerometer or inertial sensor to determine whether the patient is upright, supine, or in another posture, and to adjust calibration parameters or compensation factors accordingly. This posture-aware calibration may reduce measurement error associated with hydrostatic pressure differences or gravitational effects that vary with patient position.

[0091] In such embodiments, variation in a position of the head of the patient relative to gravity may introduce pressure offsets along a proximal catheter portion, such as at the proximal end 371 of the conduit 370, for example due to hydrostatic effects associated with elevation differences between the sensing location and other portions of the CSF pathway. The controller 120 or one of the external devices 140 may determine an appropriate calibration or compensation for such position-dependent variation using orientation information derived from the accelerometer or inertial sensor. For example, the controller 120 or one of the external devices 140 may determine a gravity vector and use the gravity vector to estimate a relative orientation of the head of the patient, and may apply a corresponding pressure offset or correction factor to the measured ICP. In some embodiments, the implant 110 includes a first accelerometer disposed within or near the cranium and a second accelerometer disposed at another location on the patient, such as at the chest or abdomen, allowing the controller 120 to determine a relative position of the head with respect to a torso of the patient. The same or3337408693.1similar calibration or compensation processes may be applied using such relative position information to determine a posture-dependent pressure offset corresponding to the elevation of the head relative to the torso and to apply the determined offset to the measured ICP to improve accuracy across different patient orientations.

[0092] In further embodiments, calibration or verification of ICP measurements by the implant 110 may be performed using defined patient positions, optionally under clinical supervision. For example, a clinician or medical practitioner may instruct the patient to assume one or more predetermined postures, such as sitting upright, lying supine, lying on a left side, or lying on a right side, and an ICP measurement may be acquired in each posture. The controller 120 or one of the external devices 140 may record the measured absolute ICP in association with posture information determined from the accelerometers at the time of each measurement and determine a corresponding posture-dependent offset. Such offsets may be stored and subsequently applied to ICP measurements based on the detected posture of the patient during operation of the implant 110. Providing clinician-guided posture sequences for calibration may accommodate multiple orientation vectors and improve repeatability and accuracy of posture-compensated ICP measurements. With this construction, once posture-dependent offsets have been established across a sufficient set of patient orientations, the implant 110 may subsequently acquire reliable ICP measurements during unsupervised operation by determining a current posture of the patient, including absolute or relative orientations of the head and torso, and applying the corresponding stored offset to the measured ICP.

[0093] In further embodiments, the implant 110 may reduce or eliminate posture-dependent pressure variation associated with a fluid column by controlling operation of a valve disposed along a CSF pathway, such as one of the valves 380, 460. For example, the controller 120 may temporarily close the valve to isolate a pressure sensing interface from CSF flow, reducing or eliminating pressure variations attributable to the weight of a fluid column extending along the3437408693.1catheter. With the valve closed, the pressure measured by the ICP sensor component may more closely reflect true ICP at the sensing location, independent of patient posture.

[0094] In some embodiments, such ICP measurements used for calibration, compensation, or diagnostic evaluation are obtained while the valve is in a closed state. By acquiring pressure measurements with the valve closed, the controller 120 may reduce the influence of dynamic CSF flow, hydrostatic effects, or posture-dependent variables, improving repeatability7and reliability' of the measured ICP. After calibration or measurement is completed, the controller 120 may return the valve to a prior operating state or to a state determined based on therapeutic or diagnostic operation procedures.

[0095] In embodiments, ambient pressure information used for calibration or compensation of ICP measurements may be derived from pressure measurements obtained at a location of the patient outside the cranium. For example, as shown in FIG. 8, the system 100 may include a sensor module 800 disposed at an abdominal location 802 of the patient and that supports acquisition of physiological and environmental parameter measurements at the abdominal location 802. The sensor module 800 may be an implantable device that includes similar features and functions in a similar manner as the implant 110 in facilitating routine operation, including, by way of example and without limitation, an internal power supply 804, a wireless communication device 810, acontroller 812, amemory 814, and coupling means for interaction with a wireless battery charger 820, all disposed within a housing 822.

[0096] With continued reference to FIG. 8, the sensor module 800 may include a pressure sensor 824 disposed in or tethered to the housing 822 at the abdominal location 802 of the patient and configured to measure an abdominal or body cavity pressure that is substantially independent of ICP. The controller 120, the controller 812, or the one or more external devices 140 may determine a pressure difference between the abdominal pressure measurement and the measured ICP, and use the determined pressure difference as an estimate of ambient or3537408693.1reference pressure affecting the patient. In some embodiments, the pressure sensor 804 in the sensor module 800 and the pressure sensor 132a in the implant 110 are used together to compensate for environmental pressure variations or altitude related effects. In further embodiments, the implant 110 or the one or more external devices 140 may include a location determination component, such as a GPS receiver, that determines geographic location and altitude of the patient. Such location and altitude information may be used alone or in combination with external data sources, such as weather services, to estimate ambient atmospheric pressure applicable to the patient. The estimated ambient pressure may be applied by the controller 120 as a calibration reference or compensation input for determining absolute or gauge ICP.

[0097] The sensor module 800 may additionally or alternatively include an accelerometer 830 that generates motion or orientation data associated with movement, posture, or activity level of the patient at the abdominal location 802, and a temperature sensor 832 configured to measure a local tissue or body temperature of the patient at the abdominal location 802. Data generated by the accelerometer 810 or the temperature sensor 832 may be transmitted to the controller 120 or the one or more external devices 140 and used in combination with sensor data obtained from the sensor assembly 132 at the cranium. In some embodiments, such data may be correlated with ICP measurements to support calibration, compensation, artifact rejection, or contextual interpretation of ICP values, including accounting for patient posture, motion, or temperature-related effects when determining absolute or gauge ICP820

[0098] With reference to FIG. 6, the external device 242, which may be a wearable that the patient always keeps within range (typically 3 meters for implanted BLE), may scan for the implant 110 and may establish contact with the implant 110. The external device 242 may obtain and validate an identification number from the implant 110. The implant 110 may preprocess its sensor readings, for example by averaging over a predetermined time window, or3637408693.1rejecting spurious samples outside of a preset range, and communicate the pre-processed data to the external device 242. Alternatively, the implant 110 may communicate only raw samples to the external device 242. The external device 242 may process the uploaded data from the implant 110, including averaging, filtering, bounding, or otherwise calibrating the received data. In some embodiments, the external device 242 compares a plurality of determined gauge ICP values with each other, including comparing successive gauge ICP values obtained over time. The external device 242 may use temperature or tilt sensor or other data from the implant 110 to process the ICP data according to algorithms or lookup tables. The external device 242 may subtract ambient pressure, measured from a pressure sensor built into the external device 242 or another ambient pressure sensor, from the ICP absolute pressure obtained from the implant 110 to compute ICP gauge pressure. The data from the implant 110 may also include implant system health data, such as battery state of charge, alerts or error codes, or other health data from the implant 110. The external device 242 may timestamp the data. The external device 242 may stamp the data with location based on GPS positioning or other inputs to the external device 242. The external device 242 may stamp the data with user inputs from controls on the external device 242 such as pushbuttons, photos, or voice commands, to indicate a condition of the patient such as headache, lightheadedness, nausea, exercise, a certain location, sleep, wakeup, etc. Instead of or in addition to an averaged ICP, the implant 110 may communicate an ICP waveform at a given sample rate.

[0099] In addition to receiving data from the implant 110, during the communication exchange, the external device 242 may communicate new settings to the implant 110 to be stored in the implant 110 at nonvolatile memory used as the storage device 124. Settings may include data rejection thresholds, number of samples to average, time window for averaging, sleep interval time, calibration formula or lookup table coefficients, BLE parameters such as advertising3737408693.1frequency and duration, and possible other settings. “Settings” may also include a firmware or software upgrade.

[0100] After the external device 242 has received a data reading from and updated settings to the implant 110, the external device 242 may wirelessly acknowledge receipt of the data to the implant 110. There may be a data integrity check, e g., a checksum between the external device 242 and implant 110, with data transmission repeated if an error is detected. The acknowledgement by the external device 242 may cause the implant 110 to enter a low power sleep state. In this state the implant 110 at the processor 122 may start an internal timer and power down all unnecessary' onboard circuits until the timer times out. The timer’s sleep interval may be a preset value stored in setting of the implant 110. The interval may be programmed to change depending on the most recent readings, for example a shorter sleep interval if the ICP is at a high value. At the end of the sleep interval the implant 110 may reawaken and repeat its measurement cycle. In some embodiments, receipt of the wireless acknowledgement causes the implant 110 to power down the sensor assembly 132 or the communications device 165 and to maintain the powered-down state while a timer defining or set to a predetermined recurring interval remains active. Upon expiration of the timer, the implant 110 repowers one or more previously powered-down circuits, including the sensor assembly 132 or the communications device 165, reawakening the onboard circuits to repeat a measurement cycle, including measuring a subsequent absolute ICP and w irelessly transmitting the measured subsequent absolute ICP to the external device 242.

[0101] In some embodiments, the implant 110 detects one or more conditions, including failure to receive an acknowledgement of a transmitted absolute ICP measurement, accumulation of a predefined amount of stored ICP data at the implant 110, or completion of a transmission or logging event. In such embodiments, in response to detecting the operating condition, the implant 110 modifies at least one operational parameter, including increasing a3837408693.1number of absolute ICP transmission attempts, adjusting the predetermined recurring interval, or initiating transmission of accumulated ICP data.

[0102] In some embodiments, the implant 110 detects one or more external context conditions, including detecting a change in ambient pressure of an environment of the patient or detecting coupling of the implant 110 with an external battery charger 170. The implant 110 detects the change in ambient pressure using onboard sensing or based on ambient pressure information received from the external device 242. The implant 110 detects coupling with the external battery charger 170 based on receipt of charging power, inductive coupling, or a charging-state signal.

[0103] In some embodiments, the external device 242 selectively shortens or lengthens the predetermined recurring interval based on an evaluation of the gauge ICP. The external device 242 shortens the predetermined recurring interval when the determined gauge ICP exceeds a predetermined threshold or when a determined trend of the gauge ICP indicates a persistent increase over time, and the external device 242 lengthens the predetermined recurring interval when the determined gauge ICP is equal to or below the predetermined threshold or when the determined trend indicates a stable or decreasing gauge ICP over time. In further embodiments, after shortening or lengthening the predetermined recurring interval, the external device 242 generates an updated predetermined recurring interval and stores the updated predetermined recurring interval for subsequent communication to the implant 110. In such embodiments, the implant 110 measures and wirelessly transmits the absolute ICP according to the updated predetermined recurring interval received from the external device 242.

[0104] In some embodiments, in response to detecting the external context condition, the implant 110 modifies at least one operational parameter. In this regard, the implant 110 modifies the operational parameter by adjusting the predetermined recurring interval, adjusting3937408693.1a predetermined threshold used to evaluate the absolute ICP, or adjusting a transmission condition for wirelessly transmitting the measured absolute ICP.

[0105] The external device 242 may have a display providing the user with data readings and system health data as described above. The external device 242 may include user controls such as buttons, voice commands, or touchscreen to provide settings changes from the user to the external device 242. The external device 242 may communicate readings to the Cloud Database through an internet gateway. The gateway could be built into the external device 242 or could be an external device 242 such as a Wi-Fi router or a cellular phone or tablet. The external device 242 may communicate to the gateway via BLE or another standard. Upload of data and download of settings to / from the Cloud Database may take place at a predetermined time interval, by user command to the external device 242, by initiation from the Cloud Database, or by an event such as an ICP reading above a certain value. The Cloud Database may have cybersecurity features and may associate the uploaded data with the appropriate patient based on an identification code sent with each data packet. The Cloud Database may carry out post-processing features, similar to those described above. The external device 242 may upload raw data to the Cloud Database for full post-processing. The Cloud Database may store calibration data and formulas needed for post-processing. The Cloud Database may use machine learning, data sorting and prioritization, artificial intelligence, trend analysis, alert generation (e.g., through a dashboard or via phone or email), error detection, event monitoring, anonymization of medical data, or any data processing or management technique known to those in the art.

[0106] The Cloud Database may be accessible by one or more remote gateways. A remote gateway may be any internet-capable device, for example for use by an authorized medical professional. The Cloud Database may control access to the ICP sensor data so that only authorized medical professionals may access each patient’s data. The remote gateway may4037408693.1allow an authorized user to change patient settings for the ICP sensor, by communicating the new settings to the Cloud Database for download to the external device 242 (directly or through another gateway on the patient side). The next time that patient’s external device 242 contacts the implant 110, it will command the implant 110 to update its settings in nonvolatile memory. In this manner, the remote gateway may adjust one or more operational parameters of the implant 110 based on user input, including at least one of the predetermined recurring interval, a predetermined threshold compared to the absolute ICP, a battery' charge level at which one or more onboard circuits are powered down, or a transmission condition for wirelessly transmitting the absolute ICP to the external device 242. In embodiments, the transmission condition may be at least one of a comparison of the measured absolute ICP to a predetermined threshold, expiration of the predetermined recurring interval, failure to receive an acknowledgement of a prior transmission, accumulation of a predefined amount of stored ICP data at the implant 110, detection of coupling of the implant 110 with an external charging device, or detection of a change in ambient pressure of an environment of the patient. The remote gateway wirelessly' transmits the adjusted operational parameter to the external device 242, optionally7through a remote network, and the external device 242 automatically forwards the adjusted operational parameter to the implant 110 as a pass-through device, without modifying the adjusted operational parameter.

[0107] In some embodiments, the external device 242 forwards the adjusted operational parameter to the implant 110 during a current duty cycle, and the implant 110 operates using the adjusted operational parameter during a subsequent duty cycle following the current duty cycle. By deferring application of the adjusted operational parameter until the subsequent duty cycle, the implant 110 avoids interrupting an ongoing measurement, transmission, or powermanagement operation during the current duty cycle, and reduces a risk of improper operation or damage to the implant 110.4137408693.1

[0108] The ICP sensor’s controller 120 may monitor battery state of charge of the power supply 134 each time it wakes up, by voltage measurement, “coulomb counting’" current integration, or other methods known in the art. In some embodiments, when the monitored battery charge state falls below a predetermined level, the implant 110 powers down the sensor assembly 132 or the communications device 165 during the predetermined recurring inter al to conserve power.

[0109] If the battery is at a predetermined low level requiring a recharge, the ICP sensor may alert the external device 242, which in turn may instruct the patient to recharge the battery. If the battery’ s state of charge reaches a second, lower threshold at which the ICP sensor is at risk of random behavior, the controller may deliberately power off the ICP sensor. The sensor may then be powered on again by application of the external battery charger 170 to the patient’s head, using a power management chipset such as the LTC4124 by Analog Devices. In some embodiments, when the battery charge state of the pow er supply 134 is restored above the predetermined level, the implant 110 repowers the sensor assembly 132 or the communications device 165 and resumes measuring and wirelessly transmitting the absolute ICP. For example, when the implant 110 detects coupling with the external battery charger 170, the implant 110 shortens the predetermined recurring interval, lowers the predetermined threshold for comparing and transmitting absolute ICP, or increases a frequency of wirelessly transmitting the absolute ICP while charging power is available. In another example, when the implant 110 detects a change in ambient pressure of the environment of the patient, the implant 110 adjusts the predetermined threshold used to evaluate the ICP to compensate for the changed environmental condition.

[0110] If the patient is instructed to recharge their battery, they may hold the external battery charger 170 against the head, near the implant 110 for a period of several minutes to several hours. The system may provide a hat or harness to hold the external battery charger 1704237408693.1in place. The external battery' charger 170 or the external device 242 may provide a signal to the user that charging is taking place, or that charging is complete. The external battery charger 170 may have physical features to allow it to align properly with the implant 110, which typically creates a palpable bump under the skin. The external battery charger 170 may take the form of a small rigid box that holds the electronics and battery' of the external battery charger 170, with a wire cable extending from the box and terminating in a thin charging antenna, e.g. a patch antenna, which is placed on the head at the location of the implant 110, and which may have mechanical features to ease placement. In this embodiment, the patient may place the electronics box in a pocket or clip it to clothing and have a simple hat or harness to hold the antenna in place allowing for hands-free operation.

[0111] In an embodiment, a cellular device such as a phone or tablet, with Bluetooth and ambient pressure measurement, may serve as the external device 242, or may sen e as a gateway to the internet that relays data between an external device 242 and an internet node. Further, the external device 242 may log the data from the implant 110 directly storing this information. The information may be provided to the user in the form of notices, alerts, cautions or warnings or may provide this information through the remote gateway to a clinician. In some embodiments, the external device 242 permits patient input of subjective symptom information, such as indications of headache, lightheadedness, nausea, or other conditions, for example via a user interface or input control. Such symptom information may be time associated with contemporaneous ICP measurements and stored or transmitted together with the ICP data to facilitate correlation of patient reported symptoms with measured physiological parameters.

[0112] The external device 242 may include a GPS system that is able to determine patient location via three axes. This, in turn, allows the external device 242 to determine the altitude and location of the patient, enabling estimation of ambient pressure based on altitude and local weather conditions. All of this information can be provided to or through the external4337408693.1device 242 to a clinician to determine the ICP of the patient at any given time or period of time. In such embodiments, the external device 242 may include an internal battery that supports portable operation and promotes patient compliance during routine use.

[0113] The power supply 134 is an internal power source of the implant 110 and enables autonomous operation of the implant 110 independent of a dedicated external reader device or power source. By incorporating the power supply 134 within the implant 110, the implant 110 may continuously or periodically measure, store, and log ICP data over extended periods of time, including during normal daily activities of the patient, without simultaneously requiring an external device, such as an external reader, the external battery charger 170, or another external power supply to be held against the patient during measurement. The controller 120 may manage power consumption of the implant 110 to support long-term operation, including entering low-power states between measurement cycles and selectively activating sensing and communication circuitry as needed.

[0114] In some embodiments, the power supply 134 stores and provides operating power to the sensor assembly 132, the controller 120, and the communications device 165 for sensing, data processing, and wireless communication functions, while a separate power source is provided for actuating a valve, such as one of the valves 380, 460. For example, the implant 110 may include a second battery or energy storage element dedicated to powering actuation of the valve, while the power supply 134 supports continuous or periodic sensing, data logging, and communication operations. With this arrangement, power demands associated with valve actuation are electrically isolated from power demands associated with sensing and communication, which may improve reliability, extend operational lifetime, and allow independent management of sensing and actuation functions within the implant 110.

[0115] What has been described above includes examples of the present specification. It is, of course, not possible to describe every conceivable combination of components or4437408693.1methodologies for purposes of describing the present specification, but one of ordinary skill in the art may recognize that many further combinations and permutations of the present specification are possible. Each of the components described above may be combined or added together in any permutation to define embodiments disclosed herein. Accordingly, the present specification is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.4537408693.1

Claims

CLAIMSWhat is claimed is:

1. A method for measuring and communicating intracranial pressure (ICP) using an implant and an external device, the method comprising:measuring an absolute ICP by the implant;comparing the measured absolute ICP to a predetermined threshold using the implant; wirelessly transmitting the measured absolute ICP to the external device at a predetermined recurring interval, or in response to the comparison; anddetermining a gauge ICP based on the measured absolute ICP and an ambient pressure using the external device.

2. The method of claim 1, wherein measuring the absolute ICP includes repeatedly measuring the absolute ICP by the implant, and wirelessly transmitting the measured absolute ICP includes wirelessly transmitting accumulated ICP data from repeated measurement cycles or the measured absolute ICP to the external device at the predetermined recurring inten al.

3. The method of claim 1, wherein the implant is implanted in a patient, the external device includes a display carried by the patient, and the method further comprises generating a notification at the display or a remote gateway from the external device, based on a comparison of the determined gauge ICP to a predetermined threshold or a trend of the determined gauge ICP.

4. The method of claim 3, wherein the external device includes a storage device, and in response to the comparison, the external device records the determined gauge ICP in the storage device when the determined gauge ICP is equal to or below the predetermined threshold, and4637408693.1the external device generates an alert to the remote gateway when the determined gauge ICP exceeds the predetermined threshold, or when the trend of the determined gauge ICP lasts longer than a predetermined period of time.

5. The method of claim 3, further comprising:measuring the ambient pressure using the external device; andcomparing the determined gauge ICP with a predetermined threshold or determining the trend of the determined gauge ICP using the external device,wherein the external device determines the gauge ICP based on the measured ambient pressure and the measured absolute ICP.

6. The method of claim 3, wherein the method further comprises:determining a plurality of gauge ICP values at the external device based on repeated measurements of the absolute ICP by the implant over time;determining a trend of the determined gauge ICP values by comparing the determined gauge ICP values with each other, including identifying an increase or decrease across the plurality of gauge ICP values overtime; andgenerating an alert at the external device or the remote gateway when the determined trend meets a predetermined threshold.

7. The method of claim 1 , wherein the implant includes a timer, a sensor assembly, and a communications device, and the method further comprises:wirelessly transmitting an acknowledgement to the implant indicating receipt of the measured absolute ICP by the external device;4737408693.1powering down the sensor assembly or the communications device while the timer is active, and until expiration of the predetermined recurring interval in response to the acknowledgement; andrepowering the sensor assembly or the communications device upon expiration of the timer, causing the implant to measure a subsequent absolute ICP using the sensor assembly, and wirelessly transmit the measured subsequent absolute ICP to the external device using the communications device at the expiration of the predetermined recurring interval.

8. The method of claim 1, further comprising:comparing the gauge ICP with a predetermined threshold or determining a trend of the gauge ICP over time; andshortening the predetermined recurring interval when the determined gauge ICP exceeds the predetermined threshold, or when the determined trend of the gauge ICP indicates an increase over time; orlengthening the predetermined recurring interval when the determined gauge ICP is equal to or below the predetermined threshold, or when the determined trend of the gauge ICP indicates a stable or decreasing gauge ICP over time.

9. The method of claim 8, whereinthe external device performs the comparison of the gauge ICP with the predetermined threshold or determines the trend of the gauge ICP over time,the external device performs the shortening or lengthening of the predetermined recurring interval based on the comparison or the determined trend of the gauge ICP. generating an updated predetermined recurring interval, and4837408693.1the implant measures and transmits the absolute ICP according to the updated predetermined recurring interval.

10. The method of claim 1, further comprising:monitoring a battery7charge state of the implant using an onboard circuit; powering down a sensor assembly or a communications device in the implant during the predetermined recurring interval when the battery charge state falls below a predetermined level; andrepowering the sensor assembly or the communications device when the battery7charge state is restored above the predetermined level.

11. The method of claim 1, further comprising:adjusting an operational parameter of the implant at a remote gatew ay based on user input, the adjusted operational parameter being the predetermined recurring interval, the predetermined threshold compared to the absolute ICP, a battery charge level at which one or more onboard circuits are powdered down, or a transmission condition for wirelessly transmitting the absolute TCP;wirelessly transmitting the adjusted operational parameter from the remote gatew ay to the external device;wirelessly transmitting the adjusted operational parameter from the external device to the implant during a current duty cycle, wherein the external device automatically forwards the adjusted operational parameter as a pass-through device between the remote gateway and the implant; andoperating the implant using the adjusted operational parameter during a subsequent duty cycle, following the current duty cycle.4937408693.

112. The method of claim 1, further comprising:detecting a condition including at least one of a failure to receive an acknowledgement of a transmitted absolute ICP measurement, accumulation of a predefined amount of stored ICP data at the implant, or completion of a transmission or logging event; and modifying at least one operational parameter of the implant in response to the detected condition, including increasing a number of absolute ICP transmission attempts, adjusting the predetermined recurring interval, or initiating transmission of accumulated ICP data.

13. The method of claim 1, further comprising:detecting a condition including at least one of a change in ambient pressure of an environment surrounding a patient with the implant, and coupling of the implant with an external batten' charger; andmodifying at least one operational parameter of the implant in response to the detected condition, including adjusting the predetermined recurring interval, adjusting the predetermined threshold compared to the measured absolute ICP, or altering a transmission condition for wirelessly transmitting the absolute ICP.

14. The method of claim 1, wherein at least one of measuring the absolute ICP, comparing the measured absolute ICP to the predetermined threshold, and wirelessly transmitting the measured ICP to the external device includes powering a pressure sensor, a controller, or a communications device of the implant with an internal power source of the implant.5037408693.

115. The method of claim 14, wherein the internal power source of the implant is a battery that stores and provides operating power for the pressure sensor, the controller, or the communications device.

16. The method of claim 15, wherein the battery is rechargeable, and the method further comprises recharging the battery' using an external battery' charger.

17. The method of claim 16, wherein the method further comprises the implant detecting a coupling with the external battery' charger, and then shortening the predetermined recurring interval, lowering the predetermined threshold for comparing and transmitting the measured absolute ICP, or increasing a frequency of wirelessly transmitting the absolute ICP in response to the detected coupling.

18. The method of claim 1, wherein wirelessly transmitting the measured absolute ICP to the external device is performed by a wireless transceiver over at least one of a 2.4 GHz ISM band frequency , or a cellular communication band frequency.

19. The method of claim 18, wherein the wireless transceiver transmits the measured absolute ICP, and the cellular communication band frequency overlaps or includes a range of 700 Megahertz (MHz) to 900 MHz, 1700 MHz to 2200 MHz, or 3300 MHz to 4200 MHz.

20. An intracranial pressure (ICP) monitoring system, comprising:a shunt that conveys cerebrospinal fluid (CSF) within a cranium;a valve disposed in the shunt, controlling flow of the CSF through the shunt;5137408693.1a first pressure sensor upstream from the valve with respect to CSF flow through the shunt, where the first pressure sensor performs a first ICP measurement;a second pressure sensor downstream from the valve with respect to CSF How through the shunt, where the second pressure sensor performs a second ICP measurement;at least one processor operatively connected to the valve, the first pressure sensor, the second pressure sensor, and an external device, wherein the at least one processor determines a differential CSF pressure in the shunt, across the valve, based on the first ICP measurement and the second ICP measurement, and generates at least one of a control signal to the valve and an alert at the external device based on the determined differential CSF pressure.

21. The system of claim 20, wherein the at least one processor is configured to determine an obstruction of the shunt, an over-drainage condition at the valve, or an under-drainage condition at the valve, based on the determined differential CSF pressure across the valve exceeding or falling below a predetermined differential pressure threshold for a predetermined period of time.

22. The system of claim 21 , wherein the at least one processor actuates the valve in response to the determined obstruction, over-drainage condition, or under-drainage condition, including actuating the valve toward a relatively open state in response to the determined obstruction or under-drainage condition, and actuating the valve toward a relatively closed state in response to the determined over-drainage condition.

23. The system of claim 20, wherein the at least one processor:determines a trend in the differential CSF pressure across the valve over time based on a plurality of successive measurement cycles by the first sensor and the second sensor; and5237408693.1generates an alert at the external device or a remote gateway, or generates a control signal to the valve in response to the determined trend remaining above a predetermined differential pressure threshold or increasing across the plurality of successive measurement cycles.

24. The system of claim 20, wherein the at least one processor:periodically compares the ICP measurements taken by the first pressure sensor and the second pressure sensor when the valve is in a closed state;determines an amount of drift between the first pressure sensor and the second pressure sensor based on the comparison;adjusts the first ICP measurement or the second ICP measurement by the determined amount of drift; anddetermines the differential CSF pressure across the valve based on the adjusted first ICP measurement or the adjusted second ICP measurement.

25. The system of claim 20, wherein the at least one processor determines an obstruction or blockage upstream of the valve when the differential CSF pressure remains elevated or increases after generating the control signal to the valve, and a difference between a first subsequent ICP measurement at the first pressure sensor and the first ICP measurement is greater than a difference between a second subsequent ICP measurement at the second pressure sensor and the second ICP measurement; andgenerates a notification at the external device or a remote gateway indicating the detected obstruction or blockage.

26. The system of claim 20, wherein the at least one processor:5337408693.1determines that the differential CSF pressure across the valve deviates from an expected differential pressure corresponding to a valve operating state positioned between a fully open state and a fully closed state by at least a predetermined threshold;maintains the valve at the valve operating state or sets the valve to a predetermined operating state in response to the detected deviation; andgenerates a notification at the external device or a remote gateway indicating the detected deviation between the first pressure sensor and the second pressure sensor.5437408693.1

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