Cerebrospinal fluid pressure measurement device

Abstract

The present invention is entitled "Cerebrospinal Fluid Pressure Measurement Device." The present invention discloses a cerebrospinal fluid pressure measurement device, comprising: a pressure gauge, the pressure gauge comprising: a hollow cylindrical body for insertion through a skull and having a lower end, an upper end, and an inner surface; a diaphragm attached to the lower end and moving under the pressure of the cerebrospinal fluid in the skull; and coils, the coils comprising a fixed coil and a moving coil, the fixed coil being disposed in the hollow cylindrical body and connected to the inner surface so as to remain fixed, the moving coil being disposed in the hollow cylindrical body and connected to the diaphragm so as to move when the diaphragm moves under the pressure, one of the coils being configured as a transmitting coil and the other of the coils being configured as a receiving coil; and a control unit applying an input signal to the transmitting coil and receiving an output signal from the receiving coil, and generating an indication of the pressure.

Description

Technical Field

[0001] The present invention relates to pressure measuring devices and particularly, but not exclusively, to cerebrospinal fluid pressure measuring devices. Background Art

[0002] There are many situations, including emergency situations as well as trauma and hydrocephalus cases, where it is important to measure the pressure of the cerebrospinal fluid (CSF) within the patient's skull. Existing systems typically use pressure gauges inserted through the skull, but these pressure gauges are relatively large and bulky, and inserting them through the skull is time-consuming.

[0003] U.S. Patent No. 4,593,703 to Cosman describes an implantable, telemetric differential pressure sensing device. The implantable device includes a planar, closed, conductive ring that moves with a flexible diaphragm. The diaphragm moves in response to a change in the differential pressure between two opposing body surfaces. The position of the conductive ring relative to a resonant circuit fixed within the device determines the resonant frequency of the resonant circuit. This resonant frequency is telemetrically measured outside the body, and its value is used to determine the differential pressure between the two body surfaces.

[0004] Published U.S. patent application 2011 / 0066072 by Kawoos et al. describes an intracranial pressure device for measuring CSF pressure within the skull, comprising a housing positioned between the scalp and the skull containing circuitry for the pressure device, and a conduit extending downward from the housing to near the CSF. A pressure sensor is coupled to the conduit and positioned to communicate with the CSF, wherein the pressure sensor directly senses the pressure of the CSF and provides a signal representing the pressure of the CSF to the pressure device circuitry via the conduit. The skull has a dura mater, and the conduit extends through an opening through the skull and through an opening through the dura mater to position the sensor in direct contact with the CSF. A fluid reservoir can communicate with the CSF via a tube and the housing. The fluid reservoir contains the CSF.

[0005] Geiger's published U.S. patent application 2006 / 0020224 describes a system and method for continuously or periodically monitoring intracranial pressure (ICP) in a patient over an extended period of time. In some cases, a caregiver may want to record ICP measurements over a longer period of time to obtain trend data. The system for monitoring ICP includes a hood-shaped, inductive power transmitting element designed to surround at least a substantial portion of the patient's head and power an implanted ICP monitor. The hood-shaped element may be a table-mounted device that curves across the width of a table or bed to provide space for the patient's head.

[0006] Published U.S. patent application 2015 / 0119752 by Seaver et al. describes an implantable subcutaneous device for measuring internal body pressure and wirelessly transmitting information corresponding to the measured internal body pressure, the implantable subcutaneous device comprising: a pressure sensor for sensing pressure in a specific area of ​​the patient's body and outputting a pressure signal corresponding to the sensed pressure; an encoder for receiving the pressure signal and encoding the signal to generate a sensor information signal to be transmitted to an external receiver; a transceiver for receiving the sensor information signal from the encoder and transmitting the sensor information signal to an external receiver; and a biocompatible housing for encapsulating the pressure sensor, encoder, and transceiver.

[0007] U.S. Patent No. 4,265,252 to Chubbuck et al. describes an implantable transducer sensor device comprising a passive RF resonant circuit having a natural frequency that is influenced by the pressure of the sensor environment within a body cavity. The transducer circuit includes an inductor and a capacitor, at least one of which varies in value in direct correlation with changes in ambient pressure to alter the resonant frequency of the circuit. The resonant frequency of the circuit can be determined externally at any point in time by applying swept-frequency electromagnetic radiation to the circuit, provided by a monitoring device that determines when some of the radiation is absorbed because its frequency matches the resonant frequency of the transducer circuit. A forced relationship exists between the sensed ambient pressure and the reactance of the reactive components of the circuit. There is a natural relationship between the piezorespontance and the resonant frequency of the circuit. Thus, an increase in ambient pressure results in a corresponding increase in frequency, and a decrease in ambient pressure results in a decrease in frequency.

[0008] Miethke et al., published US patent application 2008 / 0139959, describes an implantable device for determining intracranial pressure, comprising a microchip housed in a rigid housing. Pressure transmitted through a very thin, biocompatible diaphragm acts on the pressure measuring device via a transmission medium.

[0009] Published U.S. patent application 2006 / 0025704 by Stendel et al. describes an implantable device for measuring brain parameters. The device consists of an electronics unit and an integrated sensor unit. The electronics unit is securely and tightly sealed and reusable after sterilization. The sensor unit includes at least one single-lumen catheter and a sensor disposed therein for measuring pressure and / or temperature.

[0010] Stone's published U.S. patent application 2011 / 0160560 describes an implantable pressure sensor system having a sensor assembly configured and adapted to measure pressure in a volume, the sensor assembly including at least a first MEMS pressure sensor having a pressure sensing element responsive to an exposed pressure, an application-specific integrated circuit (ASIC) having a storage device, a temperature compensation system, a drift compensation system, and a power supply device for powering the sensor assembly, the first MEMS pressure sensor having a pressure sensing element responsive to an exposed pressure, the pressure sensing element adapted to generate a pressure sensor signal representative of the exposed pressure, the temperature compensation system adapted to correct for temperature-induced changes in the pressure sensor signal, and the drift compensation system adapted to correct for pressure- and temperature-induced drift in the pressure sensor signal. Summary of the Invention

[0011] According to an embodiment of the present disclosure, a cerebrospinal fluid pressure measuring device is provided, the cerebrospinal fluid pressure measuring device comprising: a pressure gauge, the pressure gauge comprising: a hollow cylindrical body, the hollow cylindrical body being configured to be inserted through a skull and having a lower end, an upper end, an inner surface, and an outer surface; a diaphragm attached to the lower end, the diaphragm being configured to move under the pressure of the cerebrospinal fluid in the skull; and a plurality of coils, the plurality of coils comprising a fixed coil and a moving coil, the fixed coil being disposed in the hollow cylindrical body and connected to the inner surface of the hollow cylindrical body so as to remain fixed relative to the hollow cylindrical body, the a moving coil disposed in the hollow cylindrical body and connected to the diaphragm such that the moving coil moves relative to the stationary coil when the diaphragm moves under the pressure from the cerebrospinal fluid, one coil of the plurality of coils being configured as a transmitting coil and another coil of the plurality of coils being configured as a receiving coil; and a control unit configured to contact the upper end of the hollow cylindrical body so as to apply an input signal to the transmitting coil and receive an output signal from the receiving coil in response to the input signal, and configured to generate an indication of the pressure of the cerebrospinal fluid in response to the output signal.

[0012] Additionally, according to an embodiment of the present disclosure, the outer surface of the hollow cylindrical body is threaded so that the pressure gauge can be screwed into the skull and thereby secured therein.

[0013] Additionally, in accordance with an embodiment of the present disclosure, the upper end of the hollow cylindrical body includes a driver or bolt head to facilitate screwing the pressure gauge into the skull for securing therein.

[0014] Additionally, according to an embodiment of the present disclosure, the moving coil has a first axis and the stationary coil has a second axis, the first axis being substantially parallel to the second axis.

[0015] Furthermore, according to an embodiment of the present disclosure, the first axis and the second axis are substantially collinear.

[0016] In addition, according to an embodiment of the present disclosure, a distance between the moving coil and the fixed coil in the directions of the first axis and the second axis is in a range of 0.05 mm to 0.7 mm.

[0017] Additionally, according to an embodiment of the present disclosure, the hollow cylindrical body has an outer diameter ranging from 0.5 mm to 3.5 mm.

[0018] Additionally, according to an embodiment of the present disclosure, the hollow cylindrical body comprises a tapered cylinder.

[0019] Furthermore, according to an embodiment of the present disclosure, the lower end of the hollow cylindrical body has an outer diameter ranging from 0.5 mm to 3.2 mm, the upper end of the hollow cylindrical body has an outer diameter ranging from 0.7 mm to 3.5 mm, and the hollow cylindrical body has a length measurement from the lower end to the upper end ranging from 3 mm to 8 mm long.

[0020] Additionally, according to an embodiment of the present disclosure, the outer surface of the hollow cylindrical body is threaded so that the pressure gauge can be screwed into the skull and thereby secured therein.

[0021] Additionally, in accordance with an embodiment of the present disclosure, the upper end of the hollow cylindrical body includes a driver or bolt head to facilitate screwing the pressure gauge into the skull for securing therein.

[0022] Additionally, according to an embodiment of the present disclosure, the hollow cylindrical body includes a hermetically sealed cavity including the moving coil disposed therein, the cavity being partially sealed by the diaphragm.

[0023] Furthermore, according to an embodiment of the present disclosure, the separator includes silicone.

[0024] In addition, according to an embodiment of the present disclosure, the organic silicon includes a compound having the chemical formula CH3[Si(CH3)2O]nSi(CH 3)3 of polydimethylsiloxane (PDMS).

[0025] Additionally, according to an embodiment of the present disclosure, the control unit is reversibly attachable to the upper end of the hollow cylindrical body.

[0026] Additionally, in accordance with an embodiment of the present disclosure, the control unit and the upper end include complementary interconnecting features to secure the control unit to the hollow cylindrical body.

[0027] Furthermore, in accordance with an embodiment of the present disclosure, the complementary interconnection features include a plurality of electrical connectors configured to electrically connect the control unit and the plurality of coils.

[0028] Additionally, according to an embodiment of the present disclosure, the control unit includes a memory and a processor configured to generate the indication of the pressure of the cerebrospinal fluid and store the indication in the memory.

[0029] Additionally, in accordance with an embodiment of the present disclosure, the control unit includes a power source and a data interface configured to provide the indication of the pressure stored in the memory to a remote processing device.

[0030] According to another embodiment of the present disclosure, a pressure gauge device is also provided, which includes: a hollow cylindrical body, which is used to be inserted through the skull and has a lower end, an upper end, an inner surface and an outer surface, the hollow cylindrical body including a tapered cylinder; a diaphragm attached to the lower end, the diaphragm being configured to move under the pressure of the cerebrospinal fluid in the skull, the outer surface of the hollow cylindrical body being threaded so that the pressure gauge can be screwed into the skull and thereby fastened therein; and a plurality of coils, the plurality of coils including a fixed coil and a moving coil, the fixed coil being arranged in the hollow cylindrical body and connected to the inner surface of the hollow cylindrical body so as to remain fixed relative to the hollow cylindrical body, the moving coil being arranged in the hollow cylindrical body and connected to the diaphragm so that when the diaphragm is under the pressure from the cerebrospinal fluid During downward movement, the moving coil moves relative to the fixed coil, one of the plurality of coils is configured as a transmitting coil, and another of the plurality of coils is configured as a receiving coil; wherein the upper end of the hollow cylindrical body includes a driver or screw head to facilitate screwing the pressure gauge into the skull for fastening therein; the upper end is configured for interconnection with a complementary feature structure of a control unit, the control unit being reversibly attachable to the upper end of the hollow cylindrical body; the upper end includes a plurality of electrical connectors configured to electrically connect the control unit to the plurality of coils; the control unit is configured to contact the upper end of the hollow cylindrical body so as to apply an input signal to the transmitting coil and receive an output signal from the receiving coil in response to the input signal, and is configured to generate an indication of the pressure of the cerebrospinal fluid in response to the output signal.

[0031] Additionally, according to an embodiment of the present disclosure, the moving coil has a first axis and the stationary coil has a second axis, the first axis being substantially collinear with the second axis.

[0032] Furthermore, according to an embodiment of the present disclosure, the separator includes silicone.

[0033] In addition, according to an embodiment of the present disclosure, the organic silicon includes a compound having the chemical formula CH3[Si(CH3)2O]nSi(CH 3)3 of polydimethylsiloxane (PDMS).

[0034] According to another embodiment of the present disclosure, a method for using a cerebrospinal fluid pressure measuring device is also provided, the method comprising: inserting a hollow cylindrical body of a pressure gauge through a skull, the hollow cylindrical body having a lower end, an upper end, an inner surface, and an outer surface, the pressure gauge further comprising: a diaphragm attached to the lower end, the diaphragm being configured to move under the pressure of the cerebrospinal fluid in the skull; and a plurality of coils comprising a fixed coil and a moving coil, the fixed coil being disposed in the hollow cylindrical body and connected to the inner surface of the hollow cylindrical body so as to maintain a relative pressure to the hollow cylindrical body. The invention further comprises a method of controlling a cerebrospinal fluid pressure sensor and a control unit, wherein the cerebrospinal fluid pressure sensor is fixed to the hollow cylindrical body, the moving coil being disposed in the hollow cylindrical body and connected to the diaphragm so that when the diaphragm moves under the pressure from the cerebrospinal fluid, the moving coil moves relative to the fixed coil, one coil of the plurality of coils being configured as a transmitting coil, and another coil of the plurality of coils being configured as a receiving coil; attaching a control unit to the upper end of the hollow cylindrical body; applying an input signal to the transmitting coil; receiving an output signal from the receiving coil in response to the input signal; and generating an indication of the pressure of the cerebrospinal fluid in response to the output signal.

[0035] Additionally, according to an embodiment of the present disclosure, the outer surface of the hollow cylindrical body is threaded, and the method further comprises screwing the pressure gauge into the skull to secure it therein.

[0036] Additionally, according to an embodiment of the present disclosure, the upper end of the hollow cylindrical body includes a driver or bolt head, and the method further includes screwing the pressure gauge into the skull to secure it therein.

[0037] Furthermore, according to an embodiment of the present disclosure, the moving coil has a first axis and the stationary coil has a second axis, the first axis being substantially collinear with the second axis.

[0038] Additionally, according to an embodiment of the present disclosure, the hollow cylindrical body comprises a tapered cylinder.

[0039] In addition, according to an embodiment of the present disclosure, the separator includes silicone.

[0040] In addition, according to an embodiment of the present disclosure, the organic silicon includes a compound having the chemical formula CH3[Si(CH3)2O]nSi(CH 3)3 of polydimethylsiloxane (PDMS). BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0042] Figure 1 a schematic diagrammatic view of a cerebrospinal fluid pressure measurement device constructed and operative in accordance with an embodiment of the present invention;

[0043] Figure 2A constructed and operated according to an embodiment of the present invention Figure 1 An orthogonal cross-sectional view of a manometer of a cerebrospinal fluid pressure measuring device;

[0044] Figure 2B Taken along line AA Figure 2A A longitudinal cross-section of the pressure gauge;

[0045] Figure 3 constructed and operated according to an embodiment of the present invention Figure 1 A block diagram of a control unit of a cerebrospinal fluid pressure measuring device;

[0046] Figure 4 To include Figure 3 A flowchart of exemplary steps in a method of operating a control unit of FIG. 1 ; and

[0047] Figure 5A and Figure 5B Schematic diagrammatic illustration of a cerebrospinal fluid pressure measurement device constructed and operative in accordance with an alternative embodiment of the present invention. DETAILED DESCRIPTION

[0048] Overview

[0049] By introduction, installing a pressure gauge into the skull to measure cerebrospinal fluid (CSF) pressure can involve many challenges, including the time it takes to insert the pressure gauge through the skull and secure the pressure gauge once inserted. Large, bulky pressure gauges can be uncomfortable for the patient in addition to being difficult to handle. In addition, a disadvantage of using a large pressure gauge is that a large hole may need to be prepared in the skull. Although preparing a smaller pressure gauge can alleviate some of the above challenges, a smaller pressure gauge still needs to maintain sensing accuracy and can also be difficult to handle due to its small size.

[0050] Thus, in some embodiments of the present invention, a cerebrospinal fluid pressure measuring device is provided, comprising a lightweight and compact manometer having a diameter typically in the range of 0.5 mm to 3.5 mm so as to be easily and comfortably inserted through the skull. The outer surface of the manometer may include threads so that the manometer can be screwed into the skull and thereby secured therein. Once the manometer has been inserted through the skull, a control unit may be attached to the upper end of the manometer. The control unit may power the manometer, obtain readings from the manometer, and provide an indication of the pressure to a remote processing device.

[0051] The manometer includes a coil and diaphragm arrangement described in more detail below to provide accurate pressure readings so that sensing accuracy is not compromised in a lightweight and compact manometer.The manometer typically includes biocompatible materials where contact with the skull and CSF may occur.

[0052] To facilitate insertion, the upper end of the hollow cylindrical body optionally includes a driver into which a screw drive device or tool can be reversibly inserted to facilitate screwing the pressure gauge into the skull for securing therein. The driver is optionally configured to interconnect with a complementary feature of a control unit that can be reversibly attached to the upper end of the hollow cylindrical body. In other exemplary embodiments, the upper end of the hollow cylindrical body optionally includes a screw head for engaging a wrench to facilitate screwing the pressure gauge into the skull for securing therein.

[0053] In some exemplary embodiments, the pressure gauge can be made into a tapered cylinder for easy insertion through the skull. To illustrate the compactness of the pressure gauge, the tapered cylinder can have an outer diameter of typically between 0.5 mm and 3.2 mm (e.g., 1.2 mm) at its lower end (closest to the CSF for insertion) and can have an outer diameter of typically between 0.7 mm and 3.5 mm (e.g., 1.7 mm) at its upper end (typically retained outside the skull). The pressure gauge can typically have a length measurement ranging from 3 mm to 8 mm (e.g., 4 mm to 5 mm) from its lower end to its upper end.

[0054] The diaphragm is attached to the lower end of the cylindrical body so that when the manometer is inserted through the skull, the diaphragm moves under the pressure of the CSF within the skull. The diaphragm may comprise silicone or other flexible biocompatible material. The silicone may comprise a material having the chemical formula CH3[Si(CH3)2O]nSi(CH 3)3 of polydimethylsiloxane (PDMS).

[0055] A plurality of coils, including a stationary coil and a moving coil, are disposed within a cylindrical body. The coils are typically disposed within the cylindrical body such that their axes are collinear with the axis of the cylindrical body. However, other arrangements of the coils relative to each other and the cylindrical body are possible. The stationary coil is attached to the inner surface of the cylindrical body so that it remains fixed relative to the hollow cylindrical body even when the diaphragm moves under pressure from the CSF. The moving coil, on the other hand, is attached to the diaphragm so that when the diaphragm moves under pressure from the CSF, the moving coil moves relative to the stationary coil.

[0056] The upper end of the cylindrical body typically includes an electrical connector configured to electrically connect a control unit to coils disposed within the manometer. One of the coils is designated as a transmitting coil, and the other coil is designated as a receiving coil. The designation of which coil is the receiving coil or transmitting coil is generally arbitrary. The control unit applies an input signal to the transmitting coil and receives an output signal from the receiving coil in response to the input signal. When the distance between the two coils varies depending on the pressure applied to the diaphragm, the variation is directly related to the output signal generated at the receiving coil. The control unit can generate an indication of CSF pressure in response to the output signal. The control unit may require calibration to provide a correspondence between the output signal and the corresponding pressure value.

[0057] System Description

[0058] Documents incorporated herein by reference are to be considered an integral part of this application, except that, to the extent any term is defined in these incorporated documents in a manner that contradicts a definition explicitly or implicitly set forth in this specification, only the definition in this specification shall prevail.

[0059] Now refer to Figure 1 , which is a schematic diagram of a cerebrospinal fluid pressure measurement device 10 constructed and operative in accordance with an embodiment of the present invention. The cerebrospinal fluid pressure measurement device 10 includes a pressure gauge 12 and a control unit 14. A hole may be drilled in the skull 16 using any drilling instrument suitable for the purpose. The pressure gauge 12 includes a hollow cylindrical body 18 configured for insertion through the skull 16. The hollow cylindrical body 18 is referred to as Figure 2A and Figure 2BThe hollow cylindrical body 18 may include threads on its outer surface 26 to facilitate insertion and securing of the manometer 12 within the skull 16 .

[0060] The control unit 14 is configured to contact the upper end 20 of the hollow cylindrical body 18 so as to apply an input signal to a coil disposed in the hollow cylindrical body 18 and receive an output signal from another coil disposed in the hollow cylindrical body 18. The coil is not shown. Figure 1 In, but reference Figure 2A and Figure 2B The control unit 14 is configured to generate an indication of the pressure of the CSF in the skull 16 in response to the output signal. Figure 3 and Figure 4 Described in more detail.

[0061] The control unit 14 is configured to be reversibly attached to the upper end 20 of the hollow cylindrical body 18. In an alternative exemplary embodiment, the control unit 14 may be permanently fixed to the pressure gauge 12.

[0062] The control unit 14 and the upper end 20 of the hollow cylindrical body 18 include complementary interconnecting features 22 to secure the control unit 14 to the hollow cylindrical body 18. By way of example only, the interconnecting features 22 can be configured to provide a press fit or an interlocking mechanism. In some exemplary embodiments, the control unit 14 can be threaded to the skull 16 in one or more locations. In addition or alternatively, the control unit 14 can be attached to the skull 16 using a suitable adhesive. Securing the control unit 14 to the skull 16 is particularly useful when the outer surface of the hollow cylindrical body 18 is not threaded. Even when the hollow cylindrical body 18 is threaded, the control unit 14 can be secured to the skull 16 to provide additional adhesion.

[0063] The control unit 14 and the pressure gauge 12 typically include a plurality of electrical connections 24 to electrically connect the control unit 14 to the pressure gauge 12. The electrical connections 24 are typically provided on interconnect features 22 of the pressure gauge 12 and the control unit 14.

[0064] Now refer to Figures 2A to 2B . Figure 2A According to an exemplary embodiment of the present invention, the Figure 1 An orthogonal cross-sectional view of the pressure gauge 12 of the cerebrospinal fluid pressure measurement device 10. Figure 2B For the Figure 2A A longitudinal cross-sectional view of the pressure gauge 12 taken along line AA.

[0065] The hollow cylindrical body 18 may comprise a tapered cylinder. In some exemplary embodiments, the hollow cylindrical body 18 is not tapered. The hollow cylindrical body 18 may be made of any suitably durable material. The outer surface 26 of the hollow cylindrical body 18 typically comprises a biocompatible material, such as, but not limited to, titanium or stainless steel.

[0066] The outer diameter of the hollow cylindrical body 18 is typically, but not exclusively, in the range of 0.5 mm to 3.5 mm, although smaller or larger diameters can also be achieved. When the hollow cylindrical body 18 is tapered, the lower end 28 of the hollow cylindrical body 18 can have an outer diameter (DL) typically, but not exclusively, in the range of 0.5 mm to 3.2 mm (e.g., 1.2 mm), although smaller or larger diameters can also be achieved, and the upper end 20 of the hollow cylindrical body 18 can have an outer diameter (DU) typically, but not exclusively, in the range of 0.7 mm to 3.5 mm (e.g., 1.7 mm), although smaller or larger diameters can also be achieved. The hollow cylindrical body 18 can have a length measurement (L) (height) from the lower end 28 to the upper end 20 typically, but not exclusively, in the range of 3 mm to 8 mm (e.g., 4 mm to 5 mm long), although smaller or larger lengths can also be achieved. The diameter of the hole drilled in the skull is typically, but not exclusively, equal to or greater than the diameter of the lower end 28. For example, if the diameter of the lower end 28 is 1.2 mm and the diameter of the upper end 20 is 1.7 mm, the diameter of the drilled hole may be in the range of 1.2 mm to 1.6 mm.

[0067] The outer surface 26 of the hollow cylindrical body 18 is threaded so that the pressure gauge 12 can be screwed into the skull 16 ( Figure 1 ) so as to be more easily fastened therein. The upper end 20 of the hollow cylindrical body 18 may include a driver 30 into which a screw drive tool can be reversibly inserted to help screw the pressure gauge 12 into the skull 16 so as to be fastened therein.

[0068] By way of example only, the hollow cylindrical body 18 includes a septum 32 attached to the lower end 28 of the hollow cylindrical body 18 using any suitable adhesive. The septum 32 is configured to move under the pressure of the CSF within the skull 16. The septum may include any suitable flexible biocompatible material. Silicone-based materials have been determined to be suitable for use with the septum 32. Silicone may include a material having the chemical formula CH3[Si(CH3)2O]nSi(CH 3)3 Polydimethylsiloxane (PDMS), which is similar to the material used in breast implant shells.

[0069] The manometer 12 includes a plurality of coils disposed in a hollow cylindrical body 18, the plurality of coils including a stationary coil 34 and a moving coil 36. The stationary coil 34 is connected to an inner surface 38 of the hollow cylindrical body 18 so as to remain fixed relative to the hollow cylindrical body 18. One end of the moving coil 36 is connected to the diaphragm 32 such that when the diaphragm 32 moves under pressure from the CSF, the moving coil 36 moves relative to the stationary coil 34 (arrow 46). The expected displacement of the coil 36 is typically, but not exclusively, in the range of 0.05 mm to 0.5 mm. Depending on the specific implementation, the minimum displacement measured may be approximately 0.01 mm. The moving coil 36 has an axis 40 and the stationary coil 34 has an axis 42. The axis 40 and the axis 42 are substantially parallel to each other. Although the axis 40 and the axis 42 are generally aligned with each other, the term "substantially parallel" as used in this specification and claims is defined to include axes 40, 42 that are not completely parallel but are within 30 degrees of each other. In Figure 2A and Figure 2B In the exemplary embodiment shown, axes 40, 42 are substantially colinear. Although axes 40, 42 are generally aligned, the term "substantially colinear" as used in this specification and claims is defined to include axes 40, 42 that are not completely colinear or even completely parallel but are separated by at most one-third of the average diameter of coils 34, 36 and are within 30 degrees of each other.

[0070] The spacing S between the moving coil 36 and the fixed coil 34 in the direction of the axes 40, 42 is typically, but not exclusively, in the range of 0.05 mm to 0.7 mm, for example 0.1 mm. The fixed coil 34 and the moving coil 36 need to be sufficiently separated to allow full movement of the moving coil 36 under the pressure of the CSF, while being close enough together so that the signal emitted by one coil is received by the other coil with a sufficiently large amplitude to provide a meaningful pressure reading. The thickness of the wire of the coils 34, 36 can be any suitable thickness, and the coils can have any suitable number of turns. In an exemplary embodiment, the thickness of the wire of the coils is between 0.0 mm and 0.05 mm, with each coil having 10 to 30 turns.

[0071] The stationary coil 34 and the moving coil 36 are connected to the electrical connector 24 provided in the upper end 20 of the hollow cylindrical body 18. One of the coils 34, 36 is configured as a transmitting coil, and the other of the coils 34, 36 is configured as a receiving coil. The coils 34, 36 can be configured as a transmitting coil or a receiving coil by wiring the coils 34, 36 and the control unit 14 relative to the electrical connector 24 and / or by the control unit 14 selecting which of the coils 34, 36 should be the transmitting coil and the receiving coil.

[0072] The hollow cylindrical body 18 includes a hermetically sealed cavity 44. The cavity 44 includes the stationary coil 34 and the moving coil 36 disposed therein. The cavity 44 is sealed by the diaphragm 32, the inner surface 38, and the upper end 20 of the hollow cylindrical body 18. The pressure in the cavity is typically set to be equal to about 1 atmosphere, but can be set to any suitable value.

[0073] Now refer to Figure 3 , which is constructed and operative according to an alternative embodiment of the present invention Figure 1 1 is a block diagram of the control unit 14 of the cerebrospinal fluid pressure measurement device 10. The control unit 14 may include a memory 48, a processor 50, a power supply 52, a data interface 54, and an electrical connection 24. The different elements of the control unit 14 receive power from the power supply 52. ​​The memory 48 is configured to store data (and software) used by the processor 50 and pressure data as described in more detail below. The memory 48 may include volatile memory and non-volatile memory. The data interface 54 is configured to transmit data to (and from) a remote processing device 56. The data interface 54 may use any suitable protocol, such as, but not limited to, wireless ( or ) and / or wired data transmission protocol) to transmit data.

[0074] The control unit 14 is configured to contact the hollow cylindrical body 18 ( Figures 2A to 2B ) of the upper end 20( Figures 2A to 2B ) so that an input signal is applied to the transmitting coil (e.g., the fixed coil 34) and an output signal is received from the receiving coil (e.g., the moving coil 36) in response to the input signal. When the distance between the two coils 34, 36 is adjusted according to the distance between the two coils 34, 36 and the diaphragm 32 ( Figures 2A to 2B ) varies with the pressure on the CSF, the change in distance is directly related to the output signal generated at the receiving coil. Processor 50 is configured to generate an indication of CSF pressure in response to the output signal. In an exemplary embodiment, pressure values ​​between 5 mmHg and 50 mmHg are expected to have an accuracy of approximately 0.01 mmHg. Control unit 14 can be calibrated based on multiple measurements of the output signal at known CSF pressures measured by a calibration device.

[0075] In some exemplary embodiments, the control unit 14 may include the electrical connection 24 and the data interface 54 to the remote processing device 56, but not the memory 48, the processor 50, and the power supply 52, wherein reference is made to Figure 4The functionality of the processor 50 is provided by the remote processing device 56. In other exemplary embodiments, the control unit 14 may include the electrical connections 24, the data interface 54, the processor 50, and the memory 48, but power is provided by an external power source, such as in the remote processing device 56, via a suitable connection (e.g., a USB cable or wireless power).

[0076] Now refer to Figure 4 , which includes Figure 3 Flowchart 58 of exemplary steps in a method of operating the control unit 14. Figure 3 The processor 50 is configured to generate an input signal and apply the input signal to the transmitting coil via the associated electrical connector 24 (block 60). The processor 50 is configured to receive an output signal from the receiving coil in response to the input signal (block 62). The processor 50 is also configured to generate an indication of the pressure of the CSF in response to the output signal (block 64) and store the indication in the memory 48 (block 66). The indication stored in the memory may be the output signal or a value calculated by the processor 50 and dependent on the output signal, such as, but not limited to, a pressure value in a suitable pressure unit. The indication may also be stored with a timestamp indicating the time when the pressure indication was measured. The above steps of blocks 60 to 68 may be repeated periodically (arrow 70) to provide multiple pressure readings. The processor 50 is configured to provide the indication of pressure stored in the memory 48 to the remote processing device 56 via the data interface 54.

[0077] In implementation, some or all of the functions of the processor 50 may be combined in a single physical component, or alternatively, implemented using multiple physical components. These physical components may include hard-wired or programmable devices, or a combination of the two. In some embodiments, at least some of the functions of the processing circuitry may be implemented by a programmable processor under the control of suitable software. The software may be downloaded electronically to the control unit 14 via, for example, a network. Alternatively or in addition, the software may be stored in a tangible, non-transitory computer-readable storage medium.

[0078] Now refer to Figure 5A and Figure 5B , which is a schematic diagrammatic illustration of a cerebrospinal fluid pressure measurement device 100 constructed and operative in accordance with an alternative exemplary embodiment of the present invention. Figure 5B The cerebrospinal fluid pressure measurement device 100 is shown disposed on a U.S. penny 102 to emphasize the compactness of the cerebrospinal fluid pressure measurement device 100 . Figure 5A and Figure 5B The cerebrospinal fluid pressure measurement device 100 includes a pressure gauge 112 (having a hollow cylindrical body 118 and a diaphragm 132) and a control unit 114. The cerebrospinal fluid pressure measurement device 100 is similar to the above-mentioned Figures 1 to 4The cerebrospinal fluid pressure measuring device 10 is substantially the same as described, except for the following differences. The upper end 120 of the hollow cylindrical body 118 is shaped as a bolt head 130, such as a hexagonal bolt head, to facilitate insertion of the hollow cylindrical body 118 through the skull using a wrench or similar tool. The pressure gauge 112 and the control unit 114 include interconnection features 122 configured as pins and sockets and electrical connectors 124 to provide physical and electrical interconnections between the pressure gauge 112 and the control unit 114. The interconnection features 122 may provide a press fit or may include other features to allow the pressure gauge 112 and the control unit 114 to be clicked together. The control unit 14 includes a plurality of other electrical connectors 126 for connecting to a remote processing device.

[0079] For clarity, various features of the invention described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, for simplicity, various features of the invention are described in the context of a single embodiment and may also be provided separately or in any suitable subcombination.

[0080] The above embodiments are cited by way of example, and the present invention is not limited by what has been specifically shown and described hereinabove. On the contrary, the scope of the present invention includes combinations and subcombinations of the various features described above, as well as variations and modifications thereof, which will occur to those skilled in the art upon reading the above description and which are not disclosed in the prior art.

Claims

1. A cerebrospinal fluid pressure measuring device, comprising: A pressure gauge, comprising: a hollow cylindrical body configured for insertion through the skull and having a lower end, an upper end, an inner surface, and an outer surface; a diaphragm attached to the lower end, the diaphragm being configured to move under pressure of cerebrospinal fluid within the skull; and a plurality of coils, the plurality of coils comprising a stationary coil and a moving coil, the stationary coil being disposed in the hollow cylindrical body and connected to the inner surface of the hollow cylindrical body so as to remain fixed relative to the hollow cylindrical body, the moving coil being disposed in the hollow cylindrical body and connected to the diaphragm such that when the diaphragm moves under the pressure from the cerebrospinal fluid, the moving coil moves relative to the stationary coil, one coil of the plurality of coils being configured as a transmitting coil, and another coil of the plurality of coils being configured as a receiving coil; and a control unit configured to contact the upper end of the hollow cylindrical body to apply an input signal to the transmitting coil and receive an output signal from the receiving coil in response to the input signal, and to generate an indication of the pressure of the cerebrospinal fluid in response to the output signal.

2. The device of claim 1, wherein the outer surface of the hollow cylindrical body is threaded so that the pressure gauge can be screwed into the skull and thereby secured therein.

3. The device of claim 2, wherein the upper end of the hollow cylindrical body includes a driver or bolt head to facilitate screwing the pressure gauge into the skull for securing therein.

4. The apparatus of claim 1, wherein the moving coil has a first axis and the stationary coil has a second axis, the first axis being substantially parallel to the second axis. The device of claim 4 , wherein the first axis and the second axis are substantially collinear. 6 . The device according to claim 5 , wherein a spacing between the moving coil and the fixed coil in the directions of the first axis and the second axis is in a range of 0.05 mm to 0.7 mm.

7. The device of claim 1, wherein the hollow cylindrical body has an outer diameter ranging from 0.5 mm to 3.5 mm.

8. The device of claim 1, wherein the hollow cylindrical body comprises a tapered cylinder.

9. The device of claim 8, wherein the lower end of the hollow cylindrical body has an outer diameter ranging from 0.5 mm to 3.2 mm; the upper end of the hollow cylindrical body has an outer diameter ranging from 0.7 mm to 3.5 mm; and the hollow cylindrical body has a length measurement from the lower end to the upper end ranging from 3 mm to 8 mm long.

10. The device of claim 8, wherein the outer surface of the hollow cylindrical body is threaded so that the pressure gauge can be screwed into the skull and thereby secured therein.

11. The device of claim 10, wherein the upper end of the hollow cylindrical body includes a driver or screw head to facilitate screwing the pressure gauge into the skull for securing therein.

12. The device of claim 1, wherein the hollow cylindrical body comprises a hermetically sealed cavity including the moving coil disposed therein, the cavity being partially sealed by the diaphragm.

13. The device of claim 1, wherein the membrane comprises silicone.

14. The device of claim 13, wherein the organosilicon comprises polydimethylsiloxane (PDMS) having the chemical formula CH3[Si(CH3)2O]nSi(CH3)3.

15. The device of claim 1, wherein the control unit is reversibly attachable to the upper end of the hollow cylindrical body.

16. The device of claim 15, wherein the control unit and the upper end include complementary interconnecting features to secure the control unit to the hollow cylindrical body.

17. The apparatus of claim 16, wherein the complementary interconnection features include a plurality of electrical connections configured to electrically connect the control unit and the plurality of coils.

18. The apparatus of claim 17, wherein the control unit comprises a memory and a processor, the processor being configured to generate the indication of the pressure of the cerebrospinal fluid and to store the indication in the memory.

19. The device of claim 18, wherein the control unit comprises a power source and a data interface, the data interface being configured to provide the indication of the pressure stored in the memory to a remote processing device.

20. A pressure gauge device comprising: a hollow cylindrical body for insertion through the skull and having a lower end, an upper end, an inner surface, and an outer surface, the hollow cylindrical body comprising a tapered cylinder; a diaphragm attached to the lower end, the diaphragm being configured to move under pressure of cerebrospinal fluid within the skull, the outer surface of the hollow cylindrical body being threaded so that the manometer can be screwed into the skull and thereby secured therein; as well as a plurality of coils, the plurality of coils comprising a stationary coil and a moving coil, the stationary coil being disposed in the hollow cylindrical body and connected to the inner surface of the hollow cylindrical body so as to remain fixed relative to the hollow cylindrical body, the moving coil being disposed in the hollow cylindrical body and connected to the diaphragm such that when the diaphragm moves under the pressure from the cerebrospinal fluid, the moving coil moves relative to the stationary coil, one coil of the plurality of coils being configured as a transmitting coil, and another coil of the plurality of coils being configured as a receiving coil; in The upper end of the hollow cylindrical body includes a driver or bolt head to facilitate screwing the manometer into the skull for securing therein; the upper end being configured for interconnection with a complementary feature of a control unit, the control unit being reversibly attachable to the upper end of the hollow cylindrical body; The upper end includes a plurality of electrical connectors configured to electrically connect the control unit and the plurality of coils; The control unit is configured to contact the upper end of the hollow cylindrical body to apply an input signal to the transmitting coil and receive an output signal from the receiving coil in response to the input signal, and is configured to generate an indication of the pressure of the cerebrospinal fluid in response to the output signal.

21. The apparatus of claim 20, wherein the moving coil has a first axis and the stationary coil has a second axis, the first axis being substantially collinear with the second axis.

22. The device of claim 20, wherein the membrane comprises silicone.

23. The device of claim 22, wherein the organosilicon comprises polydimethylsiloxane (PDMS) having the chemical formula CH3[Si(CH3)2O]nSi(CH3)3.

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