Method and system for measuring the degree of muscle displacement and use of the method and system in the treatment of obstructive sleep apnea - Patents.com

Abstract

The invention described herein refers to a method for measuring the degree of airway patency, e.g., muscle displacement, a system for implementing the method, and the use of the method and system in obstructive sleep apnea therapy. A method for measuring the degree of a subject's muscle contraction in response to electrical neural stimulation includes generating a modulated signal, the modulated signal comprising an electrical stimulation pattern, applying the modulated signal to at least a pair of electrodes associated with an implant unit implanted inside the subject's body, detecting movement of one or more muscles associated with the subject's airway in response to the modulated signal applied to the at least a pair of electrodes, and assigning a value to the determined movement indicative of the degree of airway patency and / or airway obstruction.

Description

[Technical field]

[0001] The invention described herein refers to a method for measuring the degree of muscle displacement, a system for implementing said method, and the use of said method and system in obstructive sleep apnea therapy. [Background technology]

[0002] Neuromodulation, i.e., electrical stimulation of nerves, is well known in the prior art as a reliable and effective type of medical treatment. It presents an opportunity to address many physiological conditions and disorders by interacting with the body's own natural nerve processes. Neuromodulation involves the inhibition (e.g., blocking), stimulation, modification, adjustment, or therapeutic modification of electrical or chemical activity within the central, peripheral, or autonomic nervous system. By modulating the activity of the nervous system, several different goals can be achieved. For example, motor neurons can be stimulated at the appropriate time to cause muscle contraction. Furthermore, sensory neurons can be blocked to relieve pain or stimulated to provide a signal to a subject. In yet other examples, modulation of the autonomic nervous system may be used to regulate various involuntary physiological parameters, such as heart rate and blood pressure. Neuromodulation may provide an opportunity to treat several diseases or physiological conditions. Various devices and techniques are used in an attempt to provide optimal stimulation of the tissue of interest.

[0003] In the context of this disclosure, the expressions "neurostimulation", "neural stimulation", "neuromodulation" and "neuromodulation" are used synonymously unless otherwise clear from the particular context. In general, the above expressions refer to the process of generating an electric field in the vicinity of a nerve or group of nerves to cause contraction of one or more muscles associated with the nerve. Similarly, the expressions "subject" and "patient" are used synonymously unless otherwise clear from the particular context. Both terms refer to a human potentially suffering from OSA.

[0004] One of the conditions to which neural modulation can be applied is obstructive sleep apnea (OSA), a breathing disorder characterized by recurrent episodes of partial or complete obstruction of the upper airway during sleep. One of the main causes of OSA is the inability of the tongue muscle to resist the negative inspiratory pressure in the pharynx due to sleep-related loss of muscle tone. As the tongue is drawn backward, this obstructs the upper airway, reducing ventilation and lowering lung and blood oxygen levels. Stimulation of the hypoglossal nerve ("hypoglossal nerve stimulation", or HGNS) contracts the tongue muscle, thereby maintaining an open, unobstructed airway. When a person who does not suffer from OSA sleeps, the pharyngeal muscles, the group of muscles that form the pharynx, relax and progressively collapse and narrow the airway. The narrowing of the airway, in turn, limits the effectiveness of the sleeper's breath and causes an increase in CO2 levels in the sleeper's blood. The increase in CO2 causes the pharyngeal muscles to contract, opening the airway and restoring proper breathing. The larger of the pharyngeal muscles involved in upper airway expansion is the genioglossus, which is one of several different muscles in the tongue.

[0005] The genioglossus muscle is involved in the forward movement of the tongue and the stiffening of the anterior pharyngeal wall. In patients with OSA, the neuromuscular activity of the genioglossus muscle is reduced compared to normal individuals, causing insufficient response and contraction to open the airway compared to normal individuals. This lack of response contributes to partial or complete airway obstruction, which significantly limits the sleeper's ability to breathe. In OSA patients, several airway obstruction events often occur during the night. Due to the obstruction, a gradual decrease in O2 levels in the blood (hypoxemia) occurs. Hypoxemia leads to night-time awakenings, which can be detected by EEG and indicate that the brain is awakened from any stage of sleep to a short awakening. During the awakening, conscious gasping or wheezing occurs, which resolves the airway obstruction. An increase in the rate of sympathetic tone activity through the release of hormones such as epinephrine and noradrenaline also often occurs as a response to hypoxemia. Increased sympathetic tone causes the heart to enlarge in an attempt to pump more blood, increasing blood pressure and heart rate, further arousing the patient after resolution of the apneic event, and as the patient returns to sleep, the airway collapses again, leading to further arousals.

[0006] In order to quantify the effectiveness of neuromodulation as a therapeutically effective method (especially HGNS), as well as for analysis purposes, it is important that therapy response is closely monitored. This is usually achieved through monitoring the subject's nasal and / or oral airflow, for example, with the use of PSG (sleep study, i.e., polysomnography) or CPAP (continuous positive airway pressure) mask. Alternatively, the patient can self-assess therapy effectiveness during wake-up titration. Other methods may include visually observing airway opening or tongue protrusion to assess whether therapy has produced the desired motor response. Further assessment of therapy response includes drug-induced or wake-up endoscopy.

[0007] The above methods have several drawbacks. Solutions involving airflow are not suitable for seamless implementation for neurostimulation in existing systems. Furthermore, using masks and the like can be perceived as cumbersome by the subject. With regard to self-assessment or visualization of airway patency or tongue protrusion, these methods can be highly subjective and therefore subject to variable results or errors. Furthermore, even objective visual assessments only provide qualitative results, not quantitative ones.

[0008] The objective technical problem of the present disclosure is to eliminate the shortcomings of the prior art and provide a method for measuring the degree of airway patency, for example, muscle displacement, to facilitate quantification of the effectiveness of neuromodulation therapy.Furthermore, the method should improve electrical neurostimulation in patients associated with OSA. Summary of the Invention [Means for solving the problem]

[0009] SUMMARY OF THEINVENTION The main features of the method according to the present disclosure are defined by claim 1. Special embodiments or advantageous variants of the method are depicted in claims 2-7. Systems for implementing the method are defined in claims 8-9. Furthermore, the use of the method is defined by claim 10.

[0010] According to a first aspect of the present disclosure, the objective technical problem is solved by a method for measuring a degree of muscle collapse and / or contraction in a subject in response to electrical nerve stimulation, the method comprising: - generating a modulated signal, the modulated signal comprising an electrical stimulation pattern; - applying a modulated signal to at least a pair of electrodes associated with an implant unit that is implanted inside the subject's body; - detecting movement of one or more muscles associated with the subject's airway in response to a modulated signal applied to at least a pair of electrodes; - assigning a value to the determined movement, which indicates the degree of airway opening and / or obstruction, e.g., muscle displacement; Includes.

[0011] Using the method as described above, the effectiveness of neurostimulation during the treatment of a patient suffering from OSA, particularly the effectiveness of stimulation of the hypoglossal nerve or cervical nerve trap, can be monitored in an easy and accurate manner. It should be understood that the hypoglossal nerve innervates the genioglossus muscle, and the cervical nerve trap innervates the subhyoid cingulum muscle, which is involved in stiffening or collapsing the subject's upper airway. The subhyoid muscles include the sternohyoid, sternothyroid, omohyoid, and thyrohyoid muscles. Furthermore, if required, the system allows for continuous monitoring over a desired period of time, providing important information regarding the long-term effectiveness of the neurostimulation therapy.

[0012] Muscle contraction in the sense of the present disclosure may refer to muscle displacement, and these terms are used synonymously unless otherwise indicated. Muscle contraction may particularly (but not exclusively) refer to displacement of the tongue of a subject or other muscles associated with the airway of a subject.

[0013] Movement of one or more muscles associated with the subject's airway, within the meaning of the present disclosure, may also include movement of the subject's jaw, since contraction of one or more of the muscles involved in tongue movement will also result in the jaw being moved. Thus, the degree of airway opening and / or airway obstruction, for example, muscle displacement, may also be determined by measuring the subject's jaw movement.

[0014] The modulated signal, including the electrical stimulation pattern, is preferably generated by an external device, which may be configured for placement beneath the subject's chin. In particular, the modulated signal may be generated by a control unit and / or by a processor, both of which may be part of the external unit. The modulated signal may further be transmitted to the implanted unit using a transmission element, which may comprise an antenna or coil associated with the control unit.

[0015] According to another embodiment, the control unit may be part of an implanted unit that is implanted directly under the skin of the subject, either instead of or in addition to the control unit of an external device. Thus, the control unit may be located directly on the muscle to be monitored, for example on the genioglossus muscle, or on one or more of the infrahyoid muscles, in particular on the sternohyoid or sternothyroid muscles. In other words, the location of the control unit is not essential to the method underlying the present disclosure. In any case, the control unit may preferably be in electrical communication with at least one motion sensing unit.

[0016] The step of applying the modulated signal to at least a pair of electrodes may preferably be implemented by an implant unit. The implant unit may be implantable near or adjacent to any muscle associated with the subject's airway, for example, the genioglossus muscle, which is innervated by the hypoglossal nerve. The implant unit may comprise an electrical circuit that receives the electrical stimulation pattern through electrical communication between an external device and the implant unit, and thus generates an electric field via the at least a pair of electrodes associated with the implant unit.

[0017] The step of determining the movement of one or more muscles associated with the subject's airway opening in response to the modulated signal may preferably be implemented by a motion sensing unit. Similarly, muscles associated with the subject's airway opening are also involved in airway obstruction, which can be detected using the method described herein. The method may further be characterized in that at least one motion sensing unit comprises at least one inertial measurement unit (IMU) and / or at least one strain gauge. According to an exemplary embodiment, the movement of one or more muscles associated with the subject's airway opening and / or obstruction may also be determined by detecting the movement of muscles associated with the subject's airway opening and / or obstruction, in particular the movement of the subject's jaw, since the movement of the subject's tongue will also result in the movement of the subject's jaw.

[0018] Using the presented method, the actual physiological effects to be achieved through the stimulation therapy, i.e., contraction (or non-contraction) of the targeted muscle or group of muscles, can be monitored rather than the symptoms of the disease or disorder. The latter may not be immediately improved by the therapy in some cases, so they may be misleading when monitored and used as a basis for adjusting the stimulation. For example, if a patient or subject suffers from a disorder such as central sleep apnea (CSA), measurements of airflow in response to neural stimulation therapy would indicate apneic events. This would suggest inefficacy of the therapy and potentially lead to a decision to increase the stimulation intensity. However, since the stimulation therapy would not be able to prevent apneic events in CSA in the first place, increasing or decreasing the stimulation intensity (or adjusting any other of the stimulation parameters) would not affect the patient's condition for sleep apnea disorder. Thus, airflow is not any viable indicator for determining the effectiveness of neural stimulation.

[0019] Using the methods described herein, the underlying neurostimulation therapy, i.e., physiological pathologies that are directly affected by muscle contraction, are monitored. In this way, it is possible to obtain accurate information regarding therapy efficacy. Based on the determined degree of muscle displacement in response to stimulation with a defined set of stimulation parameters, it is further possible to adjust those parameters to improve therapy efficacy. For example, if a set of stimulation parameters is not sufficient to cause tongue protrusion and open the airway, the underlying stimulation parameters may be adjusted accordingly, for example, by increasing the stimulation intensity.

[0020] According to further embodiments of the method, a threshold degree of airway opening and / or airway obstruction (e.g., of muscle displacement) may be predefined. In such a case, a value indicative of airway opening will be assigned to the determined muscle movement only if the threshold degree of airway opening is exceeded. Airway opening may include, for example, tongue protrusion caused by innervation of the genioglossus muscle, or widening of the upper airway caused by innervation of one or more of the infrahyoid muscles.

[0021] According to one embodiment disclosed herein, the method further includes adjusting at least one parameter of the electrical stimulation pattern in response to a value indicative of the degree of airway opening, e.g., muscle displacement. In this way, a feedback-based or closed-loop stimulation method is provided, in which the effectiveness of an ongoing stimulation session is determined by measuring the degree of displacement of the subject's muscles in response to the associated neural stimulation, and then adjusting the stimulation parameters in response to the measured degree of airway opening and / or airway obstruction. The degree of airway opening and / or airway obstruction can be determined, for example, by detecting the movement (i.e., collapsing or protruding) of the muscles associated with the tongue, or by detecting the movement of the subject's jaw. The adjustment of the at least one stimulation parameter can occur automatically, or manually (e.g., through a physician or through the subject himself), or both. In the case of automatic adjustment, the at least one stimulation parameter can be changed after a set time delay or almost immediately (i.e., in real time). This process may be automatically repeated in an iterative manner until one of the automatic adjustments of the stimulation parameters results in the determination of a value indicative of muscle contraction associated with a desired degree of airway opening and / or airway obstruction.

[0022] To achieve a feedback-based or closed-loop stimulation session, the control unit may be configured to perform logical operations such as comparing the detected degree of movement (or non-movement) of one of the muscles associated with the subject's airway to a predefined value and adjusting one or more of the stimulation parameters accordingly. For example, if the detected degree of tongue displacement or jaw movement is below a predefined value, the control unit may be configured to increase the stimulation intensity. Another example is that the control unit may be configured to trigger stimulation if the degree of tongue crushing is above a predefined value, i.e., resulting in an obstruction of the subject's airway.

[0023] Advantageously, the movement of muscles associated with the subject's airway may include muscle contraction, a change in tongue position and / or a change in the spatial orientation of the tongue within the subject, and / or a movement of the subject's jaw. In particular, but not exclusively, muscle contraction may refer to contraction of the genioglossus muscle, particularly when innervated by the hypoglossal nerve.

[0024] It is also possible that the movement of one or more muscles associated with the tongue of the subject is determined using at least one motion sensing unit. The method may further be characterized in that the at least one motion sensing unit comprises at least one inertial measurement unit and / or at least one strain gauge. According to another embodiment, the inertial measurement unit may comprise at least one accelerometer and / or at least one gyroscope and / or at least one magnetometer. Preferably, at least one accelerometer may be implemented, which may comprise a single-axis accelerometer or a multi-axis accelerometer.

[0025] The at least one parameter may comprise pulse train amplitude, pulse train length, single pulse frequency, single pulse duration, hold duration, pulse train interval, duty cycle, delay time, rise duration, step down amplitude, rise at train start duration, and / or confirm pulse / train amplitude. The stimulation parameters may be adjusted automatically based on values ​​assigned to the measured degree of airway opening and / or airway obstruction, or the parameters can be adjusted by a physician or by the patient themselves in response to receiving information that the current stimulation parameters are not sufficient.

[0026] According to another aspect of the present invention, a system for measuring a degree of airway patency and / or airway obstruction, e.g., muscle displacement in a subject, is provided, the system comprising: an implantation unit configured for implantation near or in proximity to any muscle associated with the subject's airway, such as one of the genioglossus or subhyoid cingulum muscles, the implantation unit comprising at least a pair of electrodes; an external device configured for communication with the embedded unit; at least one motion sensing unit for determining movement of one or more muscles associated with the subject's airway in response to a modulated signal applied to at least a pair of electrodes; Equipped with. The system may preferably be configured to implement the methods described herein.

[0027] In addition to the above, the system may include a control unit. The control unit may be part of an external device. In that case, the control unit may transmit modulation or stimulation input signals, e.g., stimulation parameters and power, to the implanted unit. The control unit may further receive determined data corresponding to the movement of one or more muscles associated with the tongue of the subject determined by the motion sensing unit, and assign a value to the degree of airway opening and / or airway obstruction. According to a preferred embodiment, the control unit may also adjust at least one of the stimulation parameters in response to a value indicative of the degree of airway opening and / or airway obstruction, e.g., muscle displacement.

[0028] The control unit may thus comprise one or more processors, which may include any electrical circuitry configured to perform a logical operation on at least one input variable. The at least one processor of the control unit may thus include one or more integrated circuits, microchips, microcontrollers, and microprocessors, which may be all or part of a central processing unit (CPU), digital signal processor (DSP), field programmable gate array (FPGA), or any other circuitry known to those skilled in the art that may be suitable for executing instructions or performing logical operations.

[0029] The implant unit may be configured for implantation in a location that allows for modulation of a nerve (e.g., the hypoglossal nerve). The implant unit may be located in the subject such that intervening tissue is between the implant unit and the nerve to be modulated. The intervening tissue may include muscle tissue, connective tissue, organ tissue, or any other type of biological tissue. Thus, the location of the implant unit does not require immediate contact with the nerve for effective neuromodulation. The implant unit may also be located directly adjacent to the nerve such that there is no intervening tissue.

[0030] When treating OSA, the implant unit may be located over the genioglossus muscle of the patient or subject. Such a location is suitable for modulation of the hypoglossal nerve, whose branches extend medially to and innervate the genioglossus muscle. However, the implant unit may also be configured for placement in other locations.

[0031] The external device may be configured for placement on the outside of the patient, either in direct contact with or near the patient's skin. The external device may also be configured to be affixed to the patient, for example, by adhering to the patient's skin or through a band or other device configured to hold the external device in place. Adherence of the external unit to the skin may occur such that it is near or adjacent to the location of the implant unit.

[0032] The external device may be configured for fixation to the patient. For example, the external device may be configured for placement beneath the subject's chin and / or on the front of the patient's neck. The suitability of the placement location may be determined by communication between the external device and the implant unit. The external device may comprise a housing, which may be any suitable container configured to hold electrical components. In addition, the housing may be of any suitable size and / or shape and may be rigid or flexible. Examples of housings for the external device may include one or more of patches, buttons, or other receptacles having various shapes and dimensions and constructed of any suitable material. The external device may be configured to adhere to a desired location. Thus, in some embodiments, at least one side of the housing may include an adhesive material. The adhesive material may include a biocompatible material and may allow the patient to adhere the external unit to a desired location and remove the external device upon completion of use. The adhesive may be configured for single or multiple use of the external unit. Suitable adhesive materials may include, but are not limited to, biocompatible adhesive glues, starches, elastomers, thermoplastics, and emulsions.

[0033] According to an embodiment, at least one motion sensing unit may be part of the implanted unit, and / or at least one motion sensing unit may be part of the external device. It is also possible that both the implanted unit and the external device are equipped with a motion sensing unit. If this is the case, the motion sensing units may be different from each other, i.e., the motion sensing unit of the internal unit may be a strain gauge, and the motion sensing unit of the external device may be an accelerometer. For example, if the motion sensing unit is part of the external device, the motion sensing unit may be an IMU, preferably configured to detect jaw movement, since the external device is preferably located directly under the subject's jaw, and since a stimulation event resulting in the contraction of one or more muscles related to tongue movement will also result in the movement of the subject's jaw.

[0034] If the motion sensing unit is part of an implanted unit, the motion sensing unit may preferably comprise a strain gauge, either as a stand-alone component or in conjunction with an IMU, as strain gauges are suitable for detecting and measuring muscle contractions.

[0035] According to another aspect of the present disclosure, the use of the method disclosed herein for the treatment of obstructive sleep apnea is presented. The treatment of obstructive sleep apnea, for which the present method may be used, may, for example, comprise the following steps: - receiving a modulated signal at an implant unit that is implanted at an internal location on the underside of the subject's jaw (e.g., near the genioglossus muscle); - applying a modulated signal to at least a pair of electrodes associated with the implanted unit to generate an electric field; - Causing modulation of the subject's hypoglossal nerve, or of the cervical nerve fascicle, in response to an electric field generated by at least a pair of electrodes, where the modulation of the hypoglossal nerve may be localized to the medial branch of the hypoglossal nerve and may be initiated from a single modulation site along the medial branch; may include:

[0036] Thus, at least a pair of modulation electrodes may be configured for implantation through the dermis on the underside of a subject's jaw and for placement proximate to terminal fibers of the medial branch of the hypoglossal nerve of the subject. Additionally, the implantable unit and the electrodes may be configured to cooperate to generate an electric field adapted to modulate one or more of the terminal fibers of the medial branch of the hypoglossal nerve.

[0037] Any of the embodiments, examples, or features disclosed herein may be used in combination or separately and with any one of the aspects of the disclosed subject matter. [Brief description of the drawings]

[0038] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the disclosed subject matter.

[0039] [Figure 1] FIG. 1 shows a schematic diagram of the system disclosed herein according to a first embodiment. [Diagram 2] FIG. 2 shows a schematic diagram of a system according to a second embodiment. [Diagram 3] FIG. 3 shows a schematic diagram of a system according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Detailed Description of the Drawings FIG. 1 shows a schematic diagram of a system 100 for measuring the degree of airway opening and / or airway obstruction, e.g., muscle displacement, of a subject in response to electrical neurostimulation, the muscle being part of one or more of a group of muscles involved in the subject's breathing, e.g., tongue, genioglossus, or subhyoid cingulum. The flow diagram of FIG. 1 may serve as a representation of the concept underlying the method. According to FIG. 1, a neurostimulation system 100 configured for implementing the method comprises a control unit 500 and a motion sensing unit 400. Furthermore, the system 100 may comprise an implantation unit 200 (not shown), preferably configured for implantation adjacent to any muscle associated with the subject's airway, e.g., genioglossus, and an external device 300 (not shown) configured for electrical communication with the implantation unit 200.

[0041] The implant unit 200 of the system 100, with which the method may be performed, may be implanted near one of the genioglossus muscle, innervated by the hypoglossal nerve, or the infrahyoid muscle, innervated by the cervical nerve trap. The implant unit 200 may further comprise a transmission element, which may comprise a secondary antenna or coil, and an electrical circuit that receives an electrical stimulation pattern through electrical communication between the external device 300 and the implant unit 200. In response to receiving the electrical stimulation pattern, the electrical circuit may generate an electric field through at least a pair of electrodes associated with the implant unit 200. If the electric field is strong enough and / or close enough to the nerve, the nerve will be stimulated and innervate the associated muscle, which will in turn contract. The specifications of the implant unit 200 are not limited to an embodiment, so long as the implant unit 200 is configured for use with the methods described herein.

[0042] The external device 300 of the system 100, with which the method may be performed, may be configured for placement on the outside of the patient, specifically beneath the subject's chin and / or on the front of the patient's neck. The external device 300 may thus be configured for attachment to the patient, for example, by adhering to the patient's skin or through a band or other device configured to hold the external device in place. The external device 300 may preferably comprise a housing, which may be any suitable container configured to hold electrical components. In addition, the housing may be of any suitable size and / or shape, and may be rigid or flexible. Examples of housings for the external device 300 may include one or more of a patch, button, or other receptacle having various shapes and dimensions and constructed of any suitable material. The specifications of the external device 300 are not limited to certain embodiments, so long as the implant unit 200 is configured for use with the methods described herein.

[0043] To determine the movement (i.e., contraction) of one or more muscles associated with the subject's airway in response to the electric field applied by the implanted unit 200, the system 100 includes a motion sensing unit 400 that includes at least one inertial measurement unit 401 and / or at least one strain gauge. The inertial measurement unit may include at least one accelerometer and / or at least one gyroscope and / or at least one magnetometer.

[0044] 1 may comprise a control unit 500, for example as part of the external device 300. The control unit 500 may transmit modulation or stimulation input signals, for example stimulation parameters and power, to the implanted unit 200.

[0045] According to the method depicted in FIG. 1, the control unit 500 may also receive data corresponding to the movement of one or more muscles associated with the subject's breath or airway as determined by the motion sensing unit 400 and assign a value associated with the degree of airway opening and / or airway obstruction. According to a preferred embodiment of the method, the control unit 500 may also adjust at least one of the stimulation parameters in response to the value indicative of the degree of airway opening and / or airway obstruction. Thus, the control unit 500 may comprise one or more processors, which may include any electrical circuit configured to perform a logical operation on at least one input variable. The at least one processor of the control unit 500 may include, for example, one or more integrated circuits, microchips, microcontrollers, and microprocessors, which may be all or part of a central processing unit (CPU), digital signal processor (DSP), field programmable gate array (FPGA), or any other circuit known to those skilled in the art that may be suitable for executing instructions or performing logical operations. Thus, a method for feedback-based or closed-loop neurostimulation is provided in which the effectiveness of an ongoing stimulation session is determined by measuring the degree of airway patency and then automatically adjusting stimulation parameters in response to the measured degree of airway patency. The degree of tongue protrusion of the subject can be determined, for example, by detecting movement of muscles associated with the tongue or by detecting movement of the subject's jaw. The automatic adjustment may include the control unit 500 receiving a value indicative of tongue movement from the motion sensing unit 400 and adjusting at least one stimulation parameter in response, either after a set time delay or nearly immediately (i.e., in real time).

[0046] According to FIG. 1 , the control unit 500 can be part of the external device 300 , of the implanted unit 200 , or of both the external device 300 and the implanted unit 200 .

[0047] Fig. 2 shows a schematic diagram of a system 100 according to a second embodiment for measuring the degree of airway opening and / or airway obstruction, e.g., muscle displacement, of a subject in response to electrical neural stimulation. Compared to the system of Fig. 1, the system 100 of Fig. 2 is further defined in that a motion sensing unit 400 and a control unit 500 are both shown as part of the external device 300. In this case, the motion sensing unit 400 may preferably comprise at least one inertial measurement unit, e.g., an accelerometer.

[0048] Figure 3 depicts a flow diagram of a third embodiment of a system 100 for measuring the degree of airway patency, e.g., displacement, of a subject in response to electrical neural stimulation. The system 100 of Figure 3 is further defined in that a motion sensing unit 400 and a control unit 500 are both shown as part of the implant unit 200. In this case, the motion sensing unit 400 may preferably comprise at least one strain unit configured to detect muscle contractions.

[0049] The invention is not limited to one of the embodiments described herein but can be modified in many other ways.

[0050] All features disclosed in the claims, the specification and the drawings, as well as all advantages, including architectural details, spatial arrangements and methodological steps, may be essential to the invention, either by themselves or in various combinations with one another.

[0051] List of reference numbers 100 Systems 200 Embedded Units 300 External Devices 400 Motion Sensing Unit 500 Control Unit

Claims

1. 1. A method of operating a system for measuring a subject's degree of muscle contraction in response to electrical nerve stimulation, the method comprising: a control unit of the system generating a modulated signal, the modulated signal comprising an electrical stimulation pattern; an implant unit of the system, implanted inside the subject's body, applying the modulated signal to at least a pair of electrodes associated with the implant unit; detecting, by at least one motion sensing unit of the system, movement of one or more muscles associated with the subject's airway in response to the modulated signal applied to the at least one pair of electrodes; the control unit assigning a value to the determined movement indicative of a degree of airway opening and / or airway obstruction; A method of operation comprising:

2. The method of operation further comprises: - the control unit adjusts at least one parameter of the electrical stimulation pattern in response to the value indicative of the degree of airway patency and / or airway obstruction. The method of claim 1 , comprising:

3. 2. The method of claim 1, wherein the movement of the muscles associated with the subject's airway comprises airway muscle contraction, a change in the position of the subject's tongue, and / or a change in the spatial orientation of the tongue within the subject.

4. The method of claim 1 , wherein the at least one motion sensing unit comprises at least one inertial measurement unit and / or at least one strain gauge.

5. 5. The method of claim 4, wherein the inertial measurement unit comprises at least one accelerometer and / or at least one gyroscope and / or at least one magnetometer.

6. 3. The method of claim 2, wherein the at least one parameter comprises pulse train amplitude, pulse train length, single pulse frequency, single pulse duration, hold duration, pulse train spacing, duty cycle, delay time, rise duration, step down amplitude, rise at train start duration, and / or confirmation pulse / train amplitude.

7. A system under the control of the operating method according to any one of claims 1 to 6, wherein the system comprises: - said implantation unit configured for implantation near any muscle associated with airway patency and / or airway obstruction in said subject; an external device configured for communication with said implant unit; said at least one motion sensing unit; A system comprising:

8. The system of claim 7 , wherein the at least one motion sensing unit is part of the implanted unit and / or the at least one motion sensing unit is part of the external device.

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