DEVICES AND METHODS FOR ASSESSING MOTOR POINT ELECTROMYOGRAM AS A BIOMARKER

• US 20080287820A1
• Filed: 05/16/2008
• Published: 11/20/2008
• Est. Priority Date: 05/17/2007
• Status: Active Grant

• Current Assignee: Synapse Biomedical Inc.
• Original Assignee: Synapse Biomedical Inc.
• Inventors: Ignagni, Anthony R., Onders, Raymond P.
• Granted Patent: US 9,820,671 B2
• Time in Patent Office: Days
• US Class Current: 600/529
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61N 1/3601 of respiratory organs

Abstract

Described herein are methods of detecting the presence or progression of neuromuscular disorders (including ALS) based at least in part on diaphragm EMG signals taken at different points in time from the same implanted electrode(s). Signals may be used to diagnose or to monitor progression of a disorder or to track a treatment. Thus, diaphragm EMG signal may be used as a marker (e.g., a “biomarker”) for the detection or progression of a neurological disorder such as ALS. The characteristics or parameters of diaphragm EMG signals may be used to create an activity index, which may be output or compared and further analyzed. These signals may also be analyzed to show a difference between the left and right sides of the diaphragm.

Claims

1. A system for diagnosing or tracking the progression or treatment of a neurological disorder that affects the function of a diaphragm, the system comprising:

an implantable diaphragm electrode; and

an analyzer unit for processing EMG signals from the implantable diaphragm electrode at different times and determining an activity score based on the EMG signals, the analyzer unit comprising;

index-determining logic configured to determine at least one characteristic of an EMG signal and generate an activity index based on the EMG signal characteristic(s);

a memory configured to store one or more activity index; and

a comparator configured to compare a plurality of activity indexes and determine an activity score based on the comparison.

2. The system of claim 1, further comprising an output configured to present the activity score determined by the analyzer unit.

3. The system of claim 1, further comprising a controller configured to control acquisition of EMG signals from the implantable diaphragm electrodes at different times.

4. The system of claim 1, wherein the implantable diaphragm electrode includes an anchor for securing the electrode in communication with a diaphragm.

5. The system of claim 4, wherein the anchor comprises a barb.

6. The system of claim 1, wherein the implantable diaphragm electrode is selected from the group consisting of:

a monopolar electrode, a bipolar electrode, and a tripolar electrode.

7. The system of claim 1, further comprising a sensor, wherein the sensor is configured to measure one or more of:

tidal volume, airway pressure, or abdominal pressure.

8. The system of claim 7, wherein the index-determining logic of the analyzer is configured to generate an activity index based on the EMG signal characteristic(s) and input from the sensor.

9. The system of claim 1, wherein the index analyzer unit further comprises a measuring unit for measuring at least one characteristic of an EMG signal and providing the measured characteristic to the index-determining logic.

10. The system of claim 9, wherein the measuring unit is configured to measure at least one of:

amplitude, frequency, power spectrum, time-to-peak rise time, relaxation time, compound action potential rise time, compound action potential fall time, fast twitch muscle contribution, and slow-twitch muscle contribution.

11. A method of diagnosing or tracking the progression or treatment of a neurological disorder that affects the function of a diaphragm, the method comprising:

measuring a first EMG signal at an initial recording time from one or more electrodes implanted in a diaphragm;

measuring a second EMG signal from the same one or more electrodes at a later recording time; and

comparing the first EMG signal and the second EMG signal.

12. The method of claim 11, wherein the disorder comprises any of a centrally-mediated breathing disorder or a neurodegenerative disease.

13. The method of claim 11, wherein the comparing step comprises comparing one or more of amplitude, frequency, power spectrum, time-to-peak rise time, relaxation time, compound action potential rise time, compound action potential fall time, fast twitch muscle contribution, and slow-twitch muscle contribution.

14. The method of claim 11, further comprising:

mapping the diaphragm to determine an active region of the diaphragm; and

implanting the one or more electrodes at an active region of the diaphragm.

15. The method of claim 11, further comprising:

mapping the diaphragm to determine a phrenic nerve motor point of the diaphragm; and

implanting the one or more electrodes at the phrenic nerve motor point.

16. The method of claim 15, wherein the mapping step includes applying electrical stimuli to an area of diaphragm surface and identifying a site within the area that provokes a maximal physiological response to the stimuli.

17. The method of claim 16, wherein the mapping step includes observing a physiological response to the stimuli including any of:

abdominal pressure or airway pressure, and diaphragm contraction.

18. The method of claim 11, wherein measuring the first EMG signal comprises:

selecting a duration and/or period of time for collection; and

quantifying at least one characteristic of the EMG signal over the selected time.

19. The method of claim 18, wherein the time duration of collection of the EMG signal is selecting from the group consisting of:

a single breath, a particular number of breaths, or a particular interval of time.

20. The method of claim 18, wherein the characteristic of the EMG signal quantified is selected from the group consisting of:

amplitude, frequency, power spectrum, time-to-peak rise time, relaxation time, compound action potential rise time, compound action potential fall time, fast twitch muscle contribution, and slow-twitch muscle contribution.

21. The method of claim 11, wherein the steps of measuring the first EMG signal and measuring the second EMG signal comprises filtering the EMG signals to remove or reduce electrical signals not arising from the diaphragm.

22. The method of claim 11, further comprising correlating the EMG signals with a measurement of another physiological parameter.

23. The method of claim 22, wherein the physiological parameter comprises one or more blood gas level, airway pressure, abdominal pressure, and abdominal movement.

24. A method of diagnosing or tracking the progression or treatment of a neurological disorder that affects the function of a patient'"'"'s diaphragm, the method comprising:

determining a first activity index from a patient'"'"'s diaphragm motor point EMG at a first time;

determining a second activity index from the patient'"'"'s diaphragm motor point EMG at a second time;

comparing the first activity index and the second activity index; and

characterizing the presence, progression or treatment of a neurological disorder based on the comparison between the first activity index and the second activity index.

25. The method of claim 24, further comprising mapping the patient'"'"'s diaphragm to determine a phrenic nerve motor point.

26. The method of claim 24, further comprising implanting a diaphragm electrode in or adjacent to the patient'"'"'s diaphragm at a phrenic nerve motor point.

27. The method of claim 24, wherein first and second activity indexes are determined based at least in part on one or more of:

amplitude, frequency, power spectrum, time-to-peak rise time, relaxation time, compound action potential rise time, compound action potential fall time, fast twitch muscle contribution, and slow-twitch muscle contribution.

28. The method of claim 24, wherein the first and second activity indexes are determined at least in part from EMG signals recorded while the patient is sleeping.

29. The method of claim 24, wherein the first and second activity indexes are determined at least in part from EMG signals recorded during a volitional maneuver.

30. The method of claim 29, wherein the volitional maneuver is a sniff or a maximal inhalation.

31. The method of claim 24, wherein the step of determining the first activity index comprises determining the first activity index from the patient'"'"'s diaphragm motor point EMG and a respiratory parameter value at the first time, and further wherein the step of determining the second activity index comprises determining the second activity index from the patient'"'"'s diaphragm motor point EMG and the respiratory parameter value at the second time.

32. The method of claim 31, wherein the respiratory parameters are selected from the group consisting of:

tidal volume, airway pressure, abdominal movement, abdominal pressure, and blood gas level.

33. A method of detecting the presence, progression or treatment of amyotrophic lateral sclerosis in a patient, the method comprising:

mapping the patient'"'"'s diaphragm to determine an active region;

implanting an intramuscular electrode at an active region in the patient'"'"'s diaphragm;

determining a first activity index from a diaphragm EMG detected by the implanted electrode at a first time;

determining a second activity index from a diaphragm EMG detected by the implanted electrode at a second time; and

determining the presence, progression, or treatment of amyotrophic lateral sclerosis based on a comparison between the first activity index and the second activity index.

34. The method of claim 33, wherein the step of implanting comprises implanting the electrode on or near a phrenic nerve motor point.

35. The method of claim 33, wherein the first and second activity indexes are determined at least in part from estimates of one more of EMG:

amplitude, frequency, power spectrum, time-to-peak rise time, relaxation time, compound action potential rise time, compound action potential fall time, fast twitch muscle contribution, and slow-twitch muscle contribution.