Method and Apparatus for Detection of Nervous System Disorders

• US 20100292753A1
• Filed: 06/15/2010
• Published: 11/18/2010
• Est. Priority Date: 04/21/2006
• Status: Abandoned Application

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Werder, Jonathan C., Drew, Touby A., Panken, Eric J., Carlson, David L.
• Application Number:
  US12/816,055
• Publication Number:
  US 20100292753A1
• Time in Patent Office: Days
• US Class Current: 607/45
• CPC Class Codes: A61B 5/291 for electroencephalography [EEG]
• CPC Class Codes: A61B 5/4094 Diagnosing or monitoring seizure diseases, e.g. epilepsy
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61N 1/36082 Cognitive or psychiatric applications, e.g. dementia or Alzheimer's disease
• CPC Class Codes: G16H 20/30 relating to physical therapies or activities, e.g. physiotherapy, acupressure or exercising
• CPC Class Codes: G16H 40/63 for local operation
• CPC Class Codes: G16H 40/67 for remote operation
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

Systems and methods for detecting and/or treating nervous system disorders, such as seizures. Certain embodiments of the invention relate generally to implantable medical devices (IMDs) adapted to detect and treat nervous system disorders in patients with an IMD. Certain embodiments of the invention include detection of seizures based upon comparisons of long-term and short-term representations of physiological signals. Other embodiments include prediction of seizure activity based upon analysis of physiological signal levels. An embodiment of the invention monitors the quality of physiological signals, and may be able to compensate for signals of low signal quality. A further embodiment of the invention includes detection of seizure activity following the delivery of therapy.

Claims

1. A system for detecting a neurological event following delivery of therapy, the system comprising:

an electrode for sensing EEG signals from a brain of a patient; and

an implantable medical device (IMD) coupled to the electrode and adapted to receive EEG signals, the IMD comprising a housing, a power source, and a processor, the processor adapted to

detect a first neurological event using a first detection algorithm;

initiate therapy delivery in response to detecting the first neurological event; and

detect a post-therapy neurological event after therapy delivery using a second detection algorithm different than the first detection algorithm, the second algorithm comprising

initializing a post-therapy detection counter, C, to an initial value, C₀,

acquiring a stream of EEG signal data values following the therapy delivery,

comparing the signal data values to a level cutoff,

decrementing C by a decrement amount if a given data value is below the level cutoff,

incrementing C by an increment amount if a given data value is equal to or exceeds the level cutoff,

comparing C to a post-therapy detection threshold, and

detecting the post-therapy neurological event if C equals or exceeds the post-therapy detection threshold.

2. The system of claim 1 wherein the processor is adapted to impose a time delay after therapy delivery before (1) detecting a subsequent neurological event using the first detection algorithm, and/or (2) initiating subsequent therapy delivery based on the first detection algorithm, and wherein the processor is further adapted to detect the post-therapy neurological event during the time delay.

3. The system of claim 1 wherein detecting the post-therapy neurological event comprises redetecting the first neurological event.

4. The system of claim 1, wherein the IMD is adapted to receive multiple channels of EEG signals, and wherein the counter C compared to the post-therapy detection threshold is a logical combination of counters calculated for each channel.

5. The system of claim 4 wherein the counter C compared to the post-therapy detection threshold is a maximum function of counters calculated for each channel.

6. The system of claim 4 wherein the IMD prepares to deliver a subsequent therapy when the counter C exceeds the post-therapy detection threshold.

7. The system of claim 6 wherein the IMD is adapted to deliver a therapy after the counter C has exceeded the post-therapy detection threshold for an onset duration.

8. The system of claim 6 wherein the therapy delivered in response to detecting the first neurological event and the subsequent therapy are selected from the group consisting of electrical stimulation, magnetic stimulation, and drug infusion.

9. A system for detecting a neurological event following delivery of stimulation therapy, the system comprising:

an electrode for sensing EEG signals from a brain of a patient; and

an implantable medical device (IMD) coupled to the electrode and adapted to receive EEG signals, the IMD comprising a housing, a power source, and a processor, the processor adapted to detect a first neurological event using a first detection algorithm;

initiate stimulation therapy delivery in response to detecting the first neurological event;

impose a time delay after therapy delivery before (1) detecting a subsequent neurological event using the first detection algorithm, and/or (2) initiating subsequent stimulation therapy delivery based on the first detection algorithm; and

detect a post-stimulation neurological event during the time delay using a second detection algorithm different than the first detection algorithm, the second detection algorithm comprising

initializing a post-stimulation detection counter, C, to an initial value, C₀,

acquiring a stream of EEG signal data values following the delivery of the stimulation therapy,

comparing the signal data values to a level cutoff,

decrementing C by a decrement amount if a given data value is below the level cutoff,

incrementing C by an increment amount if a given data value is equal to or exceeds the level cutoff,

comparing C to a post-stimulation detection threshold, and

detecting the post-stimulation neurological event during the time delay if C equals or exceeds the post-stimulation detection threshold.

10. The system of claim 9, wherein the IMD is adapted to receive multiple channels of EEG signals, and wherein the counter C compared to the post-stimulation detection threshold is a logical combination of counters calculated for each channel.

11. The system of claim 10 wherein the counter C compared to the post-stimulation detection threshold is a maximum function of counters calculated for each channel.

12. The system of claim 10 wherein the IMD prepares to deliver a therapy when the counter C exceeds the post-stimulation detection threshold.

13. The system of claim 12 wherein the IMD is adapted to deliver the therapy after the counter C has exceeded the post-stimulation detection threshold for an onset duration.

14. The system of claim 10 wherein the IMD is adapted to deliver electrical stimulation therapy via the electrode.

15. The system of claim 9 wherein detecting the post-stimulation neurological event during the time delay comprises redetecting the first neurological event.