METHOD AND APPARATUS FOR DETECTION OF NERVOUS SYSTEM DISORDERS

• US 20070250133A1
• Filed: 02/21/2007
• Published: 10/25/2007
• Est. Priority Date: 04/21/2006
• Status: Active Grant

• 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.
• Granted Patent: US 7,979,130 B2
• Time in Patent Office: Days
• US Class Current: 607/45
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16
• CPC Class Codes: A61B 5/372 Analysis of electroencephalograms
• CPC Class Codes: A61B 5/375 using biofeedback
• CPC Class Codes: A61B 5/386 Accessories or supplementary instruments therefor
• 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: A61N 2/006 for magnetic stimulation of nerve tissue
• CPC Class Codes: G06F 2218/14 by matching peak patterns
• CPC Class Codes: G16H 20/30 relating to physical therapies or activities, e.g. physiotherapy, acupressure or exercising
• 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, are disclosed. 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. Further embodiments of the invention include preparing for the delivery of therapy by warming up therapy delivery components prior to the expected delivery of therapy.

Claims

1. A system for detecting a neurological event, comprising:

an electrode adapted to sense an EEG signal from a brain of a patient; and

an implantable medical device (IMD) coupled to the electrode and adapted to receive the sensed EEG signal, the IMD comprising a housing, a memory, and a processor, the processor being adapted to

sample the sensed EEG signal at a sample rate to form a stream of sampled data values;

calculate an event monitoring parameter based on the stream of sampled data values;

identify an onset of a neurological event when the event monitoring parameter exceeds an onset threshold; and

initiate warm-up of stimulation circuitry when the event monitoring parameter has exceeded the onset threshold for a period of time equal to an onset duration less a warm-up period, the onset duration being a predefined period of time such that a neurological event is detected if the event monitoring parameter exceeds the onset threshold for the onset duration.

2. The system of claim 1, wherein therapy is delivered to the patient via the stimulation circuitry upon detection of the neurological event.

3. The system of claim 1, wherein the stimulation circuitry is reset if the event monitoring parameter decreases below the onset threshold before detection of the neurological event.

4. The system of claim 3, wherein the stimulation circuitry is reset a predefined time period after completion of the onset duration.

5. The system of claim 4, where the stimulation circuitry is reset following one to five sample intervals after the onset duration.

6. The system of claim 3, wherein the stimulation circuitry is reset when the event monitoring parameter decreases below the onset threshold.

7. The system of claim 1, wherein the warm-up period is long enough to allow the stimulation circuitry to prepare for therapy delivery after warm-up is initiated.

8. The system of claim 7, wherein the warm-up period is approximately equal to an amount of time needed to completely charge the stimulation circuitry.

9. A method of treating a neurological event, the method comprising:

acquiring an EEG signal comprising a stream of sampled data values;

calculating an event monitoring parameter based on the sampled data values;

comparing the event monitoring parameter to an onset threshold;

identifying an onset of a neurological event when the event monitoring parameter exceeds an onset threshold; and

initiating warm-up of stimulation circuitry when the event monitoring parameter has exceeded the onset threshold for a period of time equal to an onset duration less a warm-up period, the onset duration being a predefined period of time such that a neurological event is detected if the event monitoring parameter exceeds the onset threshold for the onset duration.

10. The method of claim 9, further comprising delivering therapy to the patient via the stimulation circuitry upon detection of the neurological event.

11. The method of claim 9, further comprising resetting the stimulation circuitry if the event monitoring parameter decreases below the onset threshold before detecting the neurological event.

12. The method of claim 11, wherein resetting the stimulation circuitry occurs after completion of the onset duration.

13. The method of claim 11, wherein resetting the stimulation circuitry occurs when the event monitoring parameter decreases below the onset threshold.

14. The method of claim 9, wherein the warm-up period is long enough to allow the stimulation circuitry to prepare for therapy delivery after warm-up is initiated.

15. The method of claim 14, wherein the warm-up period is approximately equal to the amount of time needed to completely charge the stimulation circuitry.

16. A computer-readable medium programmed with instructions for performing a method of detecting a neurological event, the medium comprising instructions for causing a programmable processor to:

sample an EEG signal at a sample rate to form a stream of sampled data values;

calculate an event monitoring parameter based on the sampled data values;

identify an onset of a neurological event when the event monitoring parameter exceeds an onset threshold; and

initiate warm-up of stimulation circuitry when the event monitoring parameter has exceeded the onset threshold for a period of time equal to an onset duration less a warm-up period, the onset duration being a predefined period of time such that a neurological event is detected if the event monitoring parameter exceeds the onset threshold for the onset duration.

17. The medium of claim 16, further adapted to cause the programmable processor to deliver therapy to the patient via the stimulation circuitry upon detection of the neurological event.