Clustering of recorded patient neurological activity to determine length of a neurological event

• US 7,933,646 B2
• Filed: 08/13/2007
• Issued: 04/26/2011
• Est. Priority Date: 10/15/2002
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Rise, Mark T., Schaffner, Scott F., Carlson, David L., Frei, Mark G., Osorio, Ivan, Giftakis, Jonathon E., Graves, Nina M.
• Primary Examiner(s): Marmor, II; Charles A
• Assistant Examiner(s): Toth; Karen E
• Application Number:
  US11/837,987
• Publication Number:
  US 20080064934A1
• Time in Patent Office: 1,352 Days
• Field of Search: 600544-545
• US Class Current: 600/544
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16
• CPC Class Codes: A61B 5/4094 Diagnosing or monitoring seizure diseases, e.g. epilepsy
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: A61M 5/1723 using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00
• CPC Class Codes: A61N 1/36025 for treating a mental or cerebral condition
• CPC Class Codes: A61N 1/36064 Epilepsy
• CPC Class Codes: A61N 1/36082 Cognitive or psychiatric applications, e.g. dementia or Alzheimer's disease
• CPC Class Codes: A61N 1/361 Phantom sensations, e.g. tinnitus

Abstract

Apparatus and method detect a detection cluster that is associated with a neurological event, such as a seizure, of a nervous system disorder and update therapy parameters that are associated with a treatment therapy. The occurrence of the detection cluster is detected when the maximal ratio exceeds an intensity threshold. If the maximal ratio drops below the intensity threshold for a time interval that is less than a time threshold and subsequently rises above the intensity threshold, the subsequent time duration is considered as being associated with the detection cluster rather than being associated with a different detection cluster. Consequently, treatment of the nervous system disorder during the corresponding time period is in accordance with one detection cluster. Treatment therapy may be provided by providing electrical stimulation, drug infusion or a combination. Therapy parameters may be updated for each m^th successive group of applications of the treatment therapy or for each n^th detection cluster.

Claims

1. A method for determining a detection cluster that is associated with a neurological event of a nervous system disorder of a patient with a medical device system, the detection cluster being associated with at least one detection that exceeds a predetermined ratio threshold for a first predetermined time duration, the method comprising the steps of:

(a) receiving a set of neurological signals, wherein each neurological signal is associated with a monitoring element; and

(b) if any neurological signal of the set of neurological signals exceeds the predetermined ratio threshold for the first predetermined time duration, adjusting by at least one processor a first duration of the detection cluster by combining a second duration of the neurological signal with the first predetermined time duration.

2. The method of claim 1, wherein the nervous system disorder is selected from the group consisting of a disorder of a central nervous system, a disorder of a peripheral nervous system, and a mental health disorder, and a psychiatric disorder.

3. The method of claim 2, wherein the nervous system disorder is selected from the group consisting of epilepsy, Parkinson'"'"'s disease, essential tremor, dystonia, multiple sclerosis (MS), anxiety, a mood disorder, a sleep disorder, obesity, and anorexia.

4. The method of claim 1, wherein the monitoring element is selected from the group consisting of an electrode and a sensor.

5. The method of claim 1, wherein the each neurological signal is selected from the group consisting of an electrical signal, a chemical signal, a biological signal, a temperature signal, a pressure signal, a respiration signal, a heart rate signal, a pH-level signal, and a peripheral nerve signal.

6. The method of claim 1, wherein the medical device system is selected from the group consisting of an external system, a hybrid system, and an implanted system.

7. The method of claim 1, further comprising the steps of:

(c) determining that all neurological signals of the set of neurological signals have a corresponding ratio less than the predetermined ratio threshold at a first instance of time;

(d) determining a second neurological signal having a subsequent ratio that is greater than or equal to the predetermined ratio threshold at a second instance of time; and

(e) if a difference between the first instance of time and the second instance of time is greater than a second predetermined time duration, disregarding the time interval between the first instance of time and the second instance of time with the duration of the detection cluster.

8. The method of claim 1, wherein a ratio that is associated with the each neurological signal is determined by dividing a short-term value by a long-term value.

9. The method of claim 1, wherein the long-term value is associated with approximately thirty minutes and the short-term value is associated with approximately two seconds.

10. The method of claim 1, further comprising the steps of:

(c) determining that all neurological signals of the set of neurological signals have a corresponding ratio less than the predetermined ratio threshold at a first instance of time;

(d) determining a second neurological signal having a subsequent ratio that is greater than or equal to the predetermined ratio threshold at a second instance of time; and

(e) if a difference between the first instance of time and the second instance of time is less than a second predetermined time duration, associating a time interval between the first instance of time and the second instance of time with the first duration of the detection cluster.

11. The method of claim 10, further comprising the step of:

(f) utilizing the corresponding ratio and the subsequent ratio to calculate an intensity of the detection cluster.

12. The method of claim 10, further comprising the step of:

(f) trending an occurrence of the detection cluster.

13. The method of claim 12, further comprising the step of:

(g) providing a report in response to step (f).

14. The method of claim 10, wherein an event burden that is associated with the nervous system disorder over a period of time is determined by a detection cluster frequency.

15. The method of claim 10, further comprising the steps of:

(f) determining an associated ratio of a corresponding neurological signal, wherein the corresponding neurological signal is a member of the set of neurological signals;

(g) if the associated ratio exceeds the predetermined ratio threshold, associating the corresponding neurological signal with the electrographic spread of the detection cluster; and

(h) repeating steps (f) and (g) in order to determine a number of neurological signals that are in involved in the neurological event, wherein the number is equal to the electrographic spread of the detection cluster.

16. The method of claim 15 comprising the further steps of:

(i) showing a graphical representation of a brain of the patient; and

(j) distinguishing any monitoring elements that correspond to the neurological signals that are involved in the neurological event in relation to the graphical representation of the brain.

17. The method of claim 15, wherein an event burden that is associated with the nervous system disorder over a period of time is determined by a conjoint measure of the cluster intensity, the cluster duration, the electrouaphic spread, and a number of detection clusters per unit time.

18. The method of claim 17, wherein the event burden is further determined by an indication of a severity of the neurological event as provided by the patient.

19. A non-transitory computer-readable medium having computer-executable instructions for performing the steps recited in claim 1.