Modulation and analysis of cerebral perfusion in epilepsy and other neurological disorders

1. A method for responding to a change in cerebral perfusion at a target site in a human patient, comprising:

calculating a variable baseline value for cerebral perfusion by sequentially measuring a first set of signals indicative of cerebral perfusion level from at least one sensor implanted in the body of the patient;

averaging the first set of cerebral perfusion measurements to obtain a variable baseline value;

setting a threshold value of cerebral perfusion which threshold value comprises a fixed relationship between a predetermined value and the variable baseline value;

measuring a second set of at least one cerebral perfusion measurement;

comparing the second set to the threshold value and if the second set is not greater than the threshold value, updating the variable baseline value by the relationship between the predetermined value and the variable baseline value.

2. The method of claim 1 , further comprising taking at least one action if the second set is greater than the threshold value wherein the at least one action comprises initiating delivery of a therapy at a predetemined therapy location.

3. The method of claim 2 , wherein the therapy is selected from the group including optical stimulation, thermal stimulation, ultrasonic stimulation, electrical stimulation, and transcranial magnetic stimulation.

4. The method of claim 2 , wherein the therapy comprises electrical stimulation delivered at or near the focus of a seizure.

5. The method of claim 2 , wherein the therapy comprises electrical stimulation, and wherein the method further comprises the step of selecting a set of electrical stimulation parameters adapted to increase perfusion.

6. The method of claim 2 , wherein the therapy comprises electrical stimulation of the caudate nucleus.

7. The method of claim 2 , wherein the therapy comprises electrical stimulation, and wherein the method further comprises the step of selecting a set of electrical stimulation parameters adapted to decrease perfusion.

8. The method of claim 2 , wherein the therapy location is selected from the group consisting of the cerebral cortex, the hippocampus, the white matter, the basal ganglia, the brain stem, the cerebellum, the spinal cord, and a peripheral nerve.

9. The method of claim 2 , wherein the action comprises changing a device mode from a first mode to a second mode.

10. The method of claim 9 , wherein the second mode enables deferred therapy delivery.

11. The method of claim 10 , wherein the deferred therapy delivery comprises scheduled therapy.

12. The method of claim 2 , further comprising the step of identifying a neurological state, and in response to the neurological state, altering the action to be performed.

13. The method of claim 12 , wherein the step of identifying a neurological state comprises identifying a measure of seizure likelihood in an epileptic patient.

14. The method of claim 12 , wherein the step of altering the action comprises selecting a therapy to be provided.

15. The method of claim 12 , wherein the step of altering the action comprises modifying a parameter for a therapy to be provided.

16. A method for responding to a change in cerebral perfusion in a human patient, comprising:

obtaining a first set of a plurality of measurements of cerebral perfusion measurements from at least one sensor implanted in a human patient;

obtaining a second set of at least one measurement of cerebral perfusion;

taking an average of the measurements in the first set to establish a baseline level;

setting a threshold to be a value having a fixed relationship with the baseline level;

comparing the second set of at least one measurement of cerebral perfusion to the threshold;

if the second set of at least one measurement of cerebral perfusion is greater than the threshold, then taking an action in response to the change in cerebral perfusion;

if the second set of at least one measurement of cerebral perfusion is not greater than the threshold, then recalculating the baseline level to be the average of the at least one measurement in the second set and a subset of the plurality of measurements in the first set.

17. The method of claim 16 , wherein the subset of the plurality of measurements in the first set is a subset containing the most recently obtained measurements in the first set.

18. The method of claim 16 , wherein the fixed relationship with the baseline level is one of a predetermined difference between the threshold and the baseline level and a predetermined factor by which the baseline level is multiplied.

19. The method of claim 16 , wherein the action taken in response to the change in cerebral perfusion is one of more of initiating delivery of electrical stimulation to a predetermined target site in the body of a patient, registering detection of a neurological condition, and initiating delivery of a drug to the patient.

20. The method of claim 16 , wherein the action taken in response to the change in cerebral perfusion is initiating delivery of electrical stimulation intended to decrease the level of cerebral perfusion at or around a predetermined target site in the brain of a patient.

21. The method of claim 16 , wherein the action taken in response to the change in cerebral perfusion is initiating delivery of electrical stimulation intended to increase the level of cerebral perfusion at or around a predetermined target site in the brain of a patient.

22. A method for responding to a change in cerebral perfusion in a human patient, comprising:

obtaining a first set of a plurality of measurements of cerebral perfusion measurements from at least one sensor implanted in a human patient;

obtaining a second set of at least one measurement of cerebral perfusion;

taking an average of the measurements in the first set to establish a baseline level;

setting a threshold to be a fixed relationship from the baseline level;

comparing the second set of at least one measurement of cerebral perfusion to the threshold;

if the second set of at least one measurement of cerebral perfusion is less than the threshold, then taking an action in response to the change in cerebral perfusion;

if the second set of at least one measurement of cerebral perfusion is not less than the threshold, then recalculating the baseline level to be the average of the at least one measurement in the second set and a subset of the plurality of measurements in the first set.

23. The method of claim 22 , wherein the subset of the plurality of measurements in the first set is a subset containing the n most recently obtained measurements in the first set.

24. The method of claim 22 , wherein the fixed relationship with the baseline level is one of a predetermined difference between the threshold and the baseline level and a predetermined factor by which the baseline level is multiplied.

25. The method of claim 22 , wherein the action taken in response to the change in cerebral perfusion is one of more of initiating delivery of electrical stimulation to a predetermined target site in the body of a patient, registering detection of a neurological condition, and initiating delivery of a drug to the patient.

26. The method of claim 22 , wherein the action taken in response to the change in cerebral perfusion is initiating delivery of electrical stimulation intended to decrease the level of cerebral perfusion at or around a predetermined target site in the brain of a patient.

27. The method of claim 22 , wherein the action taken in response to the change in cerebral perfusion is initiating delivery of electrical stimulation intended to increase the level of cerebral perfusion at or around a predetermined target site in the brain of a patient.

28. A method for responding to a change in cerebral perfusion in a human patient, comprising:

obtaining a first set of a plurality of measurements of cerebral perfusion measurements from at least one sensor implanted in a human patient;

obtaining a second set of at least one measurement of cerebral perfusion;

taking an average of the measurements in the first set to establish a baseline level;

setting a first threshold to be a value having a first fixed relationship with the baseline level and a second threshold to be a value having a second fixed relationship with the baseline level;

comparing the second set of at least one measurement of cerebral perfusion to the first threshold;

if the second set of at least one measurement of cerebral perfusion is greater than the first threshold, then taking a first action in response to the change in cerebral perfusion;

comparing the second set of at least one measurement of cerebral perfusion to the second threshold;

if the second set of at least one measurement of cerebral perfusion is less than the second threshold, then taking a second action in response to the change in cerebral perfusion;

if the second set of at least one measurement of cerebral perfusion is not greater than the first threshold and is not less than the second threshold, then recalculating the baseline level to be the average of the at least one measurement in the second set and a subset of the plurality of measurements in the first set.

29. The method of claim 28 , wherein the fixed relationship with the baseline level is one of a predetermined difference between the threshold and the baseline level and a predetermined factor by which the baseline level is multiplied.

30. The method of claim 28 , wherein the first action or the second action taken in response to the change in cerebral perfusion is one of more of initiating delivery of electrical stimulation to a predetermined target site in the body of a patient, registering detection of a neurological condition, and initiating delivery of a drug to the patient.

31. The method of claim 28 , wherein the first action or the second action taken in response to the change in cerebral perfusion is initiating delivery of electrical stimulation intended to decrease the level of cerebral perfusion at or around a predetermined target site in the brain of a patient.

32. The method of claim 28 , wherein the first action or the second action taken in response to the change in cerebral perfusion is initiating delivery of electrical stimulation intended to increase the level of cerebral perfusion at or around a predetermined target site in the brain of a patient.