Contingent cardio-protection for epilepsy patients

1. A method of treating a patient having epilepsy comprising:

receiving at least one body data stream;

analyzing the at least one body data stream using a seizure detection algorithm to detect whether or not the patient has had an epileptic seizure;

receiving a cardiac signal of the patient;

analyzing the cardiac signal to determine the patient's heart rate;

determining whether said epileptic seizure is characterized by a decrease in the patient's heart rate from a reference value or a normative value;

applying a first electrical signal to a vagus nerve of the patient, based on said determination, wherein said determination is that the patient has not had an epileptic seizure, wherein the epileptic seizure is characterized by a decrease in the patient's heart rate, wherein the first electrical signal is not a vagus nerve conduction blocking electrical signal; and

applying a second electrical signal to a vagus nerve of the patient, based on said determination, wherein said determination is that the patient has had an epileptic seizure, wherein the epileptic seizure is characterized by a decrease in the patient's heart rate, wherein the second electrical signal is a pulsed electrical signal that blocks action potential conduction in the vagus nerve.

2. The method of claim 1 , wherein determining that the patient has had an epileptic seizure characterized by a decrease in the patient's heart rate comprises:

determining a first heart rate of the patient prior to detecting the onset of an epileptic seizure;

determining a second heart rate of the patient in response to detecting the onset of the epileptic seizure using said seizure detection algorithm;

comparing the first heart rate and the second heart rate; and

determining that the seizure is characterized by a decrease in the patient's heart rate if the second heart rate is less than the first heart rate.

3. The method of claim 1 , wherein applying the second electrical signal comprises applying a high frequency pulsed electrical signal to a target site of the vagus nerve, such that at least a fraction of the axons in the vagus nerve are incapable of supporting action potential propagation across the target site.

4. The method of claim 1 , wherein applying the first electrical signal comprises applying an electrical signal according to a programmed duty cycle having at least a programmed on-time and a programmed off-time.

5. The method of claim 4 , further comprising interrupting the applying of the first electrical signal based on said determination that the patient has had an epileptic seizure characterized by a decrease in the patient's heart rate.

6. The method of claim 1 further comprising:

sensing the patient's heart rate in response to providing the second electrical signal, and modifying the second electrical signal to maintain the patient's heart rate between an upper and a lower heart rate range threshold.

7. The method of claim 1 , wherein at least one of the first electrical signal and the second electrical signal is a microburst electrical signal characterized by having a number of pulses per microburst from 2 pulses to about 25 pulses, an interpulse interval of about 2 msec to about 50 msec, an interburst period of at least 100 msec, and a microburst duration of less than about 1 sec.

8. The method of claim 1 wherein the first electrical signal is selected from 1) an electrical signal that generates action potentials in at least a population of the nerve fibers of said vagus nerve, and 2) a subthreshold electrical signal that does not generate action potentials in a population of the fibers of said vagus nerve.

9. The method of claim 2 , wherein determining a first heart rate comprises determining a heart rate during a non-seizure period.

10. The method of claim 2 , further comprising issuing a warning that that the patient has had an epileptic seizure characterized by a decrease in the patient's heart rate.

11. A method of treating a patient having epilepsy comprising:

sensing a cardiac signal and a kinetic signal of the patient;

analyzing at least one of the cardiac signal and the kinetic signal, comprising analyzing the cardiac signal to determine the patient's heart rate;

determining whether or not the patient has had an epileptic seizure based on said analyzing;

in response to a determination that the patient has had an epileptic seizure, determining whether or not the epileptic seizure is characterized by a decrease in the patient's heart rate from a reference value or a normative value,

applying a first electrical signal to a vagus nerve of the patient based on one of a) a determination that the patient has not had an epileptic seizure, and b) a determination that the patient has had an epileptic seizure that is not characterized by a decrease in the patient's heart rate, wherein the first electrical signal is not a vagus nerve conduction blocking electrical signal; and

applying a second electrical signal to a vagus nerve of the patient based on a determination that the patient has had an epileptic seizure characterized by a decrease in the patient's heart rate, wherein the second electrical signal is a pulsed electrical signal that blocks action potential conduction in the vagus nerve.

12. The method of claim 11 , wherein applying the first electrical signal comprises applying the electrical signal according to a programmed duty cycle having at least a programmed on-time and a programmed off-time.

13. The method of claim 11 , wherein applying the second electrical signal comprises applying a high frequency pulsed electrical signal to at target site of the vagus nerve using at least one electrode, such that at least a portion of the axons in the vagus nerve are incapable of supporting action potential propagation across the target site.