Contingent cardio-protection for epilepsy patients
Disclosed are methods and systems for treating epilepsy by stimulating a main trunk of a vagus nerve, or a left vagus nerve, when the patient has had no seizure or a seizure that is not characterized by cardiac changes such as an increase in heart rate, and stimulating a cardiac branch of a vagus nerve, or a right vagus nerve, when the patient has had a seizure characterized by cardiac changes such as a heart rate increase.
1. A method for detecting an epileptic event in a patient's body via one or more medical devices, comprising:
receiving a first body signal during a first time period;
receiving a second body signal during the first time period;
determining a work level;
determining whether there is a change in at least one of a direction, a latency, a magnitude, a rate, and a duration of the first body signal during the first time period;
determining a change in the work level;
determining whether there is a change in at least one of the direction, the latency, the magnitude, the rate, and the duration of the second body signal during the first time period that, based on the change in the work level, is commensurate with the change in the first body signal, in response to determining that there is the change at least one of the direction, the latency, the magnitude, the rate, and the duration of in the first body signal during the first time period;
detecting the epileptic event in response to determining that there is the change in the second body signal that based on the change in the work level is incommensurate with the change in the first body signal;
performing a responsive action in response to detecting the epileptic event, the responsive action being delivering a therapy where the therapy includes:
initiating a first electrical signal to the first cranial nerve structure of the patient using a first polarity configuration in which the first electrode functions as a cathode and the second electrode functions as an anode, the first electrical signal is configured to induce action potentials in the first cranial nerve structure, wherein a charge accumulates at the anode and the cathode as a result of the first electrical signal;
switching from the first polarity configuration to a second polarity configuration upon termination of the first electrical signal where the first electrode functions as the anode and the second electrode functions as the cathode in the second polarity configuration; and
providing a second electrical signal to the second cranial nerve structure in the second polarity configuration, the second electrical signal is configured to induce action potentials in the second cranial nerve structure where at least a portion of the second electrical signal comprises the accumulated charge from the first electrical signal.
2. The method of claim 1 , wherein detecting the epileptic event comprises:
determining a non-ictal component of the change in the first body signal based upon a contribution by a physiological or non-pathological activity in the patient's body that relates to the change in the second body signal; and
determining an ictal component of the change in at least one of: the first body signal and the second body signal based upon a difference between an entirety of the change in the first body signal, and a non-ictal component.
3. The method of claim 1 , further comprising determining an ictal component of the change in at least one of: the first body signal and the second body signal, in response to detecting the epileptic event, wherein the ictal component is based upon a difference between a value of the first body signal prior to the detecting the epileptic event and a value of the first body signal during the detecting the epileptic event.
4. The method of claim 1 , wherein determining whether there is a change in the second body signal during the first time period that is commensurate with the change in the first body signal comprises
determining a commensurate index between the first body signal and the second body signal, and
comparing the commensurate index with at least a first commensurate threshold; and
wherein determining that there is a change in the second body signal that is commensurate with the change in the first body signal comprises determining that the commensurate index is at or above the first commensurate threshold;
wherein the commensurate determination is based on a value being reached.
5. The method of claim 1 , wherein determining whether there is the change in the second body signal during the first time period that is commensurate with the change in the first body signal comprises determining an occurrence of a commensurate state between the first body signal and the second body signal;
wherein the commnsurate state determination is based on a value being reached.
6. The method of claim 5 , wherein determining the commensurate state between the first body signal and the second body signal is based on an emergence of an ictal component in the first body signal and the second body signal.
7. The method of claim 1 , further comprising determining an ictal component of the first body signal in response to a determination that there is the change in the second body signal that is commensurate with the change in the first body signal, wherein the ictal component is based on a value of the first body signal prior to the determination that there is the change in the second body signal that is commensurate with the change in the first body signal.
8. The method of claim 1 , further comprising determining there is an ictal component to the change in the first body signal in response to a determination that the change in the second body signal that is incommensurate with the change in a physiologic work level, wherein the ictal component is based on a difference between 1) a value of the first body signal after the determination that the change in the second body signal that is incommensurate with the change in the physiologic work level and 2) a value of the first body signal prior to the determination that there is no change in the second body signal.
9. The method of claim 1 , further comprising determining a first body index from the first body signal and determining a second body index from the second body signal.
10. The method of claim 1 , further comprising quantifying a commensurate level of the change in the first body signal and the change in the second body signal.