Devices and methods for monitoring non-invasive vagus nerve stimulation
Devices and methods are disclosed that treat a medical condition, such as migraine headache, by electrically stimulating a nerve noninvasively, which may be a vagus nerve situated within a patient's neck. Preferred embodiments allow a patient to self-treat his or her condition. Disclosed methods assure that the device is being positioned correctly on the neck and that the amplitude and other parameters of the stimulation actually stimulate the vagus nerve with a therapeutic waveform. Those methods comprise measuring properties of the patient's larynx, pupil diameters, blood flow within an eye, electrodermal activity and/or heart rate variability.
1. A method for treating a medical condition of a patient, the method comprising:
contacting an outer skin surface of a patient with a contact surface of a nerve stimulator;
generating an electrical impulse;
transmitting, as the contact surface contacts the outer skin surface, the electrical impulse from the nerve stimulator, non-invasively through the outer skin surface, to a nerve such that the electrical impulse modulates the nerve;
measuring a physiological response of the patient to the nerve being modulated based on the electrical impulse being transmitted to the nerve;
detecting, based on the physiological response, whether a stimulation level of the electrical impulse sufficiently modulates the nerve to treat the medical condition; and
adjusting a position of the contact surface on the outer skin surface based on the physiological response being measured.
2. The method of claim 1 , wherein the nerve stimulator comprises a housing hosting the contact surface, wherein the electrical impulse is generated within the housing.
3. The method of claim 1 , wherein measuring the physiological response comprises measuring a blood flow associated with the nerve.
4. The method of claim 1 , wherein the nerve is at least one of a vagus nerve, a cranial nerve, a peripheral nerve, or a spinal nerve.
5. The method of claim 1 , wherein measuring the physiological response comprises sensing a level of a biological marker within the patient.
6. The method of claim 1 , wherein measuring the physiological response comprises measuring a property of at least one of a voice of the patient, a laryngeal electromyographic signal, or an electroglottographic signal.
7. The method of claim 1 , wherein measuring the physiological response comprises measuring a property of an autonomic nervous system of the patient.
8. The method of claim 1 , wherein measuring the physiological response comprises measuring at least one of a vagal artery blood flow of the patient or a cerebral blood flow of the patient.
9. The method of claim 1 , wherein measuring the physiological response comprises measuring a chemical within a blood of the patient.
10. The method of claim 1 , further comprising adjusting a parameter of the electrical impulse based on the physiological response being measured, wherein the parameter comprises at least one of an amplitude of the electrical impulse, a frequency of the electrical impulse, a duration of the electrical impulse, or a waveform of the electrical impulse.
11. The method of claim 1 , wherein the electrical impulse comprises bursts of about 2 pulses per burst to about 20 pulses per burst with each of the bursts having a frequency of about 1 burst per second to about 100 bursts per second and each of the pulses having a duration of about 50 microseconds to about 1000 microseconds.
12. A system for treating a medical condition of a patient, the system comprising:
a stimulator including a contact surface that contacts an outer skin surface of a patient;
an energy source that generates an electric field such that an electric current is transmitted non-invasively from the contact surface through the outer skin surface to the nerve;
a sensor for measuring a physiological response of the patient to the nerve being modulated based on the electrical impulse being transmitted to the nerve;
a device that detects a stimulation level of the nerve based on the physiological response; and
a controller coupled to the device, wherein the controller adjusts a position of the contact surface on the outer skin surface based on the stimulation level.
13. The system of claim 12 , wherein the stimulator comprises a housing hosting the contact surface, wherein the energy source is positioned within the housing.
14. The system of claim 12 , wherein the sensor measures a blood flow associated with the nerve.
15. The system of claim 12 , wherein the nerve is at least one of a vagus nerve of the patient, a cranial nerve of the patient, a peripheral nerve of the patient, or a spinal nerve of the patient.
16. The system of claim 12 , wherein the sensor detects a level of a biological marker within the patient.
17. The system of claim 12 , wherein the sensor detects a property of an autonomic nervous system of the patient.
18. The system of claim 12 , wherein the controller adjusts at least one of an amplitude of the electric current, a frequency of the electric current, a duration of the electric current, or a waveform of the electric current.
19. The system of claim 12 , wherein the electric current comprises bursts of about 2 pulses per burst to about 20 pulses per burst with each of the bursts having a frequency of about 1 burst per second to about 100 bursts per second and each of the pulses having a duration of about 50 microseconds to about 1000 microseconds.