Non-invasive vagal nerve stimulation to treat disorders
Devices, systems and methods are disclosed for treating a variety of diseases and disorders that are primarily or at least partially driven by an imbalance in neurotransmitters in the brain, such as asthma, COPD, depression, anxiety, epilepsy, fibromyalgia, and the like. The invention involves the use of an energy source comprising magnetic and/or electrical energy that is transmitted non-invasively to, or in close proximity to, a selected nerve to temporarily stimulate, block and/or modulate the signals in the selected nerve such that neural pathways are activated to release inhibitory neurotransmitters in the patient's brain.
1. A method for treating a disorder in a patient, the method comprising:
positioning a device in contact with an outer skin surface of a patient;
generating, via the device, an electric current external to the patient; and
transmitting, via the device, the electric current transcutaneously through the outer skin surface to a vagus nerve within the patient, wherein the electric current has a frequency of between about 1000 Hz and about 10,000 HZ and a duty cycle between about 1% and about 10%.
2. The method of claim 1 wherein the frequency is between about 4000 Hz and about 6000 HZ.
3. The method of claim 1 wherein the frequency is about 5000 Hz.
4. The method of claim 1 wherein the duty cycle is between about 2% and about 5%.
5. The method of claim 1 wherein the duty cycle is about 2.5%.
6. The method of claim 1 wherein the electrical current includes bursts of pulses having a burst duration of between about 0.1 and 10 milliseconds and a burst frequency of between about 10-50 Hz.
7. The method of claim 6 wherein the burst duration is between 2 and 6 milliseconds.
8. The method of claim 6 wherein the burst frequency is between 10 and 35 Hz.
9. The method of claim 6 wherein the electrical impulses generate an electric field at the vagus nerve above a threshold for generating action potentials within A and B fibers of the vagus nerve and below a threshold for generating action potentials within C fibers of the vagus nerve.
10. The method of claim 1 wherein the electric current alone is sufficient to generate an electric field from about 10 V/m to about 600 V/m above a threshold for generating an action fiber of the vagus nerve responsible for activated one or more neural pathways causing a modulation of a neurotransmitter within a brain of the patient.
11. The method of claim 10 wherein the electric current alone is sufficient to generate an electrical field gradient at the vagus nerve greater than 2 V/m/mm.
12. The method of claim 10 wherein the electric field is sufficient to cause a release of an inhibitory neurotransmitter in the brain.
13. The method of claim 10 wherein the electric field is sufficient to cause a suppression of an excitatory neurotransmitter in the brain.
14. The method of claim 13 wherein the excitatory neurotransmitter comprises at least one of a catecholamine or acetylcholine.
15. The method of claim 12 wherein the inhibitory neurotransmitter comprises at least one of GAMA, serotonin, or norepinephrine.
16. The method of claim 12 wherein the transmitting facilitates a sufficient level of the inhibitory neurotransmitter to be release in the brain to reduce a level of glutamate in the brain.
17. The method of claim 12 wherein the inhibitory neurotransmitters are released onto airway-related vagal preganglionic neurons to reduce the release of acetycholine from the airway-related vagal preganglionic neurons.
18. The method of claim 9 wherein the electric field is below the threshold for generating action potentials within fibers of the vagus nerve responsible for modulating heart rate or blood pressure.
19. A device for treating a disorder in a patient comprising:
a housing having an electrically permeable or conducting contact surface for contacting an outer skin surface of the patient; and
an energy source within the housing configured to transmit electrical impulses through the outer skin surface of the patient to a vagus nerve within the patient, wherein the electric impulses have a frequency of between 1000 Hz and 10,000 Hz and a duty cycle between 1% and 10%.
20. The device of claim 19 wherein the frequency is between about 4000 Hz and about 6000 Hz.
21. The device of claim 19 wherein the frequency is about 5000 Hz.
22. The device of claim 19 wherein the duty cycle is between about 2% and about 5%.
23. The device of claim 19 wherein the duty cycle is about 2.5%.
24. The device of claim 19 wherein the electrical impulses include bursts of pulses having a burst duration of between about 0.1 and about 10 milliseconds and a burst frequency of between about 10-50 Hz.
25. The device of claim 24 wherein the burst duration is between about 2 and 6 milliseconds.
26. The device of claim 24 wherein the burst frequency is between about 10 and 35 Hz.
27. The device of claim 19 wherein the electrical impulses generate an electric field at the vagus nerve above a threshold for generating action potentials within A and B fibers of the vagus nerve and below a threshold for generating action potentials within C fibers of the vagus nerve.
28. The device of claim 27 wherein the electric field is between about 10 to 600 V/m.
29. The device of claim 19 wherein the electric impulses are sufficient to generate an electrical field gradient at the vagus nerve greater than 2 V/m/mm.
30. The device of claim 19 wherein the energy source comprises a signal generator and one or more electrodes coupled to the signal generator within the housing.
31. The device of claim 30 further comprising a conducting medium within the housing between the electrodes and the electrically permeable contact surface.
32. The device of claim 19 wherein the electrical impulses generate an electric field at the vagus nerve above a threshold for generating action potentials within fibers of the vagus nerve responsible for activating neural pathways causing release of inhibitory neurotransmitters within a brain of the patient.
33. The device of claim 32 wherein the inhibitory neurotransmitters comprise GABA, serotonin and/or norepinephrine.
34. The device of claim 32 wherein the inhibitory neurotransmitters are released onto airway-related vagal preganglionic neurons to reduce the release of acetycholine from the airway-related vagal preganglionic neurons.
35. The device of claim 32 wherein a sufficient level of inhibitory neurotransmitters is released in the brain of the patient to reduce a level of glutamate in the brain.
36. The device of claim 32 wherein the electric field is below the threshold for generating action potentials within fibers of the vagus nerve responsible for modulating heart rate or blood pressure.