Vagal nerve stimulation for treating or preventing stroke or transient ischemic attack

Abstract

Devices, systems and methods are disclosed for reducing inflammation associated with an aneurysm in a patient. The methods comprise transmitting impulses of energy non-invasively to selected nerve fibers, particularly those in the vagus nerve. Vagus nerve stimulation is used to modulate the release of neurotransmitters in the brain and to reduce inflammation that may lead to the formation, growth, rupture or hemorrhage of an aneurysm.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 16 / 693,088, filed Nov. 22, 2019, which is a divisional of U.S. patent application Ser. No. 13 / 952,859, filed Jul. 29, 2013, which is a Continuation in Part of U.S. patent application Ser. No. 13 / 603,781 filed Sep. 5, 2012; which is a Continuation in Part of U.S. patent application Ser. No. 13 / 222,087 filed Aug. 31, 2011; which is a Continuation in Part of U.S. patent application Ser. No. 13 / 183,765 filed Jul. 15, 2011; which is a: (1) Continuation in Part of U.S. patent application Ser. No. 13 / 183,721 filed Jul. 15, 2011; which claims the benefit of priority to U.S. Provisional Application No. 61 / 488,208 filed May 20, 2011 and U.S. Provisional Application No. 61 / 487,439 filed May 18, 2011; (2) a Continuation in Part of U.S. patent application Ser. No. 13 / 109,250 filed May 17, 2011; which claims the benefit of priority to U.S. Provisional Application No. 61 / 471,405 file...

AI Technical Summary

Benefits of technology

[0044]In one aspect of the invention, a device for reducing inflammation associated with an aneurysm in a patient comprises a housing having a contact surface for contacting an outer skin surface of a neck of the patient and an energy source within the housing and coupled to the contact surface. The energy source generates at least one electric impulse and transmits the at least one electrical impulse transcutaneously and non-invasively from the contact surface through the outer skin surface of the patient to a selected nerve fiber in the patient. The electrical impulse preferably comprises bursts of pulses with each burst having a frequency of about 1 to about 100 bursts per second and each pulse has a duration of about 100 to about 1000 microseconds in duration. The electrical impulse is preferably sufficient to modify the nerve fiber, such that inflammation associated with the aneurysm is reduced. The electrical impulse(s) may be sufficient to inhibit either the formation, growth, rupture or hemorrhage of the aneurysm.

[0046]In another aspect of the invention, a method of reducing inflammation associated with an aneurysm in a patient comprises contacting a contact surface of a housing against an outer skin surface of a neck of the patient, generating at least one or more electrical impulse with a power source in the housing and transmitting the electrical impulse(s) transcutaneously and non-invasively from the contact surface through the outer skin surface of the neck to a selected nerve fiber in the patient. The electrical impulses are preferably transmitted while the contact surface is in contact with the patient's neck and are sufficient to modify the nerve fiber, such that inflammation associated with the aneurysm is reduced.

[0057]A source of power supplies a pulse of electric charge to the electrodes or magnetic stimulator coil, such that the electrodes or magnetic stimulator produce an electric current and / or an electric field within the patient. The electrical or magnetic stimulator is configured to induce a peak pulse voltage sufficient to produce an electric field in the vicinity of a nerve such as a vagus nerve, to cause the nerve to depolarize and reach a threshold for action potential propagation. By way of example, the threshold electric field for stimulation of the nerve may be about 8 V / m at about 1000 Hz. For example, the device may produce an electric field within the patient of about 10 to about 600 V / m (preferably less than about 100 V / m) and an electrical field gradient of greater than about 2 V / m / mm. Electric fields that are produced at the vagus nerve are generally sufficient to excite all myelinated A and B fibers, but not necessarily the unmyelinated C fibers. However, by using a reduced amplitude of stimulation, excitation of A-delta and B fibers may also be avoided.

[0058]The preferred stimulator shapes an elongated electric field of effect that can be oriented parallel to a long nerve, such as a vagus. By selecting a suitable waveform to stimulate the nerve, along with suitable parameters such as current, voltage, pulse width, pulses per burst, inter-burst interval, etc., the stimulator produces a correspondingly selective physiological response in an individual patient. Such a suitable waveform and parameters are simultaneously selected to avoid substantially stimulating nerves and tissue other than the target nerve, particularly avoiding the stimulation of nerves in the skin that produce pain.

Problems solved by technology

Stroke also causes a substantial medical burden for those individuals who survive a stroke.

The estimated annual number of TIAs in the U.S. is about 200 to 500 thousand, although the number is difficult to estimate because TIAs may be under-reported, considering that they typically last less than an hour.

In amaurosis fugax, cholesterol from ruptured atherosclerotic plaques in the common or internal carotid artery or other types of emboli transiently occludes flow to the retinal artery, causing a sudden onset of monocular blindness.

However, such imaging may produce a false negative if it is performed too soon, so measurement of the patient's EEG may also be performed as a companion to the imaging, or in lieu of the imaging if CT or MRI imagers are not available.

It is impossible to know whether stroke symptoms are due to ischemia or hemorrhage based on clinical characteristics alone.

The major risk of intravenous rtPA treatment is symptomatic intracranial hemorrhage (sICH).

An older neuroprotective strategy is the use of hyperbaric oxygen, but clinical data concerning its use are inconclusive, and some data imply that the intervention may be harmful.

In these reports, AI et al note that the clinical relevance of such findings is limited because the stimulation methods are invasive.

Although non-invasive stimulation at this location can be effective for treating an inflammatory disorder, such stimulation may raise the risk of stroke.

To summarize the foregoing background information, stroke and transient ischemic attacks cause major medical and public health problems.

Current methods for treating them are only partially successful, either acutely or in the rehabilitative patient.

Although animal experiments suggest that treatment of a stroke in its acute phase using vagus nerve stimulation may be neuroprotective, methods used in those experiments are of limited utility because they are invasive.

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