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Encyclopedia > Vagus nerve stimulation

Vagus nerve stimulation (VNS) is an adjunctive treatment for certain types of intractable epilepsy and clinical depression. VNS uses a stimulator that sends electric impulses to the left vagus nerve in the neck via a lead implanted under the skin. Clinical depression (also called major depressive disorder, or sometimes unipolar when compared with bipolar disorder or sometimes called manic depression]) is a state of intense sadness, melancholia or despair that has advanced to the point of being disruptive to an individuals social functioning and/or activities of daily living. ... The vagus nerve (also called pneumogastric nerve or cranial nerve X) is the tenth of twelve paired cranial nerves, and is the only nerve that starts in the brainstem (within the medulla oblongata) and extends, through the jugular foramen, down below the head, to the abdomen. ...


One VNS implanted device consists of a titanium encased generator about the size of a pocket watch; a lithium battery to fuel the generator, with a battery life of ~6-8 years; a lead system with electrodes; and an anchor tether to secure leads to the vagus nerve. This particular device is made by Cyberonics, Inc. Other "wearable" devices are being tested and developed by other companies that involve transcutaneous stimulation and do not require irreversible surgery, damage to the vagus nerve and its surrounding tissue.


Implantation of the Cyberonics, Inc. VNS device is usually done as an out-patient procedure. The procedure goes as follows: an incision is made in the upper left chest and the generator is implanted into a little “pouch” on the left chest under the clavicle. A second incision is made in the neck, so that the surgeon can access the vagus nerve. The surgeon then wraps the leads around the left branch of the vagus nerve, and connects the electrodes to the generator. Once successfully implanted, the generator sends electric impulses to the vagus nerve at regular intervals.[1] The left vagus nerve is stimulated rather than the right because the right plays a role in cardiac function such that stimulating it could have negative cardiac effects. [2]


The exact method of therapeutic action is unknown, but VNS has been shown to affect blood flow to different parts of the brain, and affect neurotransmitters including Serotonin and Norepinephrine which are implicated in depression. Some patients experience an alteration of voice quality and loudness during the time that the pulse is being delivered to the vagus nerve. Other common side effects include hoarseness, throat pain, cough, Dyspnea and Paresthesia.[2] Serotonin (5-hydroxytryptamine, or 5-HT) is a monoamine neurotransmitter synthesized in serotonergic neurons in the central nervous system (CNS) and enterochromaffin cells in the gastrointestinal tract of animals including humans. ... Norepinephrine (INN) or noradrenaline (BAN) is a catecholamine and a phenethylamine with chemical formula C8H11NO3. ... Dyspnea (R06. ... Paresthesia or paraesthesia (in British English) is a sensation of tingling, pricking, or numbness of a persons skin with no apparent long-term physical effect, more generally known as the feeling of pins and needles or of a limb being asleep. // Transient paresthesia is the temporary sensation of tingling...


In 1997,the United States Food and Drug Administration (FDA) approved the use of VNS as an adjunctive therapy for partial-onset epilepsy. In 2005, the FDA approved the use of VNS for refractory depression. [3] The Food and Drug Administration (FDA) is an agency of the United States Department of Health and Human Services and is responsible for regulating food (humans and animal), dietary supplements, drugs (human and animal), cosmetics, medical devices (human and animal) and radiation emitting devices (including non-medical devices), biologics, and... The numerous epileptic seizure types are most commonly defined and grouped according to a scheme proposed by the International League Against Epilepsy (ILAE) in 1981. ... A term used in clinical psychiatry to describe cases of major depressive disorder that do not respond to typical modes of treatment, such as psychotherapy and common antidepressants such as SSRIs. ...


Although the use of VNS for refractory depression has been endorsed by the American Psychiatric Association, the FDA's approval of VNS for refractory depression remains controversial. According to Dr. A. John Rush, vice chairman for research in the Department of Psychiatry at the University of Texas Southwestern Medical Center at Dallas, results of the VNS pilot study showed that 40 percent of the treated patients displayed at least a 50 percent or greater improvement in their condition, according to the Hamilton Depression Rating Scale. [4][5] Many other studies concur that VNS is indeed efficacious in treating depression. However, these finding do not take into account improvements over time in patients without the device. In the only randomized controlled trial VNS failed to perform any better when turned on than in otherwise similar implanted patients whose device was not turned on.[6] To better understand the opinions of the medical professionals relating to this treatment option a compilation has been prepared from the responses to CMS (Medicare) during the write-in period from 08/07/2006 - 09/06/2006 entitled "Letters from the Medical Professionals". Due to the epidemic of medical errors, readers are cautioned to be aware that the American Psychiatric Association isnt immune to this. ... The Hamilton Depression Rating Scale is a 21-question multiple choice questionnaire which doctors may use to rate the severity of a patients depression. ...


Because the vagus nerve is associated with many different functions and brain regions, research is being done to determine its usefulness in treating other illnesses, including various anxiety disorders, Alzheimer's disease, migraines[3], and fibromyalgia.[1] Anxiety disorder is a blanket term covering several different forms of abnormal, pathological anxiety, fears, phobias and nervous conditions that may come on suddenly or gradually over a period of several years, and may impair or prevent the pursuing of normal daily routines. ...


Other brain stimulation techniques used to treat depression include Electroconvulsive therapy(ECT) and Cranial electrotherapy stimulation(CES). Deep brain stimulation is currently under study as a treatment for depression. Transcranial magnetic stimulation(TMS) is under study as a therapy for both depression and epilepsy.[2] Trigeminal Nerve Stimulation (TNS) is being researched at UCLA as a treatment for epilepsy. [7] Electroconvulsive therapy (ECT), also known as electroshock, is a psychiatric treatment in which seizures are induced by passing electricity through the brain of an anaesthetised patient. ... This does not cite its references or sources. ... In neurotechnology, deep brain stimulation (DBS) is a surgical treatment involving the implantation of a medical device called a brain pacemaker, which sends electrical impulses to specific parts of the brain. ... Transcranial magnetic stimulation (TMS) is the use of powerful rapidly changing magnetic fields to induce electric fields in the brain by electromagnetic induction without the need for surgery or external electrodes. ... Binomial name Ucla xenogrammus Holleman, 1993 The largemouth triplefin, Ucla xenogrammus, is a fish of the family Tripterygiidae and only member of the genus Ucla, found in the Pacific Ocean from Viet Nam, the Philippines, Palau and the Caroline Islands to Papua New Guinea, Australia (including Christmas Island), and the...


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  Results from FactBites:
 
Vagus nerve stimulation: A new depression treatment option - MayoClinic.com (890 words)
Vagus nerve stimulation uses electrical impulses to affect mood centers in the brain by stimulating the vagus nerve.
With vagus nerve stimulation, a device called a pulse generator is surgically implanted in the upper left side of your chest.
Vagus nerve stimulation may not be appropriate for all cases of depression.
Vagus nerve - Wikipedia, the free encyclopedia (716 words)
The vagus nerve supplies sensory parasympathetic fibers to all the organs except the suprarenal glands, from the neck down to the second segment of the transverse colon.
This means that the vagus nerve is responsible for such varied tasks as heart rate, gastrointestinal peristalsis, sweating, and quite a few muscle movements in the mouth, including speech (via the recurrent laryngeal nerve) and keeping the larynx open for breathing.
Vagus nerve stimulation therapy using a pacemaker-like device implanted in the chest is a treatment used since 1997 to control seizures in epilepsy patients and has recently been approved for treating drug-resistant cases of clinical depression.
  More results at FactBites »

 
 

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