Stimulation Vagus nerve stimulation (VNS) therapy via a
neurostimulator implanted in the chest has been used to control
seizures in
epilepsy patients and has been approved for treating drug-resistant
clinical depression. Several noninvasive VNS devices that stimulate an afferent branch of the vagus nerve are available. GammaCore is recommended by
The National Institute for Health and Care Excellence (NICE) for cluster headaches. Stimulation of the vagus nerve may be achieved by performing a
vagal maneuver: carotid sinus massage,
Valsalva maneuver, or the
diving reflex. Vagal maneuvers may be used to abort episodes of
supraventricular tachycardia. Vagus nerve blocking (VBLOC) therapy is similar to VNS but used only during the day. In a six-month
open-label trial involving three medical centers in Australia, Mexico, and Norway, vagus nerve blocking helped 31 obese participants lose an average of nearly 15 percent of their excess weight. , a yearlong
double-blind,
phase II trial had begun.
Vagotomy Vagotomy (cutting of the vagus nerve) is a now obsolete therapy that was performed for
peptic ulcer disease and now superseded by oral medications, including H2 antagonists, proton pump inhibitors and antibiotics. Vagotomy is currently being researched as a less invasive alternative weight-loss procedure to
gastric bypass surgery. The procedure curbs the feeling of hunger and is sometimes performed in conjunction with putting bands on patients' stomachs, resulting in an average of 43% of excess weight loss at six months with diet and exercise. One serious side effect of vagotomy is a
vitamin B12 deficiency later in life – perhaps after about 10 years – that is similar to
pernicious anemia. The vagus normally stimulates the stomach's
parietal cells to secrete acid and intrinsic factor.
Intrinsic factor is needed to absorb vitamin B12 from food. The vagotomy reduces this secretion and ultimately leads to deficiency, which, if left untreated, causes nerve damage, tiredness, dementia, paranoia, and ultimately death. Researchers from
Aarhus University and Aarhus University Hospital have demonstrated that vagotomy prevents (halves the risk of) the development of
Parkinson's disease, suggesting that Parkinson's disease begins in the gastrointestinal tract and spreads via the vagus nerve to the brain. Or giving further evidence to the theory that dysregulated environmental stimuli, such as that received by the vagus nerve from the gut, may have a negative effect on the dopamine reward system of the
substantia nigra, thereby causing Parkinson's disease.
Vagus nerve pathology The sympathetic and parasympathetic components of the autonomic nervous system (ANS) control and regulate the function of various organs, glands, and involuntary muscles throughout the body (e.g., vocalization, swallowing, heart rate, respiration, gastric secretion, and intestinal motility). Hence, most of the signs and symptoms of vagus nerve dysfunction, apart from vocalisation, are vague and non specific. Laryngeal nerve palsy results in paralysis of an ipsilateral vocal cord and is used as a pointer to diseases affecting the vagus nerve from its origin down to termination of its branch of the laryngeal nerve. •
Sensory neuropathy The hypersensitivity of vagal afferent nerves causes refractory or idiopathic cough.
Arnold's nerve ear-cough reflex, though uncommon, is a manifestation of a vagal sensory neuropathy and this is the cause of a refractory chronic cough that can be treated with
gabapentin. The cough is triggered by mechanical stimulation of the external auditory meatus and accompanied by other neuropathic features such as throat irritation (laryngeal paresthesia) and cough triggered by exposure to nontussive triggers such as cold air and eating (termed allotussia). These features suggest a neuropathic origin to the cough. •
Motor neuropathy Pathology of the vagus nerve proximal to the laryngeal nerve typically presents with symptom hoarse voice and physical sign of paralysed vocal cords. Although a large proportion of these are the result of idiopathic vocal cord palsy but tumours especially lung cancers are next common cause. Tumours at the apex of right lung and at the hilum of the left lung are the most common oncological causes of vocal cord palsy. Less common tumours causing vocal cord palsy includes thyroid and proximal oesophageal malignancy. ==Etymology==