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. Chagas disease The neuropathy in Chagas disease spreads in part via the major parasympathetic branches of the vagus 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. History Etymology The Latin word vagus means literally "wandering" (the words vagrant, vagabond, vague, and divagation come from the same root). Sometimes the right and left branches together are spoken of in the plural and are thus called vagi ( ). The vagus was also historically called the pneumogastric nerve since it innervates both the lungs and the stomach. Additional illustrations See also Porphyria – A rare disorder can cause seizures and damage to the vagal nerve. Vagovagal reflex Inflammatory reflex Vagus ganglion Vagus nerve stimulation Vagusstoff Polyvagal theory Gastroparesis References External links () Cranial nerves Autonomic nervous system Thorax (human anatomy) Abdomen Gustatory system