Pathology of emesis: its autonomic basis

Vagal and non-vagal pathways as well as several brainstem nuclei participate in vomiting in response to different emetic stimuli. Autonomic pathways involved in nausea are less well understood. Numerous gastrointestinal disorders with prominent nausea and vomiting including gastroparesis, cyclic vomiting syndrome, and motion sickness have associated autonomic nervous system dysfunction. Autonomic disturbances are also seen with non-gastrointestinal diseases with gut manifestations such as migraine headaches, orthostatic intolerance, and familial dysautonomia. Stimulation of emetic pathways involves activation of a range of receptor subtypes. Agents acting on these receptors form the basis for antiemetic therapies. Chemotherapy-induced nausea and vomiting, a prevalent and severe consequence of anticancer treatment, is preventable in many instances by agents acting on the autonomic nervous system. Likewise, non-medication therapies may act in part via modulation of some of these same autonomic pathways.