Tests of autonomic nervous system (ANS) function were administered to 80 adult patients with migraine (28 with disabling headaches) and 85 matched controls, in a study at the Thomas Jefferson University Hospital, Philadelphia, PA, Johns Hopkins School of Hygiene and Public Health, Albert Einstein College of Medicine, and Montefiore Medical Center, Bronx, NY. During headache-free intervals, resting diastolic, but not systolic, blood pressure was elevated in migraineurs with disabling headaches compared to nondisabled patients and controls. Pulse rate variability during deep breathing, and the Valsalva maneuver ratio, a measure of change in heart rate, were significantly lower in disabled migraineurs cf nondisabled and controls. Blood pressure response to psychological stress was not different in the 3 groups. Migraineurs with disabling headaches may be susceptible to impaired autonomic nervous responses. The link between migraine and abnormal autonomic function is unclear. The dysfunction of the ANS may increase the tendency to headaches by lowering the threshold to migraine triggers. 
COMMENT. Autonomic symptoms, including nausea, vomiting, diarrhea, pallor, flushing, and diaphoresis, are common during acute migraine headaches. Studies of autonomic nervous system (ANS) function provide variable results, some suggesting hypofunction, some hyperfunction, and some a dysregulation, the result of an imbalance of sympathetic and parasympathetic nervous sytems in migraine. The present results favor a hypofunction of the ANS in adult migraineurs, and a lowering of the threshold to migraine triggers is proposed as one possible mechanism. The degree of ANS dysfunction is related to the severity and disabling nature of the headaches.
In children with migraine equivalents, recurrent abdominal pain and cyclical vomiting are symptoms of autonomic nervous system dysfunction. Typical migraine headaches may coexist and often develop in adolescence and adulthood. The degree of nausea and vomiting exacerbates the disability of migraine sufferers and influences the route of administration of medications. (see Progress in Pediatric Neurology III, PNB Publishers, 1997;ppl76-178).