Autonomic dysfunction in migraineurs

Objective.-To evaluate autonomic function and sympathovagal balance in migraineurs and healthy controls. Background.-The pathophysiology of migraine is still largely unknown. An imbalance of the autonomic nervous system could explain many of the clinical manifestations of the disorder. Materials and Methods.-We undertook autonomic function tests in 17 women suffering from migraine (8 with aura) (average age 36 ± 7 years) and 16 healthy women (average age 34 ± 7 years). Autonomic nervous system studies consisted of tests of sympathetic function (the quantitative sudomotor axon reflex test, beat-to-beat blood pressure responses to the Valsalva maneuver, sustained handgrip, cold pressor test, and head-up tilt and tests of parasympathetic function (heart rate responses to deep breathing and the Valsalva maneuver). The data from the tilt test were further evaluated by time-frequency analysis (Wigner distribution). Results.-Subjects with migraine with aura had a smaller increase of mean blood pressure during phase IV of the Valsalva maneuver (P<0.05) and a lower blood pressure increment during the handgrip test (P=0.08); their time-frequency distribution showed reduced power at the nonrespiratory frequencies in the R-R interval at both minutes 1 (P<0.03) and 5 (P<0.04) of head-up tilt. Sympathovagal balance (a ratio of spectral power of nonrespiratory frequency variations in blood pressure to that at respiratory frequency variations in the R-R interval) was significantly increased in migraineurs, both with and without aura, by 10 minutes of head- up tilt. Conclusion.-Subjects with migraine with aura had resting supine sympathetic hypofunction and intact parasympathetic function. With head-up tilt, sympathovagal balance is increased. The dynamic alterations in autonomic nervous system function may contribute to the development of aura in patients with migraine.