Somatosensory evoked potentials in acute migraine with sensory aura

One current view of migraine pathophysiology suggests that vasospasm causes cerebral ischemia and focal symptoms during an aura and that reactive hyperemia accompanies the headaches. Eight patients with acute migraine with sensory aura were studied with somatosensory evoked potential (SEP) to examine the vascular theory of acute migraine headache. All patients had sudden onset of hemiparesthesia as an aura followed by throbbing headaches. SEPs were obtained from the median nerve stimulation in two patients during the aura phase and six during the headache phase. SEPs were abnormal in both cases during the aura phase. The abnormality consisted of attenuation of amplitude and prolongation of N19 in the sensory cortex, resulting in prolongation of central conduction time, which gradually returned to normal during the headache phase. SEPs of six other patients obtained during the headache phase were also normal. The study concludes that: (1) there is a different pathophysiology between aura and headache phase; (2) the changes of SEPs during the aura may result from cerebral ischemia; and (3) normal SEPs during the headache phase suggest that reactive hyperemia may not alter SEP wave forms.