Six migraine patients presented with episodes of impairment of consciousness and neurological deficit indicating dysfunction of upper brainstem and occipital and medial temporal lobes. These episodes were either continuous with migraine attacks or interspersed in courses of frequent migraine attacks. EEG recorded during or shortly after the episodes showed frontal intermittent rhythmic delta activity (FIRDA). The clinical and EEG changes are both explained as results of spasm of the rostral basilar artery. The episodes of impairment of consciousness are interpreted as migraine attacks with insufficient or missing vasodilatation rebound. The FIRDA pattern in these cases appears to be a sign of ischemia of the rostral basilar artery region analogous to focal slowing in “hemiplegic” migraine which indicates ischemia in other cerebrovascular regions. This view is supported by a simultaneous recording of both types of EEG changes in one patient with “hemiplegic” migraine followed by impairment of consciousness.