Familial hemiplegic migraine (FHM) is an autosomal dominant syndrome characterized by recurrent episodes of varying degrees of hemiparesis associated with migraine. The aura including hemiparesis may be prolonged and in severe attacks may often be associated with confusion or coma. We describe a case of FHM whose aura was atypically prolonged and resulted in irreversible brain deficit which on magnetic resonance imaging (MRI) was suggestive of cortical hyperperfusion. A subsequent MRI showed left brain atrophy.