Abstract
Dear Sir Headache can be an ictal epileptic manifestation (1–5), and is well illustrated by the case report of Parisi and colleagues. We have described several families with comorbidity of epilepsy and migraine and provided evidence for a single mutation causing both (6–8). In most of our patients, the distinction between epilepsy and migraine was evident. However, we agree with Parisi and colleagues that the distinction may be difficult in selected cases. We speculate that a single mutation in our families can give rise both to cortical spreading depression causing migraine, and to paroxysmal depolarizing shift, causing epileptic seizures, explaining the spectrum of phenotypes observed in these families. Since patients with a familial epilepsy–migraine syndrome can experience only epileptic seizures or only migraine, we believe that obtaining the familial phenotype is essential in establishing the correct diagnosis in all patients presenting with migraine in headache clinics or epilepsy in epilepsy clinics. Both classifications of headaches (9) and of epileptic syndromes (10) should reflect this new insight.