Alternating hemiplegia: complicated migraine of infancy.

Alternating hemiplegia in children is a rare form of "complicated" migraine. There are a number of similarities to seizure disorders and correct diagnosis may prove difficult. The clinical features of 6 patients with alternating hemiplegia are presented together with the results of electrophysiological, radiological, and biochemical studies. While there were a number of clinical similarities between the patients, extensive investigations failed to demonstrate significant abnormalities. Although a diagnosis of a seizure disorder was suggested at some time in all of the patients, in only 2 was it certain there was a fit. Headaches occurred in the eldest patient (although not always with a hemiplegic attach) while in the younger patients misery often accompanied their attacks. Intellectual status was impaired in 5 patients, although in 2 of these the cause was most likely to be perinatal difficulties. Response to various forms of treatment was generally not encouraging and concern is expressed that this alternating hemiplegia of childhood may carry an unfavourable prognosis.