Cerebral arteriovenous malformation and cluster-like headache.

Cluster headache is considered a clinically distinct entity with no underlying gross pathology. However, in rare cases this kind of headache may be mimicked by an arteriovenous malformation. A 49-year-old male is described who had severe bouts of unilateral headache resembling those of cluster headache. The usual accompanying autonomic manifestations were minor and the headache attacks were prolonged. Treatment with ergotamine tartrate and pizotifen failed. A large ipsilateral arteriovenous malformation was diagnosed. Prospectively, true clustering of the headache attacks could not be documented.