Cluster headache syndrome and migrain. Ophthalmological support for a two-entity theory.

Patients suffering from migraine, cluster headache and atypical cluster headache, including patients with chronic paroxysmal hemicrania, were studied with respect to corneal temperature, intraocular pressure and corneal indentation pulse amplitude changes during pain attacks. Significant rises in these three parameters were deomonstrated during attacks of cluster headache and atypical cluster headache, indicating that intraocular vasodilation with increased ocular blood flow occurs during attacks. No definite changes were found in migraine. The results strongly suggest that significant pathophysiological differences exist between migraine and cluster headache. The point is stressed that these disorders probably represent separate pathogenetic entities and should be classified as such, and not be grouped together within an ill-defined group of "vascular headache".