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C. Hain, MD, Chicago IL.
Cluster headache is defined as excruciating unilateral head pain which occurs in brief episodes (15 minutes-2 hours). Clusters consist of headache that occur daily for 3 weeks to 3 months, then remit. Typically there are bouts in early July and early January. It may awaken one from sleep (migraine and tension usually won't). Some experience flushing, droopy eye, nasal stuffiness, or eye tearing. Men are affected 2 to 5 times more frequently than are women (reverse of migraine). Unlike the situation for migraine, menopause does not reduce the frequency and severity of headache in women. There probably are several mechanisms for same symptom complex - migraine variant, sphenopalatine neuralgia, and perhaps a genetic syndrome involving circadian rhythms..
The reason for the peculiar periodicity of cluster headache has recently been discussed (Pringsheim T, 2002). There are two genes -- the PER or period gene located on the X chromosome and the timeless (TIM) gene. Both genes affect the suprachiasmatic (STC) nucleus of the hypothalmus. These genes generate products that control circadian rhythms. It seems reasonable to hypothesize that in cluster headache there is a disturbance of this clock.