CLUSTER HEADACHE IN IDENTICAL-TWINS

Twin brothers with cluster headache are described. Monozygosity was de monstrated by conventional genetic markers and DNA-typing. Both had '' mini-bouts' in the early stages. In the one, attacks were always excru ciatingly severe; in the other, they started out as ''mild'', eventual ly becoming more severe. Both brothers also suffered from paroxysmal t achycardia. The connection between attacks of tachycardia and cluster headache remains enigmatic. The observation of cluster headache in mon ozygotic twins underscores the importance of genetic factors in the et iology. The ratio between cluster headache prevalence in close family members vs. prevalence in the general population may be higher in clus ter headache than in migraine.