Periods of cluster headache induced by nitrate therapy and spontaneous remission of angina pectoris during active clusters.

Glyceryl trinitrate (GTN) is known to induce single extra attacks of cluster headache (CH) during active cluster periods, most probably via actions of nitric oxide (NO). Induction of whole periods of CH by organic nitrates has, however, attracted little attention in the literature. We report on eight patients with episodic CH and coexistent effort-induced angina pectoris. Cases 1-6 had been free of their headaches for many years but got recurrence of CH within a few weeks after the administration of long-acting organic nitrates (isosorbide-dinitrate, isosorbide-5-mononitrate or slow-release GTN) aimed at treating their chest pains. These nitrate-induced headache periods were more severe and had a longer duration than the previous spontaneous ones. Furthermore, one of the subjects and two additional cases experienced a marked reduction of their anginal attacks during successive CH periods. Exercise time to effort-induced angina was increased in all three patients and one of them revealed a markedly elevated threshold for eliciting ischaemic cardiac symptoms by standardized physical exercise on a cycle ergometer. We hypothesize whether extra CH periods elicited by sustained nitrate therapy and remission of angina pectoris during active clusters are caused by central mechanisms involving inhibition of sympathetic tone and effects on both cranial vessels and cardiac functions.