Abnormal Neuromuscular Transmission in Cluster Headache

Objective.—To identify and investigate any dysfunction of neuromuscular transmission in episodic cluster headache. Background.—Abnormal neuromuscular transmission has been shown in migraine with aura and in migraine without aura by using single fiber electromyography. Especially for migraine with aura, a genetic cause has been postulated. Episodic cluster headache is a primary headache disorder in which genetic factors may, at times, play a strong role. Methods.—Single fiber electromyography during voluntary contraction of the extensor digitorum communis muscle, nerve conduction studies of upper and lower extremities, and concentric needle electromyography of the extensor digitorum communis were performed on 6 patients with episodic cluster headache and 6 age‐matched normal controls. Twenty potential pairs were recorded from each subject. Twenty individual jitter values and a mean jitter value were calculated for each subject. Both mean individual jitter values and numbers of abnormal individual jitter values were compared in patients with cluster headache versus normal controls. Results.—Three of 6 patients with episodic cluster headache showed pronounced neuromuscular transmission abnormalities by single fiber electromyography. None of the controls had any neuromuscular transmission abnormality. Another patient with episodic cluster headache had borderline dysfunction of neuromuscular transmission. Transmission was clearly normal in only 2 of 6 patients with cluster headache. Conclusion.—These results suggest that episodic cluster headache may share the same abnormality of neuromuscular transmission observed in migraine.