Cluster headache: the possible significance of midline structures.

The pathogenesis of cluster headache is unknown (see, for example, Ref. 1). With regard to the main component of cluster headache, the pain itself, little information exists both as to the origin and as to the nature of the pain. Existing theories concerning cluster headache pathogenesis have been rather unproductive. In the following, evidence from seemingly totally unrelated fields that, nevertheless, possibly has a bearing on cluster headache pathogenesis will be reviewed. On rare occasions, the headache may even be bilateral (5 ) . Several variations of bilaterality have also been observed. Ekbom (6) has thus described a case with a most peculiar pattern, in which the headache during one bout, in addition to appearing on the original side, started appearing on the contralateral side; then “the headache shifted [side] in different attacks”; thereafter, a decrescendo occurred on the original side as opposed to a crescendo on the contralateral side, and, in the ultimate phase, attacks only appeared on the contralateral side. After operations on one side, pain attacks have a tendency to recur on the opposite, on the tendency to bilaterality in previously pain-free side. This was thus the case in 1 of 12 cases treated with the “combined procedure”-that is, sectioning of the cluster headache