Chronic paroxysmal hemicrania. VI. Precipitation of attacks. Further studies on the precipitation mechanism.

In four of the approximately 40 cases of chronic paroxysmal hemicrania (CPH) that are known so far, attacks that are similar to the spontaneous ones may be precipitated by head movements or pressure against certain points in the neck. Head flexion was used as the precipitation procedure in a 34-year-old female who was studied several times in the course of five years. Attacks occur within 5-40 sec, and the pain is preceded by tearing and conjunctival injection. External rubbing or external compression of the common and internal carotid arteries on the symptomatic side did not produce attacks. The combination of head flexion and external compression of the common or internal carotid arteries on the symptomatic side invariably produced an attack of usual severity and within the usual time. This investigation would seem to render unlikely the possibility of a primary vascular mediation of the signal from the neck to the ocular region. Sympathetic fibres are the likely mediators of the impulses from the neck to the ocular area.