Cluster headache. The sweating pattern during spontaneous attacks.

Sweating in the forehead, on the eyelids, in the face and on the trunk was measured with the Evaporimeter during 31 spontaneous cluster headache attacks of varying severity in 18 patients. The evaporimeter measures evaporative water loss (sweating + transepidermal water loss) rapidly and accurately as g/m2/h. The patients themselves acted as controls. Sweating was also estimated in 25 healthy individuals at a temperature of 27 +/- 1 degree C, and a mean relative humidity of 19%. During eight severe attacks, sweating in the medial part of the forehead on the symptomatic side was invariably increased. In moderate attacks the increment was less pronounced and in the inter-cycle period, no definite increase was found. The cause of increased sweating during cluster headache attacks remains enigmatic.