SUNCT syndrome: forehead sweating pattern.

The forehead sweating function has been assessed in SUNCT syndrome--a short-lasting, unilateral, neuralgiform headache syndrome with autonomic phenomena on the symptomatic side (conjunctival injection, lacrimation, etc.). In the three patients (of a total of six) who could be studied during paroxysms, increased evaporation was present on the symptomatic side of the forehead compared to the non-symptomatic side during attacks or to the symptomatic side between attacks. Basal sweating was generally within control limits, so long as the attack frequency was not so high as to influence the interictal level. During attacks precipitated by eating chocolate or sour apple (in the case of one of the patients), forehead sweating was also increased on the symptomatic side. The forehead sweating responses to heating and pilocarpine were without any notable or systematic asymmetries. The forehead sweating pattern in SUNCT syndrome may differ from the patterns in unilateral headaches like cluster headache, on the one hand (in which there is generally an asymmetry during heating and pilocarpine tests), and chronic paroxysmal hemicrania (CPH) and cervicogenic headache, on the other (where there is no systematic increase during attacks.