Idiopathic localized unilateral hyperhidrosis: case report of successful treatment with botulinum toxin type A and review of the literature.

BACKGROUND Localized unilateral hyperhidrosis (LUH) is a rare disorder of unknown origin. We describe a patient with LUH on the forearm, where a fracture was identified as a past injury. OBSERVATIONS We treated the patient with botulinum toxin type A injections, and he was complaint free during the 6 months after treatment. In addition, the initially strong positive results of the iodine starch test (Minor sweat test) were negative in the affected region after treatment. CONCLUSIONS This relatively new therapeutic modality already established for axillary, palmar, and plantar hyperhidrosis seems to be efficient in LUH. As the former therapeutic approaches are rather disappointing, and as botulinum toxin type A locally applied shows limited adverse effects, we think a trial of botulinum toxin type A is justified in cases of LUH, even as a first-line treatment. In addition, the literature considering localization and causes of LUH is reviewed.