Botulinum toxin in the treatment of focal hyperhidrosis

INTRODUCTION: Botulinum A toxin (BTX-A) acts primarily at peripheral cholinergic synapses, inhibiting the release of acetylcholine. Initially it has been used to block the neuromuscular junction in focal dystonic and spastic syndromes. Recently there has been suggestions for potential clinical indications in non-muscular diseases where cholinergic terminals play a role. GUSTATORY SWEATING: In 1995 physicians reported a long-lasting anhidrotic effect of intracutaneous BTX-A injections in patients suffering from gustatory sweating (Frey's syndrome). Consequently, a number of clinical studies demonstrated good efficacy of intradermal injections of botulinumtoxin in patients with focal hyperhidrosis. FOCAL HYPERHIDROSIS OF THE PALMS AND AXILLAE: Focal hyperhidrosis is usually confined to the palms and axillae. Excessive sweating may be a social handicap and an occupational hazard. The management of focal hyperhidrosis remains controversial. Topical antiperspirants are only effective in very mild cases. Iontophoresis with tap water or anticholinergic drugs is messy and time consuming with only short-lived effect. Sympathectomy, the cornerstone of surgical management, is usually effective in palmar hyperhidrosis. Complications of this technique include surgical risks, postoperative and cosmetic problems and compensatory hyperhidrosis. AXILLARY HYPERHIDROSIS: Several studies confirmed that intracutaneous injections of botulinum toxin are useful in the majority of patients with axillary hyperhidrosis resistant to conventional treatment. In axillary hyperhidrosis total doses are ranging from 200-400 mU Dysport or from 80 to 130 mU Botox to reach a good clinical response. Injections are usually well tolerated and no serious side-effects have been observed. The mean duration of anhidrotic effect ranges between 3 and 9 weeks. PALMAR HYPERHIDROSIS: The use of botulinumtoxin in patients with palmar hyperhidrosis is rather difficult. The therapeutic window is smaller because injections are complicated by transient weakness of the small hand-muscles. Furthermore the injections at the palms are painful which can be overcomed by application of local anaesthetics or the blockade of the ulnar and median nerves. The duration of anhidrotic effect ranges from 20 to 50 weeks. CONCLUSION: Intracutaneous injections of botulinum-toxin should be offered to patients with focal hyperhidrosis of the palms and axillae causing serious social, psychologic and occupational problems, resistant to other conventional treatment options.