Botulinum toxin A for focal hyperhidrosis in leg amputees: a case report.

Sir, Among the side-effects arising with a prosthesis, ®tting problems and dermatological complaints are the most frequent. The importance of prevention or early recognition of skin problems cannot be overemphasized to avoid bed rest and other handicaps (1). One major problem in leg amputees is stump hyperhidrosis. The use of silicone pads and other rather occlusive materials in prostheses aggravates hyperhidrosis, leading to lubrication. Whereas occlusion alone can cause hydration of the stratum corneum, the combination of lubrication with occlusion initiates prolonged disturbance of the skin's barrier function (2). Hyperhidrosis is linked to discomfort and a number of skin complaints including malodour, folliculitis and other bacterial and mycological skin disease, and the development of irritant and allergic contact dermatitis (1). Several attempts have been made to treat hyperhidrosis including topical astringent agents and tap water iontophoresis (3). Recently, botulinum toxin A (BTXA) has been used to treat focal hyperhidrosis (4, 5). BTXA is a zinc endopeptidase. The toxin is internalized by endocytosis at the axon terminal and becomes fully activated by disulphide reduction once inside the cell. BTXA targets SNAP-25 involved in acetylcholine release (6). We report a patient with leg amputation and hyperhidrosis of the stump treated successfully with BTXA for stump hyperhidrosis. A 58-year-old man, with a lower leg amputation due to osteomyelitis in 1962, was referred to the Department of Dermatology because of suspected contact dermatitis. He suffered from diabetes mellitus, stump hyperhidrosis, and nummular microbial eczema. On examination we found a lower leg amputation stump with a suction stocking prosthesis. The itching, malodorous, exudating, hyperhidrotic skin showed erythematous scaling lesions and mild distal veruccous hyperplasia. Laboratory investigations, including differential blood count, creatinine, urea, bilirubin, serum enzymes, urine analysis, total IgE, and protein electrophoresis, were normal. Several swabs were taken from the exudating skin lesions. A mixed bacterial culture was found including aerobic (Acinetobacter iwof®, Corynebacterium spp., Sphingomonas paucimobilis and saprophytic staphylococci) and anaerobic species (Camphylobacter rectus, Propionibacteria, Peptostreptococci and Bacteroides spp.). Patch testing was performed according to the German Contact Dermatitis Research Group (7). No type-IV sensitization was found against the most common allergens of the standard test, textile colours, rubbers, topical ointments and conservatives, and materials of his own prosthesis. We performed topical treatment of the microbial eczema including a povidone-iod based disinfectant and topical corticosteroid creme (initially amcinonide; later on prednicarbat). Eczema and pruritus disappeared. After informed consent we treated his stump hyperhidrosis with BTXA. Hyperhidrotic areas were identi®ed by Minor's iodineÐstarch test (8). As shown in Fig. 1, they were found on both the distal and the lateral part of the stump. For treatment, 100 U of BTXA (Botox; Allergan, Irvine, CA, USA; distributed by Merz Pharma Germany) were diluted with 4.0 ml 0.9% sterile physiological saline without preservative. The toxin was injected in amounts of 0.05 ± 0.1 ml (5 ± 10 U) strictly intracutaneous using a 30 gauge needle. Analgesic therapy was not necessary. The effect was evaluated by Minor's iodineÐstarch test 3 days later (Fig. 2). The patient had a consultation 3 months later. He was still satis®ed with the anhidrotic effect. There was no relapse of the microbial eczema. The development of functional and aesthetic leg prostheses is a great advantage for amputees. The ongoing use of the prosthesis, however, may account for some discomfort and skin problems. Sweating inside the socket is annoying and Fig. 1. Identi®cation of hyperhidrotic areas after Minor's sweat test.