Focal hyperhidrosis: diagnosis and management

Abstract

Hyperhidrosis, a condition characterized by excessive sweating, can be generalized or focal. Generalized hyperhidrosis involves the entire body and is usually part of an underlying condition, most often an infectious, endocrine or neurologic disorder. Focal hyperhidrosis is idiopathic, occurring in otherwise healthy people. It affects 1 or more body areas, most often the palms, armpits, soles or face. Almost 3% of the general population, largely people aged between 25 and 64 years, experience hyperhidrosis. The condition carries a substantial psychological and social burden, since it interferes with daily activities. However, patients rarely seek a physician's help because many are unaware that they have a treatable medical disorder. Early detection and management of hyperhidrosis can significantly improve a patient's quality of life. There are various topical, systemic, surgical and nonsurgical treatments available with efficacy rates greater than 90%-95%.

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Fig. 1: A starch iodine test is used to outline the area of excessive sweating. Iodine solution (1%–5%) is applied to a dry surface, followed by a sprinkling of starch (top). The iodine and starch interact in the presence of sweat, leaving a purplish sediment (bottom).

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Fig. 3: Intradermal botulinum toxin injections for the treatment of palmar hyperhidrosis. For palmar hyperhidrosis, intradermal injections spaced about 1–2 cm apart seem to give the best results. About 2 units of botulinum toxin A are injected per site as required, with a total dose of 100 units for each palm. The main limitation is that most patients find the injections painful and may require regional anesthesia via median, ulnar and radial nerve blocks at the wrist level. A similar technique and dosage of botulinum toxin A is used for the treatment of plantar hyperhidrosis, requiring regional nerve blocks of posterior tibial and sural nerves for anesthesia. Other methods of reducing the pain of injections have included high-intensity vibration devices, cool packs and liquid nitrogen spray, all with variable results.

Fig. 2: Intradermal botulinum toxin injections for the treatment of axillary hyperhidrosis. Focal axillary hyperhidrosis is treated with 50–200 units of botulinum toxin A per axilla. The usual starting dose is 50 units per axilla. The drug is injected intradermally using a 13-mm-long 30-gauge needle. Injections are done in a grid-like pattern in order to cover the entire affected area, with injection sites generally 1–2 cm apart. There is no difference in efficacy of botulinum toxin A in the treatment of axillary hyperhidrosis when administered by subcutaneous or intradermal injection, but intradermal injections are reported to be more painful.The subcutaneous injection technique requires further study for validation of the results.