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What is hyperhidrosis?
It is a common complaint, but it rarely signifies underlying pathology. Medical consultation may be sought because of abnormal wetness, a change in the pattern or amount of sweating, sweaty palms, stained clothing, or offensive odour. The amount that people sweat in response to the physiologic stimuli of heat, emotion, or eating varies greatly. The interaction of the person, the environment, and the emotions influences the amount of sweating. The primary physician must offer a scientific explanation and symptomatic management to the patient who complains of excessive sweating.
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What is the cause?
Sweating helps maintain temperature and fluid and electrolyte balance in the body, particularly under the environmental stress of heat. Most cases of excess sweating are caused by exaggerated physiologic responses or functional variations of no pathologic consequence. Hyperhidrosis most commonly involves the palms, soles, or axillae (arm pits). This may be a result of an increase in impulses from the central nervous system, or it may reflect underlying problems with the sweat glands. A relation to emotional stress is often noted, and the problem becomes disabling if it interferes with work or social interactions. Axillary hyperhidrosis is less common than palmar or plantar hyperhidrosis and makes frequent clothing changes necessary.
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How to diagnose hyperhidrosis?
The most common cause of localized hyperhidrosis is the normal physiologic response to everyday stress. Menopause is the leading cause of generalized sweats. Of the pathologic causes, fever is the most common. Night sweats raise the possibility of underlying infectious disease and malignancy. Central neurologic injury from stroke or tumour may produce hyperhidrosis. Peripheral neuropathy involving the autonomic nerves is associated with excess sweating, as are such medical conditions as thyrotoxicosis and, uncommonly, phaeochromocytoma. Parkinson's disease may lead to increases in both sweating and sebaceous gland activity. Various drugs, such as antipyretics, insulin, meperidine, emetics, alcohol, and pilocarpine, may induce sweating.
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How to manage hyperhidrosis?
Excessive sweating can interfere with employment and social intercourse. Many therapies have been used; several are effective, but some are associated with undesirable side effects.
Topical therapy
The most effective topical agent for use on the hands and the axillae is a 20% alcoholic solution of aluminum chloride hexahydrate (Drysol). A preparation of 6.25% aluminum tetrachloride (Xerac) is a less potent alternative. Other topical therapies include 10% formalin compresses, which work well but can induce allergic sensitization. Buffered glutaraldehyde is effective but stains the skin. Electrical current may be used to block sweat glands temporarily. Topical iontophoresis with either tap water or an anticholinergic agent and aluminum chloride can reduce sweating of the palms. Tap water units can be used at home. Response rates are in excess of 80% and have been reported with an average remission of about 1 month.
Systemic therapy
Scopolamine and other cholinergic agents decrease sweating but can cause central nervous system side effects and precipitate glaucoma or urinary obstruction in patients with underlying prostatic hypertrophy. Phenoxybenzamine, an adrenergic antagonist, has been reported to be successful in several cases of generalized hyperhidrosis.
Surgery
In rare instances of genuinely incapacitating hyperhidrosis, surgery is sometimes considered. Axillary hyperhidrosis may be cured with surgical removal of the glands in the axillae. Studies suggest that liposuction of the axillae may remove the sweat glands without altering the normal architecture. Palmar sweating may respond to sympathectomy, which can be performed endoscopically. This is a much less invasive procedure than it once was, thanks to newer instrumentation.
Botulinum A neurotoxin (Botox) has been used successfully for both axillary and palmar hyperhidrosis. Intradermal injection of Botox results in long-term reduction in sweating in both locations. When Botox is injected into the palm, some patients experienced reversible minor weakness in their handgrip.
Therapeutic recommendations
Reassure the patient that excess sweating is not the consequence of a pathologic condition once medical causes have been ruled out. For axillary sweating, recommend frequent washing and changes of clothing. For excess sweating of the palms or the axillae, recommend a 20% alcoholic solution of aluminum chloride hexahydrate (Drysol). An effective alternative is 6.25% aluminum tetrachloride (Xerac). It should be applied at bedtime and covered with a plastic food wrap; polyethylene or vinyl gloves can be worn if the palms are affected. In the morning, the treated areas should be washed with soap and water. Prescribe 1-3 consecutive treatments per week. Once dryness has been achieved, maintenance with one treatment per week should suffice.
Electrical current may be used to block sweat glands temporarily. Use of the device (Drionic) daily for 1 week may relieve sweating for up to 1 month. Intradermal injection of botulinum toxin is gaining in popularity and should also be considered as a relatively noninvasive therapy. Liposuction techniques may also be useful. If topical therapy and reassurance and less invasive approaches fail, sympathectomy performed via a thoracoscope may be considered, but only if the patient's hyperhidrosis is truly incapacitating. Referral should be made to a neurosurgeon or vascular surgeon for evaluation.
