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Sweating disorders

Sweating disorders

Hyperhidrosis

Hyperhidrosis or excess sweating most commonly affects the palms, soles and axilla and is usually idiopathic, prolonged and symmetrical. It is exacerbated by stress but is relatively independent of temperature and occurs in both warm and cold climates, although it is usually more severe with warmth. Onset is most common in childhood or around puberty, and it may spontaneously improve after the age of 25. It is estimated that 1% of the population is affected, and there may be a positive family history.

Pathological sweating can occur with fever, endocrinopathy (thyrotoxicosis, diabetes mellitus and phaeochromocytoma), certain neurological conditions (Parkinson’s disease), Raynaud’s phenomenon and following trauma (Frey’s syndrome or following cold injury). In practice, only thyrotoxicosis requires exclusion, and thyroid function testing should be done when this disorder cannot be excluded clinically.

Hyperhidrosis may be associated with bromhidrosis (unpleasant smelling perspiration). The odour is usually attributable to bacterial breakdown of the sweat; topical metronidazole, topical antiseptic soaps and perfumes may be helpful.

Flexural sites and the submammary area are also prone to hyperhidrosis; dusting powders (eg diphemanil methylsulfate 2% powder) may be useful.

Pitted keratolysis may complicate plantar hyperhidrosis, and is due to overgrowth of bacteria, usually the bacterium, Kytococcus sedentarius.[Note 1] For mild cases, no specific treatment, other than that of the hyperhidrosis, is usually required. For more severe or extensive cases, use specific therapy directed at the microbial overgrowth (eg twice daily application of erythromycin 2% gel, benzoyl peroxide 5% gel, clindamycin 1% lotion, Whitfield’s ointment). Oral erythromycin (500 mg twice daily for 7 to 10 days) is sometimes used if topical therapy fails. The condition tends to recur unless specific measures are taken to reduce the amount of sweating and to decrease maceration.

First-line therapy of hyperhidrosis consists of an antiperspirant. Simple antiperspirants provide relief for 6 to 12 hours and are most suitable for the axilla but can also be used on the palms and soles. Use

If this is not successful, use

Alternatively, refer to a dermatologist for

Tap water iontophoresis initially requires daily use, but with time a single treatment may be effective for 1 to 2 weeks. The hands and feet are placed on moistened pads for 15 to 20 minutes and batteries are used to generate a low electrical current to stimulate migration of ions across the cutaneous barrier towards the opposite sign electrode.

Anticholinergic drugs such as glycopyrronium bromide can also be delivered by iontophoresis. They are more effective than tap water alone, but are only available in specialist settings. Adverse anticholinergic effects such as tachycardia and urinary retention can occur.

Local injection of botulinum toxin type A is most useful for the axilla where little or no anaesthesia is required and the risk of inadvertent muscle weakness is minimal. Complete or near complete anhidrosis that lasts 6 to 12 months can be achieved with botulinum toxin type A (Botox) 50 units per axilla. Use on the hands often requires regional anaesthesia and there is a risk of impairment of fine motor function.

Formalin[Note 2] 2% to 6% soaks are sometimes used for the feet, but are unsuitable for the hands or axilla. Formalin is a potential contact sensitiser and is only used when all other treatments have failed.

Similarly, surgical sympathectomy (open or endoscopic) for palmar hyperhidrosis should only be considered if all other treatments have failed. Relapse after a few years and compensatory hyperhidrosis elsewhere on the body are potential complications, as is Horner’s syndrome. Excision of the axillary vault has been previously used for axillary hyperhidrosis, but the resultant scarring is considered unacceptable. Liposuction of eccrine glands from the axilla has been tried but the results are unreliable.

Miliaria

Sweat gland obstruction has the potential to produce miliaria, an itchy papular and sometimes vesicular eruption on the trunk. The level of obstruction will influence the clinical picture.

Miliaria crystallina, caused by obstruction in the stratum corneum, commonly accompanies febrile illness and profuse sweating. Miliaria rubra (prickly heat), caused by intra-epidermal obstruction, is seen in hot and humid climates and is influenced by individual susceptibility. Infants are particularly prone to this, and secondary bacterial infection with staphylococci is common. Miliaria profunda, caused by obstruction and rupture of the duct at the dermo-epidermal junction, follows repeated episodes of miliaria rubra.

The only really effective treatment is to avoid further sweating. Remove plastic mattresses or mattress protectors and use a sheepskin underlay. Calamine lotion may provide relief and topical antiseptics may prevent secondary infection. If sweating continues, recurrent episodes lasting a few days occur until the patient becomes acclimatised over the next few months. Topical corticosteroids can be used to alleviate symptoms in severe cases.

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