Disorders of Sweating

William P. Cheshire, MD; Roy Freeman, MB, ChB


Semin Neurol. 2003;23(4) 

In This Article


Generalized Hyperhidrosis

Essential or primary generalized hyperhidrosis is characterized by sweating that exceeds the amount necessary to maintain thermal regulation. Generalized sweating may occur at a lowered threshold with excessive volume loss of body fluids resulting in the potential for dehydration or electrolyte loss.[7] Hyperhidrosis may also be secondary and associated with any of numerous systemic processes and illnesses, including pheochromocytoma, thyrotoxicosis, diabetes mellitus, diabetes insipidus, hypopituitarism, anxiety, menopause, carcinoid syndrome, and drug withdrawal.[3,4,8] Nocturnal diaphoresis, in particular, may be a clue to the diagnosis of tuberculosis, lymphoma, endocarditis, diabetes, acromegaly, or Prinzmetal angina.[3,4] Amelioration of hyperhidrosis in these cases requires treatment of the underlying disease.

Penfield introduced the term "diencephalic epilepsy" to describe the syndrome of paroxysmal diaphoresis, flushing, hypertension, lacrimation, shivering, and respiratory changes in a patient with a tumor at the foramen of Monro.[9] Other authors have reported similar episodes in patients with head trauma,[10,11] neoplasia,[12] thalamic lesions,[13] and hydrocephalus.[14] Such episodes are not true epilepsy, as electroencephalography is normal and the episodes fail to respond to antiepileptic drugs. The term "paroxysmal sympathetic storms" more appropriately describes what are more likely to represent a release phenomenon or periodic functional hypothalamic disturbance that may respond to morphine or bromocryptine.[11] Shapiro syndrome is a related disorder characterized by episodic hyperhidrosis with hypothermia and is often associated with agenesis of the corpus callosum or other midline structural abnormalities.[15] These episodes may respond to clonidine,[16] glycopyrrolate,[17] or antiepileptic drugs.[7]

Several common medications occasionally produce hyperhidrosis. These include tricyclic and serotonin reuptake inhibitors, opioid analgesics, acyclovir, and naproxen.[18]

Focal Hyperhidrosis

Essential Hyperhidrosis. In contrast to the generalized distribution of thermoregulatory sweating due to exercise and heat exposure, sweating in response to emotional stimuli and mental effort involves the palms, soles, and axillae.[19,20] Sweating in these areas represents the most common form of focal hyperhidrosis. Patients with essential palmar hyperhidrosis complain of sweat constantly pouring from the skin surface and may be embarrassed to shake hands. In severe cases patients cannot use a pen without soaking the writing paper. There may be accompanying plantar hyperhidrosis with staining and damage to shoes. Topic antiperspirants containing 6 to 25% aluminum chloride in alcohol are the first line of therapy for axillary hyperhidrosis, yet are ineffective in the treatment of palmar or plantar hyperhidrosis because the skin is much thicker. Tap water iontophoresis is a safe and inexpensive therapeutic modality for palmar hyperhidrosis.[21] The mechanism may be poral plugging, and the effect is temporary, requiring ongoing therapy. Anxiolytics such as benzodiazepines may be helpful when hyperhidrosis is triggered by specific psychosocial stressors. Anticholinergic medications are seldom helpful.

Intradermal injection of botulinum toxin has been shown to decrease focal hyperhidrosis of the palms and axillae for 2 to 6 months and may be the treatment of choice for these conditions.[22,23,24,25] The treatment requires at least 20 injections per palm and can associated with transient weakness of the intrinsic hand muscles. For patients with severe, refractory palmar hyperhidrosis, satisfactory long-term results have been reported following endoscopic thoracic sympathectomy. Compensatory sweating elsewhere develops in many cases. In addition to hand dryness, side effects in a small proportion of patients include Horner syndrome, pneumothorax, gustatory hyperhidrosis, and chronic rhinitis.[26,27] The risk of adverse effects may be less with sympathotomy.[28] As the long-term recurrence rate is ~7 to 17% for palmar hyperhidrosis compared with 65% for axillary hyperhidrosis, permanent abolition of the latter is achievable only by surgical resection of axillary skin.[26,27]

Hyperhidrosis with Peripheral Neuropathy

Hyperhidrosis frequently accompanies small-fiber peripheral neuropathies. Excessive sweating may occur as a compensatory phenomenon involving proximal regions, such as the head and trunk, that are spared in a dying-back neuropathy. In addition, patients with small-fiber peripheral neuropathies may have excessive distal sweating, presumably due to spontaneous firing of injured neurons.[29] Episodic hyperhidrosis also occurs commonly in patients with familial dysautonomia (Riley-Day syndrome), a hereditary sensory and autonomic neuropathy (HSAN III) that results from a splice defect in the IKBKAP gene on chromosome 9q31.[30]

Unilateral Circumscribed Idiopathic Hyperhidrosis

Unilateral circumscribed idiopathic hyperhidrosis is an idiopathic condition in which profuse sweating occurs episodically in an area of skin sharply demarcated from the surrounding dry skin. Typically the face or arms are the involved territory. Sweating may occur spontaneously or in response to heat, psychological stimuli, or spicy foods.[20,31] Therapeutic measures include topical aluminum chloride, oral anticholinergic agents, clonidine, or local sweat gland excision ( Table 3 ).[7,32]

Hyperhidrosis with Spinal Cord Disease

Autonomic dysreflexia is a potentially life-threatening syndrome affecting patients with spinal cord injury at or above the level of T6. In these patients spinal preganglionic sympathetic neurons disconnected from supraspinal regulation episodically exhibit unchecked reflexes. Ordinary stimuli such as bowel or bladder distension, visceral stimulation, skin irritation, or orthostatic hypotension provoke an exaggerated autonomic response characterized by hypertension; profuse sweating involving the face, neck, and upper trunk; facial flushing; pounding headache; nasal congestion; piloerection; and bradycardia.[33] Patients with syringomyelia may present with focal hyperhidrosis due to segmental hyperactivity of sympathetic preganglionic neurons.[34] In some patients excessive sweating occurs in regions above or below the level of the syrinx. Hyperhidrosis may subside as spinal cord damage progresses over time[34] or following surgical drainage of the syrinx.[35]

Hyperhidrosis with Thoracic Tumors

Unilateral hyperhidrosis involving the face, neck, and thorax may signal encroachment of an ipsilateral tumor on the sympathetic chain ganglia or postganglionic sympathetic fibers. The most common are pulmonary adenocarcinoma,[36,37,38,39] mesothelioma,[40] myeloma,[41] osteoma,[42] and cervical rib.[43] Associated signs may include Horner syndrome, upper limb weakness, and sensory loss (Pancoast syndrome). In other cases, normal preserved sweating contralateral to the sympathetic deficit may be misinterpreted as regional hyperhidrosis.

Hyperhidrosis with Cerebrovascular Disease

Hemihyperhidrosis in the paretic side of the body may follow cerebral hemispheric,[44,45] brain stem,[46,47] or hypothalamic[48] infarction. The hyperhidrosis is typically acute and transient.[45,46,47,48,49] Recognition of enduring asymmetry of sweating may be delayed pending the arrival of warm weather.[46] The mechanism in some cases may be interruption of a crossed sympathoinhibitory pathway originating in the frontal operculum. In other cases normal sweating on the unaffected side may only seem unusual in juxtaposition to anhidrosis on the affected side.

Gustatory Hyperhidrosis

Ingesting highly spiced foods stimulates physiologic gustatory sweating in most people. This trigeminovascular reflex typically occurs symmetrically on the scalp or face and predominantly over the forehead, lips, and nose.[50] Pathologic facial gustatory sweating, in contrast, is usually asymmetrical and occurs independently of the nature of the ingested food. This phenomenon frequently occurs after injury or surgery in the region of the parotid gland (Frey syndrome).[51] The mechanism is ascribed to post-traumatic misdirection of regenerating parasympathetic fibers destined for the salivary glands to postganglionic sympathetic nerve fibers in the auriculotemporal nerve innervating the preauricular sweat glands and blood vessels.

Aberrant gustatory sweating follows up to 73% of surgical sympathectomies[52] and is particularly common after bilateral procedures.[53] Gustatory responses may be accompanied by facial flushing, gooseflesh, vasoconstriction, and paresthesia.[52,53] Facial sweating during salivation has also been described in diabetes mellitus,[54] cluster headache,[55,56] following chorda tympani injury,[57] and following facial herpes zoster.[58] Intradermal botulinum toxin has proven safe and effective in treating this condition.[54,59]

Cold-Induced Hyperhidrosis

Two sibships have been reported in whom exposure to cold ambient temperatures induced nuchal and truncal hyperhidrosis. Associated signs included a marfanoid appearance in two sisters[60] and orthostatic hypotension, cold-induced distal cyanosis, achalasia, and motor peripheral neuropathy in another two sisters.[61]

Hyperhidrosis with Cutaneous Disease

Several cutaneous disorders have been associated with localized hyperhidrosis. Increased sweating may occur in the region of organoid nevi, nevus sudoriferus, eccrinepilar angiomatous hamartoma, glomus tumor, and blue rubber bleb nevus. Hyperhidrosis also occurs in association with the polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes of POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome as well as over the palms and soles of patients with pachydermoperiostosis, dyskeratosis congenita, and symmetrical lividity of palms and soles.[20,21]