Causes of Secondary Hyperhidrosis: Focal hyperhidrosis

A variety of diseases can cause localized hyperhidrosis. Neurologic injury and dermatologic syndromes make up the majority of secondary causes of excessive focal sweat production.

Acute spinal cord injury would be expected to lead to loss of sweating below the site of injury, but such injuries can also lead to localized areas of hyperhidrosis seen months to years after the injury.[119] Patients with spinal cord injury at or above T6 can have autonomic dysreflexia, presenting with exaggerated responses to triggers such as bowel and bladder distention, or skin irritation. In addition to excessive sweating on the face and upper part of the trunk, patients also have flushing of the face, nasal congestion, and headache.[119] Orthostatic hypotension occurring in patients with cervical spine injury can trigger a similar exaggerated sympathetic discharge, leading to hyperhidrosis in the face, neck, and upper trunk.[119] Posttraumatic syringomyelia, a fluid-filled cavity in the spinal cord occurring months to years after the acute injury, can also cause focal hyperhidrosis.[119]

Central nervous system injuries such as strokes leading to hemispheric or medullary infarcts can lead to hyperhidrosis on the ipsilateral and contralateral side, respectively.[57]

Injury to the cranial part of the sympathetic chain by accessory cervical ribs can lead to hyperhidrosis on the face, neck, and shoulder.[57] An intrathoracic tumor impinging on the sympathetic trunk or postganglionic nerves can cause hyperhidrosis by a similar mechanism.[119] In reflex sympathetic dystrophy, hyperhidrosis is often seen in the affected area.[57]

When injury occurs to a large portion of the sympathetic chain, either in the spine or in the central nervous system, widespread anhidrosis is common. If this area of anhidrosis is sufficiently large, compensatory hyperhidrosis can occur in innervated areas. Compensatory hyperhidrosis is also seen in diabetic neuropathy, after thoracic sympathectomy, and in Ross syndrome, a rare syndrome in which anhidrosis occurs in a dermatomal pattern due to focal dysfunction of the sympathetic fibers innervating sweat glands.[57]

Conditions sometimes associated with palmoplantar hyperhidrosis include Raynaud’s disease, erthromelalgia, atrioventricular fistula, cold injury, rheumatoid arthritis, and some rare dermatologic syndromes (see below).[119]

In one type of focal hyperhidrosis, gustatory sweating, increased perspiration occurs on the cheek or mandibular area of the face simultaneously with salivation. This auriculotemporal syndrome, also known as Frey syndrome, has several causes. After inflammation or surgery near the parotid gland, “cross-talk” between regenerating nerves that cause salivation and sympathetic nerves causes excessive facial sweating. High thoracic sympathectomy and diabetic neuropathy involving nerves to the same area can also lead to this syndrome.[119] Foods known to stimulate gustatory sweating include coffee, chocolate, spicy or sour foods, hot foods, alcohol, citric acid, and/or sweets.[19,83,145] There is also an idiopathic variety of gustatory sweating that occurs only with certain foods.[19]