Anhidrosis

Excerpt

Anhidrosis is the inability to sweat. It is important to recognize anhidrosis as it can be potentially life-threatening due to heat-related illnesses. There are three main causes of anhidrosis, which are peripheral alterations in the eccrine gland itself, idiopathic, and central or neuropathic disease and/or medication that disrupts neural inputs from the anterior hypothalamus to the gland.

Causes of central/neuropathic anhidrosis can occur at any level of innervation. The disturbance can occur at the sweating center in the brain, the descending neural tract, or the sweat gland. A disruption will lead to an absence of sweating. Disruption in the neural input can be due to tumors or infarctions of the hypothalamus, pons, or medulla. Spinal cord tumors, injuries, or infarctions can disrupt the neural tract. Other etiologies such as degenerative syndromes (Shy-Drager syndrome), autoimmune autonomic neuropathy, peripheral neuropathy (diabetes, alcohol use disorder, leprosy), and drugs have all been implicated in central/neuropathic anhidrosis.

Peripheral alterations that cause anhidrosis can be congenital or acquired. In addition, forms of peripheral alterations can be due to genetic abnormalities such as incontinentia pigmenti, due to local destruction, for example, by a tumor, or obstruction by entities such as psoriasis.

As heat intolerance may be due to various underlying disorders, a detailed history is important in establishing the diagnosis. Heat intolerance can cause drowsiness, episodic inability to concentrate while in a hot environment, or fatigue, along with a decrease in the patient's normal sweating, which are clues to the diagnosis of anhidrosis. A detailed history should also include the addition of medications, medical events such as injuries, growths or radiation, alcohol consumption, the presence of autoimmune disease or diabetes mellitus, and family history.