Abstract and Introduction
The clinical spectrum of sweating disorders includes sudomotor excess and deficiency. Hyperhidrosis is characterized by sweating beyond that required to maintain a constant internal body temperature. Hypohidrosis and anhidrosis are distinguished by a reduced or absent ability to generate sweat for the purpose of evaporative heat dissipation. Whereas hyperhidrosis is usually benign, anhidrosis may predispose to hyperthermia. Either hyperhidrosis or anhidrosis may accompany a more serious underlying disorder. Correct diagnosis depends on determining the anatomical pattern of sweating and localizing the lesion within the autonomic nervous system. Sudomotor deficits may involve the frontal operculum, hypothalamus, brain stem, spinal cord, sympathetic chain ganglia, peripheral nerve, or eccrine sweat glands. Treatments for hyperhidrosis include topical aluminum chloride, oral anticholinergic agents, intradermal botulinum toxin for some localized syndromes, and thoracic ganglionic sympathotomy or sympathectomy for refractory palmar hyperhidrosis.
Eccrine gland sweating is the principal means of thermoregulatory heat dissipation in humans. If the body's internal temperature exceeds the hypothalamic set point, activation of a sympathetic reflex results in generalized sweating, vasodilatation, and hyperpnea. Evaporative heat loss thus maintains homeostasis by lowering core temperature to normal. The sweating pathway originates in the preoptic area of the anterior hypothalamus and descends uncrossed through the medial portion of the lateral funiculus of the brain stem to synapse upon preganglionic neurons in the intermediolateral column of the spinal cord. Ipsilateral postganglionic sympathetic cholinergic fibers innervate the two to four million eccrine sweat glands distributed over the body surface. These sweat glands are most numerous on the palms and soles (600 to 700 glands/cm2) and least numerous on the back (64 glands/cm2).[3,4] The face and eyelid are supplied by spinal segments TI-T4, the upper limbs by segments T2-T8, the trunk by segments T4-TI2, and the lower limbs by segments TI0-L2.[5,6]
Disorders of sweating are divided into excessive sweating (hyperhidrosis, Table 1 ) and decreased (hypohidrosis) or absent sweating (anhidrosis, Table 2 ) in response to a proportionate thermal or pharmacologic stimulus. Hyperhidrosis is more socially than medically burdensome although it can be occupationally restrictive and rarely hazardous. Anhidrosis, in contrast, may become a medical emergency leading to hyperthermia, heat exhaustion, heat stroke, or death.
Semin Neurol. 2003;23(4) © 2003 Thieme Medical Publishers
Cite this: Disorders of Sweating - Medscape - Oct 01, 2003.