Anhidrosis (from Greek ἀνἱδρώς (anídrōsis), derived from ἀν-(án → inversion prefix) and ἱδρώς (hidrṓs → sweat); also called hypohidrosis, adiaphoresis, and oligohidrosis) in the medical field means the lack, or significant reduction, of skin perspiration, sweating, or perspiration. The term adiaphoresis is derived from: ἀν- (án → inversion prefix) and διαϕόρησις (diaphórēsis → perspiration), a derivative of διαϕορέω (diaphoréō → transport, disperse); in turn, the lemma consists of the prefix δια- (through) and ϕόρησις (transport), from the theme of ϕορέω (transport).
Adiaphoresis (án → inversion prefix and diaphórēsis → perspiration) can be considered a synonym of anhidrosis, being also an alteration of sweating, in the sense of reduction or disappearance. While the reduction of sweating characterizes, however, the typical picture of hypohidrosis, these manifestations are opposed to hyperhidrosis, characterized by excessive sweat secretion.
In particular, when the secretion, by the sweat glands, is only reduced we speak of hypohidrosis: as a result, the skin is dry and parched.
It can affect limited skin areas or extend to large areas of the body (often caused by a skin trauma such as a burn, infection or other injuries), compromising, in this case, the thermo-dispersive mechanisms: since sweat is a means to disperse the excessive body temperature, following exposure to heat and / or intense physical exertion, anhidrosis exposes the body to the risk of severe hyperthermia; for a compensatory mechanism, moreover, there is hyperhidrosis of functionally normal areas.
Generalized anhidrosis is caused by the destruction of the regulatory centers of the hypothalamus or in the course of some diseases of the peripheral nervous system, by poisoning with atropine or vagolytic drugs, in a condition of dehydration of the body, as in the case of repeated diarrhea and vomiting, or even in the rare conditions of congenital absence of sweat glands; subjects affected by this manifestation, regardless of the cause, are particularly sensitive to all those conditions involving an increase in body temperature: Feverish diseases, rather high room temperature, prolonged muscular activity.
Localized anhydrosis occurs in the course of lesions of the peripheral nervous system or spinal cord (neuropathies) or skin diseases involving occlusion or destruction of the sweat ducts.