SENSITIVITY DISTURBANCES

A term used in this book to designate various conditions of reduced, exaggerated, or distorted sensitivity, either organic or functional in origin.Anesthesia is a total loss of sensitivity to stimuli due to nerve impairment or destruction, narcotic drugs, psychiatric disorder, or hypnotic suggestion. Various kinds of anesthesia—glove, stocking, trunk, girdle, garter, wrist, etc. —occur in cases of hysteria, or conversion reaction. Anesthesias of this type are psychogenic in origin, and can often be shown to serve unconscious purposes and bring secondary gains. They are distinguished from organic anesthesia due to nerve injury by the fact that the insensitive areas do not correspond to the distribution of nerve fibers. Anesthesias of taste (ageusia) and smell (anosmia) are also occasionally observed. Coleman (1964) cites the case of an elderly mother who lost her sense of smell when her only son came home night after night with the odor of alcohol on his breath. Hysterical skin anesthesias were particularly common in the Middle Ages, and were used as one of the major proofs of witchcraft. See CONVERSION REACTION, DEMONOLOGY, HYPNOSIS.Hypoesthesia, or hypesthesia, is a partial loss of sensitivity. This reaction is also a common hysterical symptom, as is the opposite extreme, hyperesthesia. In the latter case, the patient may be inordinately sensitive to one or another kind of sensory impression—to sound, light, heat, cold, and particularly to tactile stimuli. Hypersensitivity also occurs in a number of organic conditions, such as alcoholic polyneuritis and menopause.Three other types of sensitivity disturbance occasionally occur in patients with conversion reaction: analgesia, the loss or impairment of pain sensitivity; hyperalgesia, extreme sensitivity to pain; and paresthesia, which includes various sensitivity distortions such as tingling, tickling, or burning sensations. Paresthesias are also found in a variety of other disorders, including cerebral arteriosclerosis, alcoholic polyneuritis, and hyperventilation syndrome. Formication, the feeling that bugs are crawling on or under the skin, is a form of paresthesia occurring in delirium due to infection, cocaine, or acute alcoholic hallucinosisBrief mention should also be made of other sensitivity disturbances which may be due either to psychological disorders (particularly, conversion reaction), or to physical conditions associated with disease or neurological defect. Among them are gargalanesthesia, absence of tickle sense (or its opposite, hypergargalesthesia); hyper- (or hypo-) ageusia, excessive or diminished acuteness of the sense of taste; hyper- (or hypo-) kinesthesia, over- or underactivity of the sense of motion or position; hyper- (or hypo-) thermoesthe- sia, excessive or diminished sensitivity to heat; thermoanesthesia, absence of heat sense; hyper- (or hypo-) baresthe- sia, over- or underactivity of the pressure or touch sense; pallesthesia, excessive sensitivity to vibrations; palmanes- thesia, loss of sensitivity to vibrations; hyper- (or hypo-) algesia, excessive or diminished sensitivity to pain; and hyper- (or hyp-) acusia or -acusis, extreme or reduced sensitivity to sounds.