COMA. - A profound sleep-like state (from κοιμάω = I sleep) with muscular relaxation, abolition of sensibility, and loss of consciousness, while the conditions of respiration, circulation, and thermoregulation remain virtually unchanged. It is produced by various causes: disturbances in carbohydrate metabolism (hypoglycaemic and diabetic c.), accumulation in the blood of toxic metabolic substances (uraemic c., hepatic c.), severe trauma, circulatory alterations of the nervous centres due to vascular spasms or haemorrhages (v. APOPLESSIA).
From very mild forms, involving mere torpor, in which consciousness can easily be awakened by stimuli of varying strength (wakeful c.), one reaches the most serious forms with fully developed symptomatology: paralysis of the sphincters, slow and snoring respiration (stertorous respiration), difficulty in swallowing, complete extinction of consciousness. In severe c. the individual must be considered deprived of the means of establishing relations with the external world, incapable of feeling and willing. The c. may regress and the individual may recover consciousness and activity, if the cause producing the condition is remediable and is overcome.
Giuseppe de Ninno