COMA. - Deep sleep (from κοιμάω = I sleep) with muscular relaxation, abolition of sensation, loss of consciousness, while the conditions of respiration, circulation and thermoregulation remain almost unchanged. Produced by various causes: disorders of carbohydrate metabolism (hypoglycemic and diabetic c.), accumulation in the blood of toxic metabolic substances (uremic c., hepatic c.), severe trauma, circulatory alterations of the nerve centers due to vascular spasms or hemorrhages (v. APOPLEXY).
From very mild forms, with simple torpor, in which consciousness can easily be reawakened by more or less strong stimuli (waking c.), one proceeds to the most severe forms with fully developed symptomatology: paralysis of the sphincters, slow and snoring respiration (stertorous breathing), difficulty in swallowing, complete extinction of consciousness. In severe c. the individual must be considered devoid of the means to enter into relation with the external world, incapable of feeling and of willing. The c. can regress and the individual regain consciousness and activity, if the cause producing his state is remediable and is overcome.
Giuseppe de Ninno