A brain disorder caused by a deficiency of vitamins, particularly thiamine and niacin; first described in 1881 by the German neurologist Carl Wernicke (1848-1905).The principal symptoms are memory loss, confabulation, clouding of consciousness, ophthalmoplegia (paralysis of eye muscles with ptosis, or drooping of eyelids; Argyll-Robertson pupil, a failure of the pupil to respond to light changes), and ataxia, an unsteady gait resulting from damage to nerves in the brain stem. The brain stem damage is due primarily to petechial mid-brain hemorrhages brought on by the vitamin deficiencies. The onset of the disease may be acute, with nausea, vomiting, and clouded consciousness; or it may develop more slowly out of a dreamy, confused delirium and distortion of memory. The patient tends to remain apathetic, moody, irritable, and easily fatigued. In some cases the symptoms of lassitude and general weakness are the same as in beri beri. See BERI BERI, PEL- LAGRINOUS PSYCHOSIS.Korsakoff's syndrome is now generally considered to be the behavioral aspect of Wernicke’s disease. The disorder is most frequendy seen in chronic, “skid- row” alcoholics, but also occurs in cases of pernicious anemia, gastric cancer, and in vitamin-starved prisoners of war. It is seldom found in the general population today, now that the enrichment of bread and flour has been widely adopted. In most cases the psychological disturbances rapidly disappear when large doses of thiamine are administered. The neurological symptoms may take longer to overcome, and in some instances there may be permanent defects