Serious disorder caused by a deficiency of vitamin B,. It leads to haemorrhages in the brain stem and certain low-lying parts of the brain. The chief cause is failure to eat properly because of alcoholism. The symptoms include diplopia (double vision) caused by paralysis of the eye muscles and by pressure on the eyeballs. Other characteristic features are trembling hands and disorders in co-ordination, with resultant difficulty in walking and other actions of all kinds. Vitamin B, deficiency also often causes widespread neuropathy, and Korsakoff s syndrome with amnesia occurs. There are usually disturbances of consciousness. Serious B, deficiency can endanger life in the long term. Other disturbances can also arise from alcohol abuse, such as cirrhosis of the liver, anaemia and epilepsy. The diagnosis is made on the basis of the characteristic clinical picture, and the blood is also examined (with the vitamins being determined as well). Treatment consists of remaining in bed, stopping drinking alcohol, and a diet rich in calories and vitamins with injections of vitamin B, in large doses. The visual problems and the disturbances in co-ordination usually disappear within a few days under treatment. Neuropathy and Korsakoff s syndrome may continue for many months.