An acute neurological disorder characterized by the triad of ophthalmoplegia, ataxia, and disturbances of mental activity or consciousness. Eye movement abnormalities include nystagmus, external rectus palsies, and reduced conjugate gaze. THIAMINE DEFICIENCY and chronic ALCOHOLISM are associated conditions. Pathologic features include periventricular petechial hemorrhages and neuropil breakdown in the diencephalon and brainstem. Chronic thiamine deficiency may lead to KORSAKOFF SYNDROME. (Adams et al., Principles of Neurology, 6th ed, pp1139-42; Davis & Robertson, Textbook of Neuropathology, 2nd ed, pp452-3).