Presenting Symptom: coarse horizontal nystagmus on attempted gaze to the right; unable to maintain the eyes in the direction of dextroversion; similar on left; pupils abnormally large, though reactive; somewhat better vertical gaze, although there is vertical nystagmus on looking up or down; nystagmus is in direction of attempted gaze; in primary position, the eyes are quiet; upbeat nystagmus on looking up, downbeat on looking down. History: monkey on thiamine deficient diet. Disease/ Diagnosis: Wernicke Encephalopathy; Thiamine Deficiency.
