Cyclic esotropia with minimal brain dysfunction.

An eight year old with a long history of hyperkinesis and learning difficulties compatible with the diagnosis of minimal brain dysfunction developed alternate day squint known as Cyclic Esotropia. No other abnormal cyclic phenomena such as alterations in sleep structure, diurnal variations in hemoglobin, hematocrit, electrolytes, body temperature, blood pressure or pulse rate was found. In view of the fact that cyclic esotropia may represent an impairment of the "biological clock" thought to be located in the hypothalamus, detailed studies of the hypothalamic hypophyseal axis were performed and found to be normal. It is suggested that if such a biological clock is present, its location is remote from the neural circuits involved in hypothalamic-hypophyseal hormonal release.