Macrosquare-wave jerks subsiding after hydrocephalus treatment in a thalamic hemorrhage patient.

A 54-year-old man suddenly developed impaired consciousness and left hemiplegia due to a right thalamic hematoma. Emergent ventricular drainage for acute hydrocephalus improved the level of consciousness, but macrosquare-wave jerks (MSWJ) consisting of a right-ward intrusive saccade and corrective saccade appeared. The MSWJ disappeared on day 2 when follow-up CT revealed improvement of hydrocephalus. However, on day 36, after ventricular drainage was clamped, the MSWJ reappeared. After ventriculoperitoneal shunt, MSWJ again subsided. In this patient, hydrocephalus may have stretched the superior colliculus, thereby decreasing activity of the fixation neurons and then omnipause neurons, and eventually resulting in the reversible MSWJ.