Ocular lateropulsion. A sign of lateral medullary disease.

Four patients with clinically localized lesions in the lateral medulla exhibited a tonic bias of their eyes toward the damaged side despite full extracular movements. Each reported that his eyes were being pulled toward the involved side. Although the tonic bias was most prominent when fixation was inhibited, it also occurred with fixation and interfered with saccadic and smooth-pursuit eye movements. Saccades were hypometric when directed against the bias, whereas they were hypermetric when directed toward the side of the lesion. Smooth pursuit toward the intact side was severely impaired, whereas pursuit in the direction of the bias was normal or near normal. Lateropulsion of the eyes seems to be a unique sign of disease in the lateral medullary region of the brainstem.