Destruction of the internal sagittal stratum and normal smooth pursuit.

Analysis of smooth pursuit by infrared oculography showed normal horizontal smooth eye movement gain in a patient with a unilateral parietooccipital hematoma that involved the internal sagittal stratum and the adjacent tapetum and visual radiation. Normal pursuit toward the lesion is attributed to commissural transfer of visual information from the normal cerebral hemisphere to the intact extrastriate cortex of the visually deprived hemisphere. This pathophysiological correlation indicates that the occiptiomesencephalic projections of the internal sagittal stratum and the peristriate interhemispheric connections of the tapetum are not necessary for smooth pursuit system function.