Impairment of smooth pursuit in pontine lesions: functional topography based on MRI and neuropathologic findings.

Eye movements were studied in two patients with pontine lesions identified by magnetic resonance imaging in one patient and computerized tomography, with neuropathological correlation in another patient. Impairment of ipsilateral saccades were explained by unilateral lesion of the paramedian pontine reticular formation. Ipsilateral dorsolateral and lateral pontine nuclei lesions results in unilateral impairment of smooth pursuit. Bilateral damage to the dorsomedian pontine nuclei result in bidirectional horizontal smooth pursuit deficit, predominantly towards the more pathologic affected side. In addition, these bilateral lesions may also account for impairment of vertical smooth pursuit. These findings confirm that pontine nuclei are an important relay for horizontal and vertical smooth pursuit movements.