PATHOPHYSIOLOGY OF SACCADIC CONTRAPULSION IN UNILATERAL ROSTRAL CEREBELLAR LESIONS

Saccadic lateropulsion is a typical sign in Wallenberg's syndrome and midline lesions of the caudal cerebellum (oculomotor vermis, nucl. fas tigii). There are only two reports on saccadic contrapulsion (contrave rsive to the side of the lesion) after a rostral cerebellar lesion. Th e authors describe a patient with an infarction in the area of the rig ht medial branch of the superior cerebellar artery affecting the medio -lateral rostral cerebellum which showed a saccadic contrapulsion with hypermetric saccades to the left and hypometric saccades to the right . Based on recent experimental neurophysiological, anatomical and lesi on studies, which demonstrate that the caudal fastigial nucleus is ess ential for accurate saccades, it is proposed that a lesion of the effe rent pathways from the caudal fastigial nucleus to the direct premotor structures for saccades in the brainstem which cross within the cereb ellum, causes the contrapulsion seen in the patient.