Ocular contrapulsion in multiple sclerosis: clinical features and pathophysiological mechanisms

The objective was to describe in multiple sclerosis, a cerebellar eye movem ent syndrome that resulted from an acute episode of inflammatory demyelinat ion. Contrapulsion is an ocular motor disturbance characterised by a triad of (1) hypermetric saccadic eve movements in a direction opposite from a pr ecisely localised lesion within a specific white matter pathway, the uncina te fasciculus, at the level of the superior cerebellar peduncle (SCP); (2) hypometric saccades towards the side of the lesion; (3) oblique saccades di rected away from the side of the lesion on attempted vertical saccades. Infrared oculography was used to demonstrate the characteristic features of contrapulsion in two patients with multiple sclerosis. Brain MRI showed lesions within the region of tire. uncinate fasciculus and superior cerebellar peduncle in both patients. Eye movement recordings sho wed saccadic hypermetria away from the side of the lesion and saccadic hypo metria towards the Side of the lesion. The hypometria decomposed into a ser ies of stepwise movements as the eye approached the target. Oblique saccade s directed away from the side of the lesion were seen on attempted vertical saccades. In conclusion, ocular contrapulsion san be seen in patients with multiple sclerosis and results from a lesion in the region of the SCP, inv olving the uncinate fasciculus.