Retraction-convergence nystagmus: clinical and radiological study of 4 cases of vascular origin.

Retraction-convergence nystagmus is a classic finding in extensive and bilateral lesions of the dorsal midbrain, usually neoplastic and, as such, considered to signal a poor prognosis. We report 4 cases of retraction-convergence nystagmus associated with Parinaud syndrome arising from circumscribed lesions of vascular origin--3 hemorrhagic and 1 ischemic--with a completely benign course. The neuroimaging study enabled us to identify involvement of the pretectal areas and posterior commissure as well as of the dorsomedial thalamic nuclei in all cases. It thus seems that one or more of these areas must be involved in the genesis of this nystagmus.