Abstract
A 50-year-old man with left thalamo-mesencephalic hemorrhage showed ipsilateral monocular paresis of downgaze and contralateral monocular paresis of upgaze with mild depression of the contralateral eye in the primary position, right Horner's syndrome and convergence disturbance. Bell's phenomenon and conjugate horizontal eye movements were preserved. He didn't have disturbance of consciousness, motor and sensory impairments. The lesion may have affected either a unilateral rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) itself or the descending fibers from the caudomedial and the dorsolateral parts of the riMLF, with incomplete impairment of posterior commissure or the crossed fiber from the contralateral riMLF.
We present an unique disturbance of vertical eye movements caused by a hemorrhage localized in the thalamomesencephalic area. To our knowledge, there has been no previous report concerning these peculiar ocular signs. These findings of such a case support the current concept concerning the function of the riMLF.
