Nuclear and prenuclear syndromes of the oculomotor nerve

Two cases with complex oculomotor disturbances are reported. In the first case, complete Illrd nerve palsy was associated with contralateral ptosis and superior rectus palsy, suggesting involvement of the right oculomotor nucleus. Computed tomography demonstrated a paramedian infarction of the right midbrain at the level of the oculomotor nucleus. In the second case, with probable multiple sclerosis, a ‘prenuclear’ syndrome of the right oculomotor nerve was hypothesized from the presence of inter-nuclear ophthalmoplegia on gaze to the left and tonic monocular elevation paresis of the left eye. The possibility of prenuclear and nuclear syndromes of the oculomotor nerve should be added to the well-known intracerebral postnuclear syndromes of Weber, Claude, and Benedikt.