Isolated unilateral oculomotor palsy caused by pure midbrain infarction: a case report.

Multiple etiologies may cause oculomotor nerve palsies. Identification of different etiologies is very important for subsequent treatment. Midbrain infarction is a rare cause of oculomotor nerve palsy. We herein present a case of isolated unilateral oculomotor paresis caused by pure midbrain infarction. Her pupillary sphincter and inferior rectus muscles were selectively spared. The symptoms were completely relieved after two months of antiplatelet therapy. We proposed that fibers from Edinger-Westphal nucleus and inferior rectus nucleus do not course through the paramedian area of the midbrain. Our report adds to the understanding of fascicles arrangement in the midbrain.