A Rostro-Caudal Arrangement of the Oculomotor Fascicles Based on MR Findings of Midbrain Infarctions in Two Cases

ABSTRACT

A rostro-caudal topography of the oculomotor nerve fascicles is relatively well known in animal but not in human. We experienced two cases of midbrain infarctions presenting with isolated oculomotor nerve palsies. The MRI of the patient who had monocular elevation palsy with ptosis revealed a lesion in the middle to lower midbrain, whereas that of the other who had monocular depression and adduction palsy with pupillary mydriasis showed a discrete lesion in the upper to middle midbrain. We present the rostro-caudal arrangement of the oculomotor fascicles within midbrain based on MRI findings.