MONOCULAR ELEVATION PARESIS CAUSED BY AN OCULOMOTOR FASCICULAR IMPAIRMENT

A 54-year-old man developed an acquired monocular elevation paresis. F orced lid closure or oculocephalic reflexes failed to elevate the affe cted eye in contrast to the contralateral eye, which turned fully upwa rd using either maneuver. A mass lesion compressing the lateral aspect of the right oculomotor nerve at the exit of the brainstem was found. The monocular elevation paresis in this patient reflects damage of th e oculomotor nerve fascicles that supply the inferior oblique and supe rior rectus muscles. This case supports the accepted topographical fas cicular arrangement of the oculomotor nerve, with the inferior oblique and superior rectus being the most lateral and caudal, and the pupill oconstrictor fibers and the inferior rectus being most medial and rost ral.