Two Cases of Partial Oculomotor Nerve Palsy due to Midbrain Infarction

ABSTRACT

Traditionally, monocular parital oculomotor pareses are localized to the cavernous sinus or retro-orbital region and are usually caused by diabetes mellitus, aneurysms of the internal carotid artery, inflammation by vrial infection or autoimmune diseases, neuropathy or neuromuscular disesases. Although rare, the monocular partial oculomotor paresis also can be caused by lesions of ventral midbrain because of their particular topographic arrangement. We present 2 cases with fascicular oculomotor nerve involvement from midbrain lesion, who presented with monocular partial ocu-lomotor nerve palsy. One patient showed partial ptosis and slow saccadic movement of the right eye. The other patient showed parital ptosis and limitation of adduction and elevation in the left eye. They had normal pupil size and light reflexes. Brain magnetic resonance images showed focal infarction in the fascicular portion of the oculomotor nerve.