Oculomotor nerve schwannoma: MRI appearance.

The magnetic resonance imaging (MRI) appearance of oculomotor nerve schwannoma is presented. The lesion appears as a 5-mm mass arising from the cisternal segment of the nerve and is isointense to brain parenchyma on T1- and hypointense on T2-weighted images. Intravenous Gadolinium injection results in intense enhancement of the tumor. Despite its rare incidence, schwannoma should be included in the differential diagnosis of nodular enhancement of the oculomotor nerve.