Localization of traumatic oculomotor nerve palsy to the midbrain exit site by magnetic resonance imaging.

ABSTRACT

PURPOSE: To present the magnetic resonance imaging findings for a patient with traumatic oculomotor nerve injury. METHODS: We examined a patient with a right pupil-involving oculomotor nerve palsy after severe closed head trauma. RESULTS: Magnetic resonance imaging of the brain demonstrated marked signal hypointensity on gradient-echo T2*-weighted images consistent with hemorrhage at the midbrain exit site of the right oculomotor nerve. CONCLUSIONS: Distal fascicular damage or partial rootlet avulsion is a mechanism of injury in some traumatic oculomotor nerve palsies. Gradient-echo T2*-weighted magnetic resonance imaging is the most sensitive method to detect hemorrhagic changes associated with shearing injury.