A Case of Traumatic Oculomotor Nerve Palsy Diagnosed by Thin Slice MR Imaging- Running Head: III CN palsy on thin slice MRI

Cranial nerve palsies are common consequences of trauma, among which oculomotor nerve involvement is relatively common. Although it is clinically evident due to disturbance in extraocular movement, imaging diagnosis of traumatic oculomotor nerve palsy is not easy. We report a case of traumatic oculomotor nerve palsy diagnosed by high resolution thinslice magnetic resonance imaging (MRI). A 31-year-old female was brought to emergency room after fall down injury. Left oculomotor palsy was detected on neurological examination, whereas brain CT showed no definite traumatic intracranial lesion. Brain MRI with thin slice imaging technique showed enhancement of cisternal segment of right oculomotor nerve without any abnormality in contour. This type of traumatic oculomotor nerve palsy, detected only by enhancement without any abnormality in contour, has not been reported. The oculomotor palsy improved slowly over during follow-up. This case shows thin-slice MR imaging is very useful for diagnosis of cranioneuropathy.