[Isolated infranuclear oculomotor nerve palsy caused by traumatic midbrain hemorrhage: case report]

Traumatic brain stem hemorrhage is often associated with severe head injury and has a high mortality rate. When these patients survive, the midbrain syndromes are usually complicated. The authors report an unusual case with isolated oculomotor nerve palsy caused by acute traumatic midbrain hemorrhage. A 50-year-old woman was brought to Kobe City General Hospital because she had fallen off a bicycle and hit the face severely on the ground. On admission, she was drowsy. Neurological examination revealed normal muscle tone in all extremities without motor or sensory disturbance. Deep-tendon reflexes were symmetrical and there were no Babinski signs present. The left eye lid dropped and the left pupil was 5.5 mm in diameter without responses to light. The eye ball was slightly deviated to the left side on neutral position. There were no extraocular movements except for abduction to the left side. The right pupil measured 3 mm in diameter and was reactive to light promptly. Plane skull films failed to show fractures. Computed tomography (CT) scan 30 minutes after the accident suggested the existence of a hemorrhage in the anterior tegmentum of the left midbrain. Four hours later, a midbrain hemorrhage was diagnosed by consecutive CT scans. She was alert on the next day, although the third nerve palsy remained. The left blephaloptosis disappeared gradually during the next month. At 6 months after the accident, the left pupil was still dilated and did not react to light, either directly or indirectly. Medial gaze recovered almost fully, while both upward and downward movements were still limited. The mechanism of the isolated oculomotor nerve palsy in this case was discussed with a review of the related literature.