An isolated oculomotor nerve palsy and brainstem hemorrhage in a 53-year-old male patient with mild traumatic brain injury: illustrative case

Abstract

BACKGROUND: Even though head injury is one of the possible causes for oculomotor nerve palsy (ONP), it is uncommon to find an isolated ONP in a patient who sustained a traumatic brain injury (TBI). Both posttraumatic ONP and brainstem hemorrhage are more frequently seen in patients with severe TBI, and the overall outcome of ONP after head injury is poor. OBSERVATIONS: A 53-year-old male patient presented after he was hit by a speeding car from behind while he crossing a road, and then he fell face first to the ground. His Glasgow Coma Scale score was 14 of 15. He had complete ONP of the left eye, but no other neurological abnormal findings. He had a midbrain hemorrhage on neuroimaging. On 6-month follow-up, the ptosis completely resolved, and the diplopia and eye movement showed partial recovery. However, the left pupil was still dilated and nonreactive to light. LESSONS: Even though very rare, mild TBI can be associated with midbrain bleeding and an isolated ONP. The pattern of improvement of ONP starts from ptosis and then progresses to the extraocular muscles. The chance of recovery of pupillary size and reactivity to light is poor. https://thejns.org/doi/10.3171/CASE25741.