PM1069: A Stalled Gaze

Introduction: An adolescent female swimmer presented three days after she was accidentally kicked in the right side of the head while swimming and suffered a suspected concussion. She immediately complained of blurry vision, headache, and dizziness before going to the ER. Her vision on the right was reported to be 20/400, and she was transferred to a trauma center. A head CT was negative for intracranial pathology. She was referred to a retina specialist the following day, and no damage to the retina was appreciated. Her vision improved to 20/50, but she was noted to have difficulty looking to the right with her right eye. It was suggested she follow up with neuro-ophthalmology.

Case Description: Upon presentation to sports medicine clinic she had continued difficulty looking right with rightward gaze. Headache and sensitivity to light and noise were her most bothersome symptoms along with improving blurry vision. SCAT5 concussion testing was performed with no major cognitive deficits appreciated. Pertinent findings from her initial physical exam are listed as follows: Constitutional-Interactive but uncomfortable due to headache and light sensitivity. Head-NCAT. Eyes-Unable to follow finger with right eye to right of midline. Gaze intact when looking left. No ptosis. Vertical eye movements intact. Neurological-Sensation normal. Upper extremity strength and cranial nerve exam otherwise normal other than suspected cranial nerve VI deficit on right.

Discussion: Sixth cranial nerve (abducens) palsy causes impairment of the lateral rectus muscle limiting abduction of the ipsilateral eye. The sixth cranial nerve can be affected anywhere along its course from the pons and through the subarachnoid space, along the medial aspect of the temporal bone, cavernous sinus, and to the lateral rectus muscle. The differential for sixth cranial nerve palsy is broad and includes but not limited to vascular, neoplastic, infectious, traumatic, and inflammatory abnormalities along the course of the nerve. Recovery involves correcting any identifiable cause although the condition can be idiopathic or result from seemingly minor trauma. It should be differentiated from lateral gaze palsy where the paramedian pontine reticular formation (PPRF) or abducens nucleus is affected causing abnormalities of the contralateral medial rectus muscle limiting horizontal gaze with both eyes.

Conclusion: The patient was referred to neurology and followed in sports medicine periodically over the following 6 months. Neurology confirmed a sixth cranial nerve palsy. An MRI with and without contrast of the brain and orbits was performed, and the sixth cranial nerve was not compressed along its intracranial course. A course of oral steroids was prescribed with limited improvement. The patient was referred to physical therapy, occupational therapy, and ENT for vestibular rehabilitation. The patient is currently doing well, and right eye abduction is about 75% improved from initial presentation. She hopes to return to swimming.