Working Diagnosis:
1. Left temporal lobe contusion
2. Abducens nerve palsy due to trauma-related traction on the nerve
3. Midshaft right clavicle fracture

Treatment:
Patient was sent to the ER where imaging was obtained with results as noted previously. Neurosurgery was consulted, and he was kept in the hospital overnight for observation given increased risk of seizure. He was started on a 7-day course of Levetiracetam. He was released the following day and returned to clinic for follow-up of the clavicle fracture. Nonoperative management of his clavicle fracture was recommended, and his shoulder was immobilized in a sling. He was scheduled to follow up with Neurosurgery for his left temporal lobe contusion.

Outcome:
He did not experience seizure activity and Levetiracetam was discontinued after 7 days. Neurosurgery released him to care of Ophthalmology at 3 weeks post-injury. At his 10-week follow up visit in our clinic, he had regained full range of motion and strength of the right shoulder. Lateral movement of the right eye was improved to 45 degrees past midline. He was evaluated by Ophthalmology at 1 month post-injury, and a 6 month observation period was recommended with restriction of participation in projectile sports until diplopia completely resolves.

His mother was contacted by phone at 14 weeks post-injury. She reported complete resolution of diplopia. He continues to follow up with Ophthalmology and has no plans to participate in sports.

Author's Comments:
This case was of interest because of the uncommon nature of isolated sixth nerve palsy. It usually occurs in association with third and fourth cranial nerve abnormalities. Trauma and neoplasm are the two most common causes of sixth nerve palsy in children. Trauma-related palsy may be related to skull fracture, hematoma, raised intracranial pressure, or may have no other associated features. Most cases improve within 3 months and resolve by 6 months. Residual palsy at six months is likely to be permanent.

Editor's Comments:
This case highlights the importance of performing a thorough neurological exam in patients who have suffered head trauma with continued symptoms despite musculoskeletal conditions that may be the reason for the visit. Furthermore, it re-iterates the need to perform one’s own exam despite the fact that the patient had been previously evaluated and thought to be neurologically intact. The author’s thorough exam was able to detect the neurological deficit and guide the patient in the appropriate medical treatment. In patients without obvious neurologic deficits on exam, the New Orleans Criteria and Canadian CT Head Rules can assist in the decision to obtain further imaging studies.

References:
Hollis GJ. Sixth cranial nerve palsy following closed head injury in a child. J Accid Emerg Med. 1997;14:172-175.

Lee AG, Brazis PW. Sixth cranial nerve (abducens nerve) palsy in children. www.utdol.com accessed 3 March 2012.

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