A retrospective chart review of a cohort of 253 pediatric patients with sixth nerve palsies uncovered 30 cases of benign sixth nerve palsy, of which 9 were recurrent, in a study at University of Pennsylvania School of Medicine, Philadelphia. Sixth nerve palsy occurred alone in 225 patients, and the etiologies were as follows: 90 (40%) had neoplasms, 25 (11.1%) were ascribed to increased intracranial pressure, 23 (10.2%) to trauma, 14 (6.2%) an infectious etiology, 10 (4.4%) to vascular disease, 9 (4%) inflammatory disorders, 6 (2.7%) were congenital, 2 (0.9%) secondary to surgery unrelated to neoplasm, and 1 (0.4%) to radiation necrosis.

Benign sixth nerve palsy and recurrent cases had the following characteristics: a) isolated unilateral abduction palsy; b) without ptosis, papilledema or other neurologic signs; c) normal brain MRI; d) spontaneous improvement; e) without infection, inflammatory or other disease identified. The mean age at evaluation of the 30 (13.3%) benign cases was 3 years. MRIs performed in 28 (93%), and lumbar punctures in 6 were normal, Acetylcholine receptor antibody testing was negative in 11 (37%), and lyme antibody titres, and anti-Gq1b antibody testing were normal. Only one child had some residual abduction deficit at 3-year follow-up. Four patients, including 3 with recurrences, had residual esotropia but full ductions, and all were referred for strabismus surgery. [1]

COMMENT. Proposed etiologies for benign sixth nerve palsies include ophthalmoplegic migraine, myasthenia gravis, and inflammation secondary to viral infections or vaccination (Lee MS, 1999). Age and gender are important, the age being younger in the recurrent cases, and girls are affected more frequently than boys. Cases related to vaccination are also prone to recurrence. (Yousuf et al, 2007). The cases in the above study were idiopathic.