Initial treatment outcomes in chronic sixth nerve palsy

Introduction: We conducted a prospective multi-center, nonrandomized, data-collection study of patients with chronic sixth cranial nerve palsy. We evaluated success rates with conservative nonsurgical management, botulinum toxin (botox) treatment, strabismus surgery, and a combination of botox treatment and surgery. Methods: All members of the American Association for Pediatric Ophthalmology and Strabismus and the North American Neuro-Ophthalmology Society were invited to enroll patients with sixth nerve palsy or paresis of more than 6 months duration over a 2-year period (between March 1998 and February 2000). The botox and surgical groups received intervention within 3 months of enrollment. Success at 6 months from enrollment was defined as absence of diplopia in primary position and no more than 10 prism diopters (pd) distance esotropia in primary position. Patients with no follow-up were excluded. Results: Fifty-six eligible patients were enrolled by 33 investigators. Eighteen (32%) were traumatic in etiology, 15 (27%) were unknown (including presumed hypertensive), 14 (25%) were neoplastic, 2 (4%) were diabetic, and 7 (13%) were other. Twenty (35%) were managed conservatively without surgery, 10 (18%) with botox treatment, 19 (33%) with surgery, and 8 (14%) with a combination of botox treatment and surgery. Success at 6 months from enrollment was 15% in the conservatively managed cases, 10% with botox alone, 39% with surgery alone, and 25% with a combination of botox and surgery. Conclusions: This study demonstrates that management of chronic sixth nerve palsy and paresis remains challenging. Spontaneous recovery occurs but is uncommon. Botox treatment alone was rarely successful, and a single surgical procedure had a lower-than-expected success rate. Care should be taken in directly comparing success rates between treatment groups because of bias in patient selection.