The natural history of acute traumatic sixth nerve palsy or paresis

Background: Spontaneous resolution of traumatic sixth nerve palsy or paresis has been reported to range between 12% and 54%. However, previous studies have been based in tertiary referral centers, have been retrospective in nature, have included a heterogeneous group of patients, and have included patients with long-standing palsies. To provide a more accurate estimate of the true recovery rate, we performed a prospective natural history study. 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 acute traumatic sixth nerve palsy or paresis between March 1996-February 1997. Recovery at 6 months after injury was defined as absence of diplopia in primary position and less than or equal to 10 PD distance esotropia in primary position. Patients who had been treated with botulinum toxin (n = 8) within 6 months after injury and patients with <6 months of follow-up (n = 3) were excluded. Results: Thirty-three eligible patients were enrolled by 27 investigators. Twenty-five (76%) of the palsies were unilateral and 8 (24%) were bilateral. The overall spontaneous recovery rate was higher than previously reported (73%, 95% Cl 54%-87%). Spontaneous recovery was more frequent in unilateral cases (84%, 95% Cl 64%-95%) than in bilateral cases (38%, Cl 9%-76%; P = .02). Conclusions: In this prospective multicenter study of acute traumatic sixth nerve palsy or paresis, the overall spontaneous recovery rate, particularly in unilateral cases, was much higher than previously reported. Our results have important sample size implications for the planning of any randomized treatment trial and may help guide early treatment decisions.