Spontaneous recovery in post-traumatic sixth nerve palsy

Purpose. Little is known about the natural history of post-traumatic sixth nerve palsy. Previous institution based retrospective studies may have been biased towards non-recovery, since they included patients who had been referred specifically for treatment. We therefore studied patients who were seen within 6 weeks of injury to obtain a better estimate of the true spontaneous recovery rate. Methods. We retrospectively reviewed patient records over a 24 year period at our institution and identified 104 patients who had a post-traumatic sixth nerve palsy. Patients were then excluded if they had not been seen within 6 weeks of injury or had a coexisting 3rd or 4th nerve palsy. 42 patients with unilateral palsy and 13 patients with bilateral palsy fulfilled our inclusion criteria. Probabilities of recovery were estimated using Kaplan - Meier survival analysis. Results. The probability of spontaneous recovery at 6 months was 27% in unilateral palsy (95% C.I. 5-44%) and 12% in bilateral palsy (95% C.I. 0-33%). Conclusions. The probability of spontaneous recovery from post-traumatic sixth nerve palsy has been previously reported as 30-42%. Interestingly, using methods that reduce the bias towards non-recovery and analyzing the data by using survival mediods, our results suggest a lower spontaneous recovery rate. These data may help planning of therapeutic trials, however a prospective study would give a better estimate of the true recovery rate.