Recurrent laryngeal nerve injury following single- and multiple-level anterior cervical discectomy and fusion: a meta-analysis

Recurrent laryngeal nerve (RLN) palsy is a common and potentially debilitating complication of anterior cervical discectomy and fusion (ACDF). The relationship between the risk of RLN palsy and the number of operated levels remains unclear, and no previous studies address potential differences between short- and long-term RLN injury following ACDF. Electronic searches of PubMed, Cochrane, ScienceDirect and Google Scholar were performed from database inception to June 2019. Relevant studies reporting the rate of RLN palsy for patients undergoing ACDF for cervical spine pathology were identified according to predetermined inclusion and exclusion criteria. Statistical analysis was performed using fixed effects and random effects modelling. I2 and Q statistics were used to explore heterogeneity. Five studies with a total of 3,514 patients were included in the meta-analysis. The incidence of RLN palsy was found to be 1.2%. There were no statistically significant differences in the rate of RLN palsy between multiple- and single-level ACDF [odds ratio (OR) 1.04; 95% CI: 0.56-1.95; P=0.891, I2=0%]. There were similarly no statistically significant differences in RLN palsy rates for multiple- and single-level ACDF when patients were stratified based on length of follow-up of less than or greater than 12 months. This analysis suggests that there is no statistically significant association between the number of ACDF operative levels and the risk of short- or long-term RLN palsy.