Non-recurrent laryngeal nerve: surgical risk of injury in comparison
with the normal recurrent laryngeal nerve - A systematic review and
meta-analysis
Abstract
Introduction: The non-recurrent laryngeal nerve (NRLN) is a known
anatomical variation of the normal recurrent laryngeal nerve (RLN). Its
prevalence is estimated <1% and is prone to higher risk of
iatrogenic injury. The risk of injury during thyroid surgery have been
reported as variable in current literature, from 0% up to 12%. This
study aimed to systematically review the incidence of NRLN injury and
present the results through meta-analysis. The incidence of injury to
NRLN and RLN was compared and analysed to determine its statistical
significance. Methods: The PRISMA protocol was followed for an online
search of prominent literatures. Studies were selected and excluded
according to specific criteria. Quality assessment was performed, and
data was extracted. Meta-analysis was conducted for the incidence of
injury of the NRLN, and its comparison to the RLN. Results were
presented in the form of a systematic review and discussed. Results:
17 studies were included in the final analysis. It was found that the
pooled risk of NRLN injury was 7% and the risk ratio of injury in
comparison to the RLN was 3.8, showing a statistically significant
difference. Conclusion: This is the first study to report the overall
risk of injury to the NRLN and found a statistically significant
difference in comparison to the injury of RLN. This evidence provides
grounds for future surgical guidelines to prevent injury to the NRLN. It
is suggested that intra-operative nerve monitoring (IONM) should be
performed in all patients found to have NRLN pre-operatively and
intra-operatively.