Continuous Intraoperative Electromyographic Monitoring (IEMG) of Recurrent Laryngeal Nerve (RLN) using a Newly Described Scale

Document Type


Publication Date



Introduction: The objective of this study was to provide a description of the amount of recurrent laryngeal nerve (RLN) irritation during anterior cervical discectomy and fusion (ACDF) and to correlate such irritation with surgical risk factors. Additionally, the association of increased RLN irritation with postoperative hoarseness was assessed.

Methods: In a series of 91 patients undergoing ACDF, continuous intraoperative electromyographic monitoring of the vocal cords was performed. Intraoperative findings were recorded and the amount of irritation was described as the irritation score (IS) by use of an arbitrary formula (Ó (AxD)/B), where A is the amplitude of irritation, D is the duration of irritation, and B is the baseline irritation. Results were correlated with parameters that have been described in the literature to increase the risk of RLN injury. Postoperative hoarseness at 24 hours was clinically ascertained.

Results: No statistical correlation could be established between the amount of intraoperative electromyographic monitoring irritation of the RLN and postoperative hoarseness. Additionally, no correlation was observed between the degree of RLN irritation in any obvious surgical maneuver, although the presence of previous surgery, the increased number of levels, and the lower anatomical level of discectomy were associated with higher irritation as described with this scale.

Conclusions: There was no association with the amount of force applied to the RLN with standard maneuvers; although this cohort may represent a small sample, RLN injury dose not seem to be referable to any simple force pressure dynamics in a routine clinical setting.


American Association of Neurological Surgeons Annual Meeting (AANS)


San Diego, CA