Continuous intraoperative Neuromonitoring (cIONM) of the facial nerve predicts postoperative facial palsy in parotid surgery – a prospective study

Introduction Facial palsy (FP) is the most important complication of parotidectomy. Whether the use of intermittent intraoperative neuromonitoring (iIONM) reduces the rate of FP remains controversial. Continuous IONM (cIONM) showed superiority over iIONM in thyroid surgery. cIONM of the facial nerve in parotid surgery has yet not been applied.

Methods We performed a parotidectomy with anterograde facial nerve visualization using cIONM in all consecutive patients who gave written consent to participate in a prospective study (DRKS 00011051) in the period 09/2016-03/2018. An atraumatic, CE-approved stimulation electrode has been placed in 32 patients after the facial trunk had been exposed; the nerve was stimulated with 3 Hz at a low threshold over the entire duration of the preparation. Thus, numerous amplitudes and latencies could be collected for data analysis.

Results In the post-hoc analysis, a significant accuracy between the drop in amplitude (<50% of the "baseline" amplitude) and postoperative FP was recorded (p=0,001). True positive prediction of FP was noted in 14 of 16 patients, true negative in 10 of 16. The false positive rate was 6 of 16, false negative 2 of 16. The sensitivity was 87,5% (AUC 0,75) with a high negative predictive value of 83,3%.

Conclusion cIONM has a significant predictive value of postoperative FP in parotidectomy. Future developments of an acoustic warning system of the IONM devices should prevent nerve injury in real time.

 

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Conflict of Interest

The authors declare that they have no conflict of interest.

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Artikel online veröffentlicht:
12. Mai 2023