Safe distance from facial nerve for bipolar coagulation in parotid surgery-Animal study.

OBJECTIVE

Currently no data exist on what distance from facial nerve (FN) it is safe to perform bipolar cautery (BC) in parotid surgery, although frequently performed.

METHODS

The degree of damage was measured using continuous intraoperative neuromonitoring (cIONM, NIM™ 3, Medtronic) in 16 Wistar rats. Amplitude drop of at least 50% (A50) or a loss of signal (LOS) in the cIONM was defined as harmful; BC was performed in power range 20-60 W.

RESULTS

BC ≤30 W did not cause LOS (0/14 nerves). When applying 35 W, A50 occurred at 4 mm from FN and LOS was noted in 1 of 5 nerves. BC at a power of 40 to 60 W demonstrated LOS in all nerves (12/12) at a 5 mm distance.

CONCLUSION

BC up to 30 W can be safely applied up to 3 mm distance from FN. 40 to 60 W should be avoided and used only at a distance of over 6 mm from FN.

LEVEL OF EVIDENCE: NA/animal study. Laryngoscope, 135:1120-1126, 2025.