Facial nerve management in parotidectomy

Always attempt to preserve the nerve: If functioning preoperatively, one should aim to have a functioning nerve postoperatively

Intraoperative facial nerve monitoring

Reduces immediate postoperative weakness, but does not affect permanent facial nerve weakness (Sood AJ, et al. Facial nerve monitoring during parotidectomy: a systematic review and meta-analysis. Otolaryngol Head Neck Surg. 2015) Apr;152(4):631-7)
Not a substitute for knowledge of surgical anatomy of facial nerve
Not required for routine parotidectomy
Advisable for known malignant tumours requiring total parotidectomy, revision surgery or large tumours

Benign salivary tumours

Malignant tumours

Functioning, normal looking nerve may be peeled off tumour, and microscopic residuum treated with postoperative radiotherapy
If nerve is invaded/encased by tumour
Confirm malignancy on frozen section
Resect involved segment until free margins on frozen section (perineural spread can extend many centimetres beyond normal looking nerve)
Be prepared to dissect the mastoid segment of the nerve if positive margin at stylomastoid foramen
Immediately graft resected nerve, unless a small midface branch (cross-innervation in midfacial branches)

No postoperative radiotherapy or frozen section with known malignancy adherent to, or invading nerve

May need to be surgically more aggressive
Reservations about peeling nerve off tumour – but resect nerve only when the remainder of the operation is likely to achieve clear margins
Resect nerve at least 1cm beyond obvious tumour