Avoiding Damage of the Facial Nerve in Parotid Surgery

Abstract

Surgery of the parotid gland accounts for 1–2% of iatrogenic induced facial nerve injuries. In particular, after primary parotid surgery temporal and permanent facial nerve palsies occur in 10–66% and 2.5–8% of cases, respectively. However, risk of facial nerve injury increases with (1) extend of excision, (2) surgical resection of tumour recurrence, and (3) salvage surgery. Therefore, meticulous dissection and detailed knowledge of anatomic landmarks are crucial to prevent facial nerve damage. It is of utmost importance to first identify the tragal pointer of the auricle, the posterior belly of the digastric muscle and the tympanomastoid suture line as anatomic landmarks for safe dissection of the extratemporal, main trunk of the facial nerve. Thereafter, the branches of the facial nerve can be safely dissected using surgical loupes under neuromonitoring. The marginal mandibular branch, running along the body of the mandible, is at the most risk for injury during parotidectomy and even at higher risk when performing a level Ib neck dissection. Particularly for level Ib neck dissection, the topography of the marginal branch and the fact that it crosses superficially the facial artery within the plane of the platysma needs to be kept in mind. The marginal mandibular branch, in turn, can be easily identified 1–2 cm superiorly to the lower edge of the mandible where the facial artery curves upwards within the groove of mandible’s body.