Easy and Safe Method for Facial Nerve Identification in Parotid Surgery

Background A safe and easy anatomical landmark is proposed to identify the facial nerve in parotid surgery. The facial nerve forms the center point between the base of the styloid process and the origin of the posterior belly of the digastric muscle. Objective To evaluate the consistency, accuracy, and safety of the landmark in identifying the facial nerve. Methods The study was designed in three steps: a cadaver study, a radiologic study, and a prospective clinical study. Anatomy was initially studied in two cadavers. Then the images of 200 temporal styloid regions were studied for consistency of the presence of the styloid base. In the second part of the radiologic study, the distance between the styloid base and the origin of the posterior belly of the digastric muscle was studied in 50 parotid regions. The clinical study involved 25 patients who underwent parotidectomy. Results The styloid base was present in all the images studied. The mean distance between the styloid base and the origin of the posterior belly of the digastric was found to be 0.72 cm (range: 0.45-0.99 cm). The facial nerve could be identified consistently and safely in all patients. Conclusion This trident landmark provided safe, accurate, and easy identification of the facial nerve using two fixed bony landmarks.