A Handy Landmark (Triangle Technique) for Identification of the Facial Nerve during Parotid Surgery

Authors: Islam MA*, Rahman MM, Mohammad T, Kazi MM, Chowdhury NH and Khan MAM

DOI: 10.23880/ooaj-16000232

Volume 7, Issue 1

Abstract

The parotid glands are paired major salivary glands located in front of the tragus and below the ear lobule at the retromandibular area (behind the mandibular ramus and in front of the mastoid process of the temporal bone) on each side of the upper neck. The facial nerve is one of the most important structures encountered during parotidectomy. The neurovascular structures that pass through the parotid gland from lateral to medial are facial nerve, retromandibular vein, external carotid artery, superficial temporal artery and maxillary artery. Branches of the great auricular nerve enter the gland from the neck and remains superficial. Parotid surgery is indicated in certain pathological conditions namely benign and malignant neoplasm, chronic inflammatory diseases, sialolithiasis, intra-parotid cysts/sinuses and lymphadenopathy; and many more. The importance of the facial nerve and methods of identification are enumerated by the multiple anatomical landmarks during parotidectomy. The triangle landmark is one of these anatomical landmarks considering the base of the styloid process, tragal cartilage to tragal pointer and the origin of the posterior belly of the digastric muscle at the mastoid tip. Facial Nerve and the Parotid Gland: The intra-temporal facial nerve exits from the stylomastoid foramen slightly posterior to the styloid process and anteromedial to the mastoid process. The main trunk is approximately 1.3 cm in length enters into the parotid gland and divides into cervico-marginal and zygomatico-temporal branches; and of course, buccal branches (upper and lower buccal) remain common in both the divisions. The cervico-marginal branches supply the muscles of the mouth and neck; and zygomatico-temporal branches supply the muscles of the forehead and eye. The facial nerve arbitrarily divides the gland into superficial and deep lobes. Aim of the Study: The aim of this study was to locate the facial nerve trunk (FNT) very easily. Quickly and accurately at the point where the long axis along the tragal pointer from the tragus and posterior belly of the digastric from the mastoid tip meets over the styloid process.Patients and Methods: This prospective study was conducted between January 2012 to December 2022 at Tertiary care hospital. It included 117 patients: 74 (63%) males and 43 (37%) females with a mean age of 42.52 ±16.63 years. Patients presented with pleomorphic adenoma (70), chronic sialectasis (05), parotid cyst (02), parotid sinus (01), mucoepidermoid carcinoma (21) adenoid cystic carcinoma (02) and squamous cell carcinoma (01) were subjected to superficial parotidectomy and total parotidectomy. Outcome was evaluated regarding clinical success of facial nerve identification by a handy landmarktriangle technique. Results: All 117 patients underwent superficial and total parotidectomy. Facial nerve trunk was successfully identified in all the patients with no intra-operative complications. Operative time ranged from 50 to 180 minutes with a mean time 90.70 ±15.68 minutes. Facial nerve deficit of the marginal mandibular nerve (MMN) was noted in 4 patient (3.4 %), 02 had difficulty in eye closure (1.7%). No patient reported with surgical site infection, skin flap necrosis and hematoma in all the patients. Conclusion: A handy landmark-triangle technique described here facilitates the identification of facial nerve trunk during superficial parotidectomy with relative ease, safety and accuracy. This can be a very useful method to minimize the facial nerve injury during parotid surgery.

Keywords: Facial Nerve Trunk (FNT); Identification Triangle; Technique Parotid Surgery

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