Quick identification and preservation of facial nerve using only posterior belly of digastric muscle

Abstract

Parotid glands are the largest salivary glands separated into two lobes by the neurovascular plane of the facial nerve. Superficial or total parotidectomy is considered the best therapeutic option for different Parotid lesions. There are various key indicators for locating the anatomical landmarks of the facial nerve in either anterograde or retrograde manner or using nerve monitoring, microscope, gamma probe etc. The Aim here is to promptly detect and preserve the facial nerve trunk and its terminal branches during parotid surgery with using only the posterior belly of the Digastric muscle aided with microscope. This is a one-year prospective observational study of 19 cases undergoing parotidectomy. The time taken to find the facial nerve trunk and its distance from the posterior belly of the digastric muscle were documented intraoperatively followed by post-surgery cranial nerve VII’ examinations. The “facial nerve” was satisfactorily preserved in 16 out of 19 (84.21%) cases with sole usage of the “posterior belly of the digastric muscle.” The mean time to identify the FNT was calculated as: 21.78 mins. The average distance of the FNT from the anterior border of the PBDM was estimated as 6.44mm. Prompt exposure of the PBDM, followed by locating the FNT just at a distance of 6.5 mm anteromedial to PBDM, can be done within 20-22 minutes, which is found to be the quickest and easiest method to identify and preserve the facial nerve with pes anserinus using PBDM as the robust indicator, preventing facial disfigurement and mental stress to the patient.