Incidence of Displacement of Facial Nerve Trunk from Normal Anatomical Position in Cases of Benign Tumour in Superficial Lobe of Parotid Gland: A Surgical Finding and its Significance.

Purpose of current study was to find out the incidence of displacement of facial nerve trunk from its normal anatomical position in relation to size and site of tumour in superficial lobe of parotid gland and its surgical significance. In the literature, the importance was given to the anatomical variations in branching pattern of facial nerve but not deviation. The knowledge of this variation is very important to prevent its injuries during superficial parotidectomy. The present study included 60 patients who underwent superficial parotidectomy for benign tumour involving the superficial lobe of parotid gland. The site and size of tumour noted pre operatively with help of ultrasound and CT scan and pathological diagnosis was made by FNAC. The superficial parotidectomy was performed and facial nerve was identified in all cases. In our study, 23 patients out of 60 were having displacement of facial nerve trunk from its normal anatomical position found during superficial parotidectomy. 10 out of 13 patients with tumor superior to facial nerve trunk were having displacement, 7 out of 18 had deviation with tumor inferior to nerve, 6 out of 29 patients had deviation of main trunk when the tumor involved whole of superficial lobe of gland.We conclude that the facial nerve trunk cannot be always traced at normal anatomical position by following the documented anatomical landmarks because of its displacement by tumour. Knowledge of this variation of facial nerve trunk can avoid the chances of damage to this nerve during superficial parotidectomy.