Intraparotid facial nerve schwannoma: management options

Abstract

Intraparotid facial nerve schwannoma (FNS) is a very rare, benign tumour mimicking pleomorphic adenoma. Resection of this slow growing tumour may result in unnecessary facial nerve paralysis. The aim of this study is to present results of facial nerve schwannoma treatment at our institution and proposes a management plan. This is a retrospective case series of four patients, three male and one female with a mean age of 47.7 years who presented with a long-standing, asymptomatic parotid swelling. Two patients had facial weakness and underwent superficial parotidectomy, resection of tumour and facial nerve repair with a free graft from the greater auricular nerve. Two patients underwent biopsy without tumour resection. All tumours were confirmed histologically as facial nerve schwannomas. The mean follow up period was 3.5 years. Patients with resection of facial nerve schwannoma had a postoperative House Brackmann grade III and IV. Patients with biopsy had normal postoperative facial nerve function and the tumour did not grow significantly. No adverse effects or recurrence were reported. There is no preoperative diagnostic modality that can identify facial nerve schwannoma with certainty. Difficulty in locating the facial nerve intraoperatively raises suspicion of a neurogenous tumour of the facial nerve and this may prevent unnecessary damage to the nerve. Not every facial nerve schwannoma should be resected. This decision is based on (a) the extent of tumour (b) preoperative facial nerve function (c) best results achieved with nerve repair and (d) patient's preferences. Large tumours with extension into the mastoid cavity or encroachment of sensitive structures and preoperative facial weakness are indications for surgical intervention. In most other cases, biopsy and observation suffices.