Management of intratemporal facial nerve schwannomas: The evolution of treatment paradigms from 2000-2015

Abstract

Intratemporal facial nerve schwannoma (FNS) are rare benign tumors of the skull base. Many of these tumors will be detected during evaluation for symptoms suggestive of vestibular schwannoma. However, there are several signs and symptoms which can suggest the facial nerve as the origin of the tumor. Intratemporal FNS can be multiple, like “beads on a string”, or solitary lesions of the internal auditory canal. This variable tumor morphology necessitates multiple treatment options to allow patients the best chance of preservation of facial nerve function. Historically FNS were managed with resection of the nerve with cable grafting. However this leaves the patient with permanent facial weakness and asymmetry. Currently most patients find this outcome unacceptable, especially when they present with good to normal facial nerve function. Facial paralysis has a significantly negative impact on quality life, so treatment regimens that spare facial nerve function have been used in patients who present with moderate to good facial nerve function. Nerve sparing options include tumor debulking, decompression of the bony facial canal, radiosurgery, and observation. The choice of management depends on the degree of facial nerve dysfunction at presentation, hearing status in the affected ear, medical comorbidities and patient preference. Each treatment option will be discussed in detail and suggestions for patient management will be presented.

Keywords: Facial nerve schwannoma, Middle cranial fossa, Intratemporal, Translabyrinthine, Stereotactic radiosurgery, Cable graft, Tumor stripping, Facial nerve decompression

Core tip: The management of intratemporal facial nerve schwannoma (FNS) has changed over the past 15 years. Current management strategies involve tumor stripping, bony decompression, radiosurgery, and observation. Each of these treatment options are designed to minimize the risk of injury to a functional facial nerve. Complete surgical excision and cable grafting are reserved for tumors which have already resulted in severe facial weakness. Each management strategy will be discussed in detail with a management algorithm will be presented. Intratemporal FNS are unusual benign tumors affecting the facial nerve as it passes through the bony canal of the temporal bone. Previous management paradigms involved complete resection of the tumor and nerve with simultaneous cable grafting; however, patients were left with long term facial paresis. Newer treatment strategies resulting in less facial nerve morbidity have become more popular in the last 15 years including: Surgical debulking, stereotactic radiosurgery, bony decompression and observation. Each of these strategies will be discussed with emphasis on facial nerve outcomes and tumor control rates.