Outcome on hearing and facial nerve function in microsurgical treatment of small vestibular schwannoma via the middle cranial fossa approach

Abstract

Encouraging results regarding hearing preservation and facial nerve function as well as increasing understanding of the natural behaviour of vestibular schwannomas have led to the recommendation of an early treatment in small VS. The aim of the present study was to evaluate current data on functional outcome of patients with small VS treated by middle cranial fossa (MCF) approach. A retrospective chart study of all cases treated by MCF approach between October 2007 and September 2011 was performed. Records were analyzed regarding demographical data, tumor size, hearing status, vestibular function and facial nerve function. Facial nerve function was classified according to the House-Brackmann scale (HB). Hearing status was classified according to the American Association of Otolaryngology-Head and Neck Surgery (AAO-HNS) and a modified classification of Gardner and Robertson (GR). Eighty-nine patients were included in the study; 41 % of VS was classified as intracanalicular (stage 1) and 59 % as stage 2. From 65 patients with a preoperative hearing status according to AAO-HNS A or B, 74 % still presented with A or B after surgery. Using a modified GR classification, from 70 patients categorized as class I or II prior to surgery, 70 % were still class I or II. Looking to the facial nerve function 1 week after surgery, 82 % of patients presented with HB 1 or 2. Three to twelve months later, 96 % demonstrated HB 1 or 2. A persisting facial palsy was recorded in four patients. Preoperative hearing status was evaluated as a prognostic factor for postoperative hearing, whereas no influence was detected in ABR, vestibular function and tumor length. Early diagnosis of small VS due to high-sensitive MRI requires the management of this tumor entity. Natural behaviour of VS in many cases demonstrates an increase of tumor size over time with deterioration of hearing status. The presented data underline the recommendation of an early surgical treatment in small VS as a valuable option for hearing preservation in the therapy of VS.

A Percutaneous Transtubular Middle Fossa Approach for Intracanalicular Tumors

“…The main drawback of the classic MFA is the risk of retraction injury to the temporal lobe as traditionally deep midline dissection of the skull base has necessitated a certain degree of temporal retraction to gain sufficient surgical exposure (3,11,19,31). Extensive temporal retraction can result in postoperative seizures, aphasia, or other focal neurologic deficits, and/or venous complications (2,3,7,9,15,31).…”

“…Intraoperatively, the MFA provides exposure of the entire length of the IAC and its contents from the inner ear to the pons allowing the removal of both medially and laterally located tumors (2,3,16,17). Compared with the other common approaches used for the resection of vestibular tumors, the MFA provides the greatest preservation of auditory and facial nerve function-despite the fact that CN VII often is located between the surgeon and the tumor and thus subject to surgical manipulation (3,11,25). However, the complex microsurgical anatomy of the petrous bone, and the neurovascular structures it encases, and the difficulty of identifying landmarks on the petrous ridge make this a technically challenging approach (Figures 1 and 11).…”

Hearing Preservation Surgery for Vestibular Schwannomas

“…Hearing [22][23][24][25]. If hearing is saved, the durability of long-term hearing preservation is excellent [7,22,26].…”

Small Vestibular Schwannomas: Does Surgery Remain a Viable Treatment Option?

“…Following this broad paradigm shift, the past 3 decades have seen a limited number of series that address surgical treatment of small acoustic neuromas. [11][12][13][14][15][16][17][18][19][20][21][22] At the same time, however, the goals of surgical treatment have evolved significantly from tumor control and survival to functional preservation, particularly facial nerve preservation. Technological advances as well as improvements in neuroanesthesia have also redefined the safety and outcomes of surgical resection.…”