Durability of hearing preservation after microsurgical treatment of vestibular schwannoma using the middle cranial fossa approach

Abstract

V estibular schwannomas are relatively rare, accounting for approximately 8% of all intracranial tumors. 50 They arise from the vestibular portions of the eighth cranial nerve, which runs in conjunction with the seventh cranial nerve through the CPA into the IAC, where the Obersteiner-Redlich transition zone occurs. 21 Approximately 5% of cases are associated with neurofibromatosis Type 2. 51 The most common presentation is progressive unilateral hearing loss. In a natural history study by Stangerup et al., 48 growth after diagnosis of intracanalicular VS was observed in 64% of cases in the 1st year, in an additional 23% by the 2nd year, and in 5% more by the 3rd year.The widespread use of MRI has resulted in earlier diagnosis of VS, such that patients with very small lesions and excellent residual hearing in the involved ear often present for treatment consideration. Hearing preservation is a reasonable primary goal of management in such cases. Object. The middle cranial fossa (MCF) approach is a microsurgical technique described as a primary option in the treatment of small, intracanalicular schwannomas involving the eighth cranial nerve. Excellent rates of complete tumor resection, hearing preservation, preservation of facial nerve function, and low complication rates have been reproduced using this technique. However, the durability of hearing preservation attained using the various treatment options has not been adequately assessed. The purpose of this study was to evaluate the durability of long-term hearing preservation in patients with vestibular schwannoma (VS) treated via the MCF approach. The authors hypothesize that hearing preservation in these patients will prove to be durable years after treatment in a high percentage of cases.Methods. Retrospective medical chart review was performed in 103 consecutive patients undergoing resection of VS via a modified MCF approach between 1999 and 2008. Patients in whom surgical goals were gross-total resection and hearing preservation were included. Preoperative and postoperative hearing assessment was performed using standard audiometric testing, and classified according to American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) guidelines as a primary outcome measure. Outcomes and neurological complications initially, and at 1, 3, and 5 years following operation were analyzed.Results. Initial hearing preservation rates were in keeping with the best previously published results. At initial postoperative audiometric follow-up, of the patients presenting with Class A hearing, 67% remained Class A, 17% were Class B, 1% were Class C, and 15% were Class D. Of patients presenting with Class B hearing, 24% were Class A, 53% remained Class B, 6% were Class C, and 18% were Class D. Of patients presenting with Class C hearing, 100% remained Class C.To assess the durability of hearing preservation in our patients, the authors evaluated hearing function at regular intervals after the initial postoperative audiometric follow-up. Audiometric data were available ...

The Factors Associated With Tumor Stability Observed With Conservative Management of Intracanalicular Vestibular Schwannoma

“…Hearing preservation rates after stereotactic radiotherapy for VS vary widely, ranging from 41% to 76% (18,19). Hearing preservation rates after microsurgery, such as the middle fossa approach, have been reported in the literature to range from 20% to 85% (20,21). However, a meaningful comparison among the series has been difficult because grading of hearing outcomes has not always been consistent.…”

Vestibular Schwannomas: Surgical and Nonsurgical Management

“…It is generally acknowledged that for those undergoing MCF surgery hearing preservation rates are better in tumors arising medially in the IAC [4] with an adequate CSF cap lateral to the tumor buffering the cochlear modiolus (Fig. 2) and if it arises from the superior vestibular nerve (SVN) rather than the inferior vestibular nerve (IVN).…”

14 Transcranial Approaches to the Skull Base

“…• Hearing preservation following middle cranial fossa surgery is variable but has been reported in a recent large series study. 56 According to the American Academy of Otolaryngology-Head and Neck Surgery, 65% of patients with class A hearing (signifying puretone average, PTA, hearing level ≤30 decibels, and word recognition score (WRS) ≥70%) preopera tively may have preserved the same class of hearing at 5 years. The rate is 67% in patients with class B hearing (PTA hearing level >30.…”