Predicting Hearing Outcomes in Conservatively Managed Vestibular Schwannoma Patients Utilizing Magnetic Resonance Imaging

Abstract

Objective: Management of small vestibular schwannomas has evolved to where observation with interval imaging is an accepted treatment strategy. Loss of residual hearing is a known complication of observation. Magnetic resonance imaging (MRI) may provide critical information to assist in determining which tumors are at highest risk of hearing loss. We wished to determine what effect fundal cap size and cochlear fluid-attenuated inversion recovery (FLAIR) signal had on the progression of hearing loss in a large cohort of observed subjects. Study Design: Retrospective chart review. Setting: Tertiary academic referral center. Patients: Three hundred ninety-three adults with a vestibular schwannoma who underwent expectant management with serial audiograms and MRI. Interventions: Audiogram and MRI. Main Outcome Measures: Hearing outcomes included pure-tone average and word discrimination score (WRS). Cochlear FLAIR signal was measured as a ratio between the affected and nonaffected cochlea. Cerebrospinal fluid fundal cap was measured from the most lateral aspect of the tumor to the fundus of the internal auditory canal. Results: An increased cochlear FLAIR ratio was associated with a worse initial WRS (p = 0.0001, β=−0.25). A multivariate regression analysis demonstrated the variables fundal cap and initial WRS to significantly predict change in WRS over time. The larger the fundal cap size, the smaller the change in the WRS (p = 0.047, β=−0.35). Conclusions: Cerebrospinal fluid fundal cap size predicts the natural history of hearing in vestibular schwannoma patients. The presence of a smaller fundal cap is correlated with a greater risk of progression of hearing loss and should be a variable considered in the management of small vestibular schwannomas.

Sporadic Vestibular Schwannoma Size and Location Do not Correlate With the Severity of Hearing Loss at Initial Presentation

“…An even greater number of studies, however, show no significant difference in patients’ hearing between fundus, central, or porus-centered tumors ( 13 , 15 ). Furthermore, no correlation is found between lateral extent within the IAC and hearing ability, precluding a strict sublocalization criteria as a determining factor for tumor intervention ( 11 , 15 , 31 ).…”

“…Utilizing high-resolution MRI protocols, protein deposition in the cochlea and labyrinthine hypo-intensity have been investigated as contributing factors to VS-associated hearing loss (9,10). Further studies steer their focus towards the physical location of tumors, such as the superior vestibular nerve (SVN), and overall tumor size (11)(12)(13)(14). The majority of such studies remain limited by small sample size, despite the availability and inclusion of strong audiometric and imaging data.…”

“…The majority of such studies remain limited by small sample size, despite the availability and inclusion of strong audiometric and imaging data. Studies with larger populations struggle with inconsistent or incomplete MRI data ( 11 , 15 ).…”

A Case–Case Analysis of Intralabyrinthine Schwannoma Versus Intracanalicular Vestibular Schwannoma

“…Change in PTA was calculated between two audiograms at least 12 months apart, although if hearing was already classified as Class D based on AAO-HNS guidelines they were excluded from the analysis of change in hearing to prevent a floor effect. The change in PTA was divided by the number of months between the two audiograms to account for the variance in follow-up patterns (15). The location of intralabyrinthine schwannomas was grouped based on the Kennedy classification (4).…”

Current Understanding of Hearing Loss in Sporadic Vestibular Schwannomas: A Systematic Review

“…Besides, in another MRI study aiming to identify practical predictors of hearing loss in the conservatively managed SVS, the researchers considered the fundal cap as a candidate. It was measured as the maximal distance between the lateral most aspect of the tumor to the fundus or the lateral most aspect of the internal auditory canal, and its size was correlated with the word recognition score over time ( 57 ). It is valuable for future studies with larger sample size and longer observation to verify the association between hearing loss and tumor filling within IAC.…”