MRI T2-Weighted Cochlear Intensity as a Predictor of Hearing Loss with Vestibular Schwannoma Patients

Introduction: Vestibular schwannomas are benign tumors found in the internal auditory canal and cerebellopontine angle that can present with hearing loss, tinnitus, and vertigo. Advances in MRI technology and screening protocols have led to an increased incidence. While a large proportion of these tumors can undergo conservative observation, it is important to know if and when to intervene to preserve a patient’s hearing. To date, there is no single best predictor for a vestibular schwannoma patient’s audiologic outcomes. This study examines the association between cochlear intensity on T2 MR imaging and audiologic outcomes in patients.

Methods: A retrospective analysis was conducted with adult patients diagnosed with vestibular schwannoma at a single academic medical center. MRI and audiologic data were reviewed at two different time points. MRI data included tumor side, size, and location. Region of interests were placed on T2-weighted images, and cochlear and pontine intensity were used to calculate a relative signal intensity (RSI)—a ratio of cochlear-to-pontine intensity. Audiologic data included air conduction hearing values used to calculate a pure-tone average (PTA); speech recognition threshold and word recognition score were also noted; t-test and linear regressions were used to compare groups; significance was defined at α< 0.05.

Results: Forty-four patients (mean age: 65; 57% female) with unilateral vestibular schwannoma were included in the final analysis. Tumors were predominately left sided (57%). 43% of tumors were confined in the IAC and 2% in the CPA; 55% had portions in both areas. Baseline MRIs mean RSI values were 2.03 for the ipsilateral and 1.98 for the contralateral ears. Baseline audiology found mean PTA values for the ipsilateral (44.24 dB) and contralateral ears (19.01 dB). Follow-up MRIs found mean RSI values for ipsilateral (1.87) and contralateral ears (1.82). Follow-up audiology found mean PTA values for the ipsilateral (61.42 dB) and contralateral ears (22.78 dB).

Overall, RSI decreased from baseline to follow-up, while PTA increased for both ipsilateral and contralateral ears. Both ears also showed a negative correlation between initial RSI and initial PTA. A statistically significant negative correlation was found between initial ipsilateral RSI and ipsilateral PTA for patients with PTA under 40 dB (Pearson’s = −0.063; p ≤ 0.001); there was no significance between these variables in the PTA over 40-dB group. Additionally, for either ear, there was a negative albeit nonsignificant correlation between the difference in initial and follow-up PTA, and the initial and follow-up RSI.

Conclusion: This study revealed a general trend between baseline testing and follow-up testing. Overall, our study found that as RSI decreases PTA increases; however, ipsilateral and contralateral ears have different trends. This conflicted with some previous literature showing increased cochlear intensity can be used as an indicator of worse hearing. In addition, when trying to associate T2 imaging with hearing status, there may be better utility for patients still with a degree of preserved hearing, as compared with those who initially have worse hearing (evidenced by the PTA under 40-dB group finding). Further research is needed to further elucidate the relationship between these variables.

No conflict of interest has been declared by the author(s).