The Relationship between NF-2-Associated Vestibular Schwannoma Tumor Size and the Degree of Hearing Impairment

Objectives: This study aimed to evaluate the presence or absence of a correlation between the size of neurofibromatosis type 2 (NF-2) vestibular schwannomas and the level of hearing impairment. Multiple large-scale studies in the literature have demonstrated a lack of correlation between sporadic vestibular schwannoma tumor size and hearing impairment. This correlation is not well studied for NF-2-associated vestibular schwannomas. Given the earlier age of onset, bilateral involvement, and the different management approach for NF-2 associated tumors, a thorough understanding of the presence or absence of any correlation is pertinent to providing optimal patient care in this patient population.

Methods: Retrospective study at four large medical centers on 26 NF-2 patients harboring 45 vestibular schwannoma tumors. This study was based on linear regression analysis of tumor size on MRI versus various demographic and audiometric variables.

Results: The average tumor size was 15.76 mm with a range from 1.0 to 36.0 mm (SD = 10.5). Twenty-two tumors were intracanalicular (IAC), 18 tumors were located in the cerebellopontine angle (CPA) with extension into IAC, and 5 tumors were limited to the CPA. Linear regression analysis was done separately for IAC tumors, isolated CPA tumors, and CPA tumors with extension into IAC. None of the studied audiometric dependent variables (hearing threshold at a range of frequencies, pure tone average, and speech recognition threshold and score) showed any statistically significant correlation with the size of intracanalicular or isolated CPA tumors. Tumors at the CPA with IAC extension displayed a statistically significant (p < 0.05) weak correlation with hearing thresholds at 250 Hz (r = 0.45), 500 Hz(r = 0.47), 1,000 Hz (r = 0.49), 2,000 Hz(r = 0.37), 4,000 Hz(r = 0.36), and 8,000 Hz(r = 0.26). The PTA also demonstrated a weak correlation with tumor size (r = 0.46; [Fig. 1]). Furthermore, Speech recognition thresholds (SRT) were also weakly correlated to tumor size (r = 0.48). Word recognition scores (WRS) were correlated with a correlation coefficient of −0.37 ([Fig. 2]).

Conclusion: We observed a weak positive correlation between the size of CPA tumors with extension into the IAC and the studied audiometric variables. Intracanalicular tumors and isolated CPA tumors did not yield any statistically significant correlations with these variables.

Fig. 1 CPA & IAC tumors versus PTA.

Fig. 2 CPA & IAC tumors versus SRT and WRS.

Publication History

Article published online:
15 February 2022