A marked decrease in speech intelligibility is no longer a major characteristic of vestibular schwannoma in the current era.

Objectives A markedly decreased speech intelligibility is reported to be a major feature of vestibular schwannoma (VS); however, details such as the relationship between speech intelligibility and hearing levels have not yet been adequately clarified.

Methods Among 473 patients with sporadic unilateral vestibular schwannoma, scatter plots of pure tone audiometry (PTA) thresholds and speech discrimination scores were created. Simple regression analysis was conducted, and the Pearson correlation coefficient was calculated. The results were compared with those of 173 patients with asymmetric cochlear hearing loss, including the percentage of patients with unserviceable speech intelligibility.

Results In patients with vestibular schwannoma, a strong correlation was found between the speech discrimination score and PTA threshold on the affected side, regardless of Koos grade or audiogram shape. In most patients, there was no significant difference in distribution compared with patients with asymmetric cochlear hearing loss. Although the proportion of patients with unserviceable speech discrimination was higher for vestibular schwannoma than asymmetric cochlear hearing loss across all hearing levels, the condition was limited to a small number of cases; a significant difference was only observed in cases with severe hearing loss.

Conclusion Considering its relationship with hearing level, a markedly decreased speech discrimination score is no longer a major feature of vestibular schwannoma.