Case Report: Surdity on the right side in completely extracochlear (solely intravestibular) schwannoma

Introduction 

A 65-year-old female patient with a 7-year history of right surdity presented to our clinic for a cochlear implant. The surdity had subjectively developed from normacusis within 6 months. There was a tinnitus of the right side and an unsteadiness of gait in the dark.

Material and Methods 

Tone audiometry confirmed right surdity. Speech understanding on the right side was not achievable in the Freiburger speech audiogram. DPOAEs, TEOAEs, a wave I in electrocochleography and a wave V in the BERA were not derivable on the right side. In the promontorial test auditory impression was reported without threshold fading and with frequency discrimination. Surprisingly, cMRI revealed a contrast-medium enhanced mass in the right vestibule compatible with a schwannoma.

Results 

Following surgery revealed that the schwannoma was indeed completely within the vestibule and had also grown into the posterior arch. It could be removed in toto. Subsequently, a cochlear implant was inserted without complications. Intraoperative telemetry measurements showed regular values.

Conclusion 

After wound healing and adaptation, speech understanding of up to 45% at 65dB was achieved two months postoperatively. Interestingly, despite the solely vestibular location of the schwannoma, the patient was neurootologically most likely to have cochlear deafness on the right side. This suggests that, contrary to previous assumptions, hearing loss is not only caused by destruction of the cochlea or pressure on the cochlear nerve, but also by other pathomechanisms such as the production of ototoxic substances.

Publication History

Article published online:
24 May 2022