Ipsilateral and contralateral vestibular schwannomas in unilateral long-term deaf ears

Abstract

In the past decade, we have encountered two patients with unilateral long-term deaf ear having vestibular schwannoma. One was on the deaf ear in a 53 years' woman and the other was on the contralateral hearing ear in a 62 years' woman. These two patients had total deafness on the right ear since childhood, associated with absent auditory brainstem response (ABR) and caloric responses, whereas normal ABR and caloric responses were shown on the left ear. Although similar physiological findings were disclosed on the deaf ears, MRI scan demonstrated vestibular schwannoma on the different side, that is, one in deaf ear and the other in hearing ear. For the former, absent ABR and caloric results indicate that the tumor originates from the superior vestibular nerve. In contrast with the latter, normal ABR and caloric responses, but absent vestibular-evoked myogenic potentials on the hearing ear imply that the tumor originates from the inferior vestibular nerve. The ipsilateral tumor on the deaf ear underwent intracranial surgical excision, followed by radiosurgery due to tumor recurrence 10 years later, while the contralateral one on the only hearing ear received radiosurgery only. Both patients were rather well, 3 years after last treatment.