Cochlear implantation after radiation therapy for acoustic neuroma

Abstract

Neurofibromatosis type 2 (NF-2) represents the complex issue of hearing restoration after treatment for a patient with bilateral acoustic neuromas. This scenario is difficult for skull base teams considering that all treatment options (including observation of tumors) pose a risk to the patient for further or total hearing loss. In this case of a patient with bilateral deafness, restoration options were auditory brainstem or cochlear implantation (CI). The deciding factor for CI was based on the presence of a functioning cochlear nerve and blood supply. Ultimately, treatment with radiation therapy and subsequent CI proved effective as evidenced by dramatic improvement in communication (with lip reading cues) and speech perception on 1-year audiologic testing. Radiosurgery followed by CI may represent a potential emerging option for patients with NF-2.

Keywords: acoustic neuroma; auditory brainstem implantation; cochlear implantation; radiation therapy; stereotactic radiosurgery; vestibular schwannoma.

Figure 1

Components of a cochlear implant system. Internal and external components shown on patient’s right whereas external-only components are on left. External component consists of a transmitter with a magnet and a sound processor with a microphone that fits behind the ear. An external device converts sound energy into electrical energy and communicates with the internal device. Internal components include a magnet (beneath the skin and behind the ear), a receiver that accepts input from the external components, and electrodes that directly enter the cochlea for stimulation of the cochlear nerve. Magnets on the internal and external systems allow physical alignment for optimal transcutaneous communication. Inset, Enlarged view of the external and internal components (with permission from Cochlear Americas).