Intralabyrinthine Schwannomas: Management and Hearing Rehabilitation with Cochlea Implants

Abstract

Recent high-resolution temporal bone imaging and increasing awareness for the disease let to an increasing number of reports of intralabyrinthine schwannomas (ILS). ILS may be overlooked when very small and only be detected on repeated MRI-scans. The more frequently observed cochlear schwannomas usually originate from the Habenula perforata of the basal and second turn of the cochlea. Cochlear ILS may then grow secondarily into the Scala vestibuli and into the Vestibulum, while primarily vestibular ILS grow from the Vestibulum into the cochlea. They can also extent into the internal auditory canal or into the middle ear. Initial clinical symptoms are most frequently sudden hearing loss and in some patients tinnitus or vertigo. We report ~11 patients with ISL. The lesions were 6× intracochlear, 4× intravestibular, and 1× transotic. One patient showed a second intracanalicular tumor in addition to the intravestibular tumor without any radiological signs of a connection between the two tumors. This patient and four more patients opted for “Watch and Test and Scan” strategy with conventional acoustic CROS (contralateral routing of sound) rehabilitation. Six patients underwent surgery for microscopic and partially endoscopically assisted tumor removal. In two patients a transcanal approach with extended cochleostomy was chosen. Of these two, one patient received a simultaneous cochlea implant (CI) and the other a dummy electrode implantation and partial cochlear reconstruction with cartilage chips. In three patients, the tumor was removed via a labyrinthectomy with preservation of the cochlea and CI implantation as a single stage procedure. Another patient with the tumor completely filling the cochlea received a transcanal cochleostomy with preservation of the inferior part the basal turn bony wall, electrode dummy implantation and partial cochlear reconstruction with cartilage chips. All CI implanted patients experienced postoperative improvement of hearing Successful hearing rehabilitation with cochlear implants after ILS tumor removal is possible. Challenges arise with insufficient possibilities for follow-up for tumor recurrence with MRI in patients with CI. Patient requirements for optimal hearing rehabilitation have to consider the vocational situation, the hearing status of the opposite ear and balanced with the limited but growing experience with clinical, electrophysiological and radiological follow-up.