The magnetless Clarion® cochlear implant in a patient with neurofibromatosis 2

Abstract

We present our experience using the Clarion® magnetless multichannel cochlear implant with a woman profoundly deafened following bilateral acoustic neuromata as a consequence of neurofibromatosis 2 (NF2). The right neuroma had been previously removed without an attempt at neural preservation. On the left, however, a posterior fossa approach had been taken with the aim of preserving hearing. Although the left cochlear nerve appeared to be undamaged at the end of the operation, no hearing thresholds could be elicited on post-operative audiometry, because of damage either to the cochlear nerve or to the blood supply to the cochlea. Round window electrical stimulation subsequently produced a perception of sound, confirming that the cochlear nerve was capable of functioning and that a cochlear implant would be effective. Because she would need regular magnetic resonance imaging (MRI) to monitor existing and future NF2 lesions, it was decided to use a magnetless Clarion® implant, which has been shown to be MRI compatible. We report our experience of using the device in this case and discuss some of the issues related to the provision of cochlear implants to patients with NF2.

Hearing Rehabilitation in Neurofibromatosis Type 2 Patients: Cochlear versus Auditory Brainstem Implantation

“…For this reason, Neff et al [2007] stressed the importance of ESP in the assessment of the physiological viability of the cochlear nerve at the end of surgery, suggesting to delay electrophysiological evaluation 6-8 weeks after tumor removal. The same experience on initial negative result in EPS in the immediate postoperative period was described in the case reports published by Graham et al [1999] and Hoffman et al [1992]. In both studies the electrical stimulation of the cochlear nerve became successively positive and a successful cochlear implantation was performed in both patients.…”

“…In the 1990s, Cueva [1992] reported on auditory sensations elicited by electrical promontory stimulation (EPS) in a patient with preserved cochlear nerve and deafness after VS resection, demonstrating the theoretical feasibility of cochlear implantation in deafened NF2 patients with intact cochlear nerve after VS removal. Since then, histological [Belal, 2001] and clinical studies Hulka et al, 1995;Tono et al, 1996;Graham et al, 1999;Ahsan et al, 2003;Nolle et al, 2003;Aristegui and Denia, 2005] confirmed that cochlear implantation is possible in at least a subset of this special population of patients. Today, we can offer 2 options for hearing restoration, cochlear or auditory brainstem implantation, to NF2 deafened patients with an anatomically preserved cochlear nerve.…”

Cochlear Implantation after Acoustic Tumour Resection in Neurofibromatosis Type 2: Impact of Intra- and Postoperative Neural Response Telemetry Monitoring

“…In 1991, the first patient was supplied with this device [14]. However, the functional gain of CI patients (open speech) is superior to what is usually possible in ABI patients [15][16][17]. When Di Nardo et al [18] compared CI (n = 8) and ABI (n = 1) patients, the ABI patient could only recognize speech-in-context, had 86% syllable recognition (closed set) and used the ABI for 8 h only per day.…”

“…The recurring rates of these ANs largely depend on the first operation, i.e. the complete or near-complete excision of the tumour, but the regrowth of minor tumour remnants has to be considered [15,25].…”

“…a hearing sensation was found. The ECoG is the most reliable method in this respect preoperatively, but it can produce false-negative results a few weeks or at least 2 months after the AN removal [2,15]. It should therefore be repeated after some months when the postoperative swelling and scar formation is completed.…”