Cochlear implantation and auditory brainstem implantation in neurofibromatosis type 2.

Objectives/hypothesis: To report a series of patients with neurofibromatosis type 2 (NF2), where each patient underwent both cochlear implantation and auditory brainstem implantation for hearing rehabilitation, and to discuss factors influencing respective implant success.

Study Design: Retrospective case series.

Methods: Ten NF2 patients with both cochlear implantations and auditory brainstem implantations were retrospectively reviewed.

Histopathological analysis of a 15-year user of an auditory brainstem implant.

Auditory brainstem implants (ABIs) can provide highly beneficial hearing sensations to individuals deafened by bilateral vestibular schwannomas (neurofibromatosis type 2). Relatively little is known about the status of stimulated neurons after long-term ABI use. Direct examination of the cochlear nuclear complex (CN) of one 5-year ABI user indicated no deleterious effect.

Audiologic outcomes with the penetrating electrode auditory brainstem implant.

Objective: The penetrating electrode auditory brainstem implant (PABI) is an extension of auditory brainstem implant (ABI) technology originally developed for individuals deafened by neurofibromatosis type 2. Whereas the conventional ABI uses surface electrodes on the cochlear nuclei, the PABI uses 8 or 10 penetrating microelectrodes in conjunction with a separate array of 10 or 12 surface electrodes. The goals of the PABI were to use microstimulation to reduce threshold current levels, increase the range of pitch percepts, and improve electrode selectivity and speech recognition.

Auditory brainstem implants.

The development of cochlear implantation has allowed the majority of patients deafened after the development of language to regain significant auditory benefit. In a subset of patients, however, loss of hearing results from destruction of the cochlear nerves, rendering cochlear implantation ineffective. The most common cause of bilateral destruction of the cochlear nerves is neurofibromatosis type 2 (NF2).

Auditory brainstem implants: surgical aspects.

Patients with neurofibromatosis type 2 often develop bilateral life-threatening vestibular schwannoma necessitating tumor removal, which results in deafness. We developed the auditory brainstem implant (ABI) in order to be able to electrically stimulate the cochlear nucleus complex in patients with bilateral cochlear nerve injury from bilateral schwannoma. After tumor removal, the electrode array of the ABI is inserted into the lateral recess of the fourth ventricle and placed over the surface of the ventral and dorsal cochlear nuclei.

Neural response telemetry and auditory/nonauditory sensations in 15 recipients of auditory brainstem implants.

Auditory brainstem implants (ABIs) provide a means of restoring some hearing sensations to individuals with neurofibromatosis type 2 (NF2) who are deaf after vestibular schwannoma removal. In this study, neural response telemetry (NRT) was used to record electrically evoked neuronal activity near the ABI electrode array in 15 such subjects. Our interest was to investigate whether NRT recordings from the brainstem might be useful in implanting or programming ABIs.

Optimizing the clinical fit of auditory brain stem implants.

Objective: To develop and implement a new audiological fitting procedure for auditory brain stem implants (ABIs), based on an efficient algorithm, and to compare it with two procedures presently used in clinical practice.

Design: First, the different procedures were compared by using computer models and simulations with normal-hearing subjects (N = 4). This allows for an analysis of the accuracy of the procedures in a way that is not possible when testing ABI users.

The multichannel auditory brainstem implant: how many electrodes make sense?

Object: Development of multichannel auditory brainstem implant (ABI) systems has been based in part on the assumption that audiological outcome can be optimized by increasing the number of available electrodes. In this paper the authors critically analyze this assumption on the basis of a retrospective clinical study performed using the Nucleus 22 ABI surface electrode array.

Methods: The perceptual performances of 61 patients with neurofibromatosis Type 2 were tested approximately 6 weeks after an eight-electrode ABI had been implanted.

Multichannel auditory brainstem implant: update on performance in 61 patients.

Object: Neurofibromatosis Type 2 (NF2) has typically resulted in deafness after surgical removal of bilateral vestibular schwannomas (VSs). Cochlear implants are generally ineffective for this kind of deafness because of the loss of continuity in the auditory nerve after tumor removal. The first auditory brainstem implant (ABI) in such a patient was performed in 1979 at the House Ear Institute, and this individual continues to benefit from electrical stimulation of the cochlear nucleus complex.