Auditory Brainstem Implant (ABI) in Adult Non-Neurofibromatosis Type 2 Subjects

Study of Nucleus 24 and ABI541 Auditory Brainstem Implants (ABI) in Adult Non-Neurofibromatosis Type 2 Subjects

The purpose of this research study is to determine whether Auditory Brainstem Implant (ABI) can improve hearing in persons who are deaf in both ears and are not candidates for cochlear implants.

The goal of this MEEI Auditory Brainstem Implant (ABI) research study is to find new ways to improve hearing in patients who are deaf and cannot receive a cochlear implant. The ABI is a surgically placed bionic implant that converts sounds into electrical signals that are directly transmitted to the cochlear nucleus, the first auditory center of the brain. For many years, ABIs have improved the hearing of patients who are deaf due to brain tumors associated with a genetic syndrome called Neurofibromatosis Type 2 (NF2). However, a number of recent studies suggest that deaf patients who do not have NF2 and are not eligible for a cochlear implant may also benefit from placement of an ABI. These preliminary studies suggest that these non-NF2 or "nontumor" patients may actually have better outcomes after ABI surgery than patients suffering from NF2. Patients who do not have NF2 and are deaf due to damage to the hearing nerves or inner ears from infection, disease or injury are not cochlear implant candidates and there are no other options to improve hearing in these cases except for the ABI. Thus, the purpose of our study is to carefully analyze whether ABI surgery improves the hearing and quality of life of non-NF2 patients based on subjective and objective measures of their hearing before and after ABI surgery. In particular, we plan to study ABI outcomes in non-NF2 patients, characterize the parameters used on their devices, and determine the safety profile of ABIs in these patients.

Inclusion Criteria:

• 18 years of age or older

• English as the primary language

• Medically and psychologically suitable

• Willing to receive/have received meningitis / pneumococcal vaccinations

• Able to comply with study requirements, including travel to the investigational site

• Cochlear or retrocochlear anomaly/pathology that interferes with transmission of auditory information from the cochleae to the brainstem, resulting in severe to profound bilateral deafness (thresholds of 90 dB or worse in both ears on pure tone audiometry ranging from 250 to 2,000 Hz and speech recognition scores ≤ 30% in both ears). All subjects will undergo bone conduction audiometry and tympanometry to confirm sensorineural hearing loss and rule out potential middle ear disorders.

  • Conditions that cannot be otherwise treated, with conventional hearing aids or cochlear implants. If CI were previously used, subjects will have had a failed response, defined as ≤ 30% speech recognition and patient perception of inadequate benefit to continue using the device.

  • Expected subjects include those with these diagnoses:

    • Bilaterally severe/completely ossified cochleae
    • Bilateral cochlear malformations leading to poor CI outcomes
    • Bilateral temporal bone fractures, where the VIIIth cranial nerves have been disrupted
    • Bilateral cochlear nerve agenesis
    • Not a CI candidate based on above listed pathology, intolerable adverse effects with CI (e.g. stimulation of the facial nerve), or Evoked Auditory Potential testing predictive of a poor response

Exclusion Criteria:

• Anomalies/pathology involving the brainstem or cortex
• Retrocochlear pathology due to NF2 or other types of cranial nerve or brainstem neoplasm
• Co-existing medical conditions that require irradiation of the brainstem or auditory cortex
• Medical or psychological conditions that serve as contraindication to surgery
• Additional handicaps that would prevent or limit participation in evaluations
• Unrealistic patient or family expectations regarding the benefits, risks, and limitations inherent to the procedure and the prosthetic device
• Pregnant women