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

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 ne…