Deaf neurofibromatosis type 2 (NF2) patients have limited rehabilitation choices. Extracranial cochlear implants are inappropriate for NF2 patients without intact auditory nerves, a consequence of bilateral vestibular schwannomas. Intracranial cochlear nucleus brainstem and inferior colliculus midbrain implants are two possible treatment options. Those devices provide encouraging but relatively modest benefits compared to cochlear implant hearing outcomes in non-NF2 patients. The current conceptual framework for deafness rehabilitation in NF2 patients is implantation of intracranial devices to auditory structures accessible via infratentorial posterior fossa craniotomy under general anesthesia. Direct visual identification of the target auditory nucleus for implant placement is the dominant surgical technique. However, reliable placement and stable positioning of electrodes have been major challenges. An alternate strategy to possibly improve therapeutic outcomes is device implantation of the ventral medial geniculate body via supratentorial burr hole craniotomy under local anesthesia. Adaptation of established deep brain stimulation and computer assisted surgical navigation technologies to target the auditory thalamus would supplant current surgical practices. This project proposes taking initial step towards the development of a clinically deployable auditory thalamic implant. Animal studies are planned to measure electrically driven ventral medial geniculate body thalamocortical transformations that would serve as design parameters to engineer a suitable brain probe and speech processor.
Deaf patients without intact auditory nerves, such as those afflicted by neurofibromatosis type 2, have very limited rehabilitation options. Research to develop a better hearing device is necessary to meet communication needs of this underserved population. Knowledge derived from this project may also help many other hearing impaired individuals.
|Atencio, Craig A; Shih, Jonathan Y; Schreiner, Christoph E et al. (2014) Primary auditory cortical responses to electrical stimulation of the thalamus. J Neurophysiol 111:1077-87|