Long Latency Auditory Potential (P300) Outcomes in a Patient with Vestibular Schwannoma after Cochlear Implant Surgery

Abstract

Background: Neurofibromatosis type 2 (NF2) is a rare syndrome and it is usually presented with bilateral vestibular schwannomas (VS), multiple meningiomas, and other types of tumors associated to peripheral nerves. Hearing loss is one of its leading manifestations, and surgery for removal of the tumor is often required. Cochlear implant (CI) surgery is an option for auditory rehabilitation and long latency auditory potentials (P300) are becoming a very useful tool to assess hearing outcomes. Objective: To verify the presence of P300 waves during auditory and cortical function assessment in a patient submitted to VS removal and CI surgery. Design: Retrospective chart review. Case Report: A 62 years old male patient, presented at the clinic with a bilateral severe to profound hearing loss, worst at the right side. MRI scan revealed bilateral expansive tumor within the internal auditory canal expanding to cerebellopontine angle, suggestive of VS. Tumor was removed at the right side, and CI surgery was indicated for the left ear. P300 tests were performed pre-operatively, at the moment of activation, and 6 months post-operatively. After CI activation, P300 waves appeared, and presented reduced latency and increased amplitude after 6 months of CI use. Conclusion: P300 waves appear to be dependent on the auditory stimulus to be generated, showing that it can be a useful tool to estimate improvement in cortical cognitive function after restoring hearing through CI surgery after VS removal.