Recovery of useful hearing after posterior fossa surgery: The role of otoacoustic emissions. Case report

OBJECTIVE AND IMPORTANCE: Hearing preservation has become an important issue in surgical procedures involving the cerebellopontine angle (CPA). Although several prognostic factors for hearing preservation in patients with 'useful' preoperative hearing have been described, it is difficult to predict which patients have the potential for hearing preservation or recovery. Otoacoustic emission measurement is a new technique that allows recording of sounds produced by the cochlear outer hair cells as a normal byproduct of the receptor process and can be used to assess cochlear involvement in patients with hearing loss. CLINICAL PRESENTATION: We present the case of a 53-year- old patient with a recurrent arachnoid cyst of the CPA. She had noticed progressive severe hearing loss ipsilateral to the cyst that was confirmed by preoperative audiogram. TECHNIQUE: Otoacoustic emissions were obtained and were within normal limits on the involved side, suggesting that the cochlear outer hair cells were still intact and that the patient had the potential for hearing recovery. The CPA was decompressed by marsupialization of the cyst. Postoperative audiogram demonstrated a dramatic recovery of hearing to a normal level. CONCLUSION: Otoacoustic emissions clearly provide valuable information about the potential for hearing preservation/recovery after CPA surgery and have significant implications for the current neurosurgical management of these lesions.