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 (CP A). Although several prognostic factors for hearing preservation in pa tients with ''useful'' preoperative hearing have been described, it is difficult to predict which patients have the potential for hearing pr eservation or recovery. Otoacoustic emission measurement is a new tech nique that allows recording of sounds produced by the cochlear outer h air cells as a normal byproduct of the receptor process and can be use d to assess cochlear involvement in patients with hearing loss. CLINIC AL PRESENTATION: We present the case of a 53-year-old patient with a r ecurrent arachnoid cyst of the CPA. She had noticed progressive severe hearing loss ipsilateral to the cyst that was confirmed by preoperati ve audiogram. TECHNIQUE: Otoacoustic emissions were obtained and were within normal limits on the involved side, suggesting that the cochlea r outer hair cells were still intact and that the patient had the pote ntial for hearing recovery. The CPA was decompressed by marsupializati on of the cyst. Postoperative audiogram demonstrated a dramatic recove ry of hearing to a normal level. CONCLUSION: Otoacoustic emissions cle arly provide valuable information about the potential for hearing pres ervation/recovery after CPA surgery and have significant implications for the current neurosurgical management of these lesions.