Intraoperative auditory steady-state monitoring during surgery in the cerebellopontine angle for estimation of postoperative hearing classes

OBJECTIVEBrainstem auditory evoked potentials (BAEPs) have been used for intraoperative monitoring of the auditory nerve for many years. However, BAEPs yield limited information about the expected postoperative hearing quality and speech perception. The auditory steady-state response (ASSR) enables objective audiograms to be obtained in patients under anesthesia. These ASSRs could be used for intraoperative estimation of hearing classes to improve the postoperative outcome and quality of life. Studies investigating the clinical use of ASSRs during total intravenous anesthesia are currently lacking. The work presented in this article therefore investigates the application of ASSRs for intraoperative estimation of hearing classes.METHODSIn 43 patients undergoing surgery for vestibular schwannoma, ASSR measurements were performed at the beginning and end of the surgical procedure. ASSR stimuli consisted of 80-dB hearing level amplitude-modulated tones with 5-minute duration, 90-Hz modulation, and 3 different...