Evaluation of volatile and intravenous anesthetics, effects on the threshold of neuroresponse telemetry and the threshold of acoustically evoked stapedial reflex in children undergoing cochlear implant surgery

BACKGROUND AND AIMS: Congenital hearing loss affects about 1 in every 1000 live births. Cochlear implant is an effective therapeutic method for aural rehabilitation in children suffering from severe-to-profound hearing loss. The aim of this study was to compare the effects of the intravenous and inhalational anesthesia techniques on neuroauditory threshold and stapedial reflex threshold responses. MATERIAL AND METHODS: After approval of the university ethics committee and obtaining written informed parental consent, 110 children with severe or profound bilateral sensorineural hearing loss undergoing cochlear implant surgery were randomly divided in two groups. The effects of the total intravenous anesthesia (propofol and remifentanil) and inhalation anesthesia (sevoflurane) techniques were evaluated on the neuroauditory threshold and stapedial reflex threshold responses of patients. Variations in systolic and diastolic blood pressures and mean arterial blood pressure were measured in both groups. RESULTS: No significant difference was observed in the following parameters: age, weight, duration of anesthesia, and surgery. No side effects was observed in the two groups. No significant difference was found in the Telemetry Neuroal Response Test (TNRT) reflex between the two groups (P = 0.294); however, the difference between the two groups was significant (P = 0.001) for Electrical Stapedial Reflex Threshold (ESRT) reflex. In the sevoflurane group, in 39 patients in the electrode 3 and in 17 patients in the electrode 9 (compared with 20 and 6 patients in the Propofol–remifentanil group) complete suppression of stapedial reflex existed. CONCLUSION: Our results suggest that, during the cochlear implant surgery, use of inhalation anesthetics should be avoided for achieving controlled hypotension because this may suppress or even fully eliminate stapedial reflex. Remifentanil and Propofol infusion has a slight effect on hearing thresholds and is recommended for determining hearing thresholds during cochlear implant surgeries.