Hypotension as an isolated factor may not be sufficient to provoke hearing impairment

OBJECTIVE: We investigated the possible role of hypotension and related autonomic phenomena in the pathogenic mechanism of sudden sensorineural hearing loss. METHODS: Forty-nine patients belonging to the ASA I-II classes of anaesthesiological risk and submitted to a non-otological surgical procedure were examined. Each operation was performed under general anaesthesia by controlled hypotension technique. Hearing function of the patients was evaluated before and after surgery by means of a pure tone audiometry recorded by the same clinician with the same instrument. RESULTS: No cases of bilateral hearing worsening were recorded after surgery. CONCLUSIONS: An induced and controlled steady hypotension under general anaesthesia did not affect the hearing function of any of the patients. It may be supposed, therefore, that an adverse effect on the cochlear oxygenation is more likely to be caused by the sympathetic changes induced by a consistent decrease of blood pressure rather than to hypotension itself.