Auditory brain-stem responses in guinea pigs following middle ear implantation of Ceravital.

The effects on auditory function caused by implantation of the bioactive glass ceramic Ceravital in the middle ear of guinea pigs was investigated. Auditory brain-stem responses (ABR) were used to measure hearing function. A threshold shift due to a conductive hearing loss was observed immediately post-operatively. This threshold shift increased towards the 20th post-operative day and improved thereafter. Surgical manipulation of the middle ear and biochemical reactions between the Ceravital granules and the middle ear wall may have contributed respectively to the immediate and late temporary ABR threshold shift recorded. However, cochlear function was not affected by middle ear implantation of Ceravital. These results correlate well with morphological studies of Ceravital implanted in the middle ear and give further support to the safe use of Ceravital as an implantation material in middle ear reconstructive surgery.