Implantable bone conduction aids are potentially an important advance for those with a conductive hearing impairment. One system (Xomed Audiant bone conductor), which uses electromagnetic induction to vibrate a subcutaneous implanted skull magnet, has now been implanted in sufficient patients in the United Kingdom, for enough time, for its indicationsto be evaluated.
Seventeen of the total of 18 patients that have been implanted, satisfied the average threshold criterion for suitability for implantation (average bone conduction over 0.5, 1 and 2 kHz of 25 dB HL or better) yet only 10 of the 17 (59 per cent) currently use their Audiant aid. This was not because of technical reasons but was mainly influenced by the previous type of amplification. Current usage of a body level processor was 100 per cent) (6 of 6) in those that previously could only use a conventional bone conduction aid because of bilateral congenital or acquired atresia of their external auditory canals. In comparison, usage was only 36 per cent (4 of 11) in those that could potentially use a conventional ear level aid albeit with problems such as the discharge from active chronic otitis media. This relative non-use was considered due to a lack of power of the ear level processor and the general unwillingness of patients to change from an ear level to a body level device.