Abstract:

Objective    To explore bone-anchored hearing aids(BAHA) implant position and operation skill under local anaesthesia microscopy. Methods    Both 2 male patients were operated under microscopy and local anaesthesia. One was 62 years old. He had the mixed hearing loss at the left and sensorineural deafness at the right. The result of sound field examine was over 100dB in two ears, and the BAHA soft belt test was 45-100dB sharp decline type， over 4kHz was lost. In case 1, the BAHA pedestal was implanted in the conventional position on the skull, which was behind the ear groove 3cm and above the ear canal 3cm. The two was 16 years old. He had double three-auditory-ossicle malformed fixation and hearing loss, but the hearing was only a little improved after operation of two times. The result of sound field audiometry was 67.5dB， and the BAHA soft belt test was 40-50dB flat type. In case 2, the BAHA pedestal was implanted on the different position on the skull, which was in the level of the ear canal and behind the ear groove about 2cm. Results    Case 1 obtained the hearing improved about 35dB in the sound field examine post-operation. Case 2 hearing improved above 35dB. The post-operative CT revealed Case 1 pedestal had a little projecting skull bone into meninges. Case 2 pedestal was away from meninges about 2cm. Conclusion     BAHA can evidently improve hearing， and the pedestal can be implanted under local anaesthesia and microscopy in most cases. Bone is thicker at the position behind the ear canal than at the conventional position， so pedestal implantation at this position  has less probability of damage mininges than the conventional position.

Key words: Pedestal, Complication, Hearing improve, Bone-anchored hearing aids