Functional results with active middle ear implant or semi-implantable bone conduction device in patients with comparable hearing loss.

OBJECTIVE

In patients with conductive (CHL) or mixed hearing loss (MHL), hearing rehabilitation with an implantable hearing system, active middle ear implant (AMEI) or a semi-implantable bone-conduction device (SIBCD), is an option when conventional hearing aids are insufficient, or patients are unable to wear them.

DESIGN

Retrospective analysis of 20 consecutive patients (24 implants) with a comparison of demographic characteristics and audiometric results (air-bone gap = ABG, effective hearing gain = EHG, functional hearing gain = FHG, Freiburg Monosyllabic Test in quiet, Oldenburg Sentence Test in noise = OLSA).

STUDY SAMPLE: Patients, eligible for both devices, who received either AMEI or SIBCD due to CHL or MHL.

RESULTS

Analysis showed no significant differences in post-operative functional hearing results between the group of AMEI vs. SIBCD (ABG-reduction: 31.6 ± 12.4 dB HL vs. 28.0 ± 11.8 dB HL; p = 0.702; EHG: -1.6 ± 7.7 dB HL vs. -1.2 ± 4.2 dB HL; p = 0.090; FHG: 33.4 ± 12.6 dB HL vs. 26.1 ± 11.7 dB HL; p = 0.192; Freiburg: 83.0 ± 15.6% vs. 83.6 ± 14.2%; Freiburg-improvement: 57.7 ± 26.8% vs. 68.2 ± 19.7%; p = 0.294; OLSA: -2.7 ± 3.0 SNR vs. -1.4 ± 3.6 SNR; OLSA-improvement: 2.6 ± 2.1 dB vs. 3.7 ± 2.8 dB; p = 0.323). Four patients had the AMEI explanted due to insufficient functioning and later received a SIBCD.

CONCLUSIONS

Due to more challenging anatomical conditions, a surgical technique for the AMEI is more complex. However, functional results are comparable to the SIBCD. Therefore, proper patient counselling and cautious choice of the device are mandated before surgery.