Percutaneous versus transcutaneous bone conduction implant system: a feasibility study on a cadaver head.
OBJECTIVE
Percutaneous bone-anchored hearing aid (BAHA) is an important rehabilitation alternative for patients who have conductive or mixed hearing loss. However, these devices use a percutaneous and bone-anchored implant that has some drawbacks reported. A transcutaneous bone conduction implant system (BCI) is proposed as an alternative to the percutaneous system because it leaves the skin intact. The BCI transmits the signal to a permanently implanted transducer with an induction loop system through the intact skin. The aim of this study was to compare the electroacoustic performance of the BAHA Classic-300 with a full-scale BCI on a cadaver head in a sound field. The BCI comprised the audio processor of the vibrant sound bridge connected to a balanced vibration transducer (balanced electromagnetic separation transducer).


METHODS
Implants with snap abutments were placed in the parietal bone (Classic-300) and 15-mm deep in the temporal bone (BCI). The vibration responses at the ipsilateral and contralateral cochlear promontories were measured with a laser Doppler vibrometer, with the beam aimed through the ear canal.


RESULTS
Results show that the BCI produces approximately 5 dB higher maximum output level and has a slightly lower distortion than the Classic-300 at the ipsilateral promontorium at speech frequencies. At the contralateral promontorium, the maximum output level was considerably lower for the BCI than for the Classic-300 except in the 1-2 kHz range, where it was similar.


CONCLUSIONS
Present results support the proposal that a BCI system can be a realistic alternative to a BAHA.
Håkansson
Bo
B
Department of Signals and Systems, Chalmers University of Technology, Göteborg, Sweden. boh@chalmers.se
Eeg-Olofsson
Måns
M
Reinfeldt
Sabine
S
Stenfelt
Stefan
S
Granström
Gösta
G