The bone conduction implant: Clinical results of the first six patients

Abstract

Objective: To investigate audiological and quality of life outcomes for a new active transcutaneous device, called the bone conduction implant (BCI), where the transducer is implanted under intact skin.

Design: A clinical study with sound field audiometry and questionnaires at six-month follow-up was conducted with a bone-anchored hearing aid on a softband as reference device.

Study sample: Six patients (age 18-67 years) with mild-to-moderate conductive or mixed hearing loss.

Results: The surgical procedure was found uneventful with no adverse events. The first hypothesis that BCI had a statistically significant improvement over the unaided condition was proven by a pure-tone-average improvement of 31.0 dB, a speech recognition threshold improvement in quiet (27.0 dB), and a speech recognition score improvement in noise (51.2 %). At speech levels, the signal-to-noise ratio threshold for BCI was - 5.5 dB. All BCI results were better than, or similar to the reference device results, and the APHAB and GBI questionnaires scores showed statistically significant improvements versus the unaided situation, supporting the second and third hypotheses.

Conclusions: The BCI provides significant hearing rehabilitation for patients with mild-to-moderate conductive or mixed hearing impairments, and can be easily and safely implanted under intact skin.

Keywords: Bone conduction implant; active transcutaneous; audiometry; hearing loss; intact skin; patient related outcome measure; questionnaires.

Figure 1.

3D model of the audio processor (including digital signal processor, modulator, transmitter coil and retention magnet (not shown), directional microphones, battery, program selector, and volume control), and the bridging bone conductor (including receiver coil, internal retention magnet, demodulator, and transducer).

Figure 2.

Patient audiograms with air conduction (AC) and masked bone conduction (BC) thresholds. Blue symbols = left; red symbols = right; x = left AC; o = right AC;] = left masked BC; and [= right masked BC. In patients 2 and 4, some BC thresholds were not reached due to over-masking (]] or [[). Pat = patient; R = right; and L = left.

Figure 3.

Tone threshold improvements for BCI and reference device, including mean improvement and standard deviation. BCI PTA₄ = 31.0 ± 8.0 dB, and Ref PTA₄ = 23.7 ± 6.8 dB. Stars are included at frequencies where the BCI has statistically higher improvement than the reference device (α = 0.05).

Figure 4.

Signal-to-noise ratio threshold (SNR-threshold) for 50% intelligibility for the BCI, and the reference device for all patients, mean improvement, and standard deviation. BCI SRT-threshold = − 5.5 ± 2.3 dB, and Ref SRT-threshold = − 2.4 ± 3.8 dB.

Figure 5.

APHAB improvements in the four categories (ease of communication (EC), listening against background noise (BN), listening under reverberant conditions (RV), and aversiveness of sound (AV)) for the BCI and for the reference device (Ref). Mean improvements (bars) and standard deviations (error bars) are included.

Figure 6.

GBI results in the categories total score, general subscale score, social support score, and physical health score. Results for both the BCI and the reference device (Ref) are presented. Mean improvements (bars) and standard deviations (error bars) are included.