Bone-Anchored Hearing Aid System Application for Unilateral Congenital Conductive Hearing Impairment: Audiometric Results

Objective: To study the audiologic outcome of bone-anchored hearing aid (BAHA) application in patients with congenital unilateral conductive hearing impairment. Study Design: Prospective audiometric evaluation on 20 patients. Setting: Tertiary referral center. Patients: The experimental group comprised 20 consecutive patients with congenital unilateral conductive hearing impairment, with a mean air-bone gap of 50 dB. Methods: Aided and unaided hearing was assessed using sound localization and speech recognition-in-noise tests. Results: Aided hearing thresholds and aided speech perception thresholds were measured to verify the effect of the BAHA system on the hearing acuity. All patients fulfilled the criteria that the aided speech reception thresholds or the mean aided sound field thresholds were 25 dB or better in the aided situation. Most patients were still using the BAHA almost every day. Sound localization scores varied widely in the unaided and aided situations. Many patients showed unexpectedly good unaided performance. However, nonsignificant improvements of 3.0 (500 Hz) and 6.9 degrees (3,000 Hz) were observed in favor of the BAHA. Speech recognition in noise with spatially separated speech and noise sources also improved after BAHA implantation, but not significantly. Conclusion: Some patients with congenital unilateral conductive hearing impairment had such good directional hearing and speech-in-noise scores in the unaided situation that no overall significant improvement occurred after BAHA fitting in our setup. Of the 18 patients with a complete data set, 6 did not show any significant improvement at all. However, compliance with BAHA use in this patient group was remarkably high. Observations of consistent use of the device are highly suggestive of patient benefit. Further research is recommended to get more insight into these findings.