Bone anchored hearing aid in single sided deafness: outcome in right-handed patients

To assess the benefits in terms of sound localization, to evaluate speech discrimination in noise, to appraise the prosthesis benefit and to identify outcome in right and left handed patients when BAHA are implanted on the right or on the left deaf side.

Two years prospective study in a tertiary referral center. Tests consist on Hearing in Noise Test (HINT) and sound localization after 6 months of BAHA use. Quality of life was assessed by the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire. The paired T-test and the analysis of variance were used for the statistical measures.

Twenty-one subjects participated in this study. HINT: patients score better when speech and noise are spatially separated and noise is not presented to the healthy ear. In the right-handed group (left dominant brain), unaided left-implanted patients performed better than right-implanted patient when speech is in front and noise to the good ear; when speech is presented to the good ear and noise to the front, aided right-implanted patients performed better than aided left-implanted patients. Sound localization: correct answers attain 35% at best. No statistical difference between the frequencies was found, neither between the left and right implanted patients. APHAB: the score improvement is statistically significant for the global score, the background noise subscale at 5 weeks and for the reverberation subscale at 6 months.

It seems that left dominant hemisphere is able to filter crossed noise better than the right hemisphere. Results of uncrossed speech to the dominant left brain are better than the uncrossed speech to the non-dominant right brain.