Pilot study on the effectiveness of the conventional CROS, the transcranial CROS and the BAHA transcranial CROS in adults with unilateral inner ear deafness

Abstract

The objective of the present pilot study is to evaluate the effectiveness of three conventional contralateral routing of sound (CROS) hearing aids in adults with unilateral inner ear deafness. The study included tertiary referral center. Ten patients with unilateral inner ear deafness and normal hearing in the contralateral ear were selected to evaluate three different methods of amplification: the CROS hearing aid, the completely in the canal hearing aid and the bone-anchored hearing aid CROS (BAHA). Each of the three hearing aids was tried in a random order for a period of 8 weeks. Audiometric performance, including speech-in-noise, directional hearing and subjective benefit were measured after each trial period, using the APHAB, SSQ and single-sided deafness questionnaire. Sound localization performance was essentially at chance level in all four conditions. Mixed results were seen on the other patient outcome measures that alternated in favor of one of the three CROS devices. After the trial, three patients chose to be fitted with the BAHA CROS and one with the conventional CROS. In conclusion, most of the patients experienced some degree of benefit with each of the three hearing aids. Preference for one of the three hearing aids was independent of the order in which they were tried. It would be worthwhile to formulate selection criteria; still, we recommend that all patients with unilateral inner ear deafness should be offered a trial with at least the BAHA CROS.

Fig. 1

a, b S/N for a speech intelligibility of 50% with everyday Dutch sentences: with noise presented in front and speech on either the poor ear (PE) or the best ear (BE). ‘Lateral speech’ in four conditions: unaided (n = 9), conventional CROS (CROS, n = 8), completely in the canal (CIC, n = 7) and BAHA CROS (BAHA, n = 9)

Fig. 2

Mean scores of the 10 patients on the APHAB in the domains ease of communication (EC), background noise (BN), reverberation (RV) and aversiveness of sound (AV) of the APHAB in four different conditions: unaided (n = 10), conventional CROS (CROS, n = 8), completely in the canal (CIC, n = 8) and BAHA CROS (BAHA, n = 9)

Fig. 3

a Single-sided deafness (SSD) questionnaire results, with the CROS (n = 8), CIC (n = 7) and the BAHA (n = 9). Subjective benefit with each hearing aid was scored in five domains (wearing comfort, easy to use, rustle, whistle and failure) on a scale from 0 to 10. b Number of patients who indicated benefit with one of the hearing aids is indicated on the y axis. The percentage is indicated in the figure itself