Sound Localization after Canaloplasty

Abstract

Objective: Unilateral congenital aural atresia (CAA) is much more common than bilateral atresia, and subsequent unilateral hearing loss usually leads to poor sound localization. The objective of this study was to investigate the change in sound localization after canaloplasty for correction of the unilateral hearing loss.

Method: Twenty patients with unilateral CAA, who underwent canaloplasty, were enrolled. Pure tone audiometry, sound localization test, and Speech, Spatial, and Quality (SSQ) questionnaire were administered preoperatively and 6 months postoperatively. For sound localization test, 8 loudspeakers were positioned around the patient, and patients were instructed to identify the sound source.

Results: Mean air-bone gap decreased from preoperatively 54.6 dB to 25.3 dB 6 months after canaloplasty. In sound localization test, mean correct response rate and error degree at preoperative evaluation were 27.40% and 60.7°, respectively, and these were improved to 57.5% and 26.2° postoperatively. Mean correct response rate to ipsilesional stimuli following canaloplasty (left/right discrimination) improved from 29.5% to 88.2%, and that to contralesional stimuli improved from 90.0% to 98.7%. In addition, scores in the spatial domain of the SSQ questionnaire improved significantly from 6.6 to 7.5 after canaloplasty (P = .014).

Conclusion: Sound localization performance including right-left discrimination ability improved significantly 6 months following canaloplasty. Canaloplasty could restore a binaural hearing ability and may be a good treatment option to improve sound localization ability in unilateral CAA patients.