Bone-anchored hearing aid in unilateral inner ear deafness: a study of 20 patients.
OBJECTIVE
To evaluate the benefit of a bone-anchored hearing aid (BAHA) contralateral routing of sound (CROS) in 20 patients with unilateral inner ear deafness.


METHODS
21 patients were recruited; 15 had undergone acoustic neuroma surgery and 6 patients had unilateral profound hearing loss due to other causes; 1 patient was excluded. Only patients with thresholds of better than 25 dB HL (500-2000 Hz) and an air-bone gap of less than 10 dB in the best ear were included.


METHODS
Evaluation involved audiometric measurements before intervention, when fitted with a conventional CROS and after implementation and quantification of the patients' subjective benefit with a hearing aid-specific instrument: the Abbreviated Profile of Hearing Aid Benefit (APHAB).


RESULTS
Lateralization scores were not significantly different from chance (50%) in any of the three conditions. Measurements of speech perception in noise showed an increase in the signal to noise ratio (S/N ratio) with the conventional CROS (p = 0.001) and with the BAHA CROS compared to the unaided condition when speech was presented at the front with noise on the poor hearing side. On the other hand, a lower S/N ratio was seen with the BAHA CROS (p = 0.003) compared to the unaided situation when noise was presented at the front with speech on the poor hearing side. The patient outcome measure (APHAB) showed improvement, particularly with the BAHA CROS.


CONCLUSIONS
The poor sound localization results illustrate the inability of patients with unilateral inner ear deafness to localize sounds. The speech-in-noise measurements reflect the benefit of a BAHA CROS in lifting the head shadow while avoiding some of the disadvantages of a conventional CROS. The benefit of the BAHA CROS was most clearly reflected in the patients' opinion measured with the APHAB.
Hol
Myrthe K S
MK
Department of Otorhinolaryngology, University Medical Centre St. Radboud, Nijmegen, The Netherlands. m.hol@kno.umcn.nl
Bosman
Arjan J
AJ
Snik
Ad F M
AF
Mylanus
Emmanuel A M
EA
Cremers
Cor W R J
CW
D000328:Adult; D000368:Aged; D001844:Bone Conduction / Q000502:physiology*; D005260:Female; D006310:Hearing Aids; D034381:Hearing Loss / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D017755:Prosthesis Fitting; D013017:Sound Localization; D013067:Speech Perception; D016896:Treatment Outcome