Pure tone hearing thresholds and speech recognition scores in Dutch patients carrying mutations in the USH2A gene.

OBJECTIVE: To establish the audiometric profile and speech recognition characteristics in 36 Usher IIa patients, carrying one (A) or two (B) pathogenic mutations in the gene.

STUDY DESIGN: Family study.

SETTING: Tertiary referral center.

PATIENTS: Thirty six Usher IIa patients from 21 Dutch families.

METHODS: Ophthalmologic, vestibular, and audiometric examinations were performed on all patients. Cross-sectional analysis was performed on pure tone threshold data at 0.25 to 8 kHz and on speech phoneme recognition scores. Progression was evaluated using linear regression analysis on raw and presbyacusis corrected data.

RESULTS: A downsloping audiogram was found, with a mean threshold slope of -9 dB per octave, that was mildly progressive, i.e., by approximately 0.5 dB per year. Individual monaural maximum phoneme recognition scores (% correct) were analyzed in 30 patients in relation to the patient's age and level of hearing impairment characterized by a pure tone average (PTA(1-4 kHz)). The speech recognition score started to deteriorate from a score of 90% at 38 years at a rate of 0.4% per year. The 90% level was attained at 69 dB hearing level (PTA(1-4 kHz)); at higher levels of impairment, the score deteriorated at a slope of 0.6% per dB hearing level. There was no significant difference between group A and B in pure tone threshold, with or without presbyacusis correction, or phoneme recognition score as related to age or PTA(1-4 kHz).

CONCLUSIONS: Patients with various mutations in have moderate to severe hearing impairment showing mild progression at approximately 0.5 dB hearing level per year.