Measurement of Thresholds Using Auditory Steady-State Response and Cochlear Microphonics in Children with Auditory Neuropathy.

BACKGROUND: The detection of precise hearing thresholds in infants and children with auditory neuropathy (AN) is challenging with current objective methods, especially in those younger than six months of age.

PURPOSE: The aim of this study was to compare the thresholds using auditory steady-state response (ASSR) and cochlear microphonics (CM) in children with AN and children with normal hearing.

RESEARCH DESIGN: The thresholds of CM, ASSR, and visual reinforcement audiometry (VRA) tests were recorded; the ASSR and VRA frequencies used were 250, 500, 1000, 2000, and 4000 Hz.

STUDY SAMPLE: The participants in this study were 15 children with AN (27 ears) (1-7.6 years, median age 4.1 years) and ten children with normal hearing (20 ears) (1-8 years, median age four years).

DATA COLLECTION AND ANALYSIS: The thresholds of the three methods were compared, and histograms were used to represent frequency distributions of threshold differences obtained from the three methods.

RESULTS: In children with normal hearing, the average CM thresholds (84.5 dB) were significantly higher than the VRA thresholds (10.0-10.8 dB); in children with AN, both CM and VRA responses were seen at high signal levels (88.9 dB and 70.6-103.4 dB, respectively). In normal children, the difference between mean VRA and ASSR thresholds ranged from 17.5 to 30.3 dB, which was significantly smaller than the difference seen between the mean CM and VRA thresholds (71.5-72.3 dB). The correlation between VRA and ASSR in children with normal hearing ranged from 0.38 to 0.48, whereas no such correlation was seen in children with AN at any frequency (0.03-0.19).

CONCLUSIONS: Our results indicated that ASSR and CM were poor predictors of the conventional behavioral threshold in children with AN.