Multiple-ASSR thresholds in infants and young children with hearing loss.

BACKGROUND

The multiple auditory steady-state response (multiple ASSR) is a promising technique for determining thresholds for infants and children. However, there are few data for infants and young children with hearing loss where multiple-ASSR thresholds have been compared to frequency-specific gold standard (i.e., behavioral or tone-evoked auditory brainstem response [tone ABR]) measures.

PURPOSE

The study compared multiple-ASSR and tone-ABR thresholds and assessed how well "normal" ASSR levels differentiate normal from elevated thresholds.

RESEARCH DESIGN

Multiple-ASSR and tone-ABR results (to air-conduction stimuli) were obtained in infants and young children with hearing loss or normal hearing.

STUDY SAMPLE

98 infants with hearing loss (53 infants provided thresholds) and 34 infants with normal hearing.

DATA COLLECTION AND ANALYSIS

Multiple-ASSR and tone-ABR results were typically completed on the same day. Correlations between ASSR and ABR thresholds, linear regressions, and ASSR-minus-ABR threshold difference scores were calculated for each group (normal or hearing loss), and for both groups combined.

RESULTS

Multiple-ASSR thresholds (dB HL) were strongly correlated (r = .97) with tone-ABR thresholds (dB nHL) for 500, 1000, 2000, and 4000 Hz. Mean (±1 SD) difference scores (ASSR-minus-ABR) were 10.7 ± 9.0, 9.5 ± 9.4, 9.2 ± 9.0, and 6.3 ± 9.5 dB for 500, 1000, 2000, and 4000 Hz, respectively. The previously published "normal" ASSR levels accurately differentiated normal from elevated thresholds. Out of 523 tests with elevated tone-ABR thresholds, the multiple ASSR was "normal" in only 22 tests. In these 13 infants, other ASSR frequencies were elevated, and thus the infants would not have "passed" the ASSR.

CONCLUSIONS

There are few studies of infants and young children comparing ASSR thresholds to frequency-specific gold standard measures, especially using the multiple-ASSR technique. The present study, comparing multiple-ASSR to tone-ABR thresholds, nearly doubles the multiple-ASSR sample size in the literature. The results indicate that the multiple-ASSR and tone-ABR thresholds are strongly correlated, and the "normal" multiple-ASSR levels of 50, 45, 40, and 40 dB HL correctly classified children as having "normal" or "elevated" thresholds. However, due to the lack of air- and bone-conduction data in infants with different types and degrees of hearing loss, further ASSR research is needed.