Test-retest reliability of the acoustic stapedial reflex test in healthy neonates

The acoustic stapedial reflex (ASR) test has been shown to provide useful information about the function of the auditory system. However, the reliability of this test when applied to healthy neonates has not been systematically studied. This study aimed to evaluate the test-retest reliability of the ASR test in newborn babies shortly after birth.

Using a cross-sectional design, 219 healthy neonates, aged between 24 and 192 hr, who passed an automated auditory brain stem response screening test, were recruited and assessed using transient-evoked otoacoustic emissions (TEOAEs), high-frequency (1000 Hz) tympanometry, and ASR tests. One randomly selected ear from each neonate was tested. ASRs were elicited by presenting a 2 kHz pure tone and broadband noise (BBN) separately to the test ear in an ipsilateral stimulation mode using a Madsen Otoflex diagnostic immittance meter. A total of 194 (86/108 males/females; 115/79 left/right) ears, which met a set of inclusion criteria, were included in the test-retest reliability analysis for the 2-kHz tone stimulus. In addition, 123 (62/61 males/females; 77/46 left/right) ears were included in the test-retest reliability analysis for the BBN stimulus. The ASR threshold (ASRT) for each stimulus was measured. The ASR procedure was then repeated to acquire retest data.

Ipsilateral ASRs were elicited in 91.3% (200/219) of neonates, whereas the remaining 8.7% (19/219) exhibited flat tympanograms (no identifiable peak) and absent reflexes with a "refer" outcome in the TEOAE test. The mean ASRT (76.2 dB HL averaged over 194 ears) for the 2 kHz pure tone was higher than that for the BBN (64.9 dB HL averaged over 123 ears). The findings, based on the results of an analysis of variance with repeated measure, showed that the ASRTs for the retest condition did not differ significantly from those of the first test for both stimuli (p > 0.05). The ASR test also showed high test-retest reliability as demonstrated by intracorrelation coefficients across the test-retest conditions of 0.83 for the 2 kHz pure tone and 0.76 for the BBN stimulus.

This study demonstrated that ASRs could be consistently elicited from healthy neonates who showed a single-peaked configuration in the high-frequency tympanometry test and passed the automated auditory brain stem response and TEOAE tests. The findings showed that the ASRTs did not vary significantly across the test-retest conditions, and the high intracorrelation coefficients illustrate the reliability of the ASR test. Given the high test-retest reliability, the ASR test holds promise as a useful diagnostic/screening instrument in ascertaining the hearing status in neonates.