Middle ear muscle reflex measurement in neonates: comparison between 1000Hz and 226Hz probe tones

Abstract

Introduction: Middle ear muscle reflex (MEMR) evaluation assists in diagnosing hearing problems because normal responses depend on preconditions of a healthy auditory system. Studies in neonates recording the acoustic reflex with 226Hz probes have described high rates of absence. Other studies using a high frequency probe have found higher rates of presence in normal neonates. However, few studies have compared results between low and high frequency probes in the same newborns.

Objective: To comparatively assess the ipsilateral acoustic reflex recorded by 226Hz and 1000Hz probes in newborns.

Method: A total of 77 newborns, with the presence of transient otoacoustic emissions, underwent tympanometry, wideband acoustic immittance, and ipsilateral reflex investigations with 226Hz and 1000Hz tone probes.

Results: The acoustic reflex was activated at a much lower intensity with all activating stimuli using the 1000Hz probe compared with the values of the 226Hz probe. There was a higher incidence of ipsilateral acoustic reflexes recorded by the 1000Hz tone probe compared to the 226Hz tone probe. There was no correlation between the acoustic reflex thresholds and otoacoustic emissions.

Conclusion: In newborns, the acoustic reflex measurements obtained with the 1000Hz probe showed advantages over the 226Hz probe.

Keywords: Acoustic; Acoustic impedance tests; Hearing; Infant; Newborn; Reflex.