Effect of sleep stages on synchronized spontaneous otoacoustic emissions in pre-term neonates.

OBJECTIVES

In infants, auditory tests are mainly performed during sleep, since they spend most of their time asleep, and because quiet is required for the duration of the recording session to obtain a precise and reliable response. The aim of this study was to investigate the effect of sleep stages on synchronized spontaneous otoacoustic emissions (sSOAEs) in pre-term neonates at the age where the sleep states begin to be well established and auditory screening can be performed in a neonatology unit before discharge.

METHODS

Synchronized SOAEs were repeatedly recorded during a polygraphic sleep recording using the Otodynamic ILO88 system in 10 pre-term neonates at 36 weeks post-conception.

RESULTS

Variations of sSOAE peak numbers occurred in each subject during the recording session. There was no clear relation between sSOAE peak number fluctuations and the different sleep stages.

CONCLUSIONS

The sSOAE variations appeared to be closely related to experimental conditions, i.e. the mean background noise level. sSOAEs with the highest amplitude were always recorded; however, those with the smallest amplitude were the first to disappear from the recordings with higher background noise.