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Frequency shift of individual spontaneous otoacoustic emissions in preterm infants
P Brienesse1, L J Anteunis, W J Maertzdorf
1Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital Maastricht, The Netherlands.
Insights
Spontaneous otoacoustic emissions (SOAE) in preterm infants show increasing frequency with postconceptional age, suggesting cochlear maturation. This frequency shift stabilizes around 45-50 weeks PCA.
Area of Science:
- Otoacoustic Emissions
- Developmental Audiology
- Neonatal Physiology
Background:
- Spontaneous otoacoustic emissions (SOAE) are stable in adults.
- SOAE in preterm infants exhibit an upward frequency shift with increasing postconceptional age (PCA).
Purpose of the Study:
- To investigate the frequency dynamics of SOAE in preterm infants.
- To correlate SOAE frequency shifts with postconceptional age and assess cochlear maturation.
Main Methods:
- Monitoring 66 SOAE frequencies in 25 ears of 14 preterm infants (PCA 29.1-41.3 wk).
- Analyzing SOAE frequency changes over time in Hertz per week.
- Calculating the proportional shift rate relative to the baseline SOAE frequency.
Main Results:
- All but one SOAE frequency showed an upward shift.
- The mean SOAE frequency shift rate was 0.74 ± 0.39%/wk.
- The rate of frequency shift decreased with increasing PCA, predicting stabilization around 45-50 wk PCA.
Conclusions:
- The observed SOAE frequency shift is dependent on frequency and time.
- These findings strongly suggest ongoing cochlear maturation in preterm infants.
- SOAE can serve as a non-invasive indicator of auditory system development in neonates.
Abstract:
In adults, spontaneous otoacoustic emissions (SOAE) have shown a considerable frequency stability. In preterm infants, however, the SOAE proved to show an apparent and consistent upward shift of frequency at increasing postconceptional age (PCA). In 25 ears of 14 preterm infants (PCA, 29.1-41.3 wk) a total of 66 SOAE frequencies were monitored, ranging from 1611 to 5774 Hz. All but one of the SOAE frequencies shifted toward higher frequency. The SOAE frequency shift rate in Hertz per week was proportionally constant relative to the SOAE frequency. The mean shift rate was 0.74 +/- 0.39%/wk. At increasing PCA, the SOAE frequency shift rate tended to slow down. A linear fit through the data predicted the SOAE frequency to stop at about 45-50-wk PCA. The frequency dependence and time course of the SOAE frequency shift strongly suggest cochlear maturation during the last period of gestation.