Abstract:OBJECTIVE: There is controversy as to whether there are differences in brainstem development between preterm and term infants. This study examined the brainstem function of preterm infants at term and the effect of increasing stimulus rate in the detection of brainstem function through the recording of and analyzing of brainstem auditory evoked potential (BAEP) at different rates of click stimuli. METHODS: The study group included 30 preterm babies without any perinatal complication. The controls were 38 healthy term babies. The BAEP was recorded at stimulus rates of 21.1, 51.1 and 91.1/sec in these babies at 37- 42 weeks of postconceptional age. The latencies and amplitudes of WavesⅠ,Ⅲ and Ⅴ, the interpeak intervals of Ⅰ-Ⅲ,Ⅲ-Ⅴ andⅠ-Ⅴ and Ⅲ-Ⅴ/Ⅰ-Ⅲ interval ratio were analyzed. RESULTS: At a click intensity of 60 dBnHL, latencies and interpeak intervals in both groups increased but amplitudes decreased as the stimulus rate was increased. The latencies and interpeak intervals had a positive correlation with stimulus rate. In contrast, the amplitude was negatively correlated with stimulus rate. In preterm babies, Ⅰ-Ⅴ interval did not differ significantly from the controls at all three rates used. As stimulus rate increased, Ⅰ-Ⅲ interval decreased whereas Ⅲ-Ⅴ interval and Ⅲ-Ⅴ/Ⅰ-Ⅲ interval ratio increased in preterm infants. There was no obvious amplitude difference at various stimulus rates between the two groups. CONCLUSIONS: Preterm infants have an advanced development of peripheral brainstem auditory pathway but a relatively delayed central development. Increasing stimulus rate can detect more neurophysiological changes and enhance the diagnostic value of BAEP.
