Abstract:

Objective    To investigate normal parameters of the latency and the thresholds of auditory brainstem response (ABR) in infants of 3-6 months old for early treatment. Methods     40 normal infants and 20 normal adults underwent ABR tests. The infants were divided into 2 groups: group A(3-4months) and group B(5-6 months). Each group consisted of 20 infants (40 ears). The ABR data were analyzed to determine normal ranges for ABR. The influences of gender, age and ears on different sides on testing results were analyzed. Results     At 80dB nHL, the range of latency for wave Ⅰ, Ⅲ, Ⅴ of ABR in 3-4 months old infants was (1.52±0.19) ms, (4.20±0.20) ms, (6.34 ±0.26) ms, respectively; In 5-6 months old infants, the corresponding results were (1.50 ±0.09) ms, (4.05 ±0.16) ms, and (6.16±0.25) ms; In normal adults, counterparts were (1.43±0.10) ms, (3.63±0.15) ms, and (5.50±0.16) ms. The Peak latency (PL) and interval peak latency ( IPL) of infants became shorter with the increase of the age, but failed to reach adult levels even in 56 months old infants. There were significant differences for PL and IPL between group A and control group, and between group B and control group. The PL of wave Ⅲ, Ⅴ and IPL of Ⅰ-Ⅲ,Ⅰ-Ⅴ between group A and group B were significantly different.  PL and IPL of female infants were shorter than the males, except for the IPL of Ⅰ-Ⅲ in group A. There were significant differences in the PL of wave Ⅴ between male and female infants in group A. The data showed that there were significant differences in the PL of Ⅲ, Ⅴ and the IPL of Ⅰ-Ⅴ between male and female infants in group B (P<0.05), but not between the sides of ears (P>0.05). The thresholds of ABR among all infants and adults demonstrated no significant difference. Conclusion     It is necessary to set up normal criteria of ABR for infants so as to diagnose early and follow-up effectively, which makes early interventions possible.

Key words:  Auditory brainstem response;  Infant;  Normal range;  Early diagnosis