OBJECTIVETo explore the characteristics of distortion product otoacoustic emission (DPOAE), auditory brainstem response (ABR) and mismatch negativity (MMN) in guinea pigs with hyperbilirubinemia and assess the impact of hyperbilirubinemia on their hearing functions.

METHODNormal neonatal guinea pigs were randomly divided into normal control, low- and high-dose bilirubin groups. DPOAE, ABR and MMN were tested and compared between the 3 groups of guinea pigs.

RESULTSThe DPOAE was comparable between the 3 groups (P>0.05). The guinea pigs with peritoneal injection of low-dose bilirubin exhibited significantly prolonged wave III and V latencies and I-III interwave intervals during the ABR test in comparison with the control group (P<0.05). All the ABR parameters were significantly different between the high-dose bilirubin group and the control group (P<0.05). The detection rates of MMN were significantly different between the 3 groups (Chi(2)=7.438, P=0.024), and the average MMN latency was significantly shorter in the control group than in the high-dose group (P<0.05), but the amplitudes of MMN remained similar between the 3 groups (P>0.05).

CONCLUSIONSHyperbilirubinemia results impairment primarily of retrocochlear auditory pathway with relative mild damage of the cochlear. Apart from sensorineural auditory impairment, hyperbilirubinemia may also cause central auditory processing abnormalities.