Is auditory brainstem response a bilirubin neurotoxicity marker?
OBJECTIVE
To find a correlation between increasing levels of serum bilirubin and auditory brainstem responses (ABR) and to find the use of ABR as a bilirubin neurotoxicity marker.


METHODS
A prospective study of 60 neonates in which ABR of hyperbilirubinemic neonates was compared with the normal neonates. All cases with abnormal ABR were studied for 6 months and after 1 month and 6 months a repeat ABR was performed.


RESULTS
Brainstem conduction time was found to be prolonged from 5.12+/-0.26 to 5.83+/-0.14 in neonates with a mean serum bilirubin level of 16.6 mg/dL (12 mg/dL to 18 mg/dL), which was found to be additionally prolonged to 6.0+/-1.0 with an increase in mean serum bilirubin level to 21.98 mg/dL (P < .01). At first retest after 1 month, 33.33% of cases with a mean serum bilirubin level of 19.46 mg/dL and 80.00% with a mean serum bilirubin level of 15.97 mg/dL showed total recovery. After 6 months, three cases with mean serum bilirubin levels of 26.3 mg/dL and one case with a mean serum bilirubin level of 17.7 mg/dL failed to show any improvement.


CONCLUSIONS
A positive correlation was found between increasing levels of serum bilirubin and brainstem conduction time (P < .01). ABR was found to be a very sensitive tool in picking up the earliest signs of neurotoxicity. Neonates with distortion of normal wave patterns on ABR were found to have poorer prognosis compared with those with delayed inter-peak (I-P) latencies.
Department of Otolaryngology and Head-Neck Surgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
A K
AK
Gupta
S B
SB
Mann
D000158:Acoustic Impedance Tests; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D006801:Humans; D006932:Hyperbilirubinemia / Q000503:physiopathology*; D007231:Infant, Newborn; D008297:Male; D011446:Prospective Studies