Automated Auditory Brainstem Response in Neonates with Exchange Transfusion Indirect Hyperbilirubinemia Levels

Abstract

Background: Neonatal hyperbilirubinemia maybe complicated by severe neurologic disability including hearing impairment (HI). There is no agreement on the precise bilirubin level that may cause auditory affection. Aim of the work: to study the frequency of HI in neonates with indirect hyperbilirubinemia threshold for exchange transfusion (ET). Patients and Methods: This cross-sectional analytical study enrolled full-term neonates whose bilirubin levels were at the ET threshold managed by intensive phototherapy (IP) or ET. Automated auditory brainstem response (AABR) was performed within 24 hours of admission using audiometer among both groups. Results: This study included 98 full-term neonates. Forty-eight (49 %) were males and 50 (51%) were females. Their mean gestational age was 37.78±0.74 weeks. Forty-six (46.9%) neonates underwent ET while 52 (53%) improved on IP with the rapid decline of their bilirubin levels and did not undergo ET. The mean IP group bilirubin-induced neurologic dysfunction (BIND) score was 0, and reticulocyte count was 7.12±6.49% compared to 1.89±2.16 and 11.47±9.82% of ET group (p=0.001) and (p=0.004) respectively. Abnormal AABR was detected in 23 (23.5%) neonates; 8 had unilateral hearing impairment while 15 had bilateral hearing impairment. IP was associated with less HI in both ears in 3 (5.7%) compared to 12 (26.1%) who underwent ET (p=0.005).Neonates with any HI had higher total serum bilirubin (TSB) levels (p= 0.002) and BIND scores (p= 0.002). IP was associated with less (one or both ears) HI in 8 (15.3%) neonates compared to 15 (32.6%) who underwent ET (p=0.045). A TSB cut-off value of 24.5 mg/dl showed a sensitivity of 60.9% and a specificity of 81.3% while a BIND score cut-off value of ≥ 2 showed a sensitivity of 47.8% and a specificity of 86.7% for detecting any hearing impairment. Males had a higher risk for bilateral hearing impairment (p= 0.040). Conclusion: Neonates with higher bilirubin levels and BIND scores are at risk for HI. TSB and BIND score have modest sensitivity and specificity in predicting HI. IP is mandatory in all those with ET threshold bilirubin until procurement of blood to prevent HI. HI may occur despite normal BIND scores in the absence of bilirubin encephalopathy. Those who responded to IP for ET level of TSB had less frequency of HI. Males were more at risk for bilateral HI. Screening for HI among neonates who sustain hyperbilirubinemia is a necessity.

Keywords

• automated auditory brainstem response
• aabr
• bilirubin-induced neurologic dysfunction
• bind score
• exchange transfusion
• neonatal hyperbilirubinemia
• intensive phototherapy