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Indian Pediatr 2014;51: 134-135 |
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Reversibility of Brainstem Evoked Response
Audiometry Abnormalities at 3 Months in Term Newborns with
Hyperbilirubinemia
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M Vinodh, P Ambikapathy, MA Aravind and J Ganesh
From Department of Paediatrics, Government Stanley
Medical College, Chennai, TN, India.
Correspondence to: Dr M Vinodh, Department of
Paediatrics, Govt Stanley Medical College,
Chennai 600 001, TN, India.
Email: [email protected]
Received: September 13, 2012;
Initial review: October 16, 2012;
Accepted: September 05, 2013.
Published online: September 05, 2013.
PII: S097475591200803
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Background: High bilirubin level is toxic to developing brain
and auditory system but the current debate surrounds the toxicity of
bilirubin in healthy term infants. Methods: Longitudinal
observational study to find BERA abnormalities in term newborns with
isolated hyperbilirubinemia of 20 mg/dL and more and to follow up
babies at 3 months to find out about the reversibility in BERA
abnormalities noted at birth. Results: BERA abnormalities
were present in 17.64% of babies with isolated hyperbilirubinemia at
discharge. There was a reversibility of BERA abnormalities in 61.61%
during follow up. Conclusion: BERA abnormalities are
reversible in term neonates with hyperbilirubinemia.
Keywords: BERA, Follow-up, Hearing,
Outcome, Term neonates.
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Neonatal hyperbilirubinemia is
a common clinical problem. Some two-thirds of healthy term infants and
almost all premature infants develop clinical jaundice in the first week
of life. In the current era of early postnatal discharge, jaundice is
currently a common reason for readmission to the hospital in the first
week of life in Western countries [1].
High bilirubin level is toxic to developing brain and
auditory system [2], but the
current major debate surrounds the toxicity of bilirubin in otherwise
healthy term infants. The auditory abnormalities of bilirubin toxicity
is found in many cases to be reversible as age advances. The percentage
of infants with isolated hyperbilirubinemia associated with BERA
abnormalities and its reversibility is still under study.
The aim of the study was to find BERA abnormalities
in term newborns with isolated hyperbilirubinemia
≥20 mg/dL, and to
follow up the babies at 3 months to find the reversibility in BERA
abnormalities noted at birth.
Methods
This observational study was conducted in the
Neonatal intensive care unit (NICU) of Government RSRM hospital and
Stanley Medical College, Chennai. Ethical committee approval was
obtained. Consecutive sampling method
was followed. 5793 infants were screened during routine
postnatal ward rounds for a period of 7 months and 206 cases were found
to have yellowish discoloration extending beyond the thigh level. Blood
investigation for serum bilirubin was done and cases with serum
bilirubin ≥20
mg/dL were selected. The inclusion criteria were term newborn
with birth weight greater than 2500 grams and hyperbilirubinemia
≥20 mg/dL. The
exclusion criteria were LBW babies, suspected sepsis/sepsis,
prematurity, term IUGR, birth asphyxia (APGAR scores of 0-4 at 1 minute
or 0-6 at 5 minutes), overt endocrinological /metabolic
problem/neurologic causes, critically ill infant of any cause, direct
bilirubin greater than 15% of total serum bilirubin, history of ototoxic
drug intake, any congenital malformations, history suggestive of
intrauterine infections, and family history of deafness.
Babies underwent BERA (Brainstem Evoked Response
Audiometry) after discharge and abnormalities in BERA, if present, were
noted. Interpeak latencies between I-III and I-V were recorded as they
were more specific for hyperbilirubinemia associated hearing damage [3].
If abnormality was detected, babies were referred to an audiologist.
BERA was repeated in the above population around 3 months. All cases
with abnormality were followed up. Statistical analysis was done using
SPSS 16 for windows.
Results
Overall, 5793 babies were screened for inclusion in
the study, of which 206 had clinically significant icterus. Out of
these, 155 cases did not meet the inclusion/exclusion criteria. The
final study comprised of 51 babies. The mean total serum bilirubin value
was 23.02 mg/dL (range, 20-28 mg/dL).
BERA abnormalities (inclusive of I-III and I-V
abnormality) done at the time of discharge were noted in 18 (17.6%)
ears. The mean age of BERA examination after discharging the babies was
10.18 days (range, 6-18 days).
On follow up of affected cases, BERA abnormality were
noted only in 7 (38.8%) of the 18 ears that had BERA abnormality at
discharge. The mean age of repeat BERA was 77.55 days (range, 68-93
days). On comparing BERA abnormalities with parity, sex of the baby,
weight of the baby, mode of delivery, and level of bilirubin, no
significant association was found. Only two factors had significance
with BERA abnormalities, namely level of bilirubin and type of
treatment. On performing a binary logistic regression, only bilirubin
value was found to be significantly related.
Discussion
Analysis of the study results show that BERA
abnormalities were reverssible in 61.6% of the 18 ears that had
abnormalities at discharge. A similar observation was made by few
previous studies, which reported BERA abnormalities around 22% to 28 %
[4- 6]. Studies about the
reversibility of BERA abnormalities show a wide percentage variation
ranging from 64.2% to72.7%. [7-9].
The study brings three questions for further
evaluation in follow up of hyperbilirubinemia cases. One being what
would be the ideal age for screening of these infants, as early
screening results in abnormal BERA in larger number of infants which may
later reverse on follow up. Second, till what age can reversibility of
BERA occur and third, what is the exact percentage of infants who would
have persisting hearing impairment with isolated hyperbilirubinemia at
birth. Follow up studies with larger number of infants with longer
period of follow up may shed more light on these aspects.
Limitations of the study were that follow up was done
only for 3 months, and BERA was not done at discharge and at peak
levels.
Contributors: All the authors have contributed,
written, designed and approved the study.
Funding: None; Competing interests: None
stated.
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What This Study Adds?
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Abnormality of BERA, seen in
term neonates with hyperbilirubinemia, is reversible in
majority.
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