BERA in Neonates With Hyperbili

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Original Article

Brainstem Evoked Response Audiometry (BAER) inNeonates With Hyperbilirubinemia

Pramod Sharma1, N.P. Chhangani2, Kesh Ram Meena3, Rakesh Jora1, Navratan Sharma3 andB.D. Gupta4

1Assistant Professors,2Associate Professor, 3Senior Resident, 4Prof and Head, Department of Pediatrics, Umaid

Hospital for Women and Children Dr. S.N. Medical College, Jodhpur, Rajasthan, India.

ABSTRACT. Objectives :To evaluate Brainstem Evoked Response Audiometry (BAER) as an objective testing of hearingassessment in icteric babies and correlate the abnormalities with serum bilirubin levels. Methods :BAER recordings were takenin 30 icteric ferm neonates at birth, at peak of serum bilirubin levels and on a follw-up visit at 2-4 months of age. Results :Mean

latency of waves and interwave intervals on the BAER records were prolonged in icteric babies compared to the control group

suggesting early bilirubin encephalopathy. Abnormal records were obtained in 73.3% cases and the abnormality persisted inthe follow-up tracings of 23.3% of the study group. Conclusion :BAER is a sample, reliable and effective technique for

determining auditory functions in the neonates especially changes of early bilirubin toxicity.[Indian J Pediatr 2006; 73 (5) : 413-416] E-mail: drpramodsh@ hotmail. com

Key words :Brain stem evoked response; Audiometry (BAER), Neonatal Hyperbilirubinemia; Auditory functions

Neonatal Hyperbilirubinemia is an adverse perinatal MATERIAL AND METHODSclinical event that places the affected neonate at anincreased risk of hearing impairment. 1 Jaundice is a The study was conducted in the Department of Pediatriccommon finding in neonates affecting 70% of term and Medicine, Umaid Hospital Jodhpur where 30 term icteric80% of preterm neonates during the 1st week of life. An neonates with serum bilirubin >12mg% were enrolled asessential aim is the early identification of infants with the study group & 30 nonicteric babies were recruited asdeep jaundice or impaired hearing so that rehabilitation control.can be initiated when the brain is sensitive to the Neonates with complicated pregnancy, adverse

development of speech and language. neonatal events likesevere birth asphyxia,pyogenicA number of methods have been evaluated to search meningitis,severe septicemia,congenital craniofacial

for a reliable and effective technique for determining malformations or babies on mechanical ventilator wereauditory functions in the neonates. Brainstem Evoked excluded. BERA studies were performed between 2nd toResponse Audiometry (BAER) has expanded the 6th days of life. Neonates with hyperbilirubinemia werepossibility of objective testing of hearing functions. This is managed as per recommendations of Behrman et al.3

an effective and simple method that requires less co BERA was recorded as per the method described byoperation of the patient and measures the specific part of Taylor4 after taking an informed consent. Recordings werethe auditory pathway. It is not significantly altered by the taken at the time of peak hyperbilirubinemia, afterstate of consciousness, drugs and environmental factors therapy and again at the age of 24 months using thelike the sensory input to the cortex.2 Besides timely Nicolas Compass Meridian Instrument from Biomedicalrecourse to effective phototherapy and exchange USA using cup shaped silver coated electrodes of 10mmtransfusion can reverse changes in BAER. The study was diameter. Facility of automatic artifact rejection was used.

thus undertaken to study the initial BAER recordings in Sweep velocity was 10 mm/sec.and click acoustic stimuliicteric term neonates and note its correlation with serum at a rate of10/sec were presented to each ear at anbili rubin levels as also it s reversibil ity fo llowing intensity of 90dB hearing level. Subsequently stimuli attherapeutic interventions. decreasing frequencies i.e. 75,60,45 and 30 dB were

presented to each ear and recordings taken. Maskingsound of 40dB was used for the nonstimulated ear.Electrical activity was filtered and averaged to 2000responses. Latency, interpeak latencyand amplitudes ofwaves were measured placing cursors on the screen

Correspondence and Reprint requests : Dr. Pramod Sharma, 115,Roop Nagar, Paota C Road, Jodhpur, Rajasthan, India.

tracings. 5 Thereafter right and left ears were tested

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Table 1. Latency of Wave I (Msec) at Various Intensities (dB)

Intensity Study groupN=30

Mean + SDBefore Treatment After Treatment

(A) [B]

Control groupN= 30

Mean + SD(c)

A Vs B B Vs Cp values

A Vs C

3045

75

90

2.96 0.762.93 0.89

2.56 0.77

2.65 0.81

2.08 0.731.98 0.36

1.99 1.06

1.75 0.44

1.87 0.171.84 0.12

1.80 0.18

1.65 0.35

< 0.001 0.2> 0.1

> 0.4

> 0.5

< 0.05< 0.001

< 0.001

< 0.01

TABLE 2. Interwave Interval I-III (Msec) at Various Intensities (dB)

Intensity Study group Control group Values(dB) N=30 N=30

Mean + SD Mean + SDBefore Treatment After Treatment (C) A Vs B B Vs C A Vs C

(A) (B)

30 3.16 1.49 2.04 0.45 2.17 0.57 < 0.001 > 0.4 0.1 < 0.001

75 3.34 1.66 1.99 0.13 2.18 0.53 < 0.001 > 0.1 < 0.00190 2.52 0.70 2.01 0.38 2.15 0.42 < 0.01 > 0.2 < 0.02

TABLE 3. Changes in BAER in Study Group Before and after Exchange Transfusion at 90 dB

Latency Study group Control ValueMean + SD Mean + SD

Before Treatment After Treatment (n=30) A Vs B a Vs A a Vs B(n=14) (n=14) (a)

(A) (B)

I 2.67 + 0.88 2.03 + 0.77 1.65 + 0.35 < 0.05 0.1

II 3.32 + 0.45 2.74 + 0.54 2.72 + 0.32 < 0.01 0.5

III 4.59 + 0.75 4.25 + 0.75 4.28 + 0.16 < 0.05 < 0.02 > 0.1

IV 5.70 + 0.72 4.75 + 0.80 4.79 + 0.28 < 0.01 < 0.01 > 0.9

V 8.25 + 1.64 6.35 + 1.37 6.25 + 0.39 < 0.01 < 0.01 > 0.9IP IntervalsI III 3.08+ 0.57 2.08 + 0.42 2.15 + 0.42 < 0.001 0.4

I V 5.06 + 0.56 4.10 + 0.72 3.90 + 0.82 < 0.001 0.5

III V 3.12 + 0.12 1.96 + 0.41 2.07 + 0.38 < 0.001 0.4

TABLE 4. Changes in BAER in Study Group Before and after Phototherapy at 30 dB

Latency Study group Control p value30 (dB) Mean + SD Mean + SD

Before Treatment After Treatment (n=30) A Vs B a Vs A a Vs B(n=14) (n=14) (a)

(A) (B)

I 2.57 + 0.50 1.58 + 0.32 1.87 + 0.17 < 0.01 < 0.001 > 0.5II 3.37 + 0.43 2.84 + 0.45 3.17 + 0.36 < 0.01 > 0.2 > 0.1

III 5.02 + 0.85 4.34 + 0.43 4.44 + 0.78 < 0.001 < 0.05 >0.7

IV 5.67 + 0.67 5.35+0.18 5.20+0.26 < 0.01 0.3

V 7.35 + 1.35 6.75 + 0.35 7.06 + 0.33 0.5 >0.3IPIntervalsI III 2.49 + 1.26 1.71 + 0.41 2.17 + 0.57 < 0.05 > 0.4 > 0.1

I V 4.26 + 0.91 3.74 + 0.58 4.02 + 0.67 > 0.20 > 0.4 > 0.3

III V 2.23 + 0.54 2.11 + 0.16 2.01 + 0.35 > 0.20 < 0.05 > 0.3

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Brainstem Evoked Response Audiometry (BAER) in Neonates with Hyperbilirubinemia

TABLE 5. Relationship Between Latency, Interwave Interval and Serum Bilirubin at 90 dB Levels

Latency Before treatment Control Value(Serum bilirubin (mg%) Mean + SD

Mean + SD1218 1825 >25 (a) a/A a/B a/C(n=5) (n=6) (n=19)(A) (B) (C)

I 1.71 + 0.15 1.67 + 0.52 2.42 + 0.88 1.65 + 0.35 > 0.6 > 0.9 < 0.01II 2.61 + 0.08 2.65 + 0.23 3.08 + 0.59 2.72 + 0.32 > 0.7 > 0.9 < 0.02III 4.71 + 0.25 4.73 + 1.09 5.45 + 0.94 4.28 + 0.16 > 0.3 > 0.8 < 0.02IV 4.84 + 0.20 5.09 + 0.30 5.05 + 0.71 4.79 + 0.28 > 0.7 > 0.1 0.4 > 0.9 < 0.01IPIntervalsI III 1.82 + 0.36 2.05 + 0.34 2.86 + 0.64 2.15 + 0.42 > 0.1 > 0.7 0.9 > 0.9 0.3 >0.3 0.8 < 0.001II 3.40 + 0.11 3.17 + 0.01 3.17 + 0.36 > 0.3 < 0.02III 4.87 + 0.16 4.70 + 0.22 4.44 + 0.78 > 0.4 < 0.05IV 5.73 + 0.23 5.21 + 0.01 5.20 + 0.26 > 0.4 < 0.001V 7.95 + 0.91 7.21 + 1.23 7.06 + 0.33 > 0.3 < 0.05IPIntervalsI III 2.44 + 0.45 2.07 + 0.11 2.17 + 0.57 < 0.05 > 0.6I V 4.31 + 0.37 4.01 + 0.01 4.02 + 0.67 < 0.05 > 0.9III V 2.44 + 0.36 2.01 + 0.01 2.01 + 0.35 < 0.05 > 0.9

seperately with rarefaction clicks of 0.1msec durationadministered at a rate of 50 per second. 2000 responseswere averaged and minimum of two tests performed forreproducibility. 30 dB was taken as the normal thresholdof wave V. An infant was considered as passed the test ifwave V was present at 30 dB nHL in both ears or in oneear at 30 dB and in the other at 45 dB.

RESULTS

Male female ratio in the study was 1.3:1. Mean age ofbabies was 4.16 0.77 days, mean weight 3.31 0.41 kg,mean gestational age 38.83 1.26 weeks and mean serum

Bilirubin 25.97 7.28 mg/dl. Five patients had Rhincompatibility.

Mean latency of all waves was prolonged beforetreatment and reverted back to normal after phototherapyand /or exchange and this difference was statisticallysignificant at all decibels. Similarly interwave intervals I-III, IV and IIIV were also prolonged before treatmentand reverted back to normal after therapy. A total offourteen neonates with hyperbilirubinemia requiredexchange transfusion. In 7 neonates BAER remained

abnormal on followup tracings in that the interwaveinterval reverted back to normal but latency of variouswaves did not decrease significantly.

DISCUSSION

BAER was abnormal in 22/30 neonates (73.3%), which iscomparable to figures derived in other studies 6,7

Prolongation of latency of wave I as observed in our studywas similar to findings of Agarwal and Perlman but otherauthors6,8 observed that in hyperbilirubinemia wave I isnot prolonged due to noninvolvement of the cochlearnerve. Prolongation of latencies of other waves (IIV) were

observed in our study which showed a tendency to comeclose to normal following therapeutic interventions.This isin consonance to findings of other authors.68

Mean latency of various waves and interpeak distancewas compared at different serum bilirubin levels viz.12-18, 1825 and more then 25 mg% and statisticallysignificant correlation in prolongation of latency and theinter wave intervals was obtained with serum bilirubinlevels more then 25 mg%. Agarwal et al6 also foundcorrelation with serum bilirubin more then 25 mg and but

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Pramod Sharma et al

Gupta et al found such correlation only at serum bilirubin> 30%.7

After treatment BAER abnormalities in form ofprolonged interwave interval persisted only in 7 caseswhile the latencies of various waves had normalisedshowing that in most cases with hyperbilirubinemia thedeafness induced is transient and improves if treated intime and appropriately. Further follow up tracingobtained 2 to 4 months after discharge from the hospitalrevealed that responses improved in 2 more cases while 5infants continued to show persistent abnormalities.Similar findings were reported by Deorari et al9 whileother authors10 reported that on followup all neonateswith abnormal BAER showed a reversion back to normal.Improved brain functions may be due to removal ofbilirubin from the brainstem because of phototherapyand/or exchange transfusion thus postulating thehypothesis of transient bilirubin toxicity or the transientbrainstem encephalopathy. But persis tence ofabnormalities in some cases may be due to permanent

damage caused by axonal degeneration and loss ofmyelin rather than hair cell loss.11

REFERENCES

1. American Academy of Pediatrics. Joint Committee on infant

hearing: Position statement. Pediatrics 1982; 70; 496497.2. Wood S, Marcormick B, Marson S.Auditory brainstem

response in Pediatric audiology. Arch Dis Child 1988; 63 : 565-567.

3. Berhman Richard E, Kliegman Robert M, Jenson Hal B.Jaundice and hyperbilirubinemia in the newborn. Nelson TextBook of Pediatrics. 16th ed. 2001; Part XI; 513519.

4. Taylor MJ, Evoked potential in Pediatrics In Halliday AM Ed

Edinburg. edn. Evoked Potential in Clinical Testing 2nd eds.Churchill Livingstone, 1993; 489521.

5. Deurieux SA. Introduction. Brainstem evoked responseaudiometry in neonates.J Otolaryngol 1985; 14(suppl.14) : 56.

6. Agarwal VK, Shukla Rakesh, Misra PK, Kapoor RK, MalikGK.Brainstem auditory evoked response in newborn withhyperbilirubinemia. Ind J Peditr 1998: 35; 513518.

7. Gupta AK,Anand NK,Hans Raj. BAERa diagnostic tool inneonatology. Ind Pediatr 1990; 27 : 10391044.

8. Perlman M, Fainmesses P, Shohmer H, Tameris H, WazyPersmer B. Auditory nerve brainstem evoked response inhyperbilirubinemia. Pediatr 1983; 72: 703708.

9. Deorari AK, Singh M, Ahuja GK, Bisht MS, Verma A. OneYear outcome of babies with severe neonatalhyperbilirubinemia and reversible abnormality in brainstemauditory evoked responses. Ind Pediatr 1994; 31 : 915921.

10. Kramer SJ, Vertes DR, Condon M. Auditory brainstemresponse and clinical followup of highrisk infants. Pediatr1989; 83 : 385392.

11. Stockhard JJ, Rossiter VS. Clinical and pathological correlatesof brainstem auditory response abnormalities. Neurology 1977;27: 316325.

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BERA in Neonates With Hyperbili