Hearing assessment by brainstem auditory evoked responses (BAER) in neonates at risk

In the present study, brainstorm auditory evoked responses (BAER) were recorded in 68 at risk neonates discharged from the neonatal ICU of Safdarjung Hospital. The high risk group of 35 neonates included 13 neonates with multiple (3-4) risk factors and 22 neonates with single risk factors, viz., prematurity (less than 32 weeks) low birth weight (LBW) (less than 1500 g), hyperbilirubinemia requiring exchange transfusion, severe birth asphyxia, craniofacial malformations and sepsis with meningitis treated with amikacin for 3 weeks. The remaining 33 neonates were grouped in the low risk category who had only one of the following factors: prematurity (33-36 weeks)/LBW (1500-2000 g), hyperbilirubinemia requiring phototherapy, mild/moderate birth asphyxia, or sepsis treated with amikacin for 2 weeks. The test was performed at the mean conceptional age of 40.2 weeks (range 34-44 weeks) and involved determination of threshold of hearing as per presence of wave V. A normal response had wave V at 30 dB hearing level click stimulus at 50/sec from both ears or to 30 dB hearing level from one ear and 45 dB hearing level from the other ear. Thirteen neonates of the high risk group failed to produce a normal response (5 failed at 30 dB, 6 failed at 45 dB, and 2 failed at 75 dB hearing level). Forty six per cent of them had multiple high risk factors. All the low risk group neonates had normal threshold of 30 dB hearing level in the initial screening.(ABSTRACT TRUNCATED AT 250 WORDS)