Analyses Of The Characteristics Of Auditory Brainstem Response And The Relative Risk Factors Of Hearing Impairment In High-risk Neonates

Objective1. To investigate the characteristics of auditory brainstem response (ABR)and the relative risk factors of hearing impairment in high-risk neonatesfrom Neonate Intensive Care Unit (NICU) and Ordinary Neonatal Ward.2. To analyze the characteristics of ABR in high-risk neonates bydifferent gestational age.3. To analyze the characteristics of ABR in neonates withhyperbillirubinemia by different levels of serum bilirubin.Methods1. During July2012to April2012, there were212neonates hospitalizedin NICU and652neonates hospitalized in Ordinary Neonatal Ward, whoreceived ABR examinations and measured the period of latent (PL), intervalperiod of latent (IPL) and amplitude (AMP) of I, III and V waves. Any ear’sV wave minimum threshold>30dBnHL was defined as screening abnormal (notpass), and≤30dBnHL was defined as screening normal. Recorded everyhigh-risk neonate’s risk factor, and analyzed the characteristics of ABRand the relative risk factors of high-risk neonates from the two wards.2. All the high-risk neonates were categorized by different gestationalages: group I: gestational age≤34weeks, group II: gestational agebetween34to37weeks, group Ⅲ: gestational age≥37weeks. 3. Selected the term neonates with hyperbilirubinemia and excluded theneonates with hypoxic ischemic encephalopathy (HIE), intracranialhemorrhage, intracranial infection and assisted mechanical ventilation.There were totally442neonates, and were categorized by different levelsof serum bilirubin to three groups: Mild: serum bilirubin≤250umol/l,Middle: serum bilirubin between250and300umol/l, Severe: serumbilirubin≥300umol/l. Compared the characteristics of ABR of theneonates with different levels of serum bilirubin.Result1Comparison of the characteristics of ABR of high-risk neonates andanalysis of relative risk factors between NIICU and Ordinary NeonatalWard1.1There are115cases in the total212high-risk neonates from NICUV wave minimum threshold>30dBnHL, the screening abnormal rate was54.2%.There are274cases in the total652high-risk neonates from OrdinaryNeonatal Ward V wave minimum threshold>30dBnHL, the screening abnormalrate was42.0%. The screening abnormal rate of NICU was significantlyhigher than Ordinary Neonatal Ward （χ~2=9.653, P＜0.01）.1.2The ABR thresholds of left ear and right ear of the neonates from NICUwere significantly higher than Ordinary Neonatal Ward respectively （P＜0.01）.1.3Under90dBnHL stimulation, the I wave and V wave PL and I~V wave IPLof left ear and right ear of the high-risk neonates from NICU weresignificantly longer than Ordinary Neonatal Ward respectively（P＜0.01）.But there was no significant difference of the AMP between the neonatesof the two wards.1.4In Ordinary Neonatal Ward, there were167cases screening abnormalof the total344male neonates, and104cases screening abnormal of thetotal308female neonates. There was significant difference between the two genders（χ~2=18.05, P＜0.001）. Under90dBnHL stimulation, the V wavePL of both ears of male neonates were significantly longer than femaleneonates（P＜0.01）, AMP of both ears of male neonates were significantlysmaller than female neonates（P＜0.01）, the IPL of I~V waves of maleneonates were significantly longer than female neonates（P＜0.01）, andthere were no significant differences of I wave PL and AMP between thetwo genders（P＞0.05）. In NICU, there were78cases screening abnormalof the total138male neonates, and37cases screening abnormal of thetotal74female neonates. There was no significant difference between thetwo genders（χ~2=2.05, P=0.56）. Under90dBnHL stimulation, there wereno significant differences of the PL of I wave and V wave, AMP and IPLof I~V waves between the two genders（P＞0.05）.1.5In Ordinary Neonatal Ward, I wave PL and I~V IPL of left ear weresignificantly longer than right ear（P＜0.01）, I wave AMP were shorterthan the right（P＜0.05）; there were no significant differences of V wavePL and AMP between two ears（P＞0.05）. In NICU, there were no significantdifferences of PL of I and V waves and AMP between two ears（P＞0.05）.1.6In Ordinary Neonatal Ward, PL of I and V waves of high-risk neonateshad significant negative correlation with corrected gestational age（P＜0.05）, there had no significant correlation between PL of I~V waveswith birth weight（P＞0.05）. In NICU, there had no significant correlationbetween PL, AMP and IPL of I~V waves with corrected gestational age,gestational age and birth weight（P＞0.05）.1.7Logistic regression analysis revealed that hyperbilirubinemia was themain relative risk factor for ABR screening abnormal in Ordinary NeonatalWards; and assisted mechanical ventilation≥5days, birth weight<1500g,and hyperbilirubinemia were the main relative risk factors for ABRscreening abnormal in NICU.2The characteristics of ABR of neonates with different gestational ages 2.1The abnormal rate of the preterm group I (gestational age＜34weeks)was55.6%, the abnormal rate of the preterm group II (gestational agebetween34to37weeks) was49.7%, and the abnormal rate of the term group(gestational age≥37weeks) was44.9%. Preterm group I was significantlyhigher than the other two groups (P＜0.01). Preterm group II had nosignificant difference with term group (P＞0.05).2.2The I wave PL of both ears of term group was significantly shorterthan Preterm group I and II (P＜0.01). Preterm group II had no significantdifference with preterm group II (P＞0.05). There were significantdifferences of V wave PL of both ears between three groups (P＜0.05). TheIPL of wave I~V of preterm group I was significantly longer than the othertwo groups (P＜0.05), and preterm group II had no significant differencewith term group (P＞0.05).3The characteristics of ABR of neonates with different levels ofhyperbillirubinemia3.1In the total442cases of term neonates with hyperbillirubinemia,there were108cases screening abnormal of the total234male neonates,the abnormal rate was46.2%; and62cases screening abnormal of the total208female neonates, the abnormal rate was29.8%. There was significantdifference between the two genders (P＜0.01). Under90dBnHL stimulation,the V wave PL of both ears of male neonates were significantly longer thanfemale neonates（P＜0.01）, AMP of both ears of male neonates weresignificantly smaller than female neonates (P＜0.01), the IPL of I~V wavesof male neonates were significantly longer than female neonates (P＜0.01),and there were no significant differences of I wave PL and AMP betweenthe two genders (P＞0.05).3.2There were no significant differences of ABR parameters of I and Vwave between two ears in term neonates with hyperbillirubinemia.3.3The PL of wave I and V of the screening abnormal group was significantly longer than screening normal group, AMP was significantly smaller thanscreening normal group, and the IPL of wave I~V was significantly longerthan screening normal group.3.4The abnormal rate of Severe group was40.8%, there had significant difference with the Mild group (P＜0.0167);and there had no significant difference with the Middle group (P＞0.0167).There had no significant difference between Mild group and Middle group(P＞0.0167).3.5The PL of waveⅠof three groups had significant difference betweengroups (P＞0.05). PL of wave V and IPL of wave I~V of Severe group weresignificantly longer than Mild group and Middle group (P＜0.01), therehad no significant difference between Mild group and Middle group (P＞0.05).Conclusion1. The high-risk neonates from NICU were more prone to hearing impairmentthan those from Ordinary Neonatal Wards. The ABR thresholds of theneonates from NICU were higher than those of Ordinary Neonatal Wards, andPL of each waves were longer. The characteristics of ABR of high-riskneonates from NICU were more irregular, the risk factor of hearingimpairment were more complex, often combined with various risk factors,and more easy developed senorineural deafness and delayed and progressivehearing impairment. We should further enhance the follow-up visits ofneonates after discharge from NICU.2.The ABR abnormal rate of pre-term neonates whose gestational age≤34weeks were higher that term neonates and late-preterm neonates whosegestational age between34to37weeks; PL of wave I of term neonates wasshorter than preterm neonates, and there was no significant differencesbetween preterm neonates of different gestation age; PL of wave V ofpre-term neonates whose gestational age≤34weeks was significantlylonger than late-preterm and term neonates, and there was no significant differences between late-preterm neonates and term neonates. The pre-termneonates often combined with diseases as asphyxia, respiratory distressand pneumonia, and were easy to develop hearing impairment. Therefore,we should pay more attention to hearing screening of preterm neonates,especially to the small gestational age and low birth weight preterminfants. Ensure early detection, early intervention and early treatment,in order to improve the survival rates of preterm infants as well asminimize the hearing disability rate.3. In the neonates with hyperbilirubinemia, male neonates’ screeningabnormal rate was higher than female. The influence ofhyperbilirubinemia not only displayed on the increase of threshold, butalso the extension of PL and IPL, and decrease of AMP. As the serumbilirubin level increased, the PL of ABR wave extended also. When it upto a certain level, the central auditory nervous would be impact.Therefore, we should actively treat the hyperbilirubinemia of neonates,and try to avoid hearing impairment.