Brainstem auditory and visual evoked potentials in children with protein-energy malnutrition

BACKGROUND: To determine the effects of malnutrition on the developing brain with brainstem auditory evoked potentials (BAEP) and flash visual evoked potentials (fVEP). METHODS: The BAEP and fVEP of 11 kwashiorkor (8 +/- 1.56 months) and 10 marasmus (7.9 +/- 1.27 months) patients and 10 healthy control subjects (7.65 +/- 0.82 months) were recorded and the measurements were compared with each other in relation with plasma total protein and albumin levels. RESULTS: There were no differences between the mean latencies of the waves I, II, III and IV and mean interpeak latencies (IPL) of the waves I-III of the BAEP and the wave IV (N2) of the fVEP between the three groups. Mean latency of the wave V and mean IPL of the waves I-V and the waves III-V were significantly different between the three groups. The kwashiorkor group had significantly longer mean latency of the wave V than the marasmus group on the right ear and the control group on the both of the ears. The kwashiorkor group had significantly longer mean IPL of the waves I-V than the marasmus group on the right ear and than the control group on the left ear. The kwashiorkor group had also significantly longer mean IPL of the waves III-V than the control group on the left. CONCLUSIONS: The BAEP and fVEP are non-invasive electrophysiologic methods reflecting the integrity or disruption of the central neurologic pathways. The present results confirm the disruption of the central nervous system with the BAEP in children with protein-energy malnutrition, especially in kwashiorkor patients.     

Hearing impairment in preterm very low birthweight babies detected at term by brainstem auditory evoked responses

Seventy preterm babies who were born with a birthweight <1500 g were studied with brainstem auditory evoked responses (BAER) at 37-42 wk of postconceptional age. The data were compared with those of normal term neonates to determine the prevalence of hearing impairment in preterm very low birthweight (VLBW) babies when they reached term. The BAER was recorded with click stimuli at 21 s(-1). Wave I and V latencies increased significantly (ANOVA p < 0.01 and 0.001). I-V and III-V intervals also increased significantly (p < 0.05 and 0.001). Wave V amplitude and V/I amplitude ratio did not differ significantly from those in the normal term controls. Ten of the 70 VLBW babies had a significant elevation in BAER threshold (>30 dB normal hearing level). Eleven had an increase in I-V interval (>2.5 SD above the mean in the normal controls) and one had a decrease in V/I amplitude ratio (<0.45). These results suggest that 14% (10/70) of the VLBW babies had a peripheral hearing impairment and 17% (12/70) a central impairment. Three babies had both an increase in I-V interval and an elevation in BAER threshold, suggesting that 4% (3/70) had both peripheral and central impairments. Thus, the total prevalence of hearing impairment was 27% (19/70). Conclusion: About one in four preterm VLBW babies has peripheral and/or central hearing impairment at term. VLBW and its associated unfavourable perinatal factors predispose the babies to hearing impairment.     

Intrauterine growth retardation and brainstem auditory-evoked response in preterm infants

Intrauterine growth retardation is frequently associated with intrauterine undernutrition, and can deleteriously affect brain function. Twenty-eight premature small for gestational age infants were compared with 28 premature appropriate for gestational age infants to determine whether intrauterine growth retardation was associated with abnormalities in the auditory pathway in the early neonatal period. The auditory pathway was studied between 4-18 wk of life by analysis of brainstem auditory-evoked potentials elicited by a 10/s 75 decibel above normal adult hearing level (dB nHL) click stimulus presented at the infants' ears. Peak latencies of components I, III and V, and interpeak latencies I-III, III-V and I-V, yielded no statistically significant differences between groups. The present study indicates that intrauterine growth-retarded premature infants may not have abnormalities of brainstem auditory-evoked response in the early neonatal period.     

Transient neonatal hypothyroxinemia and the auditory brainstem evoked response.

Ten premature infants with low serum thyroxine levels (less than 84 nmol/L) were compared with 10 biochemically euthyroid infants to determine whether hypothyroxinemia in such infants can lead to alterations in the auditory pathway. The auditory pathway was studied between 6 and 11 wk of life by analyzing brainstem evoked potentials elicited by a 10/s, 75 dB above normal adult hearing level click stimulus presented at the infant's ears. Peak latencies of components I, III, and V and interpeak latencies I-III, III-V, and I-V did not yield statistically significant differences between groups. The present study indicates that untreated neonatal hypothyroxinemia does not lead to abnormalities of auditory brainstem evoked response.     

Auditory nerve and brainstem responses in newborn infants with hyperbilirubinemia

To assess early bilirubin toxicity, a study was made of auditory brainstem responses in relation to total bilirubin levels as well as unbound bilirubin levels in 56 hyperbilirubinemic infants (total bilirubin greater than or equal to 15.0 mg/dL) and 24 infants who did not have jaundice. The latencies of wave I at 85 dB HL (hearing level) in hyperbilirubinemic infants were significantly greater than those in the control group. The latencies of wave I and V in hyperbilirubinemic infants with unbound bilirubin levels greater than or equal to 1.0 microgram/dL (group C) were greater than those in the control group and in the hyperbilirubinemic infants with unbound bilirubin levels less than 0.5 microgram/dL (group A) and with unbound bilirubin levels less than 1.0 microgram/dL (group B). There were no significant differences of the wave I-V interpeak latency between the control infants and the hyperbilirubinemic infants. Thirty of the 80 infants showed prolonged peak latencies (greater than the mean +/- 2 SD for the control infants) of wave I and/or V in one or both ears. The incidences of the prolonged peak latencies in group B (42%) and group C (89%) were significantly greater than that in the control group (12%). The serial determinations of auditory brainstem responses in infants treated with exchange transfusions revealed that the prolonged peak latencies before exchange transfusion improved at 48 and 96 hours after the procedure for wave I, and at 24, 48, and 96 hours after the procedure for wave V. The interpeak latency of wave I-V did not change with exchange transfusion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Brainstem acoustic evoked potentials in children with developmental disabilities--a useful tool for differential diagnosis

In a retrospective study brainstem acoustic evoked potentials (BAEP) were evaluated in 222 children with psychomotor retardation or dysmorphic signs. Registrations were done, when no clear response to acoustic stimuli of medium intensity (60-80 dBA) could be obtained during clinical examination. Only 118 children (53%) had normal BAEP. 50 patients (22%) suffered from hearing impairment. 39 children (17%) showed disturbances of neuronal conduction. In 15 cases (7%) a combination of both conditions occurred. The mean age of our children with hearing impairment was 33.1 months, no case having been diagnosed before. In 57% the impairment was of the conductive type with an amount of less than 40 dB nHL This type was predominant in children with skeletal dysplasias (43%), chromosomal aberrations (43%) and malformation syndromes (40%). Severe hearing deficits of the sensorineural type with more than 69 dB nHL were found in children with malformation syndromes (28%), perinatal injuries (23%) and cns malformations (16%). As far as reference data were available, the hearing impairment in the BAEP was confirmed in 92% by our pedaudiologists. As a consequence hearing aids were first prescribed in 10 children, their medium age being 33.6 months. In 18 cases grommets were inserted. 9 children required paracentesis and 4 adenotomy. Disturbances of neuronal conduction with increased interpeak latencies and deformed potentials were predominantly found in the group of children with neurometabolic diseases (67%) and cns malformations (32%). Early diagnosis of hearing impairment in children with psychomotor retardation remains a problem as it is in the general population. More attention in clinical examination and appropriate screening is necessary. BAEP provide a powerful tool for hearing screening and additional information for differential diagnosis especially in children with neurometabolic diseases.     

Development of human peripheral hearing revealed by brainstem auditory evoked potentials

Development of human peripheral hearing from birth to 6 years was investigated by recording brainstem auditory evoked potentials (BAEPs). The threshold of BAEPs decreased rapidly during the first 3 months after birth (2.7dB/week during the neonatal period, 2.6dB/month at 1-3 months), after which further decrease occurred more slowly but continued through 1 year of age (0.26 dB/month at 3-12 months). A few days after birth, the threshold was 18 dB higher compared to the adults, and progressively decreased to 10, 5 and 2 dB at 1, 3 and 12 months, respectively. The latencies of waves I and V decreased as a function of age at a rate of 0.01 and 0.05 ms/week during the neonatal period, 0.02 and 0.10ms/month at 1-3 months and 0.014 and 0.076 ms/month at 3-12 months, respectively. Adult latency value was attained by 2 and 4 years for waves I and V, respectively. These findings suggest that although the ear is reported to be almost adult-like at birth, the immaturity in neural functional properties limits auditory sensitivity during early childhood. It appears that human peripheral hearing threshold decreases rapidly through the third postnatal month and thereafter continues to improve slowly through early childhood. It is postulated that the first 3 months after birth are likely to be a critical period in postnatal development of human peripheral hearing.     

Brainstem auditory response findings in preterm infants after necrotizing enterocolitis

Aim: To examine brainstem auditory function and detect any abnormality at term in preterm infants after neonatal necrotizing enterocolitis (NEC). Methods: Brainstem auditory evoked response (BAER) was recorded at 21/sec and 60 dB nHL in 37 preterm infants who had NEC. The data obtained at term equivalent age were analyzed and compared with those in normal term infants. Results: The threshold of BAER in infants after NEC, though slightly elevated, did not differ significantly from that in the controls. The latencies of waves I and III were slightly longer than in the controls, without any statistical significance. However, wave V latency was prolonged and differed significantly from the controls (p < 0.01). I-V interpeak interval was also prolonged (p < 0.05). The data point distribution of wave V latency and I-V interval was higher in the infants after NEC than in the controls. The amplitudes of BAER wave components in the infants after NEC did not differ significantly from those in the controls. Conclusion: Preterm infants after NEC have no major abnormality in peripheral auditory function. However, neural conduction in the brainstem auditory pathway is abnormal, suggesting that NEC adversely affects brainstem auditory conduction.     

Brainstem auditory evoked responses in very low birthweight infants with chronic lung disease.

Very low birthweight (VLBW) infants who had prolonged oxygen dependence due to chronic respiratory problems, typically neonatal chronic lung disease (CLD), are at high risk of neurodevelopmental impairment. To assess the effect of CLD on neonatal auditory function we studied brainstem auditory evoked response (BAER) in VLBW infants who suffered CLD but no other major perinatal complications or problems. At 37-42 week postconceptional age, the latencies of waves I, III and V in CLD infants were all significantly longer than in normal term infants (all p<0.001). The differences between CLD infants and the term controls were greater for the later waves than for the earlier waves. Abnormally prolonged wave latency (>2.5 SD of the mean measurement) was seen in 7 (21.2%) CLD infants for wave I, suggesting peripheral auditory impairment, 8 (24.2%) for wave III and 14 (42.4%) for wave V. I-V interval in CLD infants was significantly longer than in the term controls (p<0.001). Seven (21.2%) infants had abnormally prolonged I-V interval, suggesting brainstem or central auditory impairment. Of these infants, 2 had both prolonged wave latencies and prolonged I-V interval, suggesting both peripheral and central auditory impairment. Similar abnormalities were found in CLD infants when compared with the BAER in birthweight- and age-matched healthy VLBW infants without CLD. CONCLUSION: Neonatal auditory function is impaired, both peripherally and centrally, at term age in VLBW infants who suffer neonatal CLD.     

Effect of aminophylline on brain stem auditory evoked potentials in preterm infants.

To determine the neurophysiological effects of aminophylline on apnoea of prematurity, the brain stem auditory evoked potentials (BAEPs) of 30 apnoeic infants and 34 age matched controls were evaluated and compared. After six days of treatment with aminophylline, the brain stem conduction time (interpeak latency of I-V) in apnoeic infants decreased compared with controls of a similar postconceptional age. The mean latencies of the peaks and interpeaks of all waves except wave I were significantly lower in the apnoeic infants after than before receiving aminophylline. No significant differences were found in the latencies of BAEPs between the apnoeic infants who responded and those who did not respond to aminophylline treatment, however. These results suggest that aminophylline may enhance conduction along central auditory pathways and stimulate the regulatory effect on the respiratory centre of the brain stem.     

Mild impairment of neuro-otological function in early treated congenital hypothyroidism.

Pure tone audiometry, tympanometry, acoustic stapedial reflex thresholds (ASRTs), and auditory evoked brain stem responses (AEBRs) were carried out in 38 children with early treated congenital hypothyroidism aged 10-12 years, together with tests of vestibular function (electronystagraphy, rotational, and caloric tests). Sensorineural hearing loss with thresholds of greater than 15 dB was detected in 18 children (10 at 8 kHz only); only two children had more than 40 dB hearing loss, each in one ear. Raised ASRTs were found in eight children and two children had abnormal AEBRs. Of the 29 children tested, 12 had an abnormality of vestibular function. Although not significant at the 5% level, there was a tendency for the abnormalities to be more prevalent and severe in the children with more severe hypothyroidism, as judged by pretreatment plasma thyroxine. It is concluded that (i) mild abnormality of hearing is still common in children with congenital hypothyroidism despite early treatment but this is much less severe than that found before neonatal screening and (ii) mild abnormalities of vestibular function may be common in early treated congenital hypothyroidism.     

Auditory brain stem evoked response in normal neonates and infants

Auditory brainstem evoked responses (ABER) were recorded to provide normative data regarding the latency values, brainstem conduction times in term neonates and infants up to 24 months of age. The mean latency for wave I - 1.86 +/- 0.11 m sec, wave III - 5.11 +/- 0.31 m sec, wave V - 7.10 +/- 0.30 m sec progressively decreased at birth to wave I - 1.64 +/- 0.17 m sec, wave III - 4.40 +/- 0.27 m sec, wave V - 6.15 +/- 0.21 m sec at 12 months of age by stimulus strength of 75 decibels at a rate 20 clicks/sec. Interwave conduction times improved to I-III - 2.76 +/- 0.29 m sec, I-V - 4.51 +/- 0.29 m sec, III-V - 1.75 +/- 0.17 m sec at 12 months from I-III - 3.25 +/- 0.26 m sec, I-V - 5.23 +/- 0.23 m sec, III-V - 1.99 +/- 0.35 m sec at birth.     

Mild impairment of neuro-otological function in early treated congenital hypothyroidism

Pure tone audiometry, tympanometry, acoustic stapedial reflex thresholds (ASRTs), and auditory evoked brain stem responses (AEBRs) were carried out in 38 children with early treated congenital hypothyroidism aged 10-12 years, together with tests of vestibular function (electronystagraphy, rotational, and caloric tests). Sensorineural hearing loss with thresholds of greater than 15 dB was detected in 18 children (10 at 8 kHz only); only two children had more than 40 dB hearing loss, each in one ear. Raised ASRTs were found in eight children and two children had abnormal AEBRs. Of the 29 children tested, 12 had an abnormality of vestibular function. Although not significant at the 5% level, there was a tendency for the abnormalities to be more prevalent and severe in the children with more severe hypothyroidism, as judged by pretreatment plasma thyroxine. It is concluded that (i) mild abnormality of hearing is still common in children with congenital hypothyroidism despite early treatment but this is much less severe than that found before neonatal screening and (ii) mild abnormalities of vestibular function may be common in early treated congenital hypothyroidism.     

Narcotic and nicotine effects on the neonatal auditory system

To evaluate narcotic and nicotine effects on the neonatal auditory system, brain stem auditory evoked responses were recorded in 15 infants prenatally exposed to both narcotics and nicotine (median gestational age 38.4 weeks, median birth weight 2820 g), in 15 nicotine exposed infants (gestational age 40.0 weeks, birth weight 3000 g) and in 24 healthy term infants (gestational age 40.1 weeks, birth weight 3310 g) who served as controls. Whereas nicotine-exposed and control infants were similar in all brain stem auditory evoked response measurements, narcotic/nicotine infants had bilaterally increased wave V latencies (left: p = 0.005; right: p = 0.04) and I-V intervals (left: p = 0.02; right: p = 0.01) when compared to controls. Our findings suggest that prenatal narcotic but not nicotine exposure negatively affects maturation or integrity of the neonatal auditory brain stem tract and that neither narcotic nor nicotine exposure is associated with hearing loss in the neonate.     

Brainstem auditory evoked responses in term small for gestational age newborn infants born to undernourished mothers.

Our aim was to assess the effect of intrauterine growth retardation on neurosensory development by evaluating brainstem auditory evoked responses (BAER) in term small for gestational age (SGA) newborn infants born to undernourished mothers. This prospective clinical study included 25 singleton healthy SGA newborn infants born between 38 and 41 weeks to undernourished mothers (weight <45kg, height <145cm, haemoglobin <8g/dl, and serum albumin <2.5g/dl). An equal number of age- and sex-matched appropriate for gestational age newborn infants born to healthy mothers served as controls. Mothers with other risk factors and newborns with complications during delivery or immediate newborn period were excluded. BAER was recorded within first 3 days of life. Interpeak latency (IPL), absolute peak latency (APL) and amplitudes of various waveforms were determined and compared between the groups.No statistically significant differences were observed for the mean interpeak and absolute latencies between term SGA and AGA infants (p>0.05). The absolute peak latency (wave V) and central conduction time (I-V interval) were borderline prolonged in the study group compared with controls (p=0.051 and 0.088 respectively). Using multiple regression analysis, maternal haemoglobin was identified to be the only parameter having a negative correlation with both IPL (waves I-V) (F[1,46]=4.12, p=0.048) and APL (wave V) (F[1,46]=5.80, p=0.02). Maternal undernourishment may have a minor effect on intrauterine development of the auditory brainstem. Maternal haemoglobin is the only factor significantly associated with these changes.     

Hearing screening of high-risk newborns with brainstem auditory evoked potentials: a follow-up study

Numerous techniques have been used in attempts to find a reliable and efficient screening method for determining auditory function in the newborn. The brainstem auditory evoked potential (BAEP) is the latest method advocated for that purpose. The BAEP was evaluated as a hearing screening test in 168 high-risk newborns between 35 and 45 weeks of conceptual age. Follow-up data were obtained after 1 year (mean 17.3 months) on 134 of the infants (80%). Normal hearing was defined as a reproducible response in both ears to a 25 dB normal hearing level (nHL) click stimulus; 21 infants (12.5%) failed the initial screening test. Follow-up on 19/21 infants revealed 18 infants with normal hearing and one infant with an 80 dB nHL bilateral hearing loss substantiated. One infant with an abnormal screening test died before retesting, and the other infant was lost to follow-up but had only a unilaterally abnormal BAEP. None of the infants with a normal BAEP screening study had evidence of hearing loss on retesting. Sensitivity of the BAEP was 100%, specificity was 86%, predictive value of a positive test was 5.26%, and the predictive value of a negative test was 100%. The incidence of significant hearing loss in our population was between 0.75% (1/134 infants) confirmed, and 2.24% (3/134 infants) including infants who failed screening but were lost to follow-up. The BAEP is a sensitive procedure for the early identification of hearing-impaired newborns. However, the yield of significant hearing abnormalities was less than predicted in other studies using BAEP for newborn hearing screening.     

Development of auditory function in newborn infants revealed by auditory brainstem potentials

Auditory brainstem potentials were recorded from scalp electrodes in 42 infants ranging in gestational age from 25 to 44 weeks. The latencies of the various potential components decreased with maturation. Wave V, evoked by 65-dB sensation level clicks, changed in latency from 9.9 msec at 26 weeks of gestation of 6.9 msec at 40 weeks of gestation. Central conduction times in the auditory pathway also decreased with maturation from 7.2 msec at 26 weeks to 5.2 msec at 40 weeks. The effects of brainstem and cochlear disorders on auditory brainstem potentials were noted in several abnormal infants. The application of all of these techniques could permit an objective definition of both normal and abnormal sensory processes in newborn infants.     

Hearing screening practices among a national sample of primary care pediatricians

The objective of this study was to describe variations in hearing screening using a survey mailed to a national sample of primary care pediatricians prior to the 2003 American Academy of Pediatrics (AAP) hearing screening guidelines. Of the 390 primary care respondents, only 303 (78%) performed audiometry, routinely beginning at age 3 (32%), 4 (44%), or 5 (17%); 81% defined abnormal audiometry primarily as failure to hear at a specified decibel level: 15 dB hearing level (HL) (<1%), 16 to 20 dB HL (10%), 21 to 25 dB HL (23%), 26 to 30 dB HL (44%), 31 to 40 dB HL (16%), and more than 40 dB HL (6%). This study serves as a baseline for comparison with postguideline practices.     

Normal brainstem responses in moderately preterm infants

Abstract Aim: The aim of this study was to detect any differences in brainstem auditory evoked responses (BAERs) to different click rates between moderately preterm and term infants. Methods: BAER was recorded with 21-91/s clicks at term age (37-42 weeks postconceptional age) in 39 moderately preterm infants (gestation 33-36 weeks). The results were compared with 37 healthy term infants. Results: The latencies of waves I, III and V, and I-V interval in preterm infants were all similar to term infants at all click rates. The I-III interval decreased slightly and differed from term infants at 91/s (ANOVA, p < 0.05), while the III-V interval increased slightly. The III-V/I-III interval ratio increased slightly and differed from term infants at 91/s (p < 0.05). Wave amplitudes were similar in the two groups of infants, except an increase in wave V amplitude at 91/s in preterm infants (p < 0.05). No significant differences were found in BAER click rate-dependent changes between the two groups. Conclusion: No marked differences were found in BAER at any click rates at term age between moderately preterm and term infants, suggesting that moderately preterm birth does not have a marked effect on neonatal BAER. BAER normal data and criteria from term infants can generally be used for moderately preterm infants.     

Value of brainstem acoustic evoked potentials in posterior fossa tumours in childhood

Brainstem acoustic evoked potentials (BAEPs) were measured in 14 children with different type of posterior fossa tumours several times during the clinical course, in order to assess the value of this simple and non-invasive method in the diagnosis and follow-up of posterior fossa tumours in childhood. Eight children had midline medulloblastoma, three children had lateral astrocytoma, three had intrinsic brainstem glioma. Different BAEP patterns could be detected in different tumour's type: bilateral symmetrical or slightly asymmetrical I-V. IPL prolongation in midline medulloblastomas, unilateral or markedly asymmetrical I.-V. IPL prolongation or wave V. depression on the contralateral side in lateral astrocytomas, and severely distorted asymmetrical waveform in intrinsic brainstem gliomas. The BAEPs were abnormal earlier than CT scan in a case of craniospinal astrocytoma. BAEPs were useful in the follow-up: the effect of the preoperative chemotherapy or the progression of the inoperable tumours could be as well documented by this method, as by the CT scan. BAEPs proved effective in the assessment of postoperative neurological complications: bilateral symmetrical IPL prolongation and wave V. depression with clinical signs of increased intracranial pressure occurred in a case of postoperative occlusive hydrocephalus, unilateral IPL prolongation occurred during irradiation or chemotherapy after medulloblastoma removal as signs of cerebral oedema.