Prognostic significance of the auditory brainstem evoked response in high-risk neonates

Postnatal functional status of the brainstem auditory pathway in term infants after perinatal hypoxia-ischemia

OBJECTIVES

To examine postnatal changes in the impaired brainstem auditory pathway in term infants after perinatal hypoxia-ischemia (HI).

METHODS

Brainstem auditory evoked response (BAER) was studied at 2-4 months of age in term infants who suffered perinatal HI. The BAER data obtained at various click rates in these infants were compared with those in age-matched normal term controls to detect any abnormalities.

RESULTS

The infants after HI showed a slight elevation in BAER threshold. Four (9.8%) infants had threshold elevation. At 21/s clicks, there was a slight decrease in wave I latency, and a slight increase in wave III and V latencies. However, the I-V and I-III intervals in these infants were significantly increased (p < .05 and .05), whereas III-V interval was slightly increased. At higher click rates of 51 and 91/s, all BAER variables showed similar changes, with only small variations. An abnormal increase in the I-V and/or I-III intervals was seen in 4 (9.8%) infants, who were not associated with BAER threshold elevation.

CONCLUSIONS

At 2-4 months of age, around 20% of the infants after perinatal HI showed a moderate degree of either peripheral or central impairment of the brainstem auditor pathway. Monitoring postnatal changes could provide valuable information for postnatal care of infants after perinatal HI.

Auditory Brainstem Response in Preterm Infants in the Neonatal Intensive Care Unit

OBJECTIVE

To analyze auditory brainstem response (ABR) findings of preterm and term infants in the neonatal intensive care unit (NICU) with perinatal problems.

STUDY DESIGN

Case series with chart review.

SETTING

Secondary care hospital.

METHODS

Analysis consisted of a consecutive series of 101 infants (69 preterm and 32 term) admitted in the NICU of Hospital Fernando Fonseca between 2016 and 2018 with perinatal problems who underwent an ABR evaluation.

RESULTS

The major perinatal problems identified were hyperbilirubinemia, intravenous gentamicin >5 days, mechanical ventilation >5 days, congenital cytomegalovirus infection, meningitis, and periventricular hemorrhage. Gentamicin use significantly increased the absolute latency of wave I in preterm infants (95% CI, 0.01-0.37; P = .037). Mechanical ventilation significantly decreased the latency of wave V and intervals I-V and III-V in preterm infants (95% CI, -0.35 to -0.22; P = .026; 95% CI, -0.33 to -0.00; P = .001; 95% CI, -0.46 to 0.12; P = .049). Congenital cytomegalovirus significantly decreased interval III-V in preterm infants (95% CI, -0.36 to -0.01; P = .042).Multivariate analysis revealed that gentamicin use, lower gestational age, and lower birth weight predicted an increased ABR threshold in preterm infants (95% CI, 1.64-15.31; P = .016; 95% CI -1.72 to -0.09; P = .030; 95% CI, -14.55 to -0.63; P = .033). ABR measurements in term infants were not significantly altered, with the exception of an increased latency of wave III with a lower gestational age (95% CI, -0.49 to -0.01; P = .038).

CONCLUSIONS

These findings suggest that perinatal problems in the NICU significantly impair the ABR threshold and the auditory pathway maturational process in preterm but not term infants.

Auditory neural myelination is associated with early childhood language development in premature infants

BACKGROUND

Auditory neural myelination (ANM) as evaluated by auditory brainstem evoked response (ABR) during the neonatal period has been used as a surrogate outcome for long-term neurodevelopment. The validity of ANM as a surrogate outcome for long-term neurodevelopment has not been well studied.

AIM

Evaluate the association of ABR I-V interpeak latency (IPL), an index of ANM, at 35 week postmenstrual age (PMA) with language outcome at 3 years of age.

DESIGN

Prospective study.

SUBJECTS

24-33 week gestational age (GA) infants were eligible if they did not meet exclusion criteria: craniofacial malformation, chromosomal disorders, deafness, auditory dys-synchrony, TORCH infection, or non-English speaking parents. Infants with malignancy, head injury, encephalopathy, meningitis, blindness, or who died or relocated were also excluded.

OUTCOME MEASURES

ABRs were performed at 35 week PMA using 80 dB nHL and I-V IPL (ms) measured. Auditory Comprehension (AC) and Expressive Communication (EC) were evaluated by a speech-language pathologist at 3 years of age using Preschool Language Scale.

RESULTS

Eighty infants were studied. The mean GA and birth weight of infants were 29.2 weeks and 1336 g, respectively. There was association of worse ear I-V IPL and better ear I-V IPL with AC (Coefficient-5.4, 95% CI: -9.8 to -0.9 and Coefficient-5.5, 95% CI: -10 to-0.9, respectively) and EC (Coefficient-5.6, 95% CI: -9.5 to-1.8 and Coefficient-6.7, 95% CI: -10.6 to-2.7, respectively) after controlling for confounders.

CONCLUSION

The neonatal I-V IPL is a predictor of language development at 3 years of age in preterms.

EEG, evoked potentials and pulsed Doppler in asphyxiated term infants

OBJECTIVE

To evaluate electroencephalograms (EEG), evoked potentials (EPs) and Doppler findings in the cerebral arteries as predictors of a 1-year outcome in asphyxiated newborn infants.

METHODS

EEG and EPs (brain stem auditory (BAEP), somatosensory (SEP), visual (VEP) evoked potentials) were assessed in 30 asphyxiated and 30 healthy term infants during the first days (range 1-8). Cerebral blood flow velocities (CBFV) were measured from the cerebral arteries using pulsed Doppler at ∼24h of age. EEG, EPs, Doppler findings, symptoms of hypoxic ischemic encephalopathy (HIE) and their combination were evaluated in predicting a 1-year outcome.

RESULTS

An abnormal EEG background predicted poor outcome in the asphyxia group with a sensitivity of 67% and 81% specificity, and an abnormal SEP with 75% and 79%, respectively. Combining increased systolic CBFV (mean+3SD) with abnormal EEG or SEP improved the specificity, but not the sensitivity. The predictive values of abnormal BAEP and VEP were poor. Normal EEG and SEP predicted good outcome in the asphyxia group with sensitivities from 79% to 81%. The combination of normal EEG, normal SEP and systolic CBFV<3SD predicted good outcome with a sensitivity of 74% and 100% specificity.

CONCLUSIONS

Combining abnormal EEG or EPs findings with increased systolic CBFV did not improve prediction of a poor 1-year outcome of asphyxiated infants. Normal EEG and normal SEP combined with systolic CBFV<3SD at about 24 h can be valuable in the prediction of normal 1-year outcome.

SIGNIFICANCE

Combining systolic CBFV at 24 h with EEG and SEP examinations can be of use in the prediction of normal 1-year outcome among asphyxiated infants.

Brainstem auditory response findings in term neonates in intensive care unit

OBJECTIVES

Whether term infants in neonatal intensive care unit (NICU) have brainstem auditory abnormalities remains to be determined. This study aimed to detect any abnormality in brainstem auditory function in term neonates who are admitted to NICU.

METHODS

From a NICU, we recruited 55 term neonates with various perinatal problems. They were studied during the first week after birth using brainstem auditory evoked response (BAER), and the results were compared with normal term controls.

RESULTS

Wave I and III latencies and I-III interpeak interval of the evoked response in the NICU term neonates were similar to those in the controls. Wave V latency and I-V and III-V interpeak intervals tended to be increased at 21/s clicks. The increase was more obvious at higher rates 51 and 91/s. Analysis of variance revealed that at 21/s clicks only III-V interval was significantly increased (p < 0.05). At 51 and 91/s clicks, wave V latency and III-V and I-V intervals were significantly increased (p < 0.05-0.01). The rates of the abnormalities were seen more at higher than at lower click rates. The amplitudes of waves I, III, and V in the NICU neonates were all slightly reduced, but none differed significantly from the controls.

CONCLUSIONS

There are some abnormalities in BAER in term neonates in NICU, suggesting functional abnormality in the auditory brainstem in NICU infants.

Depressed brainstem auditory function in children with cerebral palsy

Brainstem auditory evoked responses were studied to examine brainstem auditory function in 80 children with cerebral palsy. The response waveform, particularly later waves, tended to be depressed. Thirty-three (41.3%) showed abnormal results. The main abnormality was reduced wave V amplitude. Other abnormalities were decreased V/I amplitude ratio, missing waves, prolonged I-V interval, and increased interaural difference in I-V interval. The abnormalities were persistent during the follow-up. In contrast to common findings in the responses in progressive neurologies, abnormalities in interpeak intervals were rare in children with cerebral palsy. There were some characteristic changes in the responses in certain etiologies. These results suggest that brainstem auditory function in children with cerebral palsy is depressed, which may be owing to decreased or altered neural firing or synchrony in the auditory brainstem. A detailed analysis of central components of the responses is valuable in detecting central auditory dysfunction in children with cerebral palsy.

Ethics in neonatal neurology: when is enough, enough?

Decision-making for the severely neurologically compromised newborn is fraught with considerable medical and ethical difficulties. Multiple intrinsic and extrinsic factors challenge our prognostic certainty, which then challenges our ability both to communicate and to make decisions that are rooted in basic principles of fairness and moral integrity. Clinical vignettes illustrate the difficulties and highlight the present status regarding prognostication and consideration of general ethical principles that would permit the consensual withdrawal of care (i.e., end-of-life decisions). Futility in the neonatal setting is examined, as well the mechanisms of the decision-making process and existing relevant professional guidelines.

Brainstem auditory outcomes and correlation with neurodevelopment after perinatal asphyxia

We used brainstem auditory-evoked responses and neurodevelopmental assessment to detect abnormalities and correlations between such responses and neurodevelopmental outcomes in 78 children (aged 4-12 years) who survived perinatal asphyxia. Twenty children had brainstem auditory-evoked response abnormalities, including increased threshold, reduced wave V amplitude, decreased V/I amplitude ratio, and prolonged I-V interval. Thirty-seven exhibited neurodevelopmental deficits, including cerebral palsy and developmental delay. The remaining 41 exhibited no deficits. Brainstem auditory-evoked response abnormalities were evident in 15 of 37 (40.5%) children with neurodevelopmental deficits, but in only 5 of 41 (12.2%) with no deficits, which differed significantly (chi(2) = 8.2, P < 0.05). The sensitivity, specificity, positive predictive value, and false-negative rate of brainstem auditory-evoked responses to reflect neurodevelopmental outcomes were 40.5%, 87.8%, 75.0%, and 59.5%, respectively. These findings suggest that in children who survive perinatal asphyxia, brainstem auditory impairment occurs more frequently in those with versus those without neurodevelopmental deficits. Brainstem auditory-evoked responses display a moderate correlation with clinically determined neurodevelopmental outcomes. Despite limitations, brainstem auditory-evoked response is valuable for assessing auditory and neurodevelopmental outcomes after perinatal asphyxia.

Comparison of two-step transient evoked otoacoustic emissions (TEOAE) and automated auditory brainstem response (AABR) for universal newborn hearing screening programs

OBJECTIVE

Both transitory auditory otoemissions (TEOAE) and automated auditory brainstem responses (AABR) are considered adequate methods for universal hearing screening. The goal of this study was to compare the results obtained with each device, applying the same screening procedure.

MATERIALS AND METHODS

From 2001 to 2003, all the newborns in our health area (2454 infants) were evaluated with TEOAE (ILO92, otodynamics) and all those born from 2004 to 2006 (3117) were evaluated with AABR (AccuScreen, Fischer-Zoth). The population studied included all well newborns and those admitted to neonatal intensive care units (NICU). The first screening was normally undertaken with well babies during the first 48h of life, before hospital discharge. Infants referred from this first step underwent a second screening after hospital discharge, before they were a month old.

RESULTS

The results from each study group were compared and analyzed for significant differences. TEOAE screening yielded 10.2% fail results from the first screening step; AABR gave 2.6%. In the second screening step, 2% of the newborns screened with TEOAE were referred, whereas 0.32% of those screened with AABR were referred. These differences are statistically significant.

CONCLUSIONS

Although AABR screening tests involve a slightly higher cost in time and money than TEOAE, the results obtained compensate this difference. AABR gives fewer false positives and a lower referral rate; the percent of infants lost during follow-up is consequently smaller. Therefore, in our environment, universal newborn auditory screening with AABR is more effective than that with TEOAE.

Sustained depression of brainstem auditory electrophysiology during the first months in term infants after perinatal asphyxia

OBJECTIVE

To gain further insights into the pathophysiological processes of neuronal impairment in neonatal brainstem after perinatal asphyxia.

METHODS

Maximum-length sequence brainstem auditory-evoked response (MLS BAER) was recorded with clicks at 91, 227, 455 and 910/s on days 1, 3, 5, 7, 10, 15 and 30 after birth in 108 term infants who suffered perinatal asphyxia. Wave amplitude variables in the MLS BAER were analysed in detail at 40 dB above BAER threshold in 86 infants who had no peripheral hearing impairment.

RESULTS

On day 1 the amplitudes of MLS BAER waves I, III and V were all reduced significantly at all click rates, especially at higher ones (91-910/s, ANOVA P<0.05-0.001). On day 3 these amplitudes were reduced further. On days 5 and 7, the amplitude reduction persisted and did not show any significant further changes. On days 10 and 15 the reduced amplitudes were increased slightly. On day 30 all amplitudes were still reduced significantly (P<0.05-0.0001). During the first month, the reduction of wave amplitudes was more significant for the later MLS BAER components than for the earlier ones, and occurred most significantly at 455 and 910/s clicks. By comparison, the amplitude reduction in conventional BAER was much less significant.

CONCLUSIONS

During the first month after perinatal asphyxia the amplitudes of MLS BAER waves were reduced significantly and persistently, which was more significant at higher rates of clicks than at lower rates. The reduction is much more persistent than the increase in wave latencies and intervals we previously reported.

SIGNIFICANCE

There is sustained depression of brainstem auditory electrophysiology, indicating neuronal damage of the auditory brainstem, in infants after perinatal asphyxia. This may have important clinical implications.

Functional impairment of the brainstem in infants with bronchopulmonary dysplasia

OBJECTIVES

To gain new insights into the influence of bronchopulmonary dysplasia on the immature brain and to detect abnormalities, we studied the functional integrity of the brainstem in infants with bronchopulmonary dysplasia.

METHODS

Forty-one very preterm infants with bronchopulmonary dysplasia were studied at postconceptional ages of 37 to 42 weeks. Brainstem auditory evoked responses were recorded and analyzed by using the maximal length sequence technique.

RESULTS

Compared with term control subjects, wave V latency in the maximal length sequence brainstem auditory evoked response of the infants with bronchopulmonary dysplasia increased significantly at all 91 to 910 clicks per second rates. Similarly, I-V and particularly III-V interpeak intervals increased significantly. The III-V/I-III interval ratio also increased significantly at all click rates. All of these abnormalities became more significant as the click rate was increased. Compared with healthy, very preterm control subjects, all of these maximal length sequence brainstem auditory evoked response variables increased significantly at all click rates, although the differences between the 2 groups were slightly smaller than those between the infants with bronchopulmonary dysplasia and the term control subjects. The wave I and III latencies and I-III interval in the infants with bronchopulmonary dysplasia did not show any abnormalities. The slopes of the wave V latency-rate function and I-V and particularly III-V interval-rate functions for the infants with bronchopulmonary dysplasia were significantly steeper than those for both term and healthy, very preterm control subjects. The slope of the III-V/I-III interval ratio-rate function for the infants with bronchopulmonary dysplasia was also significantly steeper than those for the 2 control groups.

CONCLUSIONS

The results suggest poor myelination and synaptic function of the brainstem in infants with bronchopulmonary dysplasia, resulting in impaired functional integrity. In comparison, peripheral neural function was relatively intact.

Reliability of hearing screening in high-risk neonates: Comparative study of otoacoustic emission, automated and conventional auditory brainstem response

OBJECTIVE

To compare the diagnostic reliability of automated transient evoked otoacoustic emissions (a-TEOAE), automated auditory brainstem response (a-ABR) and conventional brainstem auditory evoked potential (BAEP/ABR) for identification of hearing loss in high-risk neonates.

METHODS

Two hundred and six neonatal intensive care unit (NICU) admitted neonates were tested pre-discharge. Follow-up included a-TEOAE in all children, repetition of a-ABR or BAEP if failed in NICU. Sensitivity and specificity were compared and correlated with auditory risk factors.

RESULTS

BAEP had the highest sensitivity (100%) and specificity (90.8%), a-ABR the lowest (88.9% and 70.6%). A statistically significant difference in risk factors for temporary hearing loss was observed between normal and false positive a-TEOAE and BAEP, but not a-ABR outcome. Differences in specificity between a-ABR and a-TEOAE explain the pattern of "absent a-ABR/present a-TEOAE" in 13.8% of ears.

CONCLUSIONS

The BAEP appears the more reliable test for hearing screening of high-risk neonates because of highest sensitivity and specificity and should be used to confirm the diagnosis of "auditory neuropathy" in high-risk neonates. The reliability of a-ABR devices in critically ill neonates needs further investigation.

SIGNIFICANCE

This is, to our knowledge, the first attempt to compare the diagnostic reliability of a-TEOAE, a-ABR and BAEP in high-risk neonates.

Brainstem auditory evoked response at term in preterm infants after perinatal hypoxia-ischaemia

AIM

To examine brainstem auditory function in preterm infants after perinatal hypoxia-ischaemia (HI).

METHODS

Brainstem auditory evoked response (BAER) was studied at 37-42 wk postconceptional age in preterm infants who suffered perinatal HI, and were compared with those in preterm and term infants without any major perinatal problems.

RESULTS

None of the latencies of waves I, III and V in the BAER in preterm infants after perinatal HI differed significantly from those in preterm and term controls. There were also no significant differences in the I-V and I-III interpeak intervals between preterm infants after HI and the controls. However, III-V interval in infants after HI tended to increase, and was significantly longer than in term controls (p<0.01), although it did not differ significantly from that in preterm controls. Similarly, the III-V/I-III interval ratio was greater than in term controls (p<0.05), but was similar to that in preterm controls. All amplitude variables did not differ significantly from the controls.

CONCLUSION

BAER in preterm infants after perinatal HI did not differ significantly from that in preterm infants without perinatal problems, but differed slightly from that in normal term infants. The prolonged III-V interval as compared with the term controls suggests a minor impairment in central auditory function.

Brain-stem auditory function in very preterm infants with chronic lung disease: Delayed neural conduction

OBJECTIVE

To examine brain-stem auditory function at term in very preterm infants who suffered chronic lung disease (CLD).

METHODS

Brain-stem auditory evoked response (BAER) was recorded at term with clicks in 25 very preterm infants with CLD and no concomitant other major perinatal problems.

RESULTS

Compared to those in normal term controls, BAER wave V latency and I-V and III-V interpeak intervals in the CLD infants increased significantly (ANOVA P<0.01-0.001). III-V/I-III interval ratio also increased significantly (P<0.01). The latencies of waves I and III did not differ significantly from the controls. However, no abnormalities were found in BAER wave amplitudes. These BAER findings, obtained at 21/s clicks, were also seen at the rates 51 and 91/s, although the increase in III-V interval tended to be more significant. Click rate-dependent changes in BAER variables in the CLD infants were generally similar to the controls, with slight differences.

CONCLUSIONS

BAER components, mainly reflecting central auditory function, increased significantly. The increase in wave V latency and I-V interval is due to the increase in III-V interval.

SIGNIFICANCE

Neural conduction in the more central portion of the brain-stem auditory pathway is delayed and thus brain-stem auditory function is impaired in CLD infants.

Brain-stem auditory impairment during the neonatal period in term infants after asphyxia: dynamic changes in brain-stem auditory evoked response to clicks of different rates

OBJECTIVE

To explore dynamic changes in brain-stem auditory electrophysiology during the neonatal period in term infants after perinatal asphyxia.

METHODS

Sixty-eight term newborn infants who suffered asphyxia were studied on days 1, 3, 5, 7, 14 and 30 after birth. Brain-stem auditory evoked response (BAER) was recorded with clicks, delivered at 21, 51 and 91 s(-1) and > or =40 dB above BAER threshold of each subject.

RESULTS

During the neonatal period wave I latency in the infants after asphyxia increased slightly while later BAER components changed more significantly. On the first day after birth wave III and V latencies and I-V and III-V intervals increased significantly at all rates of clicks (ANOVA P<0.01-0.001). On day 3, the latencies and intervals increased further. III-V/I-III interval ratio increased at 51 and 91 s(-1), suggesting a relatively more significant increase in III-V interval than in I-III interval at higher rates. Thereafter, wave III and V latencies and all intervals decreased progressively, although these BAER variables were still significantly longer than in normal controls on days 5 and 7 (P<0.05-0.001) On day 30, all latencies and intervals approached near normal values, with a slight increase in wave V latency and I-V and III-V intervals at 51 and 91 s(-1).

CONCLUSIONS

Perinatal asphyxia has a major effect on central auditory function, resulting in acute impairment. The impairment progresses during the first 3 days and then tends towards recovery. By 1 month the impaired auditory function has largely returned to normal. Significant increase in click rates can moderately improve the detection of auditory impairment.

SIGNIFICANCE

After perinatal asphyxia early detection of hypoxic-ischaemic damage to the central auditory system and initialisation of neuroprotective and therapeutic measures during the first hours after birth are critical to prevent or reduce deterioration of central impairment.

Time course of brainstem pathophysiology during first month in term infants after perinatal asphyxia, revealed by MLS BAER latencies and intervals

Dynamic changes in electrophysiology of brainstem auditory neurons during the first month after birth were studied in 51 term infants after perinatal asphyxia using maximum length sequence brainstem auditory evoked responses. The responses were recorded on d 1, 3, 5, 7, 10, 15, and 30 after birth. On d 1, wave III and V latencies and all interpeak intervals increased significantly at all repetition rates of clicks used (91-910/s), especially the higher rates (ANOVA, p < 0.05-0.0001). On d 3, all these latencies and intervals increased further and differed more significantly from the normal control subjects. Thereafter, the latencies and intervals decreased progressively. On d 7, wave V latency and all intervals still differed significantly from the control subjects. These dynamic changes were more significant at higher rates of clicks than at lower rates. On d 10 and 15, all intervals decreased significantly. On d 30, all wave latencies decreased to the values in the normal control subjects on the same day. The intervals also approached normal values, although the III-V and I-V intervals still increased slightly. These results indicate that hypoxic-ischemic brain damage persists during the first week, with a peak on d 3, and recovers progressively thereafter. By 1 mo, the damage has largely returned to normal. Maximum length sequence brainstem auditory evoked responses results correlated well with the stage of hypoxic-ischemic encephalopathy during the first week. The present study revealed a general time course of brainstem pathophysiology after asphyxia, although there were individual variations. Our findings can be used as a reference to monitor cerebral function and help judge the value of neuroprotective or therapeutic interventions. The first week, particularly the first 3 d, is a critical period of hypoxic-ischemic brain damage, and early intervention may prevent or reduce deterioration of the damage.

The pediatric neurologist as expert witness with particular reference to perinatal asphyxia

The frequency of litigation related to alleged medical malpractice is increasing in Canada. For the neurologist, involvement in such litigation most often takes place in the context of acting as an expert witness and, for the pediatric neurologist, the most common clinical situation for which expertise is requested is that of possible perinatal asphyxia. The medical expert's primary role is to provide necessary guidance and assistance to the court, which may permit the rendering of decisions that are scientifically valid. This article will review the attributes of the medical expert witness. Aspects of perinatal asphyxia cases under litigation that commonly require the assistance of pediatric neurology expertise such as etiology, timing, extent of disability and life expectancy will also be reviewed in detail. The aim is to provide for the neurologist a clearer understanding of the responsibilities inherent in this increasing professional role.

Maximum length sequence brainstem auditory evoked responses in term neonates who have perinatal hypoxia-ischemia

Maximum length sequence brainstem auditory evoked response (BAER) was studied within the first week after birth in 28 term neonates who had perinatal hypoxia-ischemia, or asphyxia. In the BAER recorded using conventional averaging techniques (click rate 21/s), the only abnormality was a slight increase in III-V interval, in addition to an increase in wave latencies when including those who had an elevated threshold (t test, all p<0.05). In the maximum length sequence BAER, however, both the III-V and I-V intervals in the asphyxiated infants were significantly increased at all the 91/s, 227/s, 455/s, and particularly 910/s click rates (p<0.05-0.001). The I-III interval was also increased significantly at 455/s and 910/s click rates (both p< 0.05). Wave V amplitude was significantly reduced at all the click rates used (ANOVA, p<0.05-0.001), particularly at 910/s, which sometimes was the only abnormality indicative of brain damage. Both the amplitude ratios V/I and V/III were significantly decreased at 455/s and 910/s click rates (p<0.01 or 0.001). A general trend was that BAER abnormalities after hypoxia-ischemia became more prominent as click rate was increased. Significant abnormalities occurred mainly at very high click rates (455/s and 910/s), which can be achieved using the maximum length sequence technique but not by using conventional averaging techniques. Thus, this technique, which can be used at the cribside, appears to be a better method for the early detection of brain damage after hypoxia-ischemia than using conventional averaging techniques, enhancing the diagnostic value of the BAER.

Prediction of outcome at school age in neonatal intensive care unit graduates using neonatal neurologic tools

Prediction of outcome for neonatal intensive care unit graduates is clinically useful to counsel families effectively and target those who may benefit from early interventions. Evoked potentials have proven prognostic value of neurologic outcomes in early childhood; however, their long-term predictive validity remains to be determined. The objective of this prospective study was to determine the long-term predictive value of three neonatal neurologic assessments: brainstem auditory evoked potentials, somatosensory evoked potentials, and the Einstein Neonatal Neurobehavioral Assessment Scale. Seventy-eight high-risk newborns and 28 healthy controls were recruited and were assessed in the newborn period using these tests. At 8 to 9 years of age, 42 subjects and 13 controls were re-evaluated for developmental progress using a range of psychologic, sensorimotor, and neurologic measures. Findings indicated that the somatosensory evoked potential was most accurate at predicting outcome at school age, with high specificity (83-100%) across all domains tested and good sensitivity (80-100%) for intellectual performance and sensorimotor abilities. The brainstem auditory evoked potential was limited by false-negatives, whereas the neonatal neurobehavioral assessment yielded many false-positives. This study provides new evidence that associations between neonatal somatosensory evoked potentials and developmental sequelae continue to be significant at school age.

Neonatal neurologic prognostication: the asphyxiated term newborn

The pediatric neurologist is often requested to predict the neurologic outcome in an uncertain situation. A common and problematic clinical setting in which this occurs is the asphyxiated term newborn. This report reviews the predictive tools available for prognostication in this situation and formulates a practical paradigm that the authors hope will improve predictive accuracy and lessen uncertainty in this setting.

Multimodality evoked potential findings in infants with congenital heart defects

Evoked potentials are sensitive prognostic tools in young infants at risk for developmental disability. The objective of this prospective study was to determine whether infants with congenital heart defects demonstrate evoked potential abnormalities prior to or following open heart surgery, and to examine the association between these abnormalities and developmental status 1 year following surgery. A consecutive series of newborns (less than 1 month old) and infants (1 month to 2 years old) were recruited. Somatosensory and brain stem auditory evoked potentials were carried out before or after cardiac surgery, or both. One year later, neurologic examination and standardized measures of motor performance and functional independence were carried out. Twenty-seven newborns and 31 infants underwent perioperative somatosensory evoked potential recordings. Results indicate that perioperative somatosensory evoked potential abnormalities were common in newborns (41%) but not in infants (13%) with congenital heart defects. Brainstem conduction times were within normal limits in all subjects; however, 32% presented with mild elevations in hearing thresholds. All newborns with abnormal somatosensory evoked potentials had abnormal neurologic examinations both perioperatively and again 1 year after open heart surgery. Moreover, standardized developmental assessments 1 year following surgery indicate that all newborns with somatosensory evoked potential abnormalities had developmental deficits in one or more domains. Somatosensory evoked potential abnormalities in the perioperative period are common in newborns with congenital heart defects, and are strongly predictive of persistent developmental delay later.

Multimodality evoked potentials as a prognostic tool in term asphyxiated newborns

Hypoxic-ischemic (HI) events may cause permanent brain damage, and it is difficult to predict the long-term neurological outcome of survivors. Multimodality evoked potentials (MEPs), using flash visual (fVEPs), somatosensory (SEPs), and brain-stem auditory evoked potentials (BAEPs) may assess the cerebral function in term neonates. MEPs were recorded in 40 hypoxic-ischemic term or near-term neonates during the first week of life in order to predict the neurological outcome. A 3 point grading system registered either mild, moderate, or severe abnormalities. At 24 months of corrected age, the infants were assessed with a blind protocol to determine neurological development. Grade 0 fVEPs and SEPs were associated with a normal neurological status with 100% (P < 0.001) of the infants. Abnormal SEPs or total grade (VEPs + SEPs) > I were not associated with normal outcomes (P < 0.0001). Normal BAEPs did not predict a normal outcome, but severely abnormal BAEPs did predict an abnormal outcome. A significant correlation was found between EP (VEPs + SEPs) grade (r = 0.9, P < 0.0001), Sarnat stage (r = 0.6, P < 0.001), and clinical outcome. This study confirmed that both fVEPs and SEPs are more accurate as prognostic indicators for term neonates. EPs (VEPs + SEPs) also are more accurate in predicting the ultimate neurological outcome compared with the Sarnat scoring.

Maturation of peripheral and brainstem auditory function in the first year following perinatal asphyxia: a longitudinal study

Maturation of peripheral hearing and auditory brainstem following perinatal asphyxia was investigated by longitudinal recording of brainstem auditory evoked potentials (BAEP) during the first year of life in affected infants. The general maturational course of the BAEP following asphyxia was similar to that in a control group of infants with normal births, although there were some abnormalities in the BAEP Response threshold elevation seen in a few asphyxiated infants improved significantly during the first 3 months. The interpeak intervals in the asphyxiated infants did not differ significantly from that of the control-group infants except in the first month, when the I-V and III-V intervals were significantly prolonged in the severe asphyxia group. In contrast, wave V amplitude and V/I ratio were always smaller when compared to that of the control-group infants. Amplitude reduction of wave V was more sustained than the prolonged I-V interval. Persistent hearing loss and brainstem auditory impairment were seen in 6.8% and 14.6% of the asphyxiated infants, respectively. These findings suggest that asphyxia does not interfere significantly with the maturation of the auditory system in most asphyxiated infants and that sustained peripheral hearing loss and brainstem impairment occur only in a small proportion of affected infants.

Diagnostic and predictive value of auditory evoked responses in preterm infants: II. Auditory evoked responses

In this study, the diagnostic and predictive value of brainstem, middle latency, and cortical auditory evoked responses (BMC-AERs) obtained in the neonatal period in 81 preterm infants was assessed in relation to neurodevelopmental outcome. The preterm infants were neonatally classified according to risk category and gestational age. The BMC-AERs were analyzed with respect to detectability, latencies, and amplitudes as well as derived latency and amplitude measures. At 5 y of age the neurodevelopmental outcome was assessed from neurologic and neuropsychologic evaluations. The results showed that BMC-AER differences mainly correlated with risk category (low risk/high risk) and to some extent with degree of prematurity. In view of these findings the degree of prematurity and the effect of risk category have to be taken into account, when BMC-AERs are applied in the preterm period to predict neurodevelopmental outcome. In this study the BMC-AERs for infants with abnormal neurodevelopmental outcome were scarcely distinguishable from the BMC-AERs for infants with normal neurodevelopmental outcome. Thus far, this and previous reports have indicated that BMC-AERs in preterm infants are useful in maturational studies and with infants showing symptoms related to lesions or dysfunction of the peripheral and/or central auditory system. For predicting neurodevelopmental outcome in preterm infants, BMC-AERs are of limited clinical value.

Sensitivity and specificity of the neonatal brain-stem auditory evoked potential for hearing and language deficits in survivors of extracorporeal membrane oxygenation

OBJECTIVE

We determined the sensitivity and specificity of neonatal brain-stem auditory evoked potentials (BAEP) as markers for subsequent hearing impairment and for developmental problems found later in infancy and childhood.

METHODS

BAEP studies were performed before discharge in infants treated with extracorporeal membrane oxygenation (ECMO), and two specific abnormalities were analyzed: elevated threshold and delayed central auditory conduction. Behavioral audiometry was repeated during periodic follow-up until reliable responses were obtained for all frequencies, and standardized developmental testing was also conducted. The sensitivity and specificity of an elevated threshold on the neonatal BAEP for detecting subsequent hearing loss, and the relationship of any neonatal BAEP abnormality to language or developmental disorders in infancy, were calculated.

RESULTS

Test results for 46 ECMO-treated infants (57.5%) were normal, and those for 34 infants (42.5%) were abnormal, with either elevated wave V threshold, prolonged wave I-V interval, or both on neonatal BAEP recordings. Most significantly, 7 (58%) of the 12 children with subsequent sensorineural hearing loss had left the hospital after showing normal results on threshold tests. There was no significant difference in the frequency of hearing loss between subjects with abnormal (5/21, or 24%) and those with normal BAEP thresholds (7/59, or 12%; Fisher Exact Test, p = 0.28). Therefore the sensitivity of neonatal BAEP testing for predicting subsequent hearing loss was only 42%. Neonatal BAEP specificity for excluding subsequent hearing loss was 76%. In contrast, on language development testing, 19 children demonstrated receptive language delay. Of these children, 12 (63%) had abnormal neonatal BAEP recordings and 7 (37%) had a normal BAEP threshold, normal central auditory conduction test results, or both (p = 0.04).

CONCLUSIONS

Neonatal BAEP threshold recordings were of limited value for predicting subsequent hearing loss common in ECMO-treated survivors. However, an abnormal neonatal BAEP significantly increased the probability of finding a receptive language delay during early childhood, even in those with subsequently normal audiometry findings. Because neonatal ECMO is associated with a high risk of hearing and receptive language disorders, parents should be counseled that audiologic and developmental follow-up evaluations in surviving children are essential regardless of the results of neonatal BAEP testing.

Evoked potentials as predictors of outcome in neonatal intensive care unit survivors: review of the literature

Neonatal intensive care unit survivors are at substantial risk for a range of neurodevelopmental sequelae, and therefore a variety of clinical diagnostic techniques have been evaluated as predictors of outcome. We summarize the prognostic value of evoked potentials in newborns at risk. A review of the literature reveals that brainstem conduction abnormalities in auditory brainstem evoked potentials are associated with neuromotor impairment; however, there are many false negative studies. Visual evoked potentials are highly accurate in predicting neurologic deficits in early childhood in asphyxiated term neonates. Sensitivity and specificity are consistently high for somatosensory evoked potentials in term newborns; however, correlations with outcome in premature infants is controversial. Several studies have compared neonatal findings on neuroimaging studies and evoked potentials, and concordant results between these two tests are highly predictive. However, neurologic sequelae often can most accurately be predicted by visual or somatosensory evoked potentials. Evoked potentials may therefore be a useful adjunct to the clinical investigation and prognostication of outcome in the high risk newborn.

Long-term effect of perinatal and postnatal asphyxia on developing human auditory brainstem responses: brainstem impairment

Long-term effect of perinatal and postnatal asphyxia on the developing auditory brainstem was investigated in children, particularly those who exhibited residual neurodevelopmental deficits, by analyzing the central components of brainstem auditory evoked responses (BAER). The major abnormalities in the BAER were a reduction of wave V amplitude, followed by a decrease in V/I amplitude ratio, while abnormalities in interpeak intervals were relatively rare. These findings suggest that asphyxia could result in residual neural dysfunction of the brainstem but does not appear to exert any major long-term effect on neuronal transmission. BAER abnormalities occurred more frequently in the children with residual neurodevelopmental deficits than those without these deficits after perinatal asphyxia. The occurrence of BAER abnormalities was related to the duration as well as the degree of asphyxia. No significant difference was found in the abnormalities of the central BAER components between the children after perinatal asphyxia and those after postnatal asphyxia, suggesting that perinatal and postnatal asphyxia exerts a similar long-term effect on the developing central nervous system.

Prediction of outcome at school entry in neonatal intensive care unit survivors, with use of clinical and electrophysiologic techniques

OBJECTIVE

To determine the predictive value of multimodality evoked potentials as well as the neonatal neurobehavioral assessment in neonatal intensive care unit survivors at school entry.

STUDY DESIGN

In this prospective study, healthy (n = 24) and high-risk newborn infants (n = 78) were assessed in the newborn period with auditory brain-stem responses (ABRs) and somatosensory evoked potentials (SEPs), as well as the Einstein Neonatal Neurobehavioral Assessment Scale (ENNAS). Healthy and high-risk newborn infants were assessed in a blind fashion at 1, 3, and 5 years of age by a psychologist and a pediatric neurologist. Of those healthy (all 24) and high-risk newborn infants (72/78) with a neonatal ABR, SEP, or both, 62.5% were assessed at 5 years of age with the Wechsler Preschool and Primary Scale of intelligence, the Beery-Buktenica Test of Visual-Motor Integration, the Griffiths Locomotor Subscale, and neurologic examination. Chi-square analyses were carried out on neonatal and outcome measures, and sensitivity, specificity, and predictive values for each of the neonatal tests were ascertained.

RESULTS

The ENNAS and the ABR had good negative predictive value for cognitive (85.7% to 93.3%), locomotor (83.3%), and visual-motor (91.4% to 100%) performance. The ABR had good specificity, whereas the ENNAS was more sensitive. The SEP was an excellent prognostic tool, with high sensitivity (100%) and specificity (80% to 81.3%) for motor as well as cognitive domains. All infants with normal SEPs had favorable outcomes, whereas those with absent potentials did poorly. The SEP abnormalities were associated with findings on neurologic examination in all cases.

CONCLUSIONS

Normal neonatal evoked potentials and ENNAS are associated with favorable outcomes. The SEP most accurately predicts neurodevelopmental status at school entry.

Multimodality evoked responses in the neurological assessment of the newborn

In recent years increased attention has been devoted to evoked potentials (EP) in newborns. This paper reviews the literature and data from our research group in an attempt to assess the diagnostic and prognostic value of evoked responses in the first weeks of life and their use in different age-specific clinical conditions. The results show that EP are a very sensitive measure of the integrity of the sensory pathways. They make it possible to follow normal physiological maturation and the abnormalities of development resulting from neurological lesions. Repeated measurements of visual evoked potentials and somatosensorial evoked potential are prognostically useful in term infants, but seem much more limited in preterm newborns in predicting neurodevelopmental outcome.

Risk for ABR abnormalities in the nursery

The records of 1087 full- and pre-term infants with normal hearing were reviewed for auditory brain-stem response (ABR) abnormalities. Subjects were classified according to various complications common to the newborn. A logistic regression analysis was performed in order to determine the risk of incurring ABR deviations associated with specific diagnoses in the nursery. Infants exposed to cocaine in utero and those with neurological signs or demonstrable brain anomalies were 4-5 times more likely to exhibit deviant ABRs. The synergistic effects of selected predictor variables further increased the risk for abnormal responses depending on gestational age and type of disorder. These results suggest subtle neurologic influences persisting at the time of discharge.

Reliability of parental recall of developmental milestones

The developmental history is a key element of the pediatric evaluation. Precise determination of a child's milestones depends on the parent's recollection of developmental events. As part of a prospective study examining neonatal predictors of outcome, healthy and high-risk newborns were assessed by a neurologist at 1, 3, and 5 years of age. The consistency of a parent's recall of two milestones (i.e., first steps and first meaningful word) was examined at 3 and 5 years. The answers provided by the parent(s) at the first visit (mean/S.D.: 12.67/1.19 months) provided the comparison standard. Twenty-five healthy and 50 high-risk infants had acquired 1 or both developmental skills by the first visit. Of 75, 63 were reexamined at 3 and/or 5 years by the same neurologist. For first steps, excellent correlations were obtained at 3 years (r = 0.74) and modest correlations were determined at 5 years (r = 0.41). The mean difference in age reported between 1 and 3 years was 0.36 +/- 1.81 months, and 0.33 +/- 2.46 months between 1 and 5 years. For first word, correlations were poor at 3 and 5 years (r = 0.27 and r = -0.11, respectively), with mean discrepancies in recall of 2.43 +/- 4.37 months (3-year visit) and 2.74 +/- 5.56 months (5-year visit). Twenty percent (n = 13) of parents reported discrepancies of 6 or more months (mean: 9.4; range: 6-25 months). Furthermore, this error in reporting of first word was later than the correct age in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of gestational age, birth weight, and asphyxia on neonatal neurobehavioral performance

The objectives of this study were to determine the influence of birth weight, gestational age, and asphyxia on neurobehavioral performance at 40 weeks conceptional age, and to demonstrate that this performance may differ in preterm high-risk infants when using low-risk preterm rather than healthy term infant norms. A cross-sectional comparative design was used to compare neurologic behavior in healthy and high-risk newborns at 40 weeks conceptional age using the Einstein Neonatal Neurobehavioral Assessment Scale. Seventy-four high-risk newborns were selected from a consecutive sample of asphyxiated, very-low-birth-weight, and small-for-gestational-age neonates. Controls did not fulfill any of the high-risk criteria and had no pre- or perinatal complications. There were 37 healthy term and 17 low-risk preterm controls. Statistically significant differences occurred between high-risk newborns and term controls for the total score (P < .001) as well as for most individual items (P < .05). Analysis of high-risk subgroups revealed that small-for-gestational-age and term asphyxiated newborns had the most abnormal responses. When comparing test performance between preterm high-risk and term controls, the majority of test items achieved significance (P < .05); however, when compared to low-risk preterm controls, fewer items were abnormal, and the probability level on abnormal items was less significant than expected. This disparity in interpretation of neurobehavioral status in preterm high-risk neonates using a preterm versus term reference sample warrants further investigation. Appropriate normative standards for preterm infants require definition because it may increase the utility of the neonatal neurologic examination and its prognostic value.

Functional interhemispheric asymmetries at birth as demonstrated by somatosensory evoked potentials

Functional cerebral hemispheric asymmetries detectable at birth have been suggested by a number of neuroanatomic, neuroradiologic, and clinical neurophysiologic modalities. The aim of this study was to determine whether functional interhemispheric asymmetries can be identified using electrophysiologic measures. As part of a prospective study, somatosensory evoked potentials following median nerve stimulation were recorded in nine healthy full-term newborns on day 2 or 3 of life, and somatosensory evoked potentials were repeated at 2 and 6 months of age. These children were subsequently examined at 1 and 3 years of age by a pediatric neurologist and all had normal examinations. Handedness was determined at 3 years by questioning the parent and by clinical observation. Three of nine were left-handers. All three left-handers had clearly identifiable neonatal N19 parietal potentials over the right hemisphere. Following right median nerve stimulation, contralateral parietal potentials were absent on two of the three and questionable in the third. Asymmetries were not clearly present in right-handers although only one showed an increased maturation of the right hemisphere relative to the left. At 2 months of age, interhemispheric differences were no longer clearly evident. This data suggests that preferential hemispheric asymmetries are masked by 2 months of age. This differential rate of development demonstrated by neonatal somatosensory evoked potentials may be an early indicator of ultimate handedness.

[Maturation and neurological distress in the newborn]

In the newborn, structural and functional cerebral abnormalities are described as well as clinical manifestations of neurological distress, change with gestational age, and therefore with the degree of central nervous system maturation. The different maturational stages of the cerebral structure, their vascularization and myelinization from the gestational age of 24-25 weeks to the full-term neonate are briefly reported. The cerebral lesions and mechanisms of hypoxoischemic encephalopathy in the full-term neonate are summarized; an analysis of the various clinical symptoms and additional investigations (in particular the electroencephalogram) allows a precise prognosis to be made. In the premature newborn, there are 2 types of cerebral lesions: intraventricular hemorrhage and periventricular leukomalacia. The latter is primarily responsible for neurological sequelae. Clinical manifestations are poor and atypical; data based on complementary procedures (imaging and electroencephalography) allow an accurate evaluation to be made of the damage and neurological prognosis.

Short latency auditory evoked potentials recorded from non-anaesthetized thoroughbred horses

The Brainstem Auditory Evoked Potential (BAEP) is a recording of the electrical activity of the brainstem following an acoustic stimulation. Up to seven peaks may be identified within 10 ms, and are labelled I to VII. The first five of these peaks are of most clinical importance, and in normal horses, peaks I, III and V are always present at stimulus intensities of 70-100 dB. Repeated sampling of clinically normal subjects at different stimulus intensities has enabled mean latency values to be determined for the ipsilateral and contralateral peaks I, III and V, and also for the interpeak latencies (IPLs) at each intensity. The maximum, normal, absolute latency for ipsilateral peak I was 1.86 ms, for peak III, 3.53 ms and for peak V, 5.52 ms. The equivalent contralateral values were 2.50 ms, 4.44 ms and 5.59 ms. The maximum, normal, contralateral IPL for I-III was 1.78 ms, that for III-V was 2.26 ms and for I-V was 3.76 ms. The maximum, normal, contralateral IPLs were 2.17 ms for I-III, 1.41 ms for III-V and 3.32 ms for I-V. If a peak or peaks are absent or delayed, or the IPL is greater than expected, the patient can be determined to have abnormal brainstem or auditory nerve conduction. The amplitudes of peaks I and V were measured, and the ratio of amplitudes was determined, to find the normal V:I values. At a stimulus intensity of 100 dB, the ipsilateral ratio was 0.49 +/- 0.19, and the contralateral value 1.49 +/- 0.48. Dispersal values were also calculated, by dividing the height of the III-V complex by its duration. For a stimulus intensity of 100 dB, the ipsilateral dispersal value was 0.416 +/- 0.104 microV/ms, and the contralateral value of 0.473 +/- 0.074 microV/ms. A range of normal values for both V:I ratio and dispersal were calculated. Height, weight and inter-aural distance were measured, and the relationship of the various peaks and IPLs to these variables was ascertained by statistical analysis. For the ipsilateral values, the correlation between the latency of wave V, and III-V and I-V IPLs and weight were significant (P less than 0.01). Significant correlations were found between weight and the latency of contralateral waves III (P less than 0.05) and V (P less than 0.05) and the I-III (P less than 0.01) and I-V (P less than 0.001) IPLs.(ABSTRACT TRUNCATED AT 400 WORDS)

Prognostic reliability of somatosensory and visual evoked potentials of asphyxiated term infants

The purpose of this study was to determine whether SEPs would improve the predictive power of VEPs for the prognosis of asphyxiated infants. 57 term infants had SEPs and VEPs recorded during the first three days of life, during the first week and at follow-up visits. All survivors have been followed for 18 to 24 months. 34 had a normal outcome, 12 had severe neurological sequelae and 11 died. The SEPs had both high sensitivity (96 per cent) and negative predictive power (97 per cent); normal SEPs virtually guaranteed normal outcome. The VEPs had both a specificity and positive predictive power of 100 per cent; abnormal VEPs guaranteed abnormal outcome. Both together had a higher predictive power than either alone. The combination of VEPs and SEPs yields a powerful means of prognostication for term asphyxiated infants; the results suggest that both be included in the assessment of this population.

A comparison of neurobehavioral performance of healthy term and low-risk preterm infants at term

The neurobehavioral performance of a group of low-risk preterm and healthy term infants was assessed at term using the standardized Einstein Neonatal Neurobehavioral Assessment Scale. There was greater similarity than dissimilarity between the two groups; however, preterm infants demonstrated less consistent following to face and voice, and less sustained rooting and grasp reflexes. Preterm infants were more likely to have a more sustained asymmetric tonic neck reflex, a greater popliteal angle and evidence of tremor. These results support the view that processing capability appears to mature on an intrinsically programmed time- and environment-independent pathway, with environmental exposure challenging this adaptive capacity and modifying performance--predominantly with respect to reflexive elements.

Prediction of the prognosis in neonatal asphyxia by photo-evoked eyelid microvibration

Neonatal asphyxia causes hypoxic-ischemic encephalopathy and may damage the central nervous system. We studied neonatal asphyxia with photo-evoked eyelid microvibration (PEMV) which is a blink reflex elicited by photic stimuli. The latency of PEMV changed according to the severity of encephalopathy and the degree of unconsciousness. All of the neonate who had showed disappearance of PEMV died. When the prolonged latency persisted, the infant had a strong probability of sustaining neurological sequelae. PEMV provides useful information for predicting the outcome of neonatal asphyxia.

Prognostic significance of multimodality evoked response testing in high-risk newborns

Exposure to hypoxic-ischemic events in fetal or neonatal life may lead to permanent brain damage and subsequent neurodevelopmental deficits. Clinical and diagnostic tools have been somewhat helpful in identifying an at-risk group, particularly those patients sustaining significant neurologic sequelae. In this prospective study, the prognostic significance of multimodality evoked responses in high-risk newborns was examined. A group of 44 high-risk newborns, as well as 14 healthy newborns, were tested during the newborn period with auditory brainstem responses and somatosensory evoked responses; these tests were repeated at 2 and 6 months corrected age. A neonatal neurologic examination, the Einstein Neonatal Neurobehavioral Assessment Scale, was also conducted. At 1 year corrected age, both groups were assessed in a blind fashion by a pediatric neurologist and a psychologist to determine neurodevelopmental outcome. Results indicated that somatosensory evoked response abnormalities in particular predict an abnormal neurologic status at 1 year of age. Abnormalities that persisted or worsened correlated with severe neurologic impairment, whereas an abnormal somatosensory evoked response that improved or normalized in infancy was associated with mild to moderate neurologic sequelae. Increased brainstem conduction in the auditory brainstem responses was also associated with neurologic sequelae. Normal findings from auditory brainstem responses and somatosensory evoked responses predicted normal developmental scores in all areas, as well as a normal neurologic outcome at 1 year with negative predictive powers ranging from 85-100%. Evoked response testing appears to be an important adjunct to the neurologic investigation of high-risk newborns.

The effect of gestational age at birth on somatosensory-evoked potentials performed at term

Multimodality-evoked potentials are widely used in newborns to assess the maturation and integrity of the sensory pathways. Reliable normative data are needed to maximize the utility of this technique as a diagnostic and research tool. Several electrophysiologic studies on the maturational changes of the auditory brain-stem response have demonstrated that latency measurements decrease as a function of increasing conceptional age. However, maturational studies of the somatosensory-evoked potential, particularly in low-risk premature infants, are limited. The existing evoked potential literature in healthy newborns proposes that maturation of the central nervous system occurs at a predictable rate, irrespective of a given gestational age at birth. Behavioral studies of premature infants suggest that neurologic development may be altered by early extrauterine exposure. The purpose of this study was to determine whether brain-stem auditory- or somatosensory-evoked potential conduction times were comparable in premature and full-term infants matched for conceptional age. The results of this study suggest that myelination is determined by conceptional age, independent of premature birth.

Transient neurologic abnormalities and BAEPs in high-risk infants

We examined brainstem auditory evoked potentials in 2 neurodevelopmentally different groups of high-risk premature infants during the first year of life. Our 77 patients were considered at birth to be at risk for neurologic disabilities, but were found to have normal development in the second year of life. The patients were divided into 2 groups on the basis of their neurologic findings during the first year of life; 24 of the 77 patients demonstrated transient neurologic abnormalities (group I) and the remaining 53 demonstrated normal neurologic findings through the first year of life (group II). Normative data of brainstem auditory evoked potentials were obtained from 60 low-risk and neurologically normal infants. Group I patients had prolonged III-V and I-V intervals at 2 months of age or younger and poorly detectable waves VI and VII at 5 months of age or younger, compared with control subjects. Wave VI was poorly detected in group II patients only at 35-39 weeks of conceptional age. Brainstem auditory evoked potentials suggested that the patients with transient neurologic abnormalities had transient dysfunction or maturational delay in the brainstem and upper auditory pathway early in the first year of life.

Auditory brainstem evoked response inter-peak latencies in very low birthweight infants

A population of very low birthweight (VLBW) infants consisting of 41 infants (24 female) less than 1000 g birthweight and 108 infants (63 female) 1000-1499 g together with a normative group of 36 full-term infants (18 female) 2400-4500 g birthweight were used to acquire auditory brainstem evoked response data. Inter-peak latency intervals were derived from the response and the data acquired were analysed across a range of related variables. The Wave V-III peak to peak latency interval was found to have significant age-related attributes together with an interactive birthweight effect, however no significant difference was established between the VLBW and normative groups when an age correction factor was applied.