Somatosensory evoked potentials and outcome in perinatal asphyxia

Prognostic value of somatosensory-evoked potentials in the newborn with hypoxic-ischemic encephalopathy after the introduction of therapeutic hypothermia

To establish the ability of somatosensory-evoked potentials (SEPs) to detect neurological damage in neonatal patients with hypoxic-ischemic encephalopathy (HIE) treated with therapeutic hypothermia (TH). Retrospective study including 84 neonates ≥ 36 weeks of gestational age with HIE and TH with SEPs performed in the first 14 days of life. SEPs from the median nerve were performed after completion of TH. Either unilateral or bilateral absence of N20, or unilateral or bilateral latency ≥ 36 ms, was considered pathological. All newborns underwent a cerebral resonance imaging (MRI) at between days 7 and 14 of life and a neurodevelopmental evaluation using the Brunet-Lezine test at two years of age; a global Brunet-Lezine test score < 70 was considered unfavorable. The risk of moderate-to-severe alteration on basal ganglia-thalamic (BGT) and/or white matter areas on MRI for pathological SEPs was as follows: odds ratio 95% IC: 23.1 (6.9-76.9), sensitivity 78.6%, specificity 86.3%, positive predictive value 75.9%, and negative predictive value 88%. The BGT and internal capsule were the areas with the greatest risk of lesion with an altered SEPs: odds ratio 95% IC 93.1 (11.1-777.8). The risk of neurodevelopmental impairment for pathological SEPs was odds ratio 95% IC: 38.5 (4.4-335.3), sensitivity 91.7%, specificity 77.8% positive predictive value 52.4%, and negative predictive value 97.2%.

CONCLUSION

The present study demonstrates the good predictive capacity of SEPs performed in the first two weeks of life in newborns with HIE and TH to detect an increased risk of neuroimaging lesions and neurodevelopmental impairment at two years of age.

WHAT IS KNOWN

• Bilateral absence of the N20 cortical component of somatosensory evoked potentials has been associated with poor neurological outcome in neonates with hypoxic-ischemic encephalopathy.

WHAT IS NEW

• This work confirms the predictive capacity of SEPs by adding two important aspects: the value of latency when interpreting SEPs results and the absence of effect of the hypothermia method used on the results of SEPs.

The clinical effects of cerebral near-infrared spectroscopy monitoring (NIRS) versus no monitoring: a protocol for a systematic review with meta-analysis and trial sequential analysis

BACKGROUND

Multiple clinical conditions are associated with cerebral hypoxia/ischaemia and thereby an increased risk of hypoxic-ischaemic brain injury. Cerebral near-infrared spectroscopy monitoring (NIRS) is a tool to monitor brain oxygenation and perfusion, and the clinical uptake of NIRS has expanded over recent years. Specifically, NIRS is used in the neonatal, paediatric, and adult perioperative and intensive care settings. However, the available literature suggests that clinical benefits and harms of cerebral NIRS monitoring are uncertain. As rates of clinically significant hypoxic-ischaemic brain injuries are typically low, it is difficult for randomised clinical trials to capture a sufficiently large number of events to evaluate the clinical effect of cerebral NIRS monitoring, when focusing on specific clinical settings. The aim of this systematic review will be to evaluate the benefits and harms of clinical care with access to cerebral NIRS monitoring versus clinical care without cerebral NIRS monitoring in children and adults across all clinical settings.

METHODS

We will conduct a systematic review with meta-analysis and trial sequential analysis. We will only include randomised clinical trials. The primary outcomes are all-cause mortality, moderate or severe persistent cognitive or neurological deficit, and proportion of participants with one or more serious adverse events. We will search CENTRAL, EMBASE, MEDLINE, and the Science Citation Index Expanded from their inception and onwards. Two reviewers will independently screen all citations, full-text articles, and extract data. The risk of bias will be appraised using the Cochrane risk of bias tool version 2.0. If feasible, we will conduct both random-effects meta-analysis and fixed-effect meta-analysis of outcome data. Additional analysis will be conducted to explore the potential sources of heterogeneity (e.g. risk of bias, clinical setting).

DISCUSSION

As we include trials across multiple clinical settings, there is an increased probability of reaching a sufficient information size. However, heterogeneity between the included trials may impair our ability to interpret results to specific clinical settings. In this situation, we may have to depend on subgroup analyses with inherent increased risks of type I and II errors.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020202986 . This systematic review protocol has been submitted for registration in the International Prospective Register of Systematic Reviews (PROSPERO) (http://www.crd.york.ac.uk/prospero) on the 12th of October 2020 and published on the 12th of November 2020 (registration ID CRD42020202986 ).

Towards multimodal brain monitoring in asphyxiated newborns with amplitude-integrated EEG and simultaneous somatosensory evoked potentials

BACKGROUND

Somatosensory evoked potentials (SEPs) offer an additional bedside tool for outcome prediction after perinatal asphyxia.

AIMS

To assess the reliability of SEPs recorded with bifrontoparietal amplitude-integrated electroencephalography (aEEG) brain monitoring setup for outcome prediction in asphyxiated newborns undergoing therapeutic hypothermia.

STUDY DESIGN

Retrospective observational single-center study.

SUBJECTS

27 consecutive asphyxiated full- or near-term newborns (25 under hypothermia) that underwent median nerve aEEG-SEPs as part of their clinical evaluation at the neonatal intensive care unit of Helsinki University Hospital.

OUTCOME MEASURES

aEEG-SEP classification (present, absent or unreliable) was compared to classification of SEPs recorded with a full EEG montage (EEG-SEP), and outcome determined from medical records at approximately 12-months-age. Unfavorable outcome included death, cerebral palsy, or severe epilepsy.

RESULTS

The aEEG-SEP and EEG-SEP classifications were concordant in 21 of the 22 newborns with both recordings available. All five newborns with bilaterally absent aEEG-SEPs had absent EEG-SEPs and the four with outcome information available had an unfavorable outcome (one was lost to follow-up). Of the newborns with aEEG-SEPs present, all with follow-up exams available had bilaterally present EEG-SEPs and a favorable outcome (one was lost to follow-up). One newborn with unilaterally absent aEEG-SEP at 25 h of age had bilaterally present EEG-SEPs on the next day, and a favorable outcome.

CONCLUSIONS

aEEG-SEPs recorded during therapeutic hypothermia on the first postnatal days are reliable for assessing brain injury severity. Adding SEP into routine aEEG brain monitoring offers an additional tool for very early outcome prediction after birth asphyxia.

Evaluation of SEPs in asphyxiated newborns using a 4-electrode aEEG brain monitoring set-up

•

Neonatal SEPs can be reliably detected using the 4-electrode aEEG monitoring setup.

•

SEP is discernible in most fullterm newborns with 300 averages.

•

Recording SEPs jointly with aEEG facilitates SEP assessment after birth asphyxia.

Objective

To evaluate the reliability of recording cortical somatosensory evoked potentials (SEPs) in asphyxiated newborns using the 4-electrode setup applied in routine long-term amplitude-integrated EEG (aEEG) brain monitoring and to assess the number of averages needed for reliably detecting the cortical responses.

Methods

We evaluated median nerve SEPs in 50 asphyxiated full-term newborns. The SEP interpretation (present or absent) from the original recordings with 21-electrodes and approximately 600 trials served as the reference. This was compared to SEP classification (absent, present, or unreliable) based on a reduced (300 or 150) number of averages, and to classification based on only four electrodes (F3, P3, F4, P4).

Results

Compared to the original classification, cortical SEPs were uniformly interpreted as present or absent in all 50 newborns with the 4-electrode setup and 600 averages. Reducing number of averages to 300 still resulted in correct SEP interpretation in 49/50 newborns with 21-electrode setup, and 46/50 newborns with 4-electrode setup.

Conclusions

Evaluation of early cortical neonatal SEPs is reliable from the 4-electrode setup commonly used in aEEG monitoring. SEP is discernible in most newborns with 300 averages.

Significance

Adding SEP into routine aEEG monitoring offers an additional tool for early neonatal neurophysiological evaluation.

Neonatal somatosensory evoked potentials persist during hypothermia

AIM

Treatment with therapeutic hypothermia has challenged the use of amplitude-integrated electroencephalography in predicting outcomes after perinatal asphyxia. In this study, we assessed the feasibility and gain of somatosensory evoked potentials (SEP) during hypothermia.

METHODS

This retrospective study comprised neonates from 35 + 6 to 42 + 2 gestational weeks and treated for asphyxia or hypoxic-ischaemic encephalopathy at Helsinki University Hospital between 14 February 2007 and 23 December 2009. This period was partly before the introduction of routine therapeutic hypothermia, which enabled us to include normothermic neonates who would these days receive hypothermia treatment. We analysed SEPs from 47 asphyxiated neonates and compared the results between 23 normothermic and 24 hypothermic neonates.

RESULTS

Our data showed that hypothermia led to SEP latencies lengthening by a few milliseconds, but the essential gain for predicting outcomes by SEPs was preserved during hypothermia. Of the 24 hypothermic neonates, bilaterally absent SEPs were associated with poor outcome in 2/2 neonates, normal SEPs were associated with good outcomes in 13/15 neonates and 5/7 neonates with unilaterally absent or grossly delayed SEPs had a poor outcome.

CONCLUSION

Our findings indicated that SEPs were a reliable tool for evaluating the somatosensory system in asphyxiated neonates in both normothermic and hypothermic conditions.

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.

Early neurophysiology and MRI in predicting neurological outcome at 9-10 years after birth asphyxia

OBJECTIVE

To assess whether early somatosensory evoked potentials (SEP) predict long-term neurodevelopmental outcome in normothermic, full-term infants with mild to moderate neonatal encephalopathy (NE), and to compare their predictive value to already available amplitude integrated EEG (aEEG) and magnetic resonance imaging (MRI).

METHODS

Fifty-six infants with post-asphyxia NE were prospectively recruited, and their SEP, aEEG and MRI data were acquired during the first five days. Follow-up continued to 9-10 years for assessment of neuromotor and neurocognitive development. We analysed SEP latency (N1 component), normality of aEEG background pattern, as well as patterns of injury on the neonatal MRI. Neurological outcome measures at 9-10 years included conventional MRI, Movement-ABC and the WISC-III NL.

RESULTS

A SEP latency <50 ms during the first five days was associated with a normal neuromotor outcome (p < 0.03), and a prolonged day 3 latency was associated with lower childhood IQ (p = 0.02). The presence of multiple seizures in aEEG, as well as a moderate or severe injury on the neonatal MRI was associated with a poor neuromotor score (p = 0.03 and p < 0.01, respectively). Combination of multiple techniques improved prediction of long-term outcome compared to single modality.

CONCLUSION

Early SEPs provide information that is comparable to the already available aEEG and MRI paradigms in the prediction of long-term outcome of full-term infants with mild to moderate neonatal encephalopathy.

SIGNIFICANCE

The present results call for further studies using early SEP to aid early assessment of infants treated with hypothermia.

Somatosensory evoked potentials are of additional prognostic value in certain patterns of brain injury in term birth asphyxia

OBJECTIVE

(a) To relate MRI patterns of brain injury to somatosensory evoked potentials (SEPs), and (b) to determine the prognostic value of SEPs in addition to continuous EEG monitoring (cEEG) and cerebral imaging, in term asphyxiated newborns.

METHODS

Fifty one consecutive neonates were studied. Survivors were followed for at least 2 years. cEEG, started within 24h, was done for ≥ 24 h and scored. SEPs and MRIs were performed in the first week. Brain injury patterns were classified.

RESULTS

Bilaterally abnormal SEPs had a sensitivity of 90% (28/31) and specificity of 85% (17/20) in predicting a poor outcome, defined as death or severe handicap. SEPs were of particular value in predicting outcome in isolated symmetrical white matter injury and predicting the development of hemiparesis in isolated asymmetrical watershed injury. Binary logistic regression analysis revealed a significant relation to outcome separately for cEEG, deep grey matter injury on MRI and SEPs. SEPs provided additional value when added to cEEG and MRI in the model (p=0.034).

CONCLUSIONS

SEPs are of additional prognostic value after term birth asphyxia.

SIGNIFICANCE

In certain patterns of postasphyxial neonatal brain injury like asymmetrical watershed lesions and symmetrical white matter injury, EPs are complementary to information obtained from cEEG and MRI for prognostication.

Bilateral loss of cortical somatosensory evoked potential at birth predicts cerebral palsy in term and near-term newborns

Bilateral loss of cortical somatosensory evoked potential (SEP) is considered the single best indicator of adverse outcome in acute encephalopathy of adult patients and older children. This study determines whether the presence or absence of the neonatal cortical SEP can predict cerebral palsy at two years in survivors of neonatal encephalopathy scored according to Sarnat criteria. We also compare SEPs with visual evoked potentials (VEPs), the EEG and neonatal neurological status. Fifty-nine neonates admitted to the neonatal intensive care unit had SEP, VEP and EEG recordings analysed according to the presence (n=37, 63%) or absence (n=22, 37%) of neonatal encephalopathy (score >or=1). Cortical SEP was always present in the perinatal period in those surviving without major neurological disability, while it was bilaterally absent in all but one patient with a subsequent diagnosis of cerebral palsy. Multivariate analysis using the logistic regression model showed that bilateral loss of cortical SEP and Sarnat Score correctly classified the neurological outcome in all patients. Bilateral absence of cortical SEP indicates early identification of neonates at risk of cerebral palsy indicating that EPs have a clinical role in the workup of neonatal encephalopathy.

The value of brainstem evoked potential in clinical decision of a patient with hypoxic-ischemic encephalopathy

Establishing a prognosis for hypoxic-ischemic encephalopathy during the neonatal period is extremely difficult, as the neuroplasticity of the developing brain makes it almost impossible to measure the affected area. This case report describes a newborn with severe perinatal asphyxia and neonatal neurological syndrome including absent suck reflex. Normal brainstem auditory evoked potential led the diagnosis towards a transitory dysfunction of deglutition, and the subject received daily stimulation in the hospital environment. Suck developed satisfactorily by day of life 30 and the patient was released without having to be tube fed. Neurophysiologic tests can be of value in the clinical decisions and analysis of functional prognosis of patients with hypoxic-ischemic encephalopathy.

Neonatal SEP - back to bedside with basic science

Scalp-recorded somatosensory evoked potentials (SEPs) have been successfully used in neonatal assessment for several decades. The current routine SEP paradigm is markedly predictive for future cerebral palsy (CP) or other neurocognitive sequelae in brain-injured babies. Recent advances in basic science have dramatically increased our knowledge about structural-functional development of SEP-related brain mechanisms. It has thereby become apparent that preterm SEP differs from that in more mature counterparts in that it also comprises responses from transient brain structures, and hence being unique to the preterm period. It is now obvious also that several aspects in the current SEP paradigm, ranging from the type of stimulation to the methods of recording and analysis, are suboptimal for preterm babies. Recent progress in recording and analysis techniques have made it possible to combine SEP studies with EEG recordings, as well as to implement advanced analyses (e.g. time-frequency analysis) into routine practice. This review summarizes literature from relevant areas in basic science, and proposes a novel, integrated approach in neonatal SEP studies in order to significantly increase the fidelity of testing somatosensory system.

Neurologic outcome in children after extracorporeal membrane oxygenation: prognostic value of diagnostic tests

This report presents the long-term (36 months) neurologic outcome in 12 neonates and 9 children who survived after extracorporeal membrane oxygenation and attempts to identify its prognostic indicators through a prospective study in the pediatric intensive care unit of a university hospital. Outcome assessment, neurodevelopmental tests, electroencephalogram, auditory evoked potentials, visual evoked potentials, and somatosensory evoked potentials, cerebral sonography, or cerebral tomography were evaluated at the end of bypass and at 6, 12, 24, and 36 months after extracorporeal membrane oxygenation. "Before extracorporeal membrane oxygenation" variables (oxygenation index, pH, oxygen arterial partial pressure) and "during extracorporeal membrane oxygenation" variables (pH, oxygen arterial partial pressure, duration of bypass, clotting activated time, electroencephalogram) were also analyzed. A negative neurologic outcome (Glasgow Outcome Score different from "good recovery" or neurodevelopmental score less than 70) 12 months after extracorporeal membrane oxygenation was documented in 8.3% of neonates and in 30% of children who survived. There was no further change in subsequent evaluations (24 and 36 months follow-up). The most abnormal electroencephalogram during extracorporeal membrane oxygenation, the first electroencephalogram, neuroimaging score, and somatosensory evoked potentials after extracorporeal membrane oxygenation treatment were associated with negative neurologic outcome. The study documented that neonates and children treated with extracorporeal membrane oxygenation require long-term follow-up; electroencephalogram, neuroimaging score, and somatosensory evoked potentials have prognostic value for abnormal neurologic outcome.

Long-term developmental outcome of asphyxiated term neonates

Asphyxia remains one of the main causes of later disability in term infants. Despite many publications identifying possible predictors of outcome in this population of interest, little is known of the long-term developmental outcome of asphyxiated term neonates. Observational studies have largely focused on short-term outcomes, with an emphasis on significant neurologic sequelae and intellectual impairments. This article reviews the literature that has described the developmental outcome of asphyxiated term newborns. As part of this review, we have also highlighted the evolution of the definition of asphyxia and delineated appropriate markers that should be used in future research on this population.

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.

Selection of babies for intervention after birth asphyxia

Based on animal experiments, the therapeutic window for neonates with signs of perinatal hypoxia-ischaemia is probably less than 6 h, and early selection of patients is of utmost importance. In term neonates, fetal heart rate and blood flow patterns, the Apgar score, and other clinical scoring systems are insufficient to select patients for intervention, whereas umbilical artery pH<7.0 combined with umbilical arteriovenous differences in PCO(2), lactate/pyruvate ratios in cord blood, and CSF interleukin-1beta have a better predictive value. At present, neurophysiological methods such as (amplitude-integrated) EEG and evoked potentials have the best predictive value. In preterm neonates, lactate/pyruvate and uric acid measurements in cord blood, as well as neurophysiology appear to be helpful to predict brain injury, and might be used to select patients for intervention.

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.

Amplitude integrated EEG 3 and 6 hours after birth in full term neonates with hypoxic-ischaemic encephalopathy

AIM

To assess the prognostic value of amplitude integrated EEG (aEEG) 3 and 6 hours after birth.

METHODS

Seventy three term, asphyxiated infants were studied (from two different centres), using the Cerebral Function Monitor (CFM Lectromed). The different aEEG tracings were compared using pattern recognition (flat tracing mainly isoelectric (FT); continuous extremely low voltage (CLV); burst-suppression (BS); discontinuous normal voltage (DNV); continuous normal voltage (CNV)) with subsequent outcome.

RESULTS

Sixty eight infants were followed up for more than 12 months (range 12 months to 6 years). Twenty one out of 68 infants (31%) showed a change in pattern from 3 to 6 hours, but this was only significant in five cases (24%). In three this changed from BS to CNV with a normal outcome. One infant showed a change in pattern from CNV to FT and had a major handicap at follow up. Another infant showed a change in pattern from DNV to BS, and developed a major handicap at follow up. The other 16 infants did not have any significant changes in pattern: 11 infants had CLV, BS, or FT at 3 and 6 hours and died (n = 9) in the neonatal period or developed a major handicap (n = 2). Five infants had a CNV or DNV pattern at 3 and 6 hours, with a normal outcome. The sensitivity and specificity of BS, together with FT and CLV, for poor outcome at 3 hours was 0.85 and 0.77, respectively; at 6 hours 0.91 and 0.86, respectively. The positive predictive value (PPV) was 78% and the negative predictive value (NPV) 84% 3 hours after birth. At 6 hours the PPV was 86% and the NPV was 91%.

CONCLUSION

aEEG could be very useful for selecting those infants who might benefit from intervention after birth asphyxia.

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.

The predictive value of cranial ultrasound and of somatosensory evoked potentials after nerve stimulation for adverse neurological outcome in preterm infants

Thirty-nine preterm infants were studied to compare the predictive value of somatosensory evoked responses (SEPs) following median-nerve and posterior tibial-nerve stimulation with the predictive value of cranial ultrasound. With regard to the SEP, a normal median-nerve response was by no means a guarantee of a normal outcome. A normal posterior tibial-nerve response, however, almost guaranteed a normal outcome, but the test was very time consuming and the number of false positive responses was high (sensitivity 95.6%, specificity 50%). The presence of parenchymal involvement, either due to a haemorrhage or cystic leukomalacia predicted cerebral palsy with a sensitivity of 95.6% and specificity of 68.5%. The combination of an abnormal posterior tibial response and the presence of parenchymal brain lesions had the best predictive value with a sensitivity of 91.3% and a specificity of 81.2%. These results show that, although posterior tibial-nerve responses have a better predictive value than median-nerve responses, these values were lower than that of cranial ultrasound. The best prediction was obtained when a combination of posterior-tibial responses and cranial ultrasound was used.

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.

Use of evoked potentials in preterm neonates

This paper has reviewed the techniques used for recording evoked potentials in the premature infant and the early developmental changes. The maturational changes in the evoked potentials, including morphological changes, and the very rapid latency changes within the first months of life, provide an invaluable means for assessing and monitoring development within the central nervous system. The maturational changes are such that normative values are requisite, and the norms must take into account both the infant's gestational age at birth as well as the postnatal age. These norms can then be used to aid in the assessment of gestational age, and whether there has or has not been normal maturational development, either in utero or during the postnatal preterm period. Evoked potentials are of increasing value clinically in preterm neonates, primarily because of the difficulty in obtaining reliable neurological evaluation of these infants. Median nerve SEPs may provide reliable information in preterm infants at risk of PVL, and when recorded in the second week of life, predict cerebral palsy. PTN SEPs seem to be even more reliable indicators of outcome, but the difficulty in obtaining them in preterm infants needs to be taken into consideration. Further study is needed in some areas, such as in apnoeic preterm babies clearly to establish the role that evoked potentials (in this case BAEPs) may have in understanding both the aetiology and the clinical course of this dysfunction. In other conditions, such as delayed intrauterine growth, that may lead to neurological sequelae, evoked potentials can provide objective CNS assessment. Evoked potentials may also prove useful in the monitoring of treatment modalities for preterm infants. The evoked potentials are a valuable adjunct in the assessment of preterm neonates and, as their value is recognised, we expect their use to increase.

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.

Predictive value of early neuroimaging, pulsed Doppler and neurophysiology in full term infants with hypoxic-ischaemic encephalopathy

To evaluate their prognostic value, five different non-invasive techniques were used on 34 full term infants with hypoxic-ischaemic encephalopathy (HIE) within six hours of delivery. Cranial ultrasonography, the resistance index (RI) of the middle cerebral artery obtained with Doppler ultrasonography, somatosensory evoked potentials (SEPs), visual evoked potentials (VEPs) and the cerebral function monitor (CFM) were used. According to the criteria of Sarnat, 11 infants developed mild, seven moderate, and 16 severe encephalopathy. The CFM had the highest positive (PPV 84.2%) and negative predictive value (NPV 91.7%). All but one of the infants with a continuous pattern had a good outcome. The CFM of 11 cases with a suppression-burst pattern changed to a continuous pattern over 24 to 48 hours in four infants, and was associated with a normal outcome in three. All five cases with an isoelectric CFM died. The SEPs also provided useful information (PPV 81.8%; NPV 91.7%). VEPs were often delayed during the first hours or life and did not carry a poor prognosis in five of 14 cases (PPV 77.3%). Both ultrasonography and Doppler RI were of little value, as they were almost always normal at this early stage. In 34 full term infants with HIE, studied within 6 hours of life, the CFM and SEPs provided the most useful information about the expected course of encephalopathy and subsequent neurodevelopmental outcome.

Somatosensory evoked potentials predict neurologic outcome in full-term neonates with asphyxia

OBJECTIVE

To investigate the ability of somatosensory evoked potentials (SSEP) to predict neurologic outcome in term neonates with birth asphyxia.

METHODOLOGY

Upper limb SSEP were performed on nine infants of 1-7 weeks of age who had perinatal asphyxia and an encephalopathy still present at 7 days of age. Comparison was made between the cranial ultrasound, electroencephalogram (EEG), SSEP and neurologic outcome at 9-36 months.

RESULTS

Normal SSEP were found in four infants, all of whom were normal on neurologic follow up at 9-12 months. Neonatal EEG performed on two out of four of these infants were also normal, while cerebral oedema was seen on cranial ultrasound in three of the four studies. No SSEP response was seen initially in three infants, all of whom had adverse outcomes (one death, two with spastic diplegia). In contrast, their neonatal EEG had shown normal background rhythms, while two of the three cranial ultrasounds revealed oedema. For two infants the initial SSEP was absent over one hemisphere and just present over the other. Both children were abnormal on follow up at 10-12 months but did not have a hemiparesis.

CONCLUSIONS

Upper limb SSEP appear more sensitive than EEG or cranial ultrasounds in predicting the short term neurologic outcome of neonates with asphyxia.

Median nerve somatosensory evoked potentials in children receiving ECMO

Somatosensory evoked potentials (SEPs) were recorded from 11 patients receiving venoarterial extracorporeal membrane oxygenation (ECMO). Cortical responses recorded from the right and left hemispheres were compared to those from 2 other groups of children who were not receiving ECMO. One group consisted of 99 brain-injured patients, while the other consisted of a group of 17 neurologically normal controls. SEP responses from each hemisphere were categorized into 3 grades based on the N20 component--normal latency, abnormal (latency increased > 3 S.D.), or absent. For ECMO patients, 15% of tests disclosed a disagreement between the right and left hemispheres, while 27% of tests from the control group revealed a disagreement between the right and left hemispheres. SEPs were normal over the right hemisphere in 9 patients. Central conduction times obtained from the right and left hemispheres were similar in ECMO patients and were not different from those recorded from a group of patients suffering hypoxic-ischemic injuries and a group of normal controls who did not receive ECMO. The results of this pilot study suggest that SEPs may be employed to evaluate ECMO patients as they are in other brain-injured patients.

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.

Cerebral function monitoring: a method of predicting outcome in term neonates after severe perinatal asphyxia

The cerebral function monitor (CFM), a simplified one-channel EEG monitor, was evaluated in predicting outcome after severe perinatal asphyxia in 38 term infants. Survivors were followed until 1.5-2.5 years of age. All those 17 infants who survived without major neurological handicap showed continuous activity on the CFM trace during the first and/or second day of life. Twenty of the 21 infants who either died or developed severe neurological damage had burst suppression or paroxysmal activity on the first or second day of life. Thus cerebral function monitoring can be a valuable tool in predicting prognosis for infants with severe perinatal asphyxia.

Somatosensory evoked potentials following posterior tibial nerve stimulation predict later motor outcome

Posterior tibial nerve somatosensory evoked potentials (PTN-SEPs) were performed on 50 neonates at high risk of future neurodevelopmental impairment just before their discharge from the neonatal intensive-care unit. The close association of sensory pathways with motor tracts and the need for sensory input and integration for normal motor functioning would indicate that CNS lesions producing motor deficits may be detected by this method. Follow-up of these infants revealed a highly significant relationship between bilaterally abnormal PTN-SEPs and the presence of cerebral palsy at three years of age. Normal PTN-SEPs were associated with a normal outcome in 24 of 25 infants. In this group of neonates, PTN-SEPs were more predictive than cranial ultrasound.

Cortical sensory evoked potentials and communicative forebrain functions

Cortical evoked potentials were measured to visual, auditory and somatosensory stimuli in 20 subjects with serious neurodevelopmental impairments due to various etiologies. The results were compared with behavioral observations to find out whether the absence/presence of the responses corresponded to the level of social functioning. No cortical evoked potentials were elicited in two subjects, responses to the stimulation of one modality were missing in three subjects (retinal b-waves and brainstem auditory and somatosensory evoked potentials were, however, preserved in them). No communicative behavior was observed in subjects with absent responses. Ten subjects had marked deviations in the evoked potentials, the behavioral observations in them, ranging from no communication to sentenced speech. Five subjects had normal response patterns and they showed a great variety of communicative skills, including speech. The results support the view that bilateral loss of cortical somatosensory, visual, and auditory evoked potentials is a sign of loss of neural substrates of communication.

Prediction of neurodevelopmental outcome in the preterm infant: short latency cortical somatosensory evoked potentials compared with cranial ultrasound

One hundred and twenty six preterm infants, with a gestational age of 34 weeks or less, were studied to compare the predictive value of somatosensory evoked potentials (SEPs) with that of cranial ultrasound. A normal N1 latency was no guarantee of a normal outcome, nor did a persistently delayed N1 latency always correlate with a poor outcome. As a predictor of cerebral palsy, SEPs had a sensitivity of 44% and a specificity of 92%. The presence of a large haemorrhage (grade IIb/III) or cystic leukomalacia on cranial ultrasound predicted cerebral palsy with a sensitivity of 73.6% and a specificity of 83.1%. These results demonstrate that the role of SEPs recorded after median nerve stimulation is limited in preterm infants.