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

Asymmetry in sleep spindles and motor outcome in infants with unilateral brain injury

AIM

To determine whether interhemispheric difference in sleep spindles in infants with perinatal unilateral brain injury could link to a pathological network reorganization that underpins the development of unilateral cerebral palsy (CP).

METHOD

This was a multicentre retrospective study of 40 infants (19 females, 21 males) with unilateral brain injury. Sleep spindles were detected and quantified with an automated algorithm from electroencephalograph records performed at 2 months to 5 months of age. The clinical outcomes after 18 months were compared to spindle power asymmetry (SPA) between hemispheres in different brain regions.

RESULTS

We found a significantly increased SPA in infants who later developed unilateral CP (n=13, with the most robust interhemispheric difference seen in the central spindles. The best individual-level prediction of unilateral CP was seen in the centro-occipital spindles with an overall accuracy of 93%. An empiric cut-off level for SPA at 0.65 gave a positive predictive value of 100% and a negative predictive value of 93% for later development of unilateral CP.

INTERPRETATION

Our data suggest that automated analysis of interhemispheric SPA provides a potential biomarker of unilateral CP at a very early age. This holds promise for guiding the early diagnostic process in infants with a perinatally identified brain injury.

WHAT THIS PAPER ADDS

Unilateral perinatal brain injury may affect the development of electroencephalogram (EEG) sleep spindles. Interhemispheric asymmetry in sleep spindles can be quantified with automated EEG analysis. Spindle power asymmetry can be a potential biomarker of unilateral cerebral palsy.

Continous somatosensory evoked potentials and brain injury in neonatal hypoxic-ischaemic encephalopathy treated with hypothermia

AIM

To explore whether continuous somatosensory evoked potentials (SEPs) monitoring and video electroencephalograms (VEEG) accurately predict lesions observed on brain magnetic resonance imaging (MRI) in neonates with hypoxic-ischaemic encephalopathy (HIE) receiving therapeutic hypothermia.

METHOD

This prospective study included 31 neonates (16 males, 15 females; mean [SD] gestational age 39 weeks [1.67]) who received therapeutic hypothermia for HIE. Therapeutic hypothermia was provided for 72 hours, with a target temperature of 33.0°C to 34.0°C and this was followed by a rewarming rate of approximately 0.5°C per hour, up to 36.5°C. SEPs and VEEG were evaluated simultaneously and continuously for 1 hour under normothermic conditions. MRI was carried out at a mean (SD) age of 6 (2) days.

RESULTS

Our results showed a statistically significant correlation between continuous SEP and MRI scores (r=0.37, p=0.03), but not between the VEEG and MRI scores (r=0.30, p=0.09). Receiver operating characteristic analysis confirmed that continuous SEPs were highly specific and sensitive at predicting MRI abnormalities, whereas the VEEG had high specificity but low sensitivity.

INTERPRETATION

Continuous monitoring of SEPs could provide early and important prognostic information in neonates with HIE.

WHAT THIS PAPER ADDS

Early continuous somatosensory evoked potential (SEP) monitoring is correlated with hypoxic-ischaemic encephalopathy (HIE) lesions. Video electroencephalograms (VEEGs) are associated with lesions diagnosed after magnetic resonance imaging. Both showed high specificity, but VEEGs did not show high sensitivity. Continuously monitoring SEPs provides important information about HIE.

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.

Prognostic Risk Factors for Severe Outcome in the Acute Phase of Neonatal Hypoxic-Ischemic Encephalopathy: A Prospective Cohort Study

In the first days after birth, a major focus of research is to identify infants with hypoxic-ischemic encephalopathy at higher risk of death or severe neurological impairment, despite therapeutic hypothermia (TH). This is especially crucial to consider redirection of care, according to neonatal outcome severity. We aimed to seek associations between some neonatal routine parameters, usually recorded in Neonatal Intensive Care Units, and the development of severe outcomes. All consecutive patients prospectively recruited for TH for perinatal asphyxia, born between February 2009 and July 2016, were eligible for this study. Severe outcome was defined as death or major neurological sequelae at one year of age. Among all eligible neonates, the final analysis included 83 patients. Severe outcome was significantly associated with pH and base excess measured in the first hour of life, mode of delivery, Apgar score, Sarnat and Sarnat score, electroencephalogram-confirmed neonatal epileptic seizures, and antiepileptic therapy. Studying univariate analysis by raw relative risk (RR) and 95% confidence intervals (CI), severe outcome was significantly associated with pH (p = 0.011), Apgar score (p = 0.003), Sarnat score (p < 0.001), and Caesarian section (p = 0.015). Conclusions. In addition to clinical examination, we suggest a clinical-electroencephalographic protocol useful to identify neonates at high neurological risk, available before rewarming from TH.

Sensorimotor Integration in Childhood Dystonia and Dystonic Cerebral Palsy-A Developmental Perspective

Dystonia is a disorder of sensorimotor integration, involving dysfunction within the basal ganglia, cortex, cerebellum, or their inter-connections as part of the sensorimotor network. Some forms of dystonia are also characterized by maladaptive or exaggerated plasticity. Development of the neuronal processes underlying sensorimotor integration is incompletely understood but involves activity-dependent modeling and refining of sensorimotor circuits through processes that are already taking place in utero and which continue through infancy, childhood, and into adolescence. Several genetic dystonias have clinical onset in early childhood, but there is evidence that sensorimotor circuit development may already be disrupted prenatally in these conditions. Dystonic cerebral palsy (DCP) is a form of acquired dystonia with perinatal onset during a period of rapid neurodevelopment and activity-dependent refinement of sensorimotor networks. However, physiological studies of children with dystonia are sparse. This discussion paper addresses the role of neuroplasticity in the development of sensorimotor integration with particular focus on the relevance of these mechanisms for understanding childhood dystonia, DCP, and implications for therapy selection, including neuromodulation and timing of intervention.

Consensus protocol for EEG and amplitude-integrated EEG assessment and monitoring in neonates

The aim of this work is to establish inclusive guidelines on electroencephalography (EEG) applicable to all neonatal intensive care units (NICUs). Guidelines on ideal EEG monitoring for neonates are available, but there are significant barriers to their implementation in many centres around the world. These include barriers due to limited resources regarding the availability of equipment and technical and interpretive round-the-clock personnel. On the other hand, despite its limitations, amplitude-integrated EEG (aEEG) (previously called Cerebral Function Monitor [CFM]) is a common alternative used in NICUs. The Italian Neonatal Seizure Collaborative Network (INNESCO), working with all national scientific societies interested in the field of neonatal clinical neurophysiology, performed a systematic literature review and promoted interdisciplinary discussions among experts (neonatologists, paediatric neurologists, neurophysiologists, technicians) between 2017 and 2020 with the aim of elaborating shared recommendations. A consensus statement on videoEEG (vEEG) and aEEG for the principal neonatal indications was established. The authors propose a flexible frame of recommendations based on the complementary use of vEEG and aEEG applicable to the various neonatal units with different levels of complexity according to local resources and specific patient features. Suggestions for promoting cooperation between neonatologists, paediatric neurologists, and neurophysiologists, organisational restructuring, and teleneurophysiology implementation are provided.

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.

Prognostic Value of Clinical Tests in Neonates With Hypoxic-Ischemic Encephalopathy Treated With Therapeutic Hypothermia: A Systematic Review and Meta-Analysis

Background and Objective: There remains an unmet clinical need for markers that predict outcomes in the hypothermia-treated (HT) infants with HIE. The aim of this meta-analysis was to investigate the prognostic accuracy of currently available clinical tests performed in the immediate post-natal period for predicting neurological outcomes between 18 months and 3 years of age in HT near-term and term infants with perinatal asphyxia and HIE.

Methods: A comprehensive review of the Embase, Cochrane library, and PubMed databases was performed to identify studies that evaluated the prognostic value of clinical tests for neurological outcomes in HT near-term and term infants with perinatal asphyxia and hypoxic-ischemic encephalopathy. Pooled sensitivity and specificity with corresponding 95% confidence intervals and area under the receiver operating characteristic (ROC) curve (AUC) were calculated.

Results: Of the 1,144 relevant studies, 26 studies describing four clinical tests conducted in 1458 HT near-term or term infants were included. For predicting an unfavorable neurological outcome, of the imaging techniques, MRI within 2 weeks of birth performed best on sensitivity 0.85 (95% CI 0.79–0.89), specificity 0.72 (95% CI 0.66–0.77), and AUC 0.88; among the neurophysiological tests, multichannel EEG (Electroencephalogram) demonstrated the sensitivity 0.63 (95% CI 0.49–0.76), specificity 0.82 (95% CI 0.70–0.91), and AUC 0.88, and for aEEG (amplitude-integrated electroencephalography) background pattern pooled sensitivity, specificity and AUC were 0.90 (95% CI 0.86–0.94), 0.46 (95% CI 0.42–0.51), and 0.78 whereas for SEPs (Somatosensory evoked potentials), pooled sensitivity and specificity were 0.52 (95% CI 0.34–0.69), 0.76 (95% CI 0.63–0.87), and AUC 0.84, respectively.

Conclusions: In the wake of the era of TH, MRI and neurophysiological tests (aEEG or EEG) were promising predictors of adverse outcomes, while SEPs need high-quality studies to confirm the findings. Continued follow-up of the children and well-designed large prospective studies are essential to determine whether these benefits are maintained in later childhood.

Delayed neonatal visual evoked potentials are associated to asymmetric growth pattern in twins

OBJECTIVES

To study the association between intrauterine growth and visual pathways maturation by neonatal visual evoked potentials (VEPs) in twins, in view of a possible prognostic role.

METHODS

Seventy-four twin neonates from 37 pregnancies were selected based on gestational age of more than 30 weeks and uneventful perinatal clinical course. Flash VEPs were recorded at the same postmenstrual age in each twin pair. The association between P2 latency and anthropometric variables at birth was analyzed by comparison within each twin pair and regarding each variable as ordered difference between the two twins.

RESULTS

Analysis of differences within each twin pair highlighted that inter-twin difference in P2 latency was significantly related to difference in ponderal index (PI) (p = 0.048). Expressing the difference in latency as a categorical binary variable, the correlation was significant for both difference in PI, (median difference = -0.36, 95% CI -0.54 to -0.14, p = 0.001) and difference in body mass index (BMI), (median difference = -1.06, 95% CI -1.74 to -0.29, p = 0.006).

CONCLUSIONS

Lower values of PI and BMI differences are associated to delayed VEP latency in twin pairs.

SIGNIFICANCE

VEP latency suggests reduced myelination of visual pathways when difference in growth pattern occurs in twins.

Cortical responses to tactile stimuli in preterm infants

The conventional assessment of preterm somatosensory functions using averaged cortical responses to electrical stimulation ignores the characteristic components of preterm somatosensory evoked responses (SERs). Our study aimed to systematically evaluate the occurrence and development of SERs after tactile stimulus in preterm infants. We analysed SERs performed during 45 electroencephalograms (EEGs) from 29 infants at the mean post-menstrual age of 30.7 weeks. Altogether 2,087 SERs were identified visually at single-trial level from unfiltered signals capturing also their slowest components. We observed salient SERs with a high-amplitude slow component at a high success rate after hand (95%) and foot (83%) stimuli. There was a clear developmental change in both the slow wave and the higher-frequency components of the SERs. Infants with intraventricular haemorrhage (IVH; eleven infants) had initially normal SERs, but those with bilateral IVH later showed a developmental decrease in the ipsilateral SER occurrence after 30 weeks of post-menstrual age. Our study shows that tactile stimulus applied at bedside elicits salient SERs with a large slow component and an overriding fast oscillation, which are specific to the preterm period. Prior experimental research indicates that such SERs allow studying both subplate and cortical functions. Our present findings further suggest that they might offer a window to the emergence of neurodevelopmental sequelae after major structural brain lesions and, hence, an additional tool for both research and clinical neurophysiological evaluation of infants before term age.

Preterm Perinatal Hypoxia-Ischemia Does not Affect Somatosensory Evoked Potentials in Adult Rats

Somatosensory evoked potentials (SSEPs) are a valuable tool to assess functional integrity of the somatosensory pathways and for the prediction of sensorimotor outcome in perinatal injuries, such as perinatal hypoxia-ischemia (HI). In the present research, we studied the translational potential of SSEPs together with sensory function in the male adult rat with perinatal HI compared to the male healthy adult rat. Both somatosensory response and evoked potential were measured at 10-11 months after global perinatal HI. Clear evoked potentials were obtained, but there were no group differences in the amplitude or latency of the evoked potentials of the preceding sensory response. The bilateral tactile stimulation test was also normal in both groups. This lack of effect may be ascribed to the late age-of-testing and functional recovery of the rats.

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.

Evoked potentials predict psychomotor development in neonates with normal MRI after hypothermia for hypoxic-ischemic encephalopathy

OBJECTIVES

To assess the prognostic role of evoked potentials (EP) in neonates with normal magnetic resonance imaging (MRI) after therapeutic hypothermia (TH) for hypoxic-ischemic encephalopathy (HIE).

METHODS

Thirty-five neonates recruited for TH because of HIE, having normal neonatal MRI, performed neonatal somatosensory (SEP), visual (VEP) evoked potentials and electroencephalogram (EEG). The effect of SEP, VEP or EEG abnormalities on Griffith's developmental scales at 12 and 24 months was measured; positive (PPV) and negative (NPV) predictive value, sensitivity, specificity and accuracy were calculated.

RESULTS

At 24 months, 28% had global psychomotor impairment and 57% had isolated impairments. VEP abnormality was associated with impaired hearing-language score (p = 0.002) and performance score (p < 0.0001). VEP achieved best PPV (0.91, 95% C.I. 0.62-0.99) and specificity (0.93, 95% C.I. 0.70-0.99). The combination of neurophysiological tests achieved the best NPV (0.85, 95% C.I. 0.58-0.96), sensitivity (0.90, 95% C.I. 0.70-0.97), overall accuracy (0.83, 95% C.I. 0.67-0.92).

CONCLUSIONS

Psychomotor sequelae may occur in survivors of neonatal HIE with normal MRI. VEP is the single best neurophysiological prognostic marker but the combination of neurophysiological tests has a better value.

SIGNIFICANCE

When facing the challenge of neurodevelopmental prognosis in infants with normal MRI after TH, EPs are useful prognostic tools, complementary to EEG.

Bilateral loss of cortical SEPs predict severe MRI lesions in neonatal hypoxic ischemic encephalopathy treated with hypothermia

OBJECTIVE

The introduction of therapeutic hypothermia for neonatal hypoxic-ischemic encephalopathy calls for reevaluation of the prognostic role of somatosensory evoked potentials (SEPs).

METHODS

Among 80 consecutive neonates undergoing hypothermia for hypoxic-ischemic encephalopathy, 58 performed SEPs and MRI at 4-14 days of life and were recruited in this multicenter study. SEPs were scored as: 0 (bilaterally/unilaterally recorded N20) or 1 (bilaterally absent N20). The severity of brain injury was scored using MRI.

RESULTS

Bilaterally absent N20 was observed in 10/58 neonates (17%); all had moderate/severe MRI abnormalities; 36/48 neonates (75%) with score 0 at SEPs had normal MRI. The positive predictive value of SEPs on MRI outcome was of 1.00, while the negative predictive value 0.72, sensitivity 0.48, specificity 1.00, with an accuracy of 0.78 (p < .001).

CONCLUSIONS

Bilateral absence of cortical SEPs predicts moderate/severe MRI pattern of injury.

SIGNIFICANCE

Therapeutic hypothermia does not seem to significantly affect prognostic reliability of SEPs.

Multimodal neurophysiological monitoring in healthy infants born at term: normative continuous somatosensory evoked potentials data

AIM

To describe accurate, standardized 1h-multimodal neurophysiological monitoring (1h-MNM), while simultaneously recording VEEG, aEEG, and SEP-C bilaterally from median nerves, and to collect neonatal normative SEP-C data related to behavioural states.

METHOD

Twenty healthy, term newborn infants (13 males, 7 females; gestational age 37-42wks; mean 39.6wks, standard deviation [SD] 1.3wks) underwent 1h-MNM within 2 days of life, with focus on recording of the SEP-C (band-pass setting 1-100 Hz, rate of stimulation 1.1 Hz, 50 alternate stimuli).

RESULTS

1h-MNM was easily obtained with identification of cervical (N13) and cortical (N1, P1) SEP-C responses in all infants. SEP-C minimal and maximum N1 latencies/N1-P1 amplitudes were identified, bilaterally, during periods of spontaneous sleep active-quiet-active (AS-QS-AS) and quiet-wakefulness. Minimal latencies and amplitudes occurred in 60% of active sleep/quiet-wakefulness, with the maximums in 70% of quiet sleep. The SEP-C mean values were latencies of N13=13.6ms (SD 1.4ms) and N1=33.6ms (SD 3.9ms) to 34.2ms (SD 4.8ms) in left and right hemisphere respectively; central-conduction-time (CCT) (N13-N1), 20.0ms (SD 4.3ms) to 20.6ms (SD 4.8ms); N1-P1 amplitude=4.6ms (SD 2.7ms) to 3.8μV (SD 2.2μV).

INTERPRETATION

1h-MNM can record simultaneously VEEG/aEEG/SEP-C in newborn infants, showing the modulation of SEP cortical responses in relation to behavioural states in all infants studied using an appropriate neonatal method. We emphasize the importance of obtaining neonatal SEP-C normative data to better identify pathological findings in neonatal brain injury.

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.

Evoked potentials recorded during routine EEG predict outcome after perinatal asphyxia

OBJECTIVE

To evaluate the added value of somatosensory (SEPs) and visual evoked potentials (VEPs) recorded simultaneously with routine EEG in early outcome prediction of newborns with hypoxic-ischemic encephalopathy under modern intensive care.

METHODS

We simultaneously recorded multichannel EEG, median nerve SEPs, and flash VEPs during the first few postnatal days in 50 term newborns with hypoxic-ischemic encephalopathy. EEG background was scored into five grades and the worst two grades were considered to indicate poor cerebral recovery. Evoked potentials were classified as absent or present. Clinical outcome was determined from the medical records at a median age of 21months. Unfavorable outcome included cerebral palsy, severe mental retardation, severe epilepsy, or death.

RESULTS

The accuracy of outcome prediction was 98% with SEPs compared to 90% with EEG. EEG alone always predicted unfavorable outcome when it was inactive (n=9), and favorable outcome when it was normal or only mildly abnormal (n=17). However, newborns with moderate or severe EEG background abnormality could have either favorable or unfavorable outcome, which was correctly predicted by SEP in all but one newborn (accuracy in this subgroup 96%). Absent VEPs were always associated with an inactive EEG, and an unfavorable outcome. However, presence of VEPs did not guarantee a favorable outcome.

CONCLUSIONS

SEPs accurately predict clinical outcomes in newborns with hypoxic-ischemic encephalopathy and improve the EEG-based prediction particularly in those newborns with severely or moderately abnormal EEG findings.

SIGNIFICANCE

SEPs should be added to routine EEG recordings for early bedside assessment of newborns with hypoxic-ischemic encephalopathy.

Beyond the N1: A review of late somatosensory evoked responses in human infants

Somatosensory evoked potentials (SEPs) have been used for decades to study the development of somatosensory processing in human infants. Research on infant SEPs has focused on the initial cortical component (N1) and its clinical utility for predicting neurological outcome in at-risk infants. However, recent studies suggest that examining the later components in the infant somatosensory evoked response will greatly advance our understanding of somatosensory processing in infancy. The purpose of this review is to synthesize the existing electroencephalography (EEG) and magnetoencephalography (MEG) studies on late somatosensory evoked responses in infants. We describe the late responses that have been reported and discuss the utility of such responses for illuminating key aspects of somatosensory processing in typical and atypical development.

Monitoring of newborns at high risk for brain injury

Due to the increasing number of surviving preterm newborns and to the recognition of therapeutic hypothermia as the current gold standard in newborns with hypoxic-ischaemic encephalopathy, there has been a growing interest in the implementation of brain monitoring tools in newborns at high risk for neurological disorders.Among the most frequent neurological conditions and presentations in the neonatal period, neonatal seizures and neonatal status epilepticus, paroxysmal non-epileptic motor phenomena, hypoxic-ischaemic encephalopathy, white matter injury of prematurity and stroke require specific approaches to diagnosis. In this review we will describe the characteristics, aims, indications and limitations of routinely available diagnostic techniques such as conventional and amplitude-integrated EEG, evoked potentials, cranial ultrasound and brain MRI. We will conclude by briefly outlining potential future perspectives from research studies.

Prenatal ischemia deteriorates white matter, brain organization, and function: implications for prematurity and cerebral palsy

Cerebral palsy (CP) describes a group of neurodevelopmental disorders of posture and movement that are frequently associated with sensory, behavioral, and cognitive impairments. The clinical picture of CP has changed with improved neonatal care over the past few decades, resulting in higher survival rates of infants born very preterm. Children born preterm seem particularly vulnerable to perinatal hypoxia-ischemia insults at birth. Animal models of CP are crucial for elucidating underlying mechanisms and for development of strategies of neuroprotection and remediation. Most animal models of CP are based on hypoxia-ischemia around the time of birth. In this review, we focus on alterations of brain organization and functions, especially sensorimotor changes, induced by prenatal ischemia in rodents and rabbits, and relate these alterations to neurodevelopmental disorders found in preterm children. We also discuss recent literature that addresses the relationship between neural and myelin plasticity, as well as possible contributions of white matter injury to the emergence of brain dysfunctions induced by prenatal ischemia.

Somatosensory evoked potentials in neonates with hypoxic-ischemic encephalopathy treated with hypothermia

OBJECTIVE

Somatosensory evoked potentials (SEPs) are reported to have high positive predictive value (PPV) for neurodevelopmental impairment (NDI) in neonates with moderate or severe hypoxic-ischemic encephalopathy (HIE). Our objective was to assess if this predictive value remains high with the use of therapeutic hypothermia.

METHODS

A cohort of HIE neonates treated with hypothermia was recruited between September 2008 and September 2010. SEPs were elicited after hypothermia and classified as bilateral absent N19, abnormal N19 (i.e., delayed or unilateral absent), or normal. Qualitative evaluation of MRI was also performed. The primary outcome was moderate or severe NDI around 2 years of age.

RESULTS

SEPs were performed after hypothermia in 26 of 34 neonates submitted to hypothermia with adequate follow-up at a median day of life 11 (IQR 9, 13). Twenty-three (88%) had moderate encephalopathy. Eleven neonates (42%) had bilateral absent N19, 4 of whom had NDI, while fifteen neonates (58%) had either abnormal or normal N19, of whom only one had NDI. SEPs thus had a PPV of 0.36 (4/11) and a negative predictive value (NPV) of 0.93 (14/15). Eighteen neonates (69%) had brain injury on MRI. MRI thus had a PPV of 0.28 (5/18) and an NPV of 1.00 (8/8).

CONCLUSIONS

Neonates with HIE treated with hypothermia with bilateral absent N19 potentials may have a better prognosis than reported in the pre-hypothermia era. MRI also had a low PPV and high NPV. SEPs should be interpreted with caution in this new population and need to be re-evaluated in larger studies.

Early diagnosis and early intervention in cerebral palsy

This paper reviews the opportunities and challenges for early diagnosis and early intervention in cerebral palsy (CP). CP describes a group of disorders of the development of movement and posture, causing activity limitation that is attributed to disturbances that occurred in the fetal or infant brain. Therefore, the paper starts with a summary of relevant information from developmental neuroscience. Most lesions underlying CP occur in the second half of gestation, when developmental activity in the brain reaches its summit. Variations in timing of the damage not only result in different lesions but also in different neuroplastic reactions and different associated neuropathologies. This turns CP into a heterogeneous entity. This may mean that the best early diagnostics and the best intervention methods may differ for various subgroups of children with CP. Next, the paper addresses possibilities for early diagnosis. It discusses the predictive value of neuromotor and neurological exams, neuroimaging techniques, and neurophysiological assessments. Prediction is best when complementary techniques are used in longitudinal series. Possibilities for early prediction of CP differ for infants admitted to neonatal intensive care and other infants. In the former group, best prediction is achieved with the combination of neuroimaging and the assessment of general movements, in the latter group, best prediction is based on carefully documented milestones and neurological assessment. The last part reviews early intervention in infants developing CP. Most knowledge on early intervention is based on studies in high-risk infants without CP. In these infants, early intervention programs promote cognitive development until preschool age; motor development profits less. The few studies on early intervention in infants developing CP suggest that programs that stimulate all aspects of infant development by means of family coaching are most promising. More research is urgently needed.

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.

Normal visual evoked potentials in preschool children born small for gestational age

AIM

Previous studies have shown visual evoked potential (VEP) abnormalities in infants and animals born small for gestational age (SGA) compared with controls. The current exploratory study aims to investigate whether VEP abnormalities persist in older ages.

METHODS

Pattern VEP latencies were obtained in 21 children (11 girls, 10 boys), born SGA and moderately preterm, at an average age of 5 years and 8 months. Fifty-one children (24 girls, 27 boys, mean age of 5 years and 7 months), also born moderately preterm but with normal height and weight at birth, served as controls

RESULTS

Visual evoked potential results showed no significant differences in latency between children born SGA and controls born appropriate for gestational age (AGA) for either binocular stimulation, right eye or left eye stimulation.

CONCLUSIONS

Our findings do not indicate any differences in VEP latency at preschool age for children born SGA compared with children born AGA. The results may support previous studies, suggesting that children born SGA show accelerated neurophysiologic maturation during their first year of life and that previously delayed VEP latencies after catch-up stay unchanged compared with controls.