Prevention of Neurological Sequelae in Preterm Infants

BACKGROUND

Preterm birth is one of the world's critical health problems, with an incidence of 5% to 18% of living newborns according to various countries. White matter injuries due to preoligodendrocytes deficits cause hypomyelination in children born preterm. Preterm infants also have multiple neurodevelopmental sequelae due to prenatal and perinatal risk factors for brain damage. The purpose of this work was to explore the effects of the brain risk factors and MRI volumes and abnormalities on the posterior motor and cognitive development at 3 years of age.

METHODS

A total of 166 preterm infants were examined before 4 months and clinical and MRI evaluations were performed. MRI showed abnormal findings in 89% of the infants. Parents of all infants were invited to receive the Katona neurohabilitation treatment. The parents of 128 infants accepted and received Katona's neurohabilitation treatment. The remaining 38 infants did not receive treatment for a variety of reasons. At the three-year follow-up, Bayley's II Mental Developmental Index (MDI) and the Psychomotor Developmental Index (PDI) were compared between treated and untreated subjects.

RESULTS

The treated children had higher values of both indices than the untreated. Linear regression showed that the antecedents of placenta disorders and sepsis as well as volumes of the corpus callosum and of the left lateral ventricle significantly predicted both MDI and PDI, while Apgar < 7 and volume of the right lateral ventricle predicted the PDI.

CONCLUSIONS

(1) The results indicate that preterm infants who received Katona's neurohabilitation procedure exhibited significantly better outcomes at 3 years of age compared to those who did not receive the treatment. (2) The presence of sepsis and the volumes of the corpus callosum and lateral ventricles at 3-4 months were significant predictors of the outcome at 3 years of age.

Early detection and treatment of attention deficits in preterm and at term infants with risk factors for brain damage

Cognitive deficits in infants born preterm and infants at term with risk factors for brain damage are a common outcome. Attention deficits in preterm infants are related to the development of attention-deficit/hyperactivity disorder (ADHD), and therefore, there is a need for earlier evaluations and treatment procedures that are implemented before the presence of signs of ADHD.

METHODS

We studied preterm (74%) and term infants with the Infant Scale of Selective Attention (ISSA, Escala de Evaluación de la Atención Selectiva (EEAS), in Spanish). This scale evaluates both visual- and auditory-orienting attention. Two groups participated, one with attention deficits (n = 26) and another with regular performance (n = 36). An early attention-stimulation program (EASP) was implemented in the infant group with attention deficits from three to eight months of age. All infants underwent magnetic resonance imaging (MRI), and visual and auditory evoked responses were assessed.

RESULTS

All infants had prenatal and perinatal risk factors for brain damage and abnormal MRI findings, and the majority had abnormalities compatible with white matter injury. However, there were four infants with porencephalic cysts; 3 of them were in the treated group. At the beginning of the treatment, ISSA values showed differences between groups. These differences persisted for five months in the visual test and up to the sixth month in the auditory evaluation. Afterward, there were no significant differences, indicating that infants with attention deficits had satisfactorily responded to the treatment.

CONCLUSIONS

The ISSA is helpful for the early evaluation of visual and auditory attention. Infants with attention deficits react well enough after six months of EASP.

Early diagnosis and treatment of infants with prenatal and perinatal risk factors for brain damage at the neurodevelopmental research unit in Mexico

Prenatal and perinatal risk factors for perinatal brain damage frequently produce brain injuries in preterm and term infants. The early diagnosis and treatment of these infants, in the period of higher brain plasticity, may prevent the neurological and cognitive sequels that accompany these lesions. The Neurodevelopmental Research Unit at the Institute of Neurobiology of the National Autonomous University of Mexico has taken this endeavor. A multidisciplinary approach is followed. Pediatric, neurologic and rehabilitation clinical studies, MRI, EEG, visual and auditory evoked responses, and Bayley II evaluations are carried out initially. Infants are followed up to 8 years, with periodic appointments for evaluation and treatment. Katona's neurohabilitation method is used for initial diagnosis and treatment. Selective visual and auditory attention are explored from 3 months of age. This method was created in the Unit and, if deficiencies are observed, the method also describes the treatment to avoid subsequent alterations of these processes. Deficiencies in the acquisition of language are evaluated from 4 months of age, implementing treatment through instructions to parents on how they should teach their children to speak. This method has also been developed in the Unit and is in its validation process. In the MRI, we pay special attention to subtle and diffuse patterns, due to the high frequency with which they appear in contemporary cohorts at a national and international level. More than 80% of these infants showed abnormal MRI findings that should be taken into consideration. The outcome of children at 8 years old showed that 78%, 76% and 78% of extremely preterm, very preterm and late preterm, respectively, had a normal neurodevelopment. In term infants, only 69% had a normal neurodevelopment; in this group, the majority of infants had very severe brain lesions. Conclusions: It is necessary to evaluate, at an early age, all newborns with prenatal and perinatal risk factors for brain damage. Special attention should be payed to all premature newborns and those newborns who have been discharged from the intensive care unit.

Long-term therapeutic effects of Katona therapy in moderate-to-severe perinatal brain damage

AIM

To determine the long-term efficacy of Katona therapy and early rehabilitation of infants with moderate-to-severe perinatal brain damage (PBD).

METHODS

Thirty-two participants were recruited (7-16 years) and divided into 3 groups: one Healthy group (n = 11), one group with PBD treated with Katona methodology from 2 months of corrected age, and with long-term follow-up (n = 12), and one group with PBD but without treatment in the first year of life due to late diagnosis of PBD (n = 9). Neuropediatric evaluations, motor evoked potentials (MEPs) and magnetic resonance images (MRI) were made. The PBD groups were matched by severity and topography of lesion.

RESULTS

The patients treated with Katona had better motor performance when compared to patients without early treatment (Gross Motor Function Classification System levels; 75% of Katona group were classified in levels I and II and 78% of patients without early treatment were classified in levels III and IV). Furthermore, independent k-means cluster analyses of MRI, MEPs, and neuropediatric evaluations data were performed. Katona and non-treated early groups were classified in the same MRI cluster which is the expected for PBD population patients. However, in MEPs and neuropediatric evaluations clustering, the 67% of Katona group were assigned into Healthy group showing the impact of Katona therapy over the patients treated with it. These results highlight the Katona therapy benefits in early rehabilitation of infants with moderate-to-severe PBD.

CONCLUSIONS

Katona therapy and early rehabilitation have an important therapeutic effect in infants with moderate-to-severe PBD by decreasing the severity of motor disability in later stages of life.

How to Obtain Reliable Visual Event-related Potentials in Newborns

The present study discusses the characteristics of visual event-related potentials (VEPs) and outlines methodological steps for obtaining reliable measurements in newborns. Obtaining high-quality, reliable VEPs is crucial for the early detection of abnormal development of the central nervous system in at-risk newborns, and for implementing successful early interventions. Recommendations are based on a previous study which showed that when post-conceptional age, polysomnography-identified sleep stages, and light-emitting diodes (LEDs) googles as the luminous source are controlled, no more than 4 repetitions of VEP averages are required to obtain replicable recordings, variability decreases, and reliable VEPs can be obtained. By controlling for these sources of variability and using statistical analyses, we were able to clearly and reliably identify the amplitude and latency of three main components (NII, PII and NIII) present in 100% of newborns (n = 20) during active sleep. Recording VEPs during awake states, quiet sleep and transitional sleep is not recommended because VEP morphology may differ significantly from one average to the next, leading to the risk of misleading clinical prognoses. Moreover, it is easier to obtain VEPs during active sleep because this state can be clearly and reliably identified at this stage of development, sleep cycles are short enough to allow measurements to be taken in a reasonable time, and the method does not require new o expensive equipment.

Los padres como promotores del desarrollo de lenguaje de bebés prematuros: propuesta de intervención temprana

Cualquier programa de intervención puede beneficiarse de la participación de los padres, pero es necesario darles información de cómo pueden estimular el lenguaje de sus hijos. El objetivo fue entrenar a los padres acerca de lo que debían esperar del desarrollo del lenguaje de sus hijos y brindarles técnicas de estimulación de este para evitar secuelas. Se estudiaron 21 bebés prematuros mexicanos y se comprobó que, después del entrenamiento, los padres se sentían más capaces de estimular a sus hijos. A los bebés se les aplicó una prueba de lenguaje al año y a los tres años de edad; en ambas obtuvieron puntajes normales para su edad. Se concluye que los padres son buenos promotores del lenguaje en bebés prematuros

Visual evoked potentials are similar in polysomnographically defined quiet and active sleep in healthy newborns

Morphology and late components of evoked potentials change depending on wake-sleep stages in adults. Visual Evoked potentials (VEPs) have been frequently studied in newborns to identify abnormal development of visual pathways; however, large variability has been reported and there is uncertainty as to the effect of sleep stages on VEPs in neonates.

OBJECTIVE

To describe the characteristics of VEPs in one month old, healthy full-term newborns during active sleep (AS) and quiet sleep (QS), defined by simultaneous polysomnography (PSG).

METHODS

VEPs were obtained by monocular LEDs stimulation of each eye during AS and QS, in 20 healthy full-term newborns (gestational age 37-40 weeks) with normal birth weights and normal prenatal Doppler ultrasound indices. Latencies and amplitudes of N2, P2 and N3 components in AS and QS were compared, and their association with absolute power of EEG frequency bands, assessed.

RESULTS

There were no significant differences in VEP morphology, latencies and amplitudes between sleep states. Typical wave forms were obtained in all newborns in AS; however, no VEPs could be identified clearly in 3 newborns in QS; QS VEPs were less reliable than in AS: more averaging was required; correlation was significantly lower between the VEP averages; and a larger number of babies needed more than two averages to obtain replicable responses needed for clinical purposes.

CONCLUSIONS

These results indicate that changes in amplitude and latency of some VEP components observed in NREM and REM sleep in adults are not yet present in one month old newborns probably due to immaturity of cortical and sleep mechanisms. VEPs are more reliable during AS than QS in newborns. Systematic VEP recording during AS, and polysomnographic control to identify this stage, are highly recommended as methods that can increase there liability of neonatal VEPs.

Stable Sparse Classifiers Identify qEEG Signatures that Predict Learning Disabilities (NOS) Severity

In this paper, we present a novel methodology to solve the classification problem, based on sparse (data-driven) regressions, combined with techniques for ensuring stability, especially useful for high-dimensional datasets and small samples number. The sensitivity and specificity of the classifiers are assessed by a stable ROC procedure, which uses a non-parametric algorithm for estimating the area under the ROC curve. This method allows assessing the performance of the classification by the ROC technique, when more than two groups are involved in the classification problem, i.e., when the gold standard is not binary. We apply this methodology to the EEG spectral signatures to find biomarkers that allow discriminating between (and predicting pertinence to) different subgroups of children diagnosed as Not Otherwise Specified Learning Disabilities (LD-NOS) disorder. Children with LD-NOS have notable learning difficulties, which affect education but are not able to be put into some specific category as reading (Dyslexia), Mathematics (Dyscalculia), or Writing (Dysgraphia). By using the EEG spectra, we aim to identify EEG patterns that may be related to specific learning disabilities in an individual case. This could be useful to develop subject-based methods of therapy, based on information provided by the EEG. Here we study 85 LD-NOS children, divided in three subgroups previously selected by a clustering technique over the scores of cognitive tests. The classification equation produced stable marginal areas under the ROC of 0.71 for discrimination between Group 1 vs. Group 2; 0.91 for Group 1 vs. Group 3; and 0.75 for Group 2 vs. Group1. A discussion of the EEG characteristics of each group related to the cognitive scores is also presented.

Clinical neuroimaging in the preterm infant: Diagnosis and prognosis

Perinatal care advances emerging over the past twenty years have helped to diminish the mortality and severe neurological morbidity of extremely and very preterm neonates (e.g., cystic Periventricular Leukomalacia [c-PVL] and Germinal Matrix Hemorrhage - Intraventricular Hemorrhage [GMH-IVH grade 3-4/4]; 22 to < 32 weeks of gestational age, GA). However, motor and/or cognitive disabilities associated with mild-to-moderate white and gray matter injury are frequently present in this population (e.g., non-cystic Periventricular Leukomalacia [non-cystic PVL], neuronal-axonal injury and GMH-IVH grade 1-2/4). Brain research studies using magnetic resonance imaging (MRI) report that 50% to 80% of extremely and very preterm neonates have diffuse white matter abnormalities (WMA) which correspond to only the minimum grade of severity. Nevertheless, mild-to-moderate diffuse WMA has also been associated with significant affectations of motor and cognitive activities. Due to increased neonatal survival and the intrinsic characteristics of diffuse WMA, there is a growing need to study the brain of the premature infant using non-invasive neuroimaging techniques sensitive to microscopic and/or diffuse lesions. This emerging need has led the scientific community to try to bridge the gap between concepts or ideas from different methodologies and approaches; for instance, neuropathology, neuroimaging and clinical findings. This is evident from the combination of intense pre-clinical and clinicopathologic research along with neonatal neurology and quantitative neuroimaging research. In the following review, we explore literature relating the most frequently observed neuropathological patterns with the recent neuroimaging findings in preterm newborns and infants with perinatal brain injury. Specifically, we focus our discussions on the use of neuroimaging to aid diagnosis, measure morphometric brain damage, and track long-term neurodevelopmental outcomes.

Electroencephalographic characterization of subgroups of children with learning disorders

Electroencephalographic alterations have been reported in subjects with learning disorders, but there is no consensus on what characterizes their electroencephalogram findings. Our objective was to determine if there were subgroups within a group of scholars with not otherwise specified learning disorders and if they had specific electroencephalographic patterns. Eighty-five subjects (31 female, 8-11 years) who scored low in at least two subscales -reading, writing and arithmetic- of the Infant Neuropsychological Evaluation were included. Electroencephalograms were recorded in 19 leads during rest with eyes closed; absolute power was obtained every 0.39 Hz. Three subgroups were formed according to children's performance: Group 1 (G1, higher scores than Group 2 in reading speed and reading and writing accuracy), Group 2 (G2, better performance than G1 in composition) and Group 3 (G3, lower scores than Groups 1 and 2 in the three subscales). G3 had higher absolute power in frequencies in the delta and theta range at left frontotemporal sites than G1 and G2. G2 had higher absolute power within alpha frequencies than G3 and G1 at the left occipital site. G3 had higher absolute power in frequencies in the beta range than G1 in parietotemporal areas and than G2 in left frontopolar and temporal sites. G1 had higher absolute power within beta frequencies than G2 in the left frontopolar site. G3 had lower gamma absolute power values than the other groups in the left hemisphere, and gamma activity was higher in G1 than in G2 in frontopolar and temporal areas. This group of children with learning disorders is very heterogeneous. Three subgroups were found with different cognitive profiles, as well as a different electroencephalographic pattern. It is important to consider these differences when planning interventions for children with learning disorders.

Development of Emotional Face Processing in Premature and Full-Term Infants

The rate of premature births has increased in the past 2 decades. Ten percent of premature birth survivors develop motor impairment, but almost half exhibit later sensorial, cognitive, and emotional disabilities attributed to white matter injury and decreased volume of neuronal structures. The aim of this study was to test the hypothesis that premature and full-term infants differ in their development of emotional face processing. A comparative longitudinal study was conducted in premature and full-term infants at 4 and 8 months of age. The absolute power of the electroencephalogram was analyzed in both groups during 5 conditions of an emotional face processing task: positive, negative, neutral faces, non-face, and rest. Differences between the conditions of the task at 4 months were limited to rest versus non-rest comparisons in both groups. Eight-month-old term infants had increases ( P ≤ .05) in absolute power in the left occipital region at the frequency of 10.1 Hz and in the right occipital region at 3.5, 12.8, and 16.0 Hz when shown a positive face in comparison with a neutral face. They also showed increases in absolute power in the left occipital region at 1.9 Hz and in the right occipital region at 2.3 and 3.5 Hz with positive compared to non-face stimuli. In contrast, positive, negative, and neutral faces elicited the same responses in premature infants. In conclusion, our study provides electrophysiological evidence that emotional face processing develops differently in premature than in full-term infants, suggesting that premature birth alters mechanisms of brain development, such as the myelination process, and consequently affects complex cognitive functions.

3D Statistical Parametric Mapping of EEG Source Spectra by Means of Variable Resolution Electromagnetic Tomography (VARETA)

This article describes a new method for 3D QEEG tomography in the frequency domain. A variant of Statistical Parametric Mapping is presented for source log spectra. Sources are estimated by means of a Discrete Spline EEG inverse solution known as Variable Resolution Electromagnetic Tomography (VARETA). Anatomical constraints are incorporated by the use of the Montreal Neurological Institute (MNI) probabilistic brain atlas. Efficient methods are developed for frequency domain VARETA in order to estimate the source spectra for the set of 103–105 voxels that comprise an EEG/MEG inverse solution. High resolution source Z spectra are then defined with respect to the age dependent mean and standard deviations of each voxel, which are summarized as regression equations calculated from the Cuban EEG normative database. The statistical issues involved are addressed by the use of extreme value statistics. Examples are shown that illustrate the potential clinical utility of the methods herein developed.

Visual Evoked Potentials in Infants With Diffuse Periventricular Leukomalacia

Periventricular leukomalacia (PVL) is characterized by necrosis of the cerebral white matter in the dorsolateral portions of the lateral ventricles. PVL causes motor, sensory, and cognitive deficits. The aim of this study was to analyze the conduction characteristics of the visual pathway in infants with diffuse PVL using visual evoked potentials (VEPs). We studied 11 healthy infants (mean age 3.3 ± 1.3 months) and 17 with diffuse PVL (mean age 2.9 ± 0.8 months and mean gestational age 31.9 ± 3.1 weeks). The N75, P100, and N135 wave latencies; the interwave N75-P100 and P100-N135 latencies; and the N75-P100 and P100-N135 amplitudes were measured in the occipital leads. VEPs were recorded during binocular stimulation at an angle of 120' from the Fz-Oz lead. Healthy children had mean N75, P100, and N135 wave latencies of 84.4 ± 5.8, 143.4 ± 30.6 and 222.9 ± 40.4 ms, respectively. The mean interwave N75-P100 and P100-N135 latencies were 59.0 ± 28.6 and 79.5 ± 13.6 ms, respectively. Compared with the healthy group, infants with PVL had longer N75 and N135 latencies at 92.3 ± 15.3 (P = .05) and 265.0 ms ± 60.3 (P = .05), respectively. The interwave latency P100-N135 (105.5 ± 29.1 ms; P = .017) was longer in children with PVL than in healthy infants. Infants with diffuse PVL had mild alterations in their N75, P100 and, particularly, their N135 latencies. These increases in P100-N135 interwave latencies could be because of damage to the geniculocortical pathways and V2-V3 networks.

The functional significance of delta oscillations in cognitive processing

Ample evidence suggests that electroencephalographic (EEG) oscillatory activity is linked to a broad variety of perceptual, sensorimotor, and cognitive operations. However, few studies have investigated the delta band (0.5-3.5 Hz) during different cognitive processes. The aim of this review is to present data and propose the hypothesis that sustained delta oscillations inhibit interferences that may affect the performance of mental tasks, possibly by modulating the activity of those networks that should be inactive to accomplish the task. It is clear that two functionally distinct and potentially competing brain networks can be broadly distinguished by their contrasting roles in attention to the external world vs. the internally directed mentation or concentration. During concentration, EEG delta (1-3.5 Hz) activity increases mainly in frontal leads in different tasks: mental calculation, semantic tasks, and the Sternberg paradigm. This last task is considered a working memory task, but in neural, as well as phenomenological, terms, working memory can be best understood as attention focused on an internal representation. In the Sternberg task, increases in power in the frequencies from 1 to 3.90 Hz in frontal regions are reported. In a Go/No-Go task, power increases at 1 Hz in both conditions were observed during 100-300 ms in central, parietal and temporal regions. However, in the No-Go condition, power increases were also observed in frontal regions, suggesting its participation in the inhibition of the motor response. Increases in delta power were also reported during semantic tasks in children. In conclusion, the results suggest that power increases of delta frequencies during mental tasks are associated with functional cortical deafferentation, or inhibition of the sensory afferences that interfere with internal concentration. These inhibitory oscillations would modulate the activity of those networks that should be inactive to accomplish the task.

Visuospatial working memory in toddlers with a history of periventricular Leukomalacia: an EEG narrow-band power analysis

BACKGROUND

Periventricular Leukomalacia (PVL) affects white matter, but grey matter injuries have also been reported, particularly in the dorsomedial nucleus and the cortex. Both structures have been related to working memory (WM) processes. The aim of this study was to compare behavioral performances and EEG power spectra during a visuospatial working memory task (VSWMT) of toddlers with a history of PVL and healthy toddlers.

METHODOLOGY/PRINCIPAL FINDINGS

A prospective, comparative study of WM was conducted in toddlers with a history of PVL and healthy toddlers. The task responses and the EEG narrow-band power spectra during a VSWMT were compared in both groups. The EEG absolute power was analyzed during the following three conditions: baseline, attention and WM retention. The number of correct responses was higher in the healthy group (20.5 ± 5.0) compared to the PVL group (16.1 ± 3.9) (p = 0.04). The healthy group had absolute power EEG increases (p ≤ 0.05) during WM compared to the attention condition in the bilateral frontal and right temporal, parietal and occipital regions in frequencies ranging from 1.17 to 2.34 Hz and in the right temporal, parietal and occipital regions in frequencies ranging from 14.06 to 15.23 Hz. In contrast, the PVL group had absolute power increases (p ≤ 0.05) in the bilateral fronto-parietal, left central and occipital regions in frequencies that ranged from 1.17 to 3.52 Hz and in the bilateral frontal and right temporal regions in frequencies ranging from 9.37 to 19.14 Hz.

CONCLUSIONS/SIGNIFICANCE

This study provides evidence that PVL toddlers have visuospatial WM deficits and a very different pattern of absolute power increases compared to a healthy group of toddlers, with greater absolute power in the low frequency range and widespread neuronal networks in the WM retention phase.

Effect of hearing aids on auditory function in infants with perinatal brain injury and severe hearing loss

BACKGROUND

Approximately 2-4% of newborns with perinatal risk factors present with hearing loss. Our aim was to analyze the effect of hearing aid use on auditory function evaluated based on otoacoustic emissions (OAEs), auditory brain responses (ABRs) and auditory steady state responses (ASSRs) in infants with perinatal brain injury and profound hearing loss.

METHODOLOGY/PRINCIPAL FINDINGS

A prospective, longitudinal study of auditory function in infants with profound hearing loss. Right side hearing before and after hearing aid use was compared with left side hearing (not stimulated and used as control). All infants were subjected to OAE, ABR and ASSR evaluations before and after hearing aid use. The average ABR threshold decreased from 90.0 to 80.0 dB (p = 0.003) after six months of hearing aid use. In the left ear, which was used as a control, the ABR threshold decreased from 94.6 to 87.6 dB, which was not significant (p>0.05). In addition, the ASSR threshold in the 4000-Hz frequency decreased from 89 dB to 72 dB (p = 0.013) after six months of right ear hearing aid use; the other frequencies in the right ear and all frequencies in the left ear did not show significant differences in any of the measured parameters (p>0.05). OAEs were absent in the baseline test and showed no changes after hearing aid use in the right ear (p>0.05).

CONCLUSIONS/SIGNIFICANCE

This study provides evidence that early hearing aid use decreases the hearing threshold in ABR and ASSR assessments with no functional modifications in the auditory receptor, as evaluated by OAEs.

Neurofeedback in healthy elderly human subjects with electroencephalographic risk for cognitive disorder

In normal elderly subjects, the best electroencephalogram (EEG)-based predictor of cognitive impairment is theta EEG activity abnormally high for their age. The goal of this work was to explore the effectiveness of a neurofeedback (NFB) protocol in reducing theta EEG activity in normal elderly subjects who present abnormally high theta absolute power (AP). Fourteen subjects were randomly assigned to either the experimental group or the control group; the experimental group received a reward (tone of 1000 Hz) when the theta AP was reduced, and the control group received a placebo treatment, a random administration of the same tone. The results show that the experimental group exhibits greater improvement in EEG and behavioral measures. However, subjects of the control group also show improved EEG values and in memory, which may be attributed to a placebo effect. However, the effect of the NFB treatment was clear in the EG, although a placebo effect may also have been present.

Electrophysiological auditory responses and language development in infants with periventricular leukomalacia

This study presents evidence suggesting that electrophysiological responses to language-related auditory stimuli recorded at 46weeks postconceptional age (PCA) are associated with language development, particularly in infants with periventricular leukomalacia (PVL). In order to investigate this hypothesis, electrophysiological responses to a set of auditory stimuli consisting of series of syllables and tones were recorded from a population of infants with PVL at 46weeks PCA. A communicative development inventory (i.e., parent report) was applied to this population during a follow-up study performed at 14months of age. The results of this later test were analyzed with a statistical clustering procedure, which resulted in two well-defined groups identified as the high-score (HS) and low-score (LS) groups. The event-induced power of the EEG data recorded at 46weeks PCA was analyzed using a dimensionality reduction approach, resulting in a new set of descriptive variables. The LS and HS groups formed well-separated clusters in the space spanned by these descriptive variables, which can therefore be used to predict whether a new subject will belong to either of these groups. A predictive classification rate of 80% was obtained by using a linear classifier that was trained with a leave-one-out cross-validation technique.

3D statistical parametric mapping of quiet sleep EEG in the first year of life

This paper extends previously developed 3D SPM for Electrophysiological Source Imaging (Bosch et al., 2001) for neonate EEG. It builds on a prior paper by our group that established age dependent means and standard deviations for the scalp EEG Broad Band Spectral Parameters of children in the first year of life. We now present developmental equations for the narrow band log spectral power of EEG sources, obtained from a sample of 93 normal neonates from age 1 to 10 months in quiet sleep. The main finding from these regressions is that EEG power from 0.78 to 7.5 Hz decreases with age and also for 45-50 Hz. By contrast, there is an increase with age in the frequency band of 19-32 Hz localized to parietal, temporal and occipital areas. Deviations from the norm were analyzed for normal neonates and 17 with brain damage. The diagnostic accuracy (measured by the area under the ROC curve) of EEG source SPM is 0.80, 0.69 for average reference scalp EEG SPM, and 0.48 for Laplacian EEG SPM. This superior performance of 3D SPM over scalp qEEG suggests that it might be a promising approach for the evaluation of brain damage in the first year of life.

QEEG norms for the first year of life

BACKGROUND

QEEG allows a more objective evaluation of cerebral electrical activity as well as the production of topographical maps for easier comprehension. Here we have developed qEEG norms for the first year of life using methods previously published for other age ranges, including for example, regression for Gausssianity before Z transformation. These norms constitute a non-invasive and low cost tool for the functional evaluation of the infant's brain.

RESULTS

Developmental equations were obtained from 101 healthy infants recording at spontaneous quiet sleep stage II. Polynomial regression equations, with age as independent variable, were calculated for full Broad Band Spectral Parameters (BBSP) using the Least Squares technique. Interpolated maps of the BBSP values or their Z transformation were constructed for linked-ear reference, average reference and Laplacian montages. All montages produced similar tendency curves and Z maps of absolute and relative power, and mean frequency at all frequency bands. The norms obtained were validated against an independent group of 50 healthy infants and some pathological cases. 91-98% of cases were well classified as normal across all measures and montages. To exemplify, two pathological cases are presented of which their qEEG maps show resemblance to CT and MRI.

CONCLUSIONS

These qEEG norms are highly useful as an aid to visual interpretation and for the study of pathology further evolution as well as for assessment of infants showing brain risk factors. To our knowledge this is the first normative qEEG study for the initial year of life with such large sample and validation-group.

Motor potentials by magnetic stimulation in periventricular leukomalacia

Periventricular leukomalacia is characterized by damage to the brain's white matter and impairments in motor function. Motor-evoked potentials by transcranial magnetic stimulation evaluate corticospinal tract function. We analyzed alterations in motor-evoked potentials in newborns with periventricular leukomalacia. Thirty infants (aged 4.37 +/- 1.1 months mean +/- S.D.) were divided into three groups: 10 healthy, and 10 with focal and 10 with diffuse periventricular leukomalacia. Potentials recorded in the right abductor pollicis brevis of healthy infants indicated a total motor conduction time of 26.3 +/- 2.4 ms, central motor conduction time of 17.0 +/- 2.6 ms, and central motor conduction velocity of 12.3 +/- 2.2 m/s. In the tibialis anterior, total motor conduction time was 27.4 +/- 2.6 ms; central motor conduction time was 16.7 +/- 2.8 ms, and central motor conduction velocity was 25.2 +/- 3.4 m/s. In the focal periventricular leukomalacia and diffuse periventricular leukomalacia groups, an increase in central motor conduction time and a decrease in central motor conduction velocity (P < 0.05) were evident, without differences between the two groups. Motor-evoked potentials in periventricular leukomalacia revealed an increase in central motor conduction time and a decrease in central motor conduction velocity, without differences between diffuse and focal types.

EEG sources in a group of patients with major depressive disorders

EEG sources were assessed in a group of patients with major moderate-severe depressive disorder (MDD) as classified by trained clinicians according to DSM-IV criteria. Frequency Domain Variable Resolution Electromagnetic Tomography (FD-VARETA) was used to calculate EEG sources. The Z-values indicated that EEG sources were abnormal (increase in current density) in all patients, with most demonstrating abnormal EEG sources in both hemispheres but with maximal inverse solution located primarily in the right. Twenty-nine patients had a predominant topography of the abnormal EEG maximal inverse solution in the frontal lobes. The remaining seven patients had a bilateral abnormal increase in current density in the superior parietal lobe. The EEG maximal abnormal inverse solution frequency was observed in both hemispheres such that the increases in current density were prevalent in alpha and theta bands. The results suggest that any of the two hemispheres could be affected by MDD, but abnormal EEG sources can be found more frequently in the right one, with the maximal abnormal inverse solution at the alpha and theta bands in frontal and parietal cortices.

Effects of two different cycles of vagus nerve stimulation on interictal epileptiform discharges

PURPOSE

To evaluate the effects of two cycles of vagus nerve stimulation (VNS), 30 s/5 min and 7 s/18 s on the interictal epileptiform discharges (IEDs).

METHODS

Twenty patients were studied, 12 with generalized and 8 with partial seizures. An EEG of 120 channels was performed during 3 different conditions, each one lasting 30 min: basal state (BS), 30 s/5 min and 7 s/18 s VNS cycles. The number and duration of IEDs, time of IEDs in 1 min (TIEDM), IEDs/NIEDs index and the spike-free period (SFP) were determined.

RESULTS

In 16 patients (80%), IED decreased during 30 s/5 min cycle (Group 1) and increased in 4 (Group 2). In Group 1, during the 30 s/5 min cycle the following variables showed a decrease: TIEDM, from 12.64 s to 9.62 s (p=0.001); IED/NIED index, from 0.53 to 0.31 (p=0.021), and IED duration, from 1.57 s to 1.05 s (p=0.015); whereas SFP duration increased from 20.06 s to 37.73 s (p=0.008). The decrease in IED was 41% and the increase in SFP 88%. In the 7s/18s cycle, only SFP had an increase, 72% (p<0.043). In Group 2, an increase in IED during both cycles was found. In the 30 s/5 min cycle, TIEDM increased 56% (p=0.042) and IED/NIED index 259% (p=0.040).

CONCLUSION

VNS modifies IED in an acute form, in 80% of patients the 30 s/5 min cycle decreases the epileptiform activity and it is not modified by 7 s/18 s cycle. In 20% of patients, both cycles increase the epileptiform activity.