Adult EEG Research Articles

Outcome prediction by amplitude-integrated EEG in adults with hypoxic ischemic encephalopathy

IntroductionAmplitude-integrated electroencephalography (aEEG) had been widely used in predicting outcome in infants with hypoxic ischemic encephalopathy (HIE). We aimed to evaluate the use of aEEG as a quantitative predictor of outcome in adult patients with HIE. MethodsaEEG and Glasgow coma scale (GCS) were recorded for patients with HIE within 72h of onset. aEEG traces were categorized as Grade I (normal amplitude): upper margin of aEEG activity >10μV, lower margin >5μV; Grade II (moderately abnormal amplitude): upper margin of aEEG activity >10μV, lower margin ≤5μV, or with suppressed amplitude, upper margin ≤10μV, lower margin >5μV; Grade III (mild abnormality): either upper margin <10μV, lower margin <5μV. GCS was graded as I (9–14), grade II (4–8), or grade III (3). Cerebral performance category scores (CPCs) were determined 1 and 3 month after clinical evolution. CPC 1,2 were defined as favorable outcome; CPC 3,4,5 were considered as poor outcome. Results30 cases met inclusion criteria. Both the aEEG grade and GCS scores correlated significantly with short-term outcome, and cases with a worse aEEG grade were more likely to have an unfavorable short-term outcome. Since the number of patients is really too small for long-term outcome analysis, we did not perform the analysis of aEEG, GCS and longer-term outcome. There was significant difference of clinical findings among aEEG classifications, while no statistical difference was found of causes of HIE. ConclusionsaEEG is a reliable predictor of short-term outcome in HIE, and aEEG results within 72h after onset were associated with neurodevelopmental outcome at 1 mo following clinical evolution.

Investigating Social Cognition in Infants and Adults Using Dense Array Electroencephalography (&lt;sub&gt;d&lt;/sub&gt;EEG)

Dense array electroencephalography (dEEG), which provides a non-invasive window for measuring brain activity and a temporal resolution unsurpassed by any other current brain imaging technology1,2, is being used increasingly in the study of social cognitive functioning in infants and adults. While dEEG is enabling researchers to examine brain activity patterns with unprecedented levels of sensitivity, conventional EEG recording systems continue to face certain limitations, including 1) poor spatial resolution and source localization3,4,2) the physical discomfort for test subjects of enduring the individual application of numerous electrodes to the surface of the scalp, and 3) the complexity for researchers of learning to use multiple software packages to collect and process data. Here we present an overview of an established methodology that represents a significant improvement on conventional methodologies for studying EEG in infants and adults. Although several analytical software techniques can be used to establish indirect indices of source localization to improve the spatial resolution of dEEG, the HydroCel Geodesic Sensor Net (HCGSN) by Electrical Geodesics, Inc. (EGI), a dense sensory array that maintains equal distances among adjacent recording electrodes on all surfaces of the scalp, further enhances spatial resolution4,5,6 compared to standard dEEG systems. The sponge-based HCGSN can be applied rapidly and without scalp abrasion, making it ideal for use with adults7,8, children9,10,11, and infants12, in both research and clinical4,5,6,13,14,15 settings. This feature allows for considerable cost and time savings by decreasing the average net application time compared to other dEEG systems. Moreover, the HCGSN includes unified, seamless software applications for all phases of data, greatly simplifying the collection, processing, and analysis of dEEG data. The HCGSN features a low-profile electrode pedestal, which, when filled with electrolyte solution, creates a sealed microenvironment and an electrode-scalp interface. In all Geodesic dEEG systems, EEG sensors detect changes in voltage originating from the participant's scalp, along with a small amount of electrical noise originating from the room environment. Electrical signals from all sensors of the Geodesic sensor net are received simultaneously by the amplifier, where they are automatically processed, packaged, and sent to the data-acquisition computer (DAC). Once received by the DAC, scalp electrical activity can be isolated from artifacts for analysis using the filtering and artifact detection tools included in the EGI software. Typically, the HCGSN can be used continuously for only up to two hours because the electrolyte solution dries out over time, gradually decreasing the quality of the scalp-electrode interface. In the Parent-Infant Research Lab at the University of Toronto, we are using dEEG to study social cognitive processes including memory, emotion, goals, intentionality, anticipation, and executive functioning in both adult and infant participants.

Investigating Social Cognition in Infants and Adults Using Dense Array Electroencephalography (&lt;sub&gt;d&lt;/sub&gt;EEG)

Dense array electroencephalography (dEEG), which provides a non-invasive window for measuring brain activity and a temporal resolution unsurpassed by any other current brain imaging technology1,2, is being used increasingly in the study of social cognitive functioning in infants and adults. While dEEG is enabling researchers to examine brain activity patterns with unprecedented levels of sensitivity, conventional EEG recording systems continue to face certain limitations, including 1) poor spatial resolution and source localization3,4,2) the physical discomfort for test subjects of enduring the individual application of numerous electrodes to the surface of the scalp, and 3) the complexity for researchers of learning to use multiple software packages to collect and process data. Here we present an overview of an established methodology that represents a significant improvement on conventional methodologies for studying EEG in infants and adults. Although several analytical software techniques can be used to establish indirect indices of source localization to improve the spatial resolution of dEEG, the HydroCel Geodesic Sensor Net (HCGSN) by Electrical Geodesics, Inc. (EGI), a dense sensory array that maintains equal distances among adjacent recording electrodes on all surfaces of the scalp, further enhances spatial resolution4,5,6 compared to standard dEEG systems. The sponge-based HCGSN can be applied rapidly and without scalp abrasion, making it ideal for use with adults7,8, children9,10,11, and infants12, in both research and clinical4,5,6,13,14,15 settings. This feature allows for considerable cost and time savings by decreasing the average net application time compared to other dEEG systems. Moreover, the HCGSN includes unified, seamless software applications for all phases of data, greatly simplifying the collection, processing, and analysis of dEEG data.The HCGSN features a low-profile electrode pedestal, which, when filled with electrolyte solution, creates a sealed microenvironment and an electrode-scalp interface. In all Geodesic dEEG systems, EEG sensors detect changes in voltage originating from the participant's scalp, along with a small amount of electrical noise originating from the room environment. Electrical signals from all sensors of the Geodesic sensor net are received simultaneously by the amplifier, where they are automatically processed, packaged, and sent to the data-acquisition computer (DAC). Once received by the DAC, scalp electrical activity can be isolated from artifacts for analysis using the filtering and artifact detection tools included in the EGI software. Typically, the HCGSN can be used continuously for only up to two hours because the electrolyte solution dries out over time, gradually decreasing the quality of the scalp-electrode interface.In the Parent-Infant Research Lab at the University of Toronto, we are using dEEG to study social cognitive processes including memory, emotion, goals, intentionality, anticipation, and executive functioning in both adult and infant participants.

Quantitative EEG in adults with attention-deficit/hyperactivity disorder

Quantitative EEG in adults with attention-deficit/hyperactivity disorder

The development of a technique for the recording of the intrapartum fetal electroencephalogram – a feasibility trial

BackgroundIntrapartum fetal monitoring is a standard part of perinatal care, despite a lack of robust evidence that it reduces morbidity and mortality in low risk pregnancies. The main premise is...

Polyspike Ictal Onset Absence Seizures

Polyspike ictal-onset absence seizures may predict an unfavorable response to treatment in patients with epilepsy. The authors assessed absences in adults with idiopathic generalized epilepsy (IGE) associated with polyspike onset before classic 3-Hz generalized spike-and-waves (GSW). Seven adults with absences undergoing video EEG were accompanied by 3-Hz GSW, preceded by polyspike-ictal onset by >1 second in two or more seizures. The clinical profile, interictal, and ictal EEG noted had at least 1-year follow-up. A total of 1,164 patients underwent video EEG, with 58 (5%) receiving a diagnosis of IGE or subsyndrome. All seven patients with absence seizures had an ictal EEG pattern of polyspike onset prior to 3-Hz GSW. Four female and three male adults (mean age, 28.9 years) had absence as their primary seizure type. All but one had seizure onset between 4 and 20 years and failed at least two broad-spectrum antiepileptic drug trials. Typical features of IGE were normal neurologic examination, brain MRI, and 3- to 3.5-Hz GSW and generalized polyspike-and-waves on interictal EEG. Atypical features included learning disability (2 of 7), absence status (1 of 7), and paroxysmal fast activity during nonrapid eye movement sleep (3 of 7). Polyspikes are common during video EEG in adults with IGE. Absence seizures with polyspike onset 3-Hz GSW suggest an intermediary form of IGE that may be drug resistant.

The Effects of Donepezil on Postlearning Sleep EEG of Healthy Older Adults

Aging is associated with cholinergic hypofunction and memory decline. Cholinergic activity also plays a crucial role in sleep-dependent memory consolidation. The acetylcholinesterase inhibitor (AChE-I) donepezil has been found to increase sleep-related procedural memory consolidation in healthy older adults in a previous study. Data of the former study were reanalyzed with regard to the effects of donepezil on the sleep EEG of healthy older adults. This analysis was conducted with a special focus on spectral parameters of sleep, which have previously been linked to plasticity-related processes during sleep, i.e., sigma and delta activity. Forty-two participants (aged: 60-77 years) received 5 mg of the AChE-I donepezil orally 30 min before bedtime in a placebo-controlled, double-blind design. Power values for EEG delta, theta, alpha1, alpha 2, sigma, beta and gamma frequency bands were calculated for stage 2 NREM sleep, SWS and REM sleep. In line with our hypotheses, the AChE-I donepezil led to an increase in sigma activity during stage 2 NREM sleep and delta activity during slow wave sleep. These results suggest that an AChE-I facilitates processes of sleep-dependent memory consolidation in older adults.

Functional Connectivity and Aging: Comodulation and Coherence Differences

ABSTRACT Introduction. Misconceptions about coherence and comodulation has hindered their simultaneous use in assessing electroencephalography (EEG). Coherence refers to phase synchrony, whereas comodulation refers to magnitude synchrony. Child and adult EEG data were analyzed for age functions to demonstrate coherence and comodulation differences. Method. Eyes closed resting EEG was analyzed for 101 children and adults between ages of 5 and 35 years (34 female, 67 male; M age = 17.5 years). Spectral analysis focused on site-centered connectivity of 10 frequency bands. Site-centered connectivity refers to averaged coherence or comodulation associated with a site, an estimate of its network traffic. Results. Site-centered coherence and comodulation increased with age for frequencies below 30 Hz in most sites. Age-related changes in anterior connectivity occurred for adults but not for children. The strongest age function was found for alpha comodulation at electrode site T5. Differences in coherence and co...

EEG in adults with Attention-Deficit/Hyperactivity Disorder

Attention-Deficit/Hyperactivity Disorder (AD/HD) is the most common psychiatric disorder of childhood, but it is becoming increasingly apparent that more than half the childhood sufferers will continue to manifest symptoms of the disorder as adults. While the EEG of children with AD/HD has been extensively examined, comparatively little research has been conducted into the EEG of adults with the disorder. This study thus investigated the EEG of 20 adult males with AD/HD, and an age- and gender-matched control group, during an eyes-closed resting condition. The EEG was Fourier transformed to provide absolute and relative power estimates for the delta, theta, alpha and beta bands. The AD/HD group had significantly less absolute delta and more relative theta, across the entire scalp, than the control group. In absolute beta, the AD/HD group had less power at the midline, and an enhancement in power in the right posterior region. These results are similar to those found in children with AD/HD, and may suggest the presence of a processing deficit. A right posterior elevation in beta activity was also found, which could be related to the ongoing presence of reading disabilities in these subjects.

THE JOHNS HOPKINS ATLAS OF DIGITAL EEG: AN INTERACTIVE TRAINING GUIDE

THE JOHNS HOPKINS ATLAS OF DIGITAL EEG: AN INTERACTIVE TRAINING GUIDE edited by Gregory L. Krauss and Robert S. Fisher , 360 pp., The Johns Hopkins University Press, 2007, $125 The greatest strength of this 360-page atlas with over 200 examples of adult and pediatric EEG is the interactive EEG program on the included DVD. The reader can either select a specific EEG finding or …

Relationship between adult attachment patterns, emotional experience and EEG frontal asymmetry

This study investigated whether adult attachment styles influence subjective and neurophysiological aspects of emotion. Self-reported emotional arousal and pleasantness and EEG frontal asymmetry were analysed while subjects watched emotional video-clips inducing happiness, fear and sadness with attachment-related content. Results showed a clear difference between attachment patterns on emotional arousal, resting frontal asymmetry and fluctuating asymmetry changes. Avoidant individuals responded to positive stimuli with less arousing subjective experience and right frontal asymmetry. In turn, preoccupied individuals showed higher arousal feelings and wider frontal left activation. Opposite patterns were observed in response to fear. These findings support the involvement of attachment in modelling individual emotional response and underlying brain functional processes, accounting partly for individual variability in human emotion.

Interictal EEG in Temporal Lobe Epilepsy in Childhood

The authors clarified the value of interictal discharges and verified which extratemporal regions may also show epileptiform activity in temporal lobe epilepsy (TLE) in childhood. Thirty consecutive patients aged 3 to 18 years (mean age = 12.16 years; 16 male) with TLE associated with hippocampal atrophy were studied. Each patient had 1 to 15 interictal EEG recordings (mean: 5.6; total = 192 EEGs). Video-EEG monitoring was performed in 20 patients. All patients had MRI. The findings were compared with a control group of 53 consecutive TLE adult outpatients with hippocampal atrophy. Each adult patient underwent 3 to 21 routine EEGs (mean: 10.67; total = 566). Interictal EEGs of children with TLE showed extratemporal epileptiform discharges more frequently than EEGs of adults with TLE. Frontal, parietal, and occipital discharges were more frequently seen in children (P < 0.05). These results suggest a close interaction between temporal and other cerebral regions in children with epilepsy and provide further evidence of the existence of neural networks.

Normal Adult EEG and Patterns of Uncertain Significance

A thorough understanding of a normal EEG is critical in defining those patterns that are abnormal. Because EEG is unique in the ability to support a clinical diagnosis of epilepsy, epileptiform patterns merit careful consideration. Certain benign patterns maybe epileptiform, yet can occur in healthy individuals without epilepsy. Understanding normal EEG and the benign variants will help to minimize over-interpretation and possibly avoid overtreatment of patients during routine clinical practice.

To BIS or Not to BIS? That Is the Question

T his editorial accompanies two papers (1,2) on the use of the Bispectral Index (BIS) as a sedation index in children. Before discussing the salient elements and findings of these papers, it is instructive to consider what processed electroencephalogram (EEG) monitors actually measure. As an analogy, consider the dark days before the introduction of pulse oximetry into clinical practice, when clinicians generally used something that might approximate to a four-point scale (pink/slightly blue/ dark blue/black) to assess oxygenation. The introduction of pulse oximetry gave a continuous measure of oxygen saturation as a percentage of saturated hemoglobin and quickly became the gold standard for measuring oxygenation, despite the lack of prospective randomized trial evidence of improved outcomes (3). Similarly, we have multiple discontinuous clinical scales for describing sedation levels in adults, including the Observer’s Assessment of Alertness and Sedation (OAAS) and the Ramsay scales. The purpose of processed EEG monitors is to provide a continuous measure that encompasses the full range of sedation levels measured by the discontinuous scales. Pulse oximetry measures a physiological parameter that most physicians can readily understand (oxygen saturation). In contrast, processed EEG monitors calculate a mathematical abstraction of the electroencephalogram, a concept less familiar and less accessible to the practicing clinician. BIS was derived by empirically estimating the EEG parameters that best predicted OAAS measurements in a large patient and volunteer database of subjects receiving hypnotics and opioids. As a continuous measure that correlates to OAAS measures obtained from subjects receiving hypnotic drugs, BIS may be described as a “probability of state” measure, reflecting the complex nature of consciousness (4). Being derived from the OAAS, BIS should be expected to correlate well with the OAAS. The correlation would probably be less strong with other rating scales, such as the Ramsay scale, the modified maintenance of wakefulness test (MMWT) scale used in pediatrics, or the University of Michigan sedation scale (UMSS). These latter scales were not part of the database used to develop the BIS monitor, and the original database was entirely constructed from adult EEG data. Normal pediatric EEG differs markedly from adult EEG, displaying more variation than adult EEG (5,6). This may make processed EEG parameters less reliable in children. In general, the electrical activity of the brain changes during growth and development, warranting age-specific considerations and cautious interpretation of EEG data in the pediatric population. Despite such theoretical concerns, studies suggest that the performance of BIS in pediatric patients older than 6 months of age may be similar to that of adults (7–9). In younger infants, brain maturation and development may render processed EEG measures unreliable. However, McDermott et al. (8) still found a significant correlation between BIS and the UMSS in patients younger than 6 months of age in a small group of patients. In this issue of Anesthesia & Analgesia, Malviya et al. (1) report on the observed relationship between BIS and two observational measures, the UMSS and MMWT, in children 1 month to 17 years conceptual age. In lieu of clinical guidelines that call for delineation of sedation states, the investigators were particularly interested in the ability of different measures to discriminate conscious from deep sedation. Data from 39 patients were included, comprising repeated measurements (about 8 per individual on average) of sedation indices after unspecified procedures that required sedation/analgesia or general anesthesia. The authors report good correlation between UMSS and BIS ( 0.73), indicating reasonable concordance between these discontinuous and continuous scales. This supports the validity of BIS as a pediatric sedation monitor and complements similar reports by this group (10) and others (8). MMWT scores, by contrast, correlated weakly (0.36) with BIS, in contrast to earlier Dr. Peter S. Sebel is a paid consultant to Aspect Medical Systems. Accepted for publication November 16, 2005. Address correspondence and reprint requests to Peter S. Sebel, MB BS, PhD, MBA, Department of Anesthesiology, Emory University School of Medicine, 49 Jesse Hill Jr. Drive, SE, Atlanta, GA 30303. Address e-mail to peter_sebel@emoryhealthcare.org.

Screening of EEG Referrals by Neurologists Leads to Improved Healthcare Resource Utilization

The objective of this study was to determine if screening by a neurologist of all non-neurologist electroencephalogram (EEG) referrals prior to approval reduces the number of inappropriate requests. This retrospective survey included 600 consecutive EEG requisitions referred to the Anaheim Kaiser Permanente Neurodiagnostic Laboratory to rule out epilepsy. Patients with established epilepsy referred for a repeat EEG for management issues were excluded. Three groups of EEG referrals were analyzed. Each group consisted of 200 EEGs (100 pediatric and 100 adult EEGs). The first group was referred directly by non-neurologists, the second group was referred by non-neurologists with scrutiny by a neurologist, and the third group was referred by a neurologist directly. In the pediatric group, the ratio of abnormal EEG vs normal EEG was 1:3.35 in the first group, 1:0.69 in the second group and 1:0.33 in the third group. In the adult group, the ratio of abnormal EEGs vs normal EEGs was 1:2.23 in the first group, 1:0.82 in the second group and 1:0.45 in the third group. In the combined pediatric and adult groups, the ratio of abnormal EEG vs normal EEG was 1:2.70 in the first group, 1:0.75 in the second group and 1:0.39 in the third group. There was a significant difference between the results of the EEGs ordered by non-neurologists directly versus non-neurologists with scrutiny (p=.334, chi-square test). Scrutiny by a neurologist of EEG referrals from non-neurologists led to a reduction in the number of normal EEG results. This suggests that inappropriate EEG requests for non-epileptic patients that yield normal EEG results are significantly reduced with scrutiny. This can help reduce the indiscriminate overuse of EEGs by non-neurologists thereby leading to better utilization of healthcare resources.

Quantitative EEG analysis in dexamphetamine-responsive adults with attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (AD/HD) is recognized as a disorder affecting children and adolescents and has more recently been documented to continue into adulthood in a proportion of patients. One of the common treatments for AD/HD is the use of stimulant medications. Numerous studies have examined the therapeutic effects of stimulant medications in children, adolescents and adults with the disorder, reporting improvements in attention, concentration, and hyperactive and impulsive behaviours. Several studies have also examined the effects of stimulants on the electroencephalograph (EEG) of children and adolescents with the disorder, but to date, there have been no studies examining the effects of stimulant medication on the EEG of adults with AD/HD. In the present study, we aimed to replicate previous EEG findings in adults with AD/HD relative to controls and to examine whether there was any change in this profile following treatment with dexamphetamine. The EEG was recorded at rest in an eyes-open condition from 50 adults diagnosed with AD/HD and assessed as good responders to treatment, both before and after treatment with dexamphetamine, and 50 control subjects. The pre-medication results are similar to those found in previous research that compared the EEGs of adults with AD/HD and control subjects. Following medication, there was a significant reduction in slow wave activity in the AD/HD group to levels similar to those in the control group. These results suggest that changes in brain function of good responders to dexamphetamine, as reflected in the EEG, may underlie the behavioural improvements observed in the clinical setting.

Heritability of background EEG across the power spectrum

We estimated the genetic and nongenetic (environmental) contributions to individual differences in the background EEG power spectrum in two age cohorts with mean ages of 26.2 and 49.4 years. Nineteen-lead EEG was recorded with eyes closed from 142 monozygotic and 167 dizygotic twin pairs and their siblings, totaling 760 subjects. We obtained power spectra in 24 bins of 1 Hz ranging from 1.0 to 25.0 Hz. Generally, heritability was highest around the alpha peak frequency and lower in the theta and delta bands. In the beta band heritability gradually decreased with increasing frequency, especially in the temporal regions. Genetic correlations between power in the classical broad bands indicated that half to three-quarters of the genetic variance can be attributed to a common source. We conclude that across the scalp and most of the frequency spectrum, individual differences in adult EEG are largely determined by genetic factors.

Chronotype and Sex Effects on Sleep Architecture and Quantitative Sleep EEG in Healthy Young Adults

To evaluate the influence of chronotype (morning types and evening types) on sleep stages and quantitative sleep electroencephalograms when constraints on the sleep schedule are minimal and when sex difference is taken into account. A 48-hour session in the laboratory, including 2 nights of polysomnography, preceded by 7 days of ambulatory actigraphy. Chronobiology laboratory. Twenty-four healthy young subjects: 12 morning types and 12 evening types selected by questionnaire. Each group included 6 men and 6 women. None. A polysomnography night of 8 hours in duration was recorded according to preferred sleep schedule. Sleep-stage analysis revealed that morning types and evening types did not differ in sleep architecture. However, morning-type men showed a higher percentage of stage 1 sleep and lower sleep efficiency than evening-type men. Electroencephalogram spectral analysis was conducted in non-rapid eye movement sleep for 6 frequency bands. Morning types had more spectral power in low sigma (12-14 Hz) compared with evening types. The most robust difference between women and men was found in high sigma (14-16 Hz) and was not present between chronotypes. The decay rate of slow-wave activity (1-5 Hz) tended to be faster in morning types compared with evening types (P = .06). This rate was almost identical for women and men. These results agree with the hypothesis that homeostatic sleep regulation differs between morning types and evening types, with morning types showing indications of a higher rate of dissipation of sleep pressure during the night. Morningness-eveningness seems to affect sleep in a sex-specific manner, with men being more affected by their chronotype.

Benign EEG Variants

ABSTRACT.EEG is a valuable tool that assists in the accurate diagnosis of seizure disorders. The precise interpretation of EEG requires an ability to recognize patterns that are benign in nature but may be misinterpreted as indicative of a seizure tendency. This review will summarize benign variants encountered in adult EEGs including: small sharp spikes, wicket spikes, fourteen- and six-hertz positive bursts, six-hertz spike and wave, rhythmic temporal theta bursts of drowsiness, subclinical rhythmic electroencephalographic discharge in adults, and midline theta rhythms. Although most of these patterns are relatively uncommon, it is imperative that the clinical neurophysiologist identifies them as benign variants.

Review of Neonatal EEG

ABSTRACT.Neonatal electroencephalography (EEG) presents some of the most difficult challenges in EEG interpretation. It differs significantly in many ways from EEG of older children and adults. Technologically, acquisition of a neonatal EEG is significantly more difficult and different than an adult EEG. There are numerous features that are age-specific and change almost week-to-week in the preterm infant. Some features may be normal at one age and abnormal if they persist for several weeks. Many of these features also have different implications in neonates as compared to older individuals. These issues mandate a different approach to neonatal EEG interpretation. In this article an overview of neonatal EEG is presented. After a brief discussion of relevant technical issues, various normal EEG features encountered in neonates are discussed. This is followed by a discussion of the ontogeny of EEG, starting from the age of viability to the first few months of life. A description of various abnormalities follows. Finally, an approach to analysis of a neonatal EEG is presented.