Baseline EEG Research Articles

Associations Between Maternal Stress, Early Language Behaviors, and Infant Electroencephalography During the First Year of Life.

Associations have been observed between socioeconomic status (SES) and language outcomes from early childhood, but individual variability is high. Exposure to high levels of stress, often associated with low-SES status, might influence how parents and infants interact within the early language environment. Differences in these early language behaviors, and in early neurodevelopment, might underlie SES-based differences in language that emerge later on. Analysis of natural language samples from a predominantly low-/mid-income sample of mother-infant dyads, obtained using the Language Environment Analysis (LENA) system, found that maternal reports of exposure to stressful life events, and perceived stress, were negatively correlated with child vocalizations and conversational turns when infants were 6 and 12 months of age. Greater numbers of vocalizations and conversational turns were also associated with lower relative theta power and higher relative gamma power in 6- and 12-month baseline EEG - a pattern that might support subsequent language development.

Associations between maternal stress, early language behaviors, and infant electroencephalography during the first year of life

Associations have been observed between socioeconomic status (SES) and language outcomes from early childhood, but individual variability is high. Exposure to high levels of stress, often associated with low-SES status, might influence how parents and infants interact within the early language environment. Differences in these early language behaviors, and in early neurodevelopment, might underlie SES-based differences in language that emerge later on. Analysis of natural language samples from a predominantly low-/mid-income sample of mother-infant dyads, obtained using the Language Environment Analysis (LENA) system, found that maternal reports of exposure to stressful life events, and perceived stress, were negatively correlated with child vocalizations and conversational turns when infants were 6 and 12 months of age. Greater numbers of vocalizations and conversational turns were also associated with lower relative theta power and higher relative gamma power in 6- and 12-month baseline EEG - a pattern that might support subsequent language development.

Predictors of one-year language and seizure outcomes in children with epileptic encephalopathy with continuous spike-and-wave during sleep (CSWS)

PurposeEpileptic encephalopathy with continuous spike-and-wave during sleep (CSWS), with its associated impact on language, is an important cause of morbidity with epilepsy in children. The effects of various treatment-approaches and the aetiological/electrophysiological factors affecting therapeutic response are not fully understood. MethodA retrospective study of patients admitted to the institute and diagnosed to have CSWS pattern on EEG was conducted. Spike and Wave Frequency/100 s(SWF) was calculated from sleep-EEG records. Language development and seizure outcomes were assessed at baseline and 1 year. ResultsFifty-two children were included (idiopathic CSWS, N = 19; symptomatic CSWS N = 33).The 2 groups differed in terms of younger age at seizure onset in symptomatic CSWS (p = 0.006), early age at language regression (p = 0.046), history of neonatal seizures (p = 0.038) and slowing of background activity on EEG (p = 0.024). Language regression was noted in 63.5 % of the cohort. Twenty-five (48%) patients received steroids with improvement in seizures (p < 0.001). Twenty-one (40.3 %) received steroids and intravenous immunoglobulin (IVIG) with improvement in seizure score (p = 0.002) at 1 year. Both immune-modulation arms irrespective of etiological subgroups had comparable proportions of children with expressive and receptive language gains. On 1 year follow-up, seizure remission was noted in 13(25 %) patients, with improved seizure score in 32/39 (61.5 %) patients and language improvement in 32 children (60.8 %). Patients with normal background on baseline EEG, generalised spikes, absent frontal-negative spikes and SWF < 170 were found to have improved language estimates on follow-up. ConclusionsDespite clinical and therapeutic outcome differences between idiopathic and symptomatic CSWS, immune-modulation appears effective irrespective of aetiology. Analysis of EEG variables enables prediction of language outcomes at 1 year follow-up.

Transcranial direct current stimulation improves tinnitus perception and modulates cortical electrical activity in patients with tinnitus: A randomized clinical trial

ObjectivesThis study aims to determine whether transcranial direct current stimulation (tDCS): a) is effective in the treatment of tinnitus by decreasing its annoyance and severity; b) modulates the cortical electrical activity of such individuals. MethodsA double-blind, placebo-controlled clinical trial was conducted with 24 patients with tinnitus, randomized into two groups: Group 1 (n = 12) received anodal tDCS over the left temporoparietal area (LTA) and cathodal tDCS over the right dorsolateral prefrontal cortex (DLPFC) and Group 2 (n = 12) received placebo intervention. Tinnitus perception using a visual analog scale (VAS) and the Tinnitus Handicap Inventory (THI) questionnaire, in addition to electroencephalogram (EEG) was measured with eyes opened and closed at baseline and after the intervention. For the treatment, patients were subjected to five consecutive sessions of tDCS with the anodal electrode over the LTA and cathodal electrode over the right DLPFC (7 × 5 cm, 2 mA for 20 min). tDCS was turned off after 30 s in the sham group. ResultsActive tDCS significantly improved tinnitus annoyance and severity. It was associated with decreased beta and theta EEG frequency bands with eyes opened and decreased alpha frequency with eyes closed. sLORETA identified changes in frequency bands in the frontal, temporoparietal, and limbic regions. Finally, there were negative correlations between baseline EEG frequency bands and tDCS-induced change in tinnitus annoyance and severity. ConclusionsThese results demonstrate that tDCS modulates the EEG activity and alleviates tinnitus perception. This effect may be related to baseline EEG activity.

Cognitive decline in Parkinson's disease is associated with reduced complexity of EEG at baseline.

Parkinson’s disease is a neurodegenerative disorder requiring motor signs for diagnosis, but showing more widespread pathological alterations from its beginning. Compared to age-matched healthy individuals, patients with Parkinson’s disease bear a 6-fold lifetime risk of dementia. For individualized counselling and treatment, prognostic biomarkers for assessing future cognitive deterioration in early stages of Parkinson’s disease are needed. In a case–control study, 42 cognitively normal patients with Parkinson’s disease were compared with 24 healthy control participants matched for age, sex and education. Tsallis entropy and band power of the δ, θ, α, β and γ-band were evaluated in baseline EEG at eyes-open and eyes-closed condition. As the θ-band showed the most pronounced differences between Parkinson’s disease and healthy control groups, further analysis focussed on this band. Tsallis entropy was then compared across groups with 16 psychological test scores at baseline and follow-ups at 6 months and 3 years. In group comparison, patients with Parkinson’s disease showed lower Tsallis entropy than healthy control participants. Cognitive deterioration at 3 years was correlated with Tsallis entropy in the eyes-open condition (P < 0.00079), whereas correlation at 6 months was not yet significant. Tsallis entropy measured in the eyes-closed condition did not correlate with cognitive outcome. In conclusion, the lower the EEG entropy levels at baseline in the eyes-open condition, the higher the probability of cognitive decline over 3 years. This makes Tsallis entropy a candidate prognostic biomarker for dementia in Parkinson’s disease. The ability of the cortex to execute complex functions underlies cognitive health, whereas cognitive decline might clinically appear when compensatory capacity is exhausted.

Intraoperative Cortical Asynchrony Predicts Abnormal Postoperative Electroencephalogram

Postoperative electroencephalograms (EEGs) can identify seizure activity and neurologic dysfunction in high-risk neonates requiring cardiac surgical procedures. Although intraoperative EEG monitoring is uncommon, variations in cerebral blood flow and temperature during antegrade cerebral perfusion (ACP) can manifest as cortical asynchrony during EEG monitoring. We hypothesized that intraoperative EEG cortical asynchrony would identify neonates at risk for abnormal postoperative EEG tracings. Neonates requiring ACP for cardiac repair or palliation had continuous baseline, intraoperative, and postoperative hemodynamic and EEG monitoring. Synchronous and asynchronous cortical bursts were quantified during (1) cooling before ACP, (2) ACP, and (3) rewarming. Asynchronous bursts were defined as interhemispheric variations in electrical voltage or frequency. Neonates were divided into 2 groups, those with and without an abnormal postoperative EEG, which was defined as either persistent asynchrony for more than 2 hours or seizure activity on EEG. Among 40 neonates, 296 asynchronous bursts were noted, most commonly during rewarming. Eight (20%) neonates had an abnormal postoperative EEG (seizure activity,n= 3; persistent asynchrony, n= 5). Baseline demographics and intraoperative hemodynamics were similar between the groups. However, the total number of intraoperative asynchronous bursts was greater in neonates with an abnormal postoperative EEG (17 [11, IQR:24] vs 3[IQR:1, 7]; P < .001). Multivariate analysis confirmed that the number of asynchronous bursts was independently associated with an abnormal postoperative EEG (odds ratio,1.35; confidence interval,:1.10, 1.65; P= .004). Neonates with a greater number of intraoperative asynchronous cortical bursts had an abnormal postoperative EEG.

Increased epileptogenicity in a mouse model of neurofibromatosis type 1

RationaleNeurofibromatosis type 1 (NF1) is associated with higher rates of epilepsy compared to the general population. Some NF1 patients with epilepsy do not have intracranial lesions, suggesting the genetic mutation itself may contribute to higher rates of epilepsy in these patients. We have recently demonstrated increased seizure susceptibility in the Nf1+/− mouse, but it is unknown whether this model displays altered epileptogenicity, as has been reported in patients with NF1. The aim of this study was to determine whether the Nf1+/− mouse is more susceptible to electrical kindling-induced epileptogenesis. MethodsYoung male or female adult Nf1+/− or Nf1+/+ (wild-type; WT) mice were implanted with electrodes for neocortical or hippocampal kindling paradigms. Neocortical kindling was performed for 40 stimulation sessions followed by baseline EEG monitoring to detect possible SRSs. Hippocampal kindling was performed with a modified extended kindling paradigm, completed to a maximum of 80 sessions to try to induce spontaneous repetitive seizures (SRSs). Western blot assays were performed in naïve and kindled mice to compare levels of Akt and MAPK (ERK1/2), proteins downstream of the NF1 mutation. ResultsThe average initial neocortical after-discharge threshold (ADT) was significantly lower in the Nf1+/− group, which also required fewer stimulations to reach stage 5 seizure, had greater average seizure severity across all kindling sessions, had a greater number of convulsive seizures, and had a faster progression of after-discharge duration and Racine score during kindling. No WT mice exhibited SRS after neocortical kindling, versus 33% of Nf1+/− mice. The average initial hippocampal ADT was not significantly different between the WT and Nf1+/− groups, nor was there a difference in the number of stimulations required to reach the kindled state. The WT group had a significantly higher average seizure severity across all kindling sessions as compared with the Nf1+/− mice. The WT group also had faster progression of the Racine seizure score over the kindling sessions, mainly due to a faster increase in seizures severity early during the kindling process. However, SRSs were seen in 50% of Nf1+/− mice after modified extended kindling and in no WT mice. Western blots showed hippocampal kindling increased the ratio of phosphorylated/total Akt in both the WT and Nf1+/− mice, while neocortical kindling led to increased ratios of phosphorylated/total Akt and MAPK in Nf1+/− mice only. ConclusionsWe have demonstrated for the first time an increased rate of epileptogenesis in an animal model of NF1 with no known macroscopic/neoplastic brain lesions. This work provides evidence for the genetic mutation itself playing a role in seizures and epilepsy in patients with NF1, and supports the use of the Nf1+/− mouse model in future mechanistic studies.

O10.2. DEFICIENT VISUAL ODDBALL STIMULUS PROCESSING PREDICTS PSYCHOSIS ONSET: RESULTS FROM THE NORTH AMERICAN PRODROME LONGITUDINAL STUDY

BackgroundClinical outcomes vary among young people with the psychosis risk syndrome (PRS), with approximately 20% of individuals progressing to a psychotic disorder over 2–3 years and 30% achieving clinical remission. The identification of neurophysiological abnormalities associated with schizophrenia that predate and predict psychosis onset may enhance the accuracy of clinical outcome prediction in the PRS and help elucidate the pathogenic mechanisms of psychosis onset. Auditory P300 event-related potential (ERP) component amplitude reductions are well established in schizophrenia and reflect early attention-mediated information processing deficits. Recent studies employing auditory oddball tasks have shown that P300 amplitude deficits in PRS individuals are associated with later clinical outcomes, including both conversion to full-blown psychosis and remission from the at-risk state. The present study examined whether these effects extend to P300 in the visual modality using visual oddball task data collected as part of the North American Prodrome Longitudinal Study. Specifically, we evaluated whether visual P300 amplitudes are reduced in the PRS and predict future clinical outcomes.Methods540 individuals meeting PRS criteria and 229 healthy individuals completed baseline EEG recording during a visual oddball task. Visual P300 subcomponents were measured in response to two stimulus types: (1) infrequent target stimuli, reflecting top-down allocation of attention (target P3b), and (2) infrequent non-target novel distractor stimuli, reflecting bottom-up orienting of attention (novelty P3a). P300 amplitudes of PRS participants who converted to psychosis (n=70) were compared with those of PRS non-converters who were followed clinically for 24 months and continued to be symptomatic (n=131) or fully remitted from the PRS (n=87).ResultsGroup comparison effects did not differ by stimulus type. Visual P300 amplitudes were not significantly reduced in the PRS group relative to healthy individuals (p=.25). However, baseline target P3b and novelty P3a amplitudes were reduced in PRS individuals who later converted to psychosis relative to all PRS non-converters, including those who remitted (p=.006, d=.44) and those who remained symptomatic (p=.015, d=.37), as well as healthy individuals (p=.001, d=.44). Baseline P300 amplitudes were similar among healthy controls, PRS remitters, and PRS individuals who remained symptomatic (ps>.45). Moreover, visual P300 amplitudes differentiated future psychosis converters after accounting for PRS symptom severity. Finally, both target P3b and novelty P3a amplitudes predicted the time to psychosis onset in PRS participants (p=.03 and p=.02, respectively), such that more deficient P300 amplitudes were associated with shorter time to conversion.DiscussionBaseline visual P300 amplitudes were reduced in future PRS converters relative to non-converters, with effect sizes comparable to those reported in previous auditory P300 studies of the PRS. Results implicate visual P300 as a neurophysiological vulnerability marker that predicts clinical outcomes among PRS individuals, including future transition to psychosis. Accordingly, together with prior auditory P300 studies, results suggest that P300 may have the potential to contribute to personalized early intervention in the PRS by distinguishing individuals with the greatest risk for psychotic illness, who require the most aggressive treatment, from those who may need minimal intervention.

EEG Education in Neurology Residency – Baseline EEG Knowledge and Resident Perception (1415)

EEG Education in Neurology Residency – Baseline EEG Knowledge and Resident Perception (1415)

Report of a Case of Creutzfeldt-Jakob Disease With an Unusual Clinical Presentation.

We describe the clinical features, neuropsychological tests, laboratory, electroencephalography (EEG), magnetic resonance imaging (MRI) and positron emission tomography (PET) findings of a 59-year-old woman who presented to our Centre for cognitive impairment since few months, with language disturbances, particularly anomia, dyscalculia, and memory loss. The clinical and neuropsychological features were non-specific and overlapping with those of other rapidly progressing neurodegenerative disorders. However, brain MRI played a pivotal role in the diagnosis, showing cortical diffusion restriction, particularly in the parietal lobes and posterior cingulum, with sparing of the perirolandic cortex, typical of Creutzfeldt-Jakob disease (CJD). Brain MRI abnormalities were visible since the first evaluation and remained stable at 2 and 6 weeks follow up. Basal ganglia and thalami were never involved. PET showed left lateralized reduced glucose metabolism, with partial overlap with MRI signal abnormalities. Despite MRI were strongly indicative of CJD, clinical, laboratory and EEG findings did not fulfill the diagnostic criteria for CJD which applied at the time of clinical assessment. Indeed, neither myoclonus, visual or cerebellar signs or akinetic mutism were present. Also, the characteristic periodic sharp wave complexes were absent at baseline EEG, and the CSF assay for 14–3–3 was negative. We, therefore, performed a real-time quaking-induced conversion (RT-QuIC) assay on a frozen sample of corticospinal fluid (CSF), which showed a positive result. RT-QuIC is a prion protein conversion assay that has shown high diagnostic sensitivity and specificity for the diagnosis of CJD. RT-QuIC has been recently incorporated in the National CJD Research and Surveillance Unit and Center for Disease Control and Prevention (CDC) diagnostic criteria for CJD. The fatal evolution of the disease brought the patient to death 13 months after symptoms onset. Pathology proved the diagnosis of sporadic CJD, subtype MM/MV 2C.

Delirium after cardiac arrest: Phenotype, prediction, and outcome

AimTo establish incidence, phenotype, long-term functional outcome, and early EEG predictors of delirium after cardiac arrest. MethodsThis is an ad hoc analysis of a prospective cohort study on outcome prediction of comatose patients after cardiac arrest. Patients with recovery of consciousness, who survived until hospital discharge, were subdivided in groups with and without delirium based on psychiatric consultation. Delirium phenotype and medical treatment were retrieved from patient files. All other data were prospectively collected. We used univariate analyses of baseline and early EEG characteristics for identification of possible delirium predictors. Association of delirium with neurological recovery at six months was analyzed with multinomial logistic regression analysis. ResultsOf 233 patients, 141 survived until hospital discharge, of whom 47 (33%) were diagnosed with delirium. There were no differences in baseline characteristics between patients with and without delirium. All delirious patients were treated with relatively high dosages of psychopharmaceuticals, mostly haloperidol and benzodiazepine agonists. Prevalent characteristics were disturbed cognition, perception and psychomotor functioning (98%). Half of the patients had language disorders or shouting. Delirium was associated with longer ICU and hospital admission, and more frequent discharge to rehabilitation centre or nursing home. There was a trend towards poorer neurological recovery. EEG measurements within 12 h after cardiac arrest could predict delirium with 91% specificity and 40% sensitivity. DiscussionDelirium is common after cardiac arrest, and probably leads to longer hospitalization and poorer outcome. Optimal treatment is unclear. Early EEG holds potential to identify patients at risk.

Could EEG Help Predict Antidepressant Response?

Could EEG Help Predict Antidepressant Response?

Use of Machine Learning for Predicting Escitalopram Treatment Outcome From Electroencephalography Recordings in Adult Patients With Depression

Social and economic costs of depression are exacerbated by prolonged periods spent identifying treatments that would be effective for a particular patient. Thus, a tool that reliably predicts an individual patient's response to treatment could significantly reduce the burden of depression. To estimate how accurately an outcome of escitalopram treatment can be predicted from electroencephalographic (EEG) data on patients with depression. This prognostic study used a support vector machine classifier to predict treatment outcome using data from the first Canadian Biomarker Integration Network in Depression (CAN-BIND-1) study. The CAN-BIND-1 study comprised 180 patients (aged 18-60 years) diagnosed with major depressive disorder who had completed 8 weeks of treatment. Of this group, 122 patients had EEG data recorded before the treatment; 115 also had EEG data recorded after the first 2 weeks of treatment. All participants completed 8 weeks of open-label escitalopram (10-20 mg) treatment. The ability of EEG data to predict treatment outcome, measured as accuracy, specificity, and sensitivity of the classifier at baseline and after the first 2 weeks of treatment. The treatment outcome was defined in terms of change in symptom severity, measured by the Montgomery-Åsberg Depression Rating Scale, before and after 8 weeks of treatment. A patient was designated as a responder if the Montgomery-Åsberg Depression Rating Scale score decreased by at least 50% during the 8 weeks and as a nonresponder if the score decrease was less than 50%. Of the 122 participants who completed a baseline EEG recording (mean [SD] age, 36.3 [12.7] years; 76 [62.3%] female), the classifier was able to identify responders with an estimated accuracy of 79.2% (sensitivity, 67.3%; specificity, 91.0%) when using only the baseline EEG data. For a subset of 115 participants who had additional EEG data recorded after the first 2 weeks of treatment, use of these data increased the accuracy to 82.4% (sensitivity, 79.2%; specificity, 85.5%). These findings demonstrate the potential utility of EEG as a treatment planning tool for escitalopram therapy. Further development of the classification tools presented in this study holds the promise of expediting the search for optimal treatment for each patient.

The Impact of Electroacupuncture at Hegu, Shousanli, and Quchi Based on the Theory "Treating Flaccid Paralysis by Yangming Alone" on Stroke Patients' EEG: A Pilot Study.

Background In China, electroacupuncture based on meridians theory “treating flaccid paralysis by Yangming alone” has been widely used for stroke rehabilitation in clinical practice. The aim of this study was to explore the electroencephalography change of electroacupuncture intervention on strokes patients with flaccid paralysis. Methods Twenty-three stroke patients with flaccid paralysis and six stroke patients with spasticity accepted electroacupuncture with the acupoints Hegu [LI4], Shousanli [LI10], and Quchi [LI11] for 20 minutes and their EEG data were recorded before, during, and after the electroacupuncture intervention. Results Compared with the baseline EEG signals before electroacupuncture, the ipsilesional and contralesional beta-band average power of patients with flaccid paralysis and spasticity were significantly increased during the needles retention stage and decreased slightly after removing the needles. The significant decrease of the ipsilesional and contralesional delta band average power in patients with flaccid paralysis occurred during the electroacupuncture stimulation, and they increased after the removal of the needles. The ipsilesional delta band average power of patients with spasticity significantly decreased during the electroacupuncture stimulation. Conclusion From this pilot electrophysiological study, we provided a possible electrophysiological mechanism of the curative effect of electroacupuncture for stroke rehabilitation.

Comparative Analysis of Depth of Meditation Between Long-Term and Short Term Meditators using Electroencephalography

Background and Aim: The present study was designed to evaluate the brain electrical activity among Long-term meditators (LTMs) and Short-term meditators (STMs) using Electroencephalography (EEG). Methods: This prospective study involved 40 mins of EEG recordings, carried out twice i.e. at Day 0 (Baseline) and at Day 10 (During meditation) in thirty-four (34) participants. Twelve (12) apparently healthy male, right-handed, practicing preksha meditation (Since >5 years, at least 5 days a week) were recruited as long-term meditators; Twelve (12) subjects who attended the 10-days short-term yoga-based lifestyle intervention program were recruited as short-term meditators; Ten (10) male healthy controls, who did not participate in any dietary/yoga intervention were recruited among the staff members. The EEG waves were analyzed at Day 0 and at Day 10 using Wilcoxon Signed Rank test and Repeated measured ANOVA respectively. One-way ANOVA was used for the baseline EEG waves activity comparison among LTMs vs. STMs vs. Controls. The response to photic stimulation was also assessed during meditation. Results: Significant different patterns of alpha and theta waves (p<0.05) activity was observed for LTM vs. STM during meditation vs. baseline. Also, significant different baseline EEG waves (p<0.05) were observed among LTM vs. STM vs. Controls. Conclusion: Findings may be useful in defining the basic EEG features to differentiate meditators based on the duration of practice of meditation and depth of meditation.

Prediction of individual responses to electroconvulsive therapy in patients with schizophrenia: Machine learning analysis of resting-state electroencephalography

BackgroundElectroconvulsive therapy (ECT) has strong efficacy in patients with treatment refractory schizophrenia. However, access to ECT has been limited by high costs, professional labor, treatment duration, and significant adverse effects. To provide support for the decision to perform ECT, we aimed to predict individual responses to ECT among patients with schizophrenia using machine learning analysis of resting-state electroencephalography (EEG). MethodsForty-seven patients diagnosed with schizophrenia or schizoaffective disorder with EEG recordings before the course of ECT were treated at Seoul National University Hospital. Among these patients, 29 were responders who showed scores of 3 or less on the Clinical Global Impression Severity scale after the course of ECT. Transfer entropy (TE), which represents information flow, was extracted from baseline EEG data and used as a feature. Feature selection was performed with four methods, including Random Subset Feature Selection (RSFS). The random forest classifier was used to predict individual ECT responses. ResultsThe averaged TE, especially in frontal regions, was higher in ECT responders than in nonresponders. A predictive model using the RSFS method classified ECT responders and nonresponders with 85.3% balanced accuracy, 85.2% accuracy, 88.7% sensitivity, and 81.8% specificity. The positive predictive value was 82.6%, and the negative predictive value was 88.2%. ConclusionsThe results of the current study suggest that higher effective connectivity in frontal areas may be associated with a favorable ECT response. Furthermore, personalized decisions to perform ECT in clinical practice could be augmented by resting-state EEG biomarkers of the ECT response in schizophrenia patients.

Efficacy, retention, and safety of brivaracetam in adult patients with genetic generalized epilepsy

ObjectiveThe aim of this study was to evaluate the efficacy, tolerability, and retention of brivaracetam (BRV) in genetic generalized epilepsy (GGE) in real-life practice. MethodsThis is a retrospective cohort study of adult patients with GGE in whom BRV was started between 2016 and 2018, completing a follow-up period of ≥6 months. Clinical and electroencephalogram (EEG) characteristics were analyzed at baseline and at follow-up as outcome measures. ResultsBrivaracetam was started in 37 patients (mean age: 29.9 ± 12.3 years; 73% women). Juvenile myoclonic epilepsy was the most common syndrome (43.2%). The primary indications for starting BRV were lack of efficacy (51.4%) and adverse events (AEs) (27%) of other antiepileptic drugs (AEDs). In total, 32.4% of patients received BRV monotherapy. Retention rate at 6 months was 81.1%; 83.8% of patients were considered responders, and 62.2% achieved seizure freedom. The primary reasons for withdrawal were treatment-emergent adverse events (TEAEs, 57.1%) and lack of efficacy (42.9%). The higher number of prior AED use was a risk factor for a lack of response [median = 4 (interquartile range (IQR): 3–4) vs 2 (IQR: 1–3); p < 0.05]. Patients with a previous response to valproic acid tended to have a higher response rate to BRV (86.7% vs 50%, p = 0.169). Eighty-three point eight percent (83.8%) of previous levetiracetam (LEV) responders also showed a good response to BRV. In terms of patients who presented LEV-related AEs, AE resolution was observed in 79.8%, particularly with regard to psychiatric AEs. Follow-up EEGs were compared with baseline EEGs in 25 patients (67.6%) during follow-up. Most patients showed a reduction (52%) or no change (36%) in interictal epileptiform discharge (IED) frequency. SignificanceBrivaracetam shows good responder and retention rates in GGE and is generally well tolerated. It is an appropriate alternative treatment for GGE, especially in refractory epilepsy and when other AEDs are not tolerated.

Consistency of quantitative electroencephalography features in a large clinical data set

Objective. Despite their increasing use and public health importance, little is known about the consistency and variability of the quantitative features of baseline electroencephalography (EEG) measurements in healthy individuals and populations. This study aims to investigate population consistency of EEG features. Approach. We propose a non-parametric method of evaluating consistency of commonly used EEG features based on counts of non-significant statistical tests using a large data set. We first replicate stationarity results of absolute band powers using coefficients of variation. We then determine feature stationarity, intra-subject consistency, inter-subject consistency, and intra- versus inter-subject consistency across different epoch lengths for 30 features. Main results. We find in general that features with normalizing constants are more stationary. We also find entropy, median, skew, and kurtosis of EEG to behave as baseline EEG metrics. However, other spectral and signal shape features have stronger intra-subject consistency and thus are better for distinguishing individuals. Significance. These results provide data-driven non-parametric methods of identifying EEG features and their spatial characteristics ideal for various EEG applications, and determining future EEG feature consistencies using an existing EEG data set.

INNV-38. RATE OF EEG IN GLIOMA PATIENTS: SHOULD THIS BE PART OF STANDARD OF CARE FOR NEW BRAIN TUMOR PATIENTS?

Abstract Current guidelines recommend antiepileptic drug (AED) therapy for glioma patients only in patients who have experienced a seizure. There is no current recommendation in regards to performing EEG monitoring in glioma patients. Thus, typically only clinical seizures have prompted AED therapy in glioma patients. Our purpose was to investigate the rate of EEG monitoring in glioma patients entered into our glioma registry, along with seizure and AED rates. Using our glioma registry to date, of 167 glioma patients, 119 patients had EEGs performed during their clinical course. Of those 119 patients, 104 glioma patients had either clinical or electrographic seizure activity and all 104 were on AEDs. This observation indicates that baseline eeg monitoring might be considered in all newly diagnosed glioma patients to reduce seizure incidence, potentially, starting AED prophylaxis if epileptiform activity is seen on EEG prior to clinical seizure activity to potentially reduce morbidity and healthcare costs related to clinical seizure activity. This warrants further prospective study.

Models for the Quantitative Prediction of Therapeutic Responses Based on the Baseline EEG Parameters in Depressive Patients

To determine the possibility for individualized quantitative prediction of therapeutic responses in depressive patients from the baseline EEG parameters, we conducted a correlational analysis of relationships between the baseline EEG spectral power values (80 variations in total) recorded in 42 depressive patients before the start of the therapeutic course and clinical quantitative assessments of the post-treatment mental conditions of these patients. Based on these data, regression models were built for individualized quantitative prediction of therapeutic response, including no more than three pre-treatment EEG parameters and describing up to 75% of the variance in clinical post-treatment assessment values. On the one hand, our results confirm the possibility of designing fairly accurate mathematical models for the individualized quantitative prediction of therapeutic responses in depressive patients by a small number of baseline neurophysiological parameters. On the other hand, the employed mathematical approaches make it possible to clarify the neurophysiological mechanisms underlying depressive disorders.