Epileptiform Patterns Research Articles

Time series segmentation for recognition of epileptiform patterns recorded via microelectrode arrays in vitro.

Epilepsy is a prevalent neurological disorder that affects approximately 1% of the global population. Approximately 30-40% of patients respond poorly to antiepileptic medications, leading to a significant negative impact on their quality of life. Closed-loop deep brain stimulation (DBS) is a promising treatment for individuals who do not respond to medical therapy. To achieve effective seizure control, algorithms play an important role in identifying relevant electrographic biomarkers from local field potentials (LFPs) to determine the optimal stimulation timing. In this regard, the detection and classification of events from ongoing brain activity, while achieving low power consumption through computationally inexpensive implementations, represents a major challenge in the field. To address this challenge, we here present two algorithms, the ZdensityRODE and the AMPDE, for identifying relevant events from LFPs by utilizing time series segmentation (TSS), which involves extracting different levels of information from the LFP and relevant events from it. The algorithms were validated validated against epileptiform activity induced by 4-aminopyridine in mouse hippocampus-cortex (CTX) slices and recorded via microelectrode array, as a case study. The ZdensityRODE algorithm showcased a precision and recall of 93% for ictal event detection and 42% precision for interictal event detection, while the AMPDE algorithm attained a precision of 96% and recall of 90% for ictal event detection and 54% precision for interictal event detection. While initially trained specifically for detecting ictal activity, these algorithms can be fine-tuned for improved interictal detection, aiming at seizure prediction. Our results suggest that these algorithms can effectively capture epileptiform activity, supporting seizure detection and, possibly, seizure prediction and control. This opens the opportunity to design new algorithms based on this approach for closed-loop stimulation devices using more elaborate decisions and more accurate clinical guidelines.

Clinical and Functional Correlates of Manifestations of Epileptic Seizures in Children with Benign Epileptiform Patterns on Electroencephalogram

Clinical and Functional Correlates of Manifestations of Epileptic Seizures in Children with Benign Epileptiform Patterns on Electroencephalogram

Time is brain: detection of nonconvulsive seizures and status epilepticus during acute stroke evaluation using point-of-care electroencephalography

Seizures are both a common mimic and a potential complication of acute stroke. Although EEG can be helpful to evaluate this differential diagnosis, conventional EEG infrastructure is resource-intensive and unable to provide timely monitoring to match the emergent context of a stroke code. We aimed to evaluate the real-world use and utility of a point-of-care EEG device as an adjunct to acute stroke evaluation. We performed a retrospective observational cohort study at a tertiary care community teaching hospital by identifying patients who underwent point-of-care EEG monitoring using Rapid Response EEG system (Ceribell Inc., Sunnyvale, CA) during stroke code evaluation of acute neurological deficits during the study period from January 1, 2020 to December 31, 2020. We assessed the frequency of seizures and highly epileptiform patterns among patients with either confirmed strokes or stroke mimics. Point-of-care EEG monitoring was used in the wake of a stroke code in 70 patients. Of these, neuroimaging and clinical information resulted in a diagnosis of stroke in 38 patients (28 ischemic, 6 hemorrhagic, 4 transient ischemic attack; median NIHSS score of 6.5 [IQR 2.0-12.0]) and absence of any stroke in 32 patients. Point-of-care EEG detected seizures and highly epileptiform patterns in 6 (15.8 %) stroke patients and 11 (34.4 %) stroke-mimic patients, including 2 patients with persistent expressive aphasia due to repeated focal seizures. Point-of-care EEG has utility for detecting nonconvulsive seizures in patients undergoing acute stroke evaluations.

Evolution of EEG Findings in Patients with Acute Brain Injury.

Increasing use of continuous EEG monitoring (cEEG) provides the opportunity to observe temporal trends in EEG patterns during the acute phase of brain injury. These trends have not been extensively documented. We conducted a retrospective chart review of patients undergoing cEEG between January 1st and June 30th, 2019, at two academic medical centers. Only patients with acute brain injury having electrographic or electroclinical seizures or epileptic EEG findings on day one of monitoring and ≥ two calendar days of cEEG were included. The temporal evolution of EEG patterns was depicted as a heatmap. Of 1356 screened patients, 101 met the study criteria. Clinical acute symptomatic seizures occurred in 30 patients (29.7%) prior to EEG. The median number of days of cEEG was four (IQR 3-6). Amongst patients with electrographic seizures, status epilepticus, generalized periodic discharges, or sporadic epileptiform discharges, 24.6% had improvement and 54.1% had resolution of epileptic EEG findings by the final day of monitoring. In contrast, 65% with lateralized periodic discharges or lateralized rhythmic delta activity persisted or worsened. Overall, 61.4% (62/101) showed either improvement (19.8%) or resolution (41.6%) of their EEG findings prior to hospital discharge. Of the 36 patients with follow-up EEGs at a median of 4.5 (IQR 3-8) months after admission for acute brain injury, 83% (30/36) showed either improvement (1/36; 2.7%) or resolution (29/36; 80.6%). We observed a trend towards normalization of most epileptiform patterns except LPDs and LRDA, over time in patients with acute brain injury. The clinical significance of this trend as it relates to antiseizure medication treatment and neurologic outcomes warrants further investigation in an independent cohort.

Rapid Electroencephalography and Artificial Intelligence in the Detection and Management of Nonconvulsive Seizures

Nonconvulsive status epilepticus is a commonly overlooked cause of altered mental status. This study assessed nonconvulsive status epilepticus prevalence in emergency department (ED) patients with acute neurologic presentations using limited electroencephalogram (EEG) coupled with artificial intelligence (AI)-enhanced seizure detection technology. We then compared the accuracy of the AI EEG interpretations to those performed by an epileptologist. In a prospective observational cohort analysis, adult patients with unexplained mental status changes identified by emergency physicians received expedited placement of a limited EEG. Data collected encompassed patient demographics, clinical history, EEG interpretations by the AI algorithm and epileptologists, treatments, and disposition determinations. There were 134 device applications on 132 patients (2 received the device twice) enrolled in the study, but 16 were missing data critical for identification or analysis and 9 did not meet the selection criteria. Of the 108 limited EEGs interpreted by an epileptologist, 69 were abnormal (diffuse slowing, highly epileptiform patterns, or spikes and sharps), 41 were normal, 5 were uninterpretable, and 3 captured episodes of seizure or status epilepticus. Limited EEG AI interpretation detected >90% seizure burden in 2 of 3 cases of seizure or status epilepticus as well as in 2 abnormal EEGs and 1 normal EEG, providing a sensitivity of 66.7% (95% confidence interval 9.4 to 99.2), a specificity of 97.0% (95% confidence interval 91.5 to 99.4), and a disease prevalence of 2.9%. Limited AI-enhanced EEG can detect nonconvulsive status epilepticus in the ED; however, the technology tended to overestimate seizure burden in our cohort. This study found a lower nonconvulsive status epilepticus prevalence compared to prior literature reports.

Comparison of Continuous Intracortical and Scalp Electroencephalography in Comatose Patients with Acute Brain Injury.

Depth electroencephalography (dEEG) is a recent invasive monitoring technique used in patients with acute brain injury. This study aimed to describe in detail the clinical manifestations of nonconvulsive seizures (NCSzs) with and without a surface EEG correlate, analyze their long-standing effects, and provide data that contribute to understanding the significance of certain scalp EEG patterns observed in critically ill patients. We prospectively enrolled a cohort of 33 adults with severe acute brain injury admitted to the neurological intensive care unit. All of them underwent multimodal invasive monitoring, including dEEG. All patients were scanned on a 3T magnetic resonance imaging scanner at 6months after hospital discharge, and mesial temporal atrophy (MTA) was calculated using a visual scale. In 21 (65.6%) of 32 study participants, highly epileptiform intracortical patterns were observed. A total of 11 (34.3%) patients had electrographic or electroclinical seizures in the dEEG, of whom 8 had both spontaneous and stimulus-induced (SI) seizures, and 3 patients had only spontaneous intracortical seizures. An unequivocal ictal scalp correlate was observed in only 3 (27.2%) of the 11 study participants. SI-NCSzs occurred during nursing care, medical procedures, and family visits. Subtle clinical manifestations, such as restlessness, purposeless stereotyped movements of the upper limbs, ventilation disturbances, jerks, head movements, hyperextension posturing, chewing, and oroalimentary automatisms, occurred during intracortical electroclinical seizures. MTA was detected in 18 (81.8%) of the 22 patients. There were no statistically significant differences between patients with MTA with and without seizures or status epilepticus. Most NCSzs in critically ill comatose patients remain undetectable on scalp EEG. SI-NCSzs frequently occur during nursing care, medical procedures, and family visits. Semiology of NCSzs included ictal minor signs and subtle symptoms, such as breathing pattern changes manifested as patient-ventilator dyssynchrony.

Characterizing Seizure-Onset Patterns With the Responsive Neurostimulation System.

The responsive neurostimulation system (RNS) aims to improve seizures by delivering electrical stimulation in response to epileptiform patterns detected by electrocorticograms. Seizure-onset patterns (SOPs) correspond to outcomes in intracranial EEG (IC-EEG), although whether this is true for RNS is unknown. This study characterizes common RNS SOPs and correlates them with seizure outcomes. Among 40 patients with RNS implants, long-episode electrocorticogram characteristics of each patient's seizures were classified by visual analysis as one of the eight patterns previously described in IC-EEG. Correlation between each type of SOP and eventual seizure outcome was analyzed, with ≥50% improvement in a number of patient-reported seizure counts defined as a favorable outcome. Across 263 LEs analyzed, the most common SOP observed was low-voltage fast activity. There was no difference between the distribution of RNS SOPs and that of IC-EEG SOPs described in the literature (Kolmogorov-Smirnov test, P = 0.98). Additionally, there was no correlation between any particular SOP and favorable outcomes (Fisher's omnibus test, P = 0.997). This initial description of RNS SOPs finds them to be similar to previously described IC-EEG SOPs, which suggests similar prognostic/therapeutic potential. However, we found that RNS efficacy is independent of patient SOP, suggesting that RNS is likely an equally effective treatment for all SOPs. Future research on stimulation parameters for particular RNS SOPs and correlation with IC-EEG SOPs in the same patients would be instrumental in guiding personalized neurostimulation.

Seizure-like Symptoms Induced by Hypomagnesemia in a Patient with Incomplete Small Bowel Obstruction; A Case Report.

Seizure-like symptoms are rare in older patients without brain damage. Small bowel obstruction is a common clinical disorder for older patients that can cause electrolyte disturbances and nutritional disorders. Hypomagnesemia is a frequently overlooked electrolyte disorder. Moreover, magnesium deficiency can lead to severe seizure-like symptoms. An 85-year-old man was admitted to the hospital with weakness and slow movement. Shortly after hospitalization, he experienced incomplete small bowel obstruction; thus, parenteral nutrition and intravenous esomeprazole were administered. When intestinal obstruction was relieved, the patient suddenly experienced seizure-like symptoms three times, and 24-h electroencephalogram did not capture any epileptiform pattern. After excluding other causes, we considered serum magnesium deficiency as a diagnosis. Low serum magnesium levels were related to a shortage of absorption due to small bowel obstruction, excess excretion of renal dysfunction, and the use of proton pump inhibitor. However, the exact mechanism underlying the hypomagnesemia-induced seizure-like activity remained unclear. After adjusting the nutritional support and magnesium supplementation, the patient's serum magnesium level returned to normal, and he was free of seizure-like activity. Hypomagnesemia is often asymptomatic, but it can lead to severe seizure-like symptoms. It is important to pay attention to the serum magnesium level and nutritional intake in patients with an incomplete small bowel obstruction.

Robust compression and detection of epileptiform patterns in ECoG using a real-time spiking neural network hardware framework

Interictal Epileptiform Discharges (IED) and High Frequency Oscillations (HFO) in intraoperative electrocorticography (ECoG) may guide the surgeon by delineating the epileptogenic zone. We designed a modular spiking neural network (SNN) in a mixed-signal neuromorphic device to process the ECoG in real-time. We exploit the variability of the inhomogeneous silicon neurons to achieve efficient sparse and decorrelated temporal signal encoding. We interface the full-custom SNN device to the BCI2000 real-time framework and configure the setup to detect HFO and IED co-occurring with HFO (IED-HFO). We validate the setup on pre-recorded data and obtain HFO rates that are concordant with a previously validated offline algorithm (Spearman’s ρ = 0.75, p = 1e-4), achieving the same postsurgical seizure freedom predictions for all patients. In a remote on-line analysis, intraoperative ECoG recorded in Utrecht was compressed and transferred to Zurich for SNN processing and successful IED-HFO detection in real-time. These results further demonstrate how automated remote real-time detection may enable the use of HFO in clinical practice.

Comparative analysis of EEG in patients with schizophrenia receiving various atypical antipsychotics

Aim. To conduct a comprehensive analysis of EEG recordings of schizophrenia patients receiving atypical antipsychotics as monotherapy.Materials and methods. We examined 94 patients with schizophrenia aged 33 [28; 40] years with a disease duration of 10 [4; 15] years. The patients were divided into 5 groups depending on the antipsychotic drugs they took: 1) risperidone – 31 patients; 2) quetiapine – 20 patients; 3) aripiprazole – 11 patients; 4) olanzapine – 13 patients; 5) clozapine – 19 patients. EEG was recorded during wakefulness with closed eyes (background test), 3-minute hyperventilation, and rhythmic photostimulation in all patients. To describe and interpret the received recordings, the EEG classification according to J. Micoulaud – Franchi et al. was used.Results. EEG modifications (score > 1A) were observed in 61.7% (n = 58) of patients. In the group of patients receiving risperidone, EEG modifications were found in 48.4% of cases, in patients taking quetiapine – in 70% of cases, aripiprazole – in 63.6% of cases, olanzapine – in 61.5% of cases, clozapine – in 73.7% of cases. The frequency of epileptiform patterns in patients receiving olanzapine was significantly higher than in those taking risperidone (p = 0.033) and clozapine (p = 0.032). Slowing in the EEG (score > 1) was more often observed in patients taking clozapine – 63.2% (n = 12), olanzapine – 61.5% (n = 8), and quetiapine – 60% (n = 12). Slower EEG waves were less common in patients receiving aripiprazole – 45.5% (n = 5) and risperidone – 45.2% (n = 14). In the group of patients with EEG slowing (score > 1), the dose of chlorpromazine equivalent was significantly greater compared to patients with normal EEG (p = 0.00046).Conclusion. The data obtained demonstrate changes in EEG parameters during monotherapy with atypical antipsychotics and indicate their dose-dependent effect on the bioelectrical activity of the brain.

Factors Affecting the Activation and Appearances of Epileptiform Abnormalities in Routine Electroencephalography by Different Provocation Methods

Objective: The objective of this study was to observe the effects of various clinical factors on the activation and appearance of epileptiform abnormalities (EAs) in routine electroencephalography (rEEG) by different provocation methods. Methods: This observational study involved a review of 136 patients presented for EEG recording due to various indications and their EEG showing EAs during various provocation methods. Results: Generalized spike-wave discharges (GSWDs) were the most frequent activated epileptiform pattern observed in, 81 (59.1%) recordings. This pattern was seen mainly in females 49 (P = 0.00), in patients with generalized seizures 48 (P = 0.00), in prolonged EEG records 3 (P = 0.03), and in both genetic 35 (P = 0.00) and lesional epilepsies 21 (P = 0.00). Focal sharp waves with bilateral synchrony (FSWSBS) were the most activated ictal pattern (P = 0.00). Ictal EAs after hyperventilation (HV) (P = 0.03) and intermittent photic stimulation (IPS) (P = 0.01) were mainly observed in patients with uncontrolled seizures (P = 0.00), and immune-mediated epilepsy (P = 0.02). Females sex (odds ratio [OR]: 1.33, confidence interval [CI]: 0.6–2.6; P = 0.25), bilateral tonic–clonic seizures (OR: 1.17, CI: 0.5–2.4; P = 0.31) and lesional epilepsies (OR: 1.45, CI: 0.7–2.9; P = 0.20) had risk of activation of EAs by provocation methods; however this risk was not statistically significant. While sleep deprivation (SD) (OR: 6.33, CI: 2.2–18.2; P = 0.00), nonrapid eye movement sleep (NREM) (OR: 2.41, CI: 1.0–5.4; P = 0.00), and prolong EEG recording (OR: 1.91, CI: 0.9–3.9; P = 0.04) were leading to a statistically significant risk of activation and appearances of EAs due to provocation. Conclusion: Different provocation methods can activate and augment the variety of EEG patterns of diverse clinical significance. Detection of activated ictal EAs is dependent on various patient factors, including seizure control, and the provocation method applied. Further larger prospective cohort studies with adequate sample sizes are warranted.

Generalisability of epileptiform patterns across time and patients

The complexity of localising the epileptogenic zone (EZ) contributes to surgical resection failures in achieving seizure freedom. The distinct patterns of epileptiform activity during interictal and ictal phases, varying across patients, often lead to suboptimal localisation using electroencephalography (EEG) features. We posed two key questions: whether neural signals reflecting epileptogenicity generalise from interictal to ictal time windows within each patient, and whether epileptiform patterns generalise across patients. Utilising an intracranial EEG dataset from 55 patients, we extracted a large battery of simple to complex features from stereo-EEG (SEEG) and electrocorticographic (ECoG) neural signals during interictal and ictal windows. Our features (n = 34) quantified many aspects of the signals including statistical moments, complexities, frequency-domain and cross-channel network attributes. Decision tree classifiers were then trained and tested on distinct time windows and patients to evaluate the generalisability of epileptogenic patterns across time and patients, respectively. Evidence strongly supported generalisability from interictal to ictal time windows across patients, particularly in signal power and high-frequency network-based features. Consistent patterns of epileptogenicity were observed across time windows within most patients, and signal features of epileptogenic regions generalised across patients, with higher generalisability in the ictal window. Signal complexity features were particularly contributory in cross-patient generalisation across patients. These findings offer insights into generalisable features of epileptic neural activity across time and patients, with implications for future automated approaches to supplement other EZ localisation methods.

A Clinical Case of Corticospinal Tract Reorganization of Supplementary Motor Area in a Child After Acute Hypoxic Brain Injury

We present clinical observation of a 3-year-old child during recovery after acute hypoxic brain injury (freshwater drowning). Using diagnostic transcranial magnetic stimulation and magnetic resonance tractography with reconstruction of the corticospinal tract (CST) originated from the primary motor cortex and supplementary motor area (SMA), we determined that hypoxic brain injury induced activation of CST from the SMA. The period of reorganization was associated with the development of epileptiform patterns, that confirms the transient hyperexcitability of cortical neurons. Our findings indicate no recovery of motor function after acute hypoxic brain injury when CST originated only from SMA.

Occurrence and determinants of seizures and their impact on tuberculous meningitis: a prospective evaluation.

To assess the incidence of seizures and the factors contributing to poor outcomes in patients with tuberculous meningitis (TBM). In this prospective observational study, 129 patients with TBM were enrolled at the Department of Neurology, King George's Medical University, Uttar Pradesh, India, from April 2021 to April 2023. Detailed clinical history, neurological examinations, baseline laboratory tests, contrast-enhanced Magnetic resonance imaging (MRI) and electroencephalography (EEG) were obtained for all patients. Patients received anti-tuberculous therapy and, if necessary, anti-epileptic treatment. Patients were followed for 6months, with outcomes evaluated using the Modified Rankin Scale (MRS). Of the 129 patients, 48 (37.2%) reported seizures. Advanced TBM stage (p = 0.040, OR = 2.50 95% CI:1.02-6.07), cortical involvement (p = .0.013, OR = 2.58 95% CI:1.20-5.51) and spike-wave discharges in the EEG (p = 0.001) were significantly associated with seizure occurrence. After multivariate analysis, only cortical involvement (p = 0.031, OR = 2.34, 95% CI:1.08-5.08) emerged as independent predictor of for seizures. Focal to bilateral seizures (p = 0.008, OR = 9.41, 95% CI: 1.76-74.04), status epilepticus (p = 0.002, OR = 8.00, 95% CI: 1.86-34.32), and rifampicin resistance (p = 0.022, OR = 9.25, 95% CI: 1.43-59.50) were significantly associated with poor outcomes at the 6-month mark. Seizures were significantly associated with advanced stage of the disease, cortical involvement on neuro-imaging and epileptiform pattern on EEG. Additionally, focal to bilateral seizures and status epilepticus adversely affected the outcome.

Comorbidity of cerebral palsy and epilepsy with autism in children

Background. Cerebral palsy is often combined with epilepsy (up to about 50 % of children). The treatment of epilepsy limits the rehabilitation of cerebral palsy, and the rehabilitation of cerebral palsy often provokes epileptic seizures. Epilepsy in children with cerebral palsy is often manifested in a form of developmental and epileptic encephalopathy with spike-and-wave activation in sleep, which is characterized by epileptiform activity according to the type of benign epileptiform patterns of childhood with a high index on the electroencephalogram (up to 100 %), severe epileptic seizures of a status course, and mental disorders by type autism-like behavior (the so-called atypical autism) and disorders of speech communication. The problem of comorbidity of cerebral palsy, epilepsy and autism remains relevant and needs further study.Aim. To study the features of autism spectrum disorder in a group of children with a combination of cerebral palsy and epilepsy.Materials and methods. We examined 100 patients aged 3–10 years with various forms of cerebral palsy, combined with epilepsy, to identify the clinical features of autism spectrum disorder. Criteria for inclusion in the study: age 3–10 years; verified diagnosis of epilepsy in combination with cerebral palsy and autism spectrum disorder; informed consent of the patient’s parents to participate in the study. Criteria for exclusion from the study: severe somatic diseases and disorders of the sense organs (in particular, kyphoscoliosis, gastrostomy and others, as well as deafness, blindness); age less than 3 or more than 10 years.Results. The average age of visiting a psychiatrist was 5.4 ± 0.5 years. The reasons for visit were: violation of the communication (76 %), decreased eye contact (75 %), lack of compassion for surrounding or adjacent animals (100 %), dysphoric disorders (77.1 %), aggression (55 %), autoaggression (40 %), phobias (90 %), impaired speech development (18 %). Perinatal brain damage was diagnosed in 100 % of cases. Epilepsy was manifested by focal motor seizures. Patients with complex treatment (drugs and pedagogical correction) have more pronounced positive dynamics compared with patients who received only drug therapy or only rehabilitation (p <0.05).Conclusion. In children with a combination of cerebral palsy and epilepsy, the cause of autism is perinatal lesions of the central nervous system, as well as the severity of motor pathology and the presence of continued epileptiform activity on the electroencephalogram. Autism in this group of children requires timely recognition and medical and pedagogical correction.

Quantitative EEG analysis in typical absence seizures: unveiling spectral dynamics and entropy patterns.

A typical absence seizure is a generalized epileptic event characterized by a sudden, brief alteration of consciousness that serves as a hallmark for various generalized epilepsy syndromes. Distinguishing between similar interictal and ictal electroencephalographic (EEG) epileptiform patterns poses a challenge. However, quantitative EEG, particularly spectral analysis focused on EEG rhythms, shows potential for differentiation. This study was designed to investigate discernible differences in EEG spectral dynamics and entropy patterns during the pre-ictal and post-ictal periods compared to the interictal state. We analyzed 20 EEG ictal patterns from 11 patients with confirmed typical absence seizures, and assessed recordings made during the pre-ictal, post-ictal, and interictal intervals. Power spectral density (PSD) was used for the quantitative analysis that focused on the delta, theta, alpha, and beta bands. In addition, we measured EEG signal regularity using approximate (ApEn) and multi-scale sample entropy (MSE). Findings demonstrate a significant increase in delta and theta power in the pre-ictal and post-ictal intervals compared to the interictal interval, especially in the posterior brain region. We also observed a notable decrease in entropy in the pre-ictal and post-ictal intervals, with a more pronounced effect in anterior brain regions. These results provide valuable information that can potentially aid in differentiating epileptiform patterns in typical absence seizures. The implications of our findings are promising for precision medicine approaches to epilepsy diagnoses and patient management. In conclusion, our quantitative analysis of EEG data suggests that PSD and entropy measures hold promise as potential biomarkers for distinguishing ictal from interictal epileptiform patterns in patients with confirmed or suspected typical absence seizures.

Cortical spreading depolarization is a potential target for rat brain excitability modulation by Galanin

The inhibitory neuropeptide Galanin (Gal) has been shown to mediate anticonvulsion and neuroprotection. Here we investigated whether Gal affects cortical spreading depolarization (CSD). CSD is considered the pathophysiological neuronal mechanism of migraine aura, and a neuronal mechanism aggravating brain damage upon afflictions of the brain. Immunohistochemistry localized Gal and the Gal receptors 1-3 (GalR1-3) in native rat cortex and evaluated microglial morphology after exposure to Gal. In anesthetized rats, Gal was applied alone and together with the GalR antagonists M40, M871, or SNAP 37889 locally to the exposed cortex. The spontaneous electrocorticogram and CSDs evoked by remote KCl pressure microinjection were measured. In rat cortex, Gal was present in all neurons of all cortical layers, but not in astrocytes, microglia and vessels. GalR2 and GalR3 were expressed throughout all neurons, whereas GalR1 was preponderantly located at neurons in layers IV and V, but only in about half of the neurons. In susceptible rats, topical application of Gal on cortex decreased CSD amplitude, slowed CSD propagation velocity, and increased the threshold for KCl to ignite CSD. In some rats, washout of previously applied Gal induced periods of epileptiform patterns in the electrocorticogram. Blockade of GalR2 by M871 robustly prevented all Gal effects on CSD, whereas blockade of GalR1 or GalR3 was less effective. Although microglia did not express GalRs, topical application of Gal changed microglial morphology indicating microglial activation. This effect of Gal on microglia was prevented by blocking neuronal GalR2. In conclusion, Gal has the potential to ameliorate CSD thus reducing pathophysiological neuronal events caused by or associated with CSD.

Point-of-care electroencephalography enables rapid evaluation and management of non-convulsive seizures and status epilepticus in the emergency department.

To describe our institutional experience with point-of-care electroencephalography (pocEEG) and its impact on the evaluation/management of suspected non-convulsive seizures in the emergency department (ED). We retrospectively identified 157 adults who underwent pocEEG monitoring in our community hospital ED in 1 year. We calculated the time to obtain pocEEG in the ED (door-to-EEG time) and examined the impact of pocEEG findings (categorized as seizure, highly epileptiform patterns, slowing, or normal activity) on antiseizure medication treatment. PocEEG revealed seizures (14%, n=22), highly epileptiform patterns (22%, n=34), slowing (44%, n=69), and normal activity (20%, n=32). The median door-to-EEG time (from initial ED evaluation to pocEEG monitoring) was only 1.2hours (interquartile range 0.1-2.1) even though 55% of studies were performed after-hours (5 pm-9 am). Most patients were admitted (54% to the intensive care unit, 41% to floor). Antiseizure medication treatment occurred pre-pocEEG in 93 patients (59%) and post-pocEEG in 88 patients (56%). By reviewing the relationship between pocEEG monitoring and antiseizure medication management, we found a significant association between pocEEG findings and changes in management(P<0.001). Treatment escalation occurred more frequently in patients with epileptiform activity (seizures or highly epileptiform patterns, 52%) than patients with non-epileptiform activity (normal or slow, 25%, P<0.001), and avoidance of treatment escalation occurred more frequently in patients with normal or slow activity (27%) than patients with seizures or highly epileptiform patterns (2%, P<0.001). Our study, the largest to date describing the real-world use of pocEEG in emergency medicine, found that rapid EEG acquisition in the ED was feasible in a community hospital and significantly affected the management of suspected non-convulsive seizures.

Bronchoscopy-Associated Cerebral Arterial Air Embolism Presenting with Acute Ischemic Stroke and Status Epilepticus (P12-5.013)

<h3>Objective:</h3> To describe a rare cause of iatrogenic air embolism, causing acute ischemic stroke complicated by status epilepticus. <h3>Background:</h3> The incidence of vascular air embolism during bronchoscopy is estimated to be 2.65 per 100,000 hospitalizations, with 30% of these involving endovascular procedures. A recent case report and literature review identified only 5 cases of cerebral arterial air embolism following bronchoscopy. A small minority of acute ischemic strokes present with seizures, even fewer with status epilepticus. <h3>Design/Methods:</h3> NA <h3>Results:</h3> An 81-year-old woman with past medical history significant for hypertension and CREST syndrome presented to an outside hospital for elective bronchoscopy with biopsy of pulmonary nodules. Post-procedurally, she was noted to have new left-sided hemiparesis. Non-contrast CT head demonstrated a small arterial air embolism in the right frontal lobe. She was brought to the Emergency Department and sustained a bilateral tonic-clonic seizure lasting 30 seconds, resolving with intravenous lorazepam. Prior to returning to her mental status baseline, she had recurrent seizure activity, refractory to benzodiazepines, requiring an intravenous phenytoin load, intubation for airway protection, and sedation with propofol. She was transferred to our institution’s neurocritical care unit where repeat CT head exhibited sulcal effacement and she was treated with hypertonic saline for cerebral edema. Continuous EEG did not reveal any epileptiform patterns but the patient was started on levetiracetam for her acute symptomatic seizures. MRI later revealed small infarcts in multiple vascular territories. She was ultimately extubated and at the time of discharge to short-term rehabilitation, her only deficit was 4+/5 strength throughout the left arm, which normalized by 1-month follow-up. She was eventually weaned off of levetiracetam in the outpatient setting. <h3>Conclusions:</h3> This case adds to our understanding of this rare procedural complication and, given the complications of her stroke by status epilepticus and cerebral edema, highlights the potential severity of these injuries. <b>Disclosure:</b> Dr. Sutherland has received personal compensation in the range of $0-$499 for serving as a Consultant for McGraw-Hill. Dr. Gummerson has nothing to disclose. Dr. Sharma has nothing to disclose.

FLAIR-hyperintense lesions in anti-MOG-associated encephalitis with seizures overlaying anti-N-methyl-D-aspartate receptor encephalitis: a case report and literature review

FLAIR-hyperintense lesions in anti-MOG-associated encephalitis with seizures (FLAMES) has been identified increasingly frequently in recent years. However, this rare MOG antibody disease may coexist with anti-N-methyl-D-aspartate receptor encephalitis (anti-NMDARe), in an overlap syndrome with unknown clinical features and prognosis. We report a new case of this overlap syndrome and present a systematic review of similar cases in the literature to provide information on the clinical presentation, MRI features, EGG abnormalities, treatment, and prognosis of patients with this rare syndrome. A total of 12 patients were analyzed in the study. The most common clinical manifestations of FLAMES overlaid with anti-NMDARe were epilepsy (12/12), headache (11/12), and fever (10/12). Increases in intracranial pressure (median: 262.5 mmH2O, range: 150-380 mmH2O), cerebrospinal fluid (CSF) leukocyte count (median: 128×106/L, range: 1-610×106/L), and protein level (median: 0.48 g/L) were also observed. The median CSF anti-NMDAR antibody titer was 1:10 (1:1-1:32), while the median serum MOG antibody titer was 1:32 (1:10-1:1024). Seven cases exhibited unilateral cortical FLAIR hyperintensity, and five cases (42%) had bilateral cortical FLAIR hyperintensity, including four cases involving the bilateral medial frontal lobes. Of the 12 patients, five showed lesions at other sites (e.g., the brainstem, corpus callosum, or frontal orbital gyrus) before or after the development of cortical encephalitis. EEG showed slow waves in four cases, spike-slow waves in two cases, an epileptiform pattern in one case, and normal waves in two cases. The median number of relapses was two. Over a mean follow-up period of 18.5 months, only one patient experienced residual visual impairment, while the remaining 11 patients had good prognoses. FLAMES alone is difficult to distinguish from overlap syndrome based on clinical features. However, FLAMES with bilateral medial frontal lobe involvement suggests the presence of the overlap syndrome.