Search

Dynamic 2-[18F] fluoro-2-deoxy-D-glucose positron emission tomography (dFDG-PET) for human brain imaging has considerable clinical potential, yet its utilization remains limited. A key challenge in the quantitative analysis of dFDG-PET is characterizing a patient-specific blood input function, traditionally reliant on invasive arterial blood sampling. This research introduces a novel approach employing non-invasive deep learning model-based computations from the internal carotid arteries (ICA) with partial volume (PV) corrections, thereby eliminating the need for invasive arterial sampling. We present an end-to-end pipeline incorporating a 3D U-Net based ICA-net for ICA segmentation, alongside a Recurrent Neural Network (RNN) based MCIF-net for the derivation of a model-corrected blood input function (MCIF) with PV corrections. The developed 3D U-Net and RNN was trained and validated using a 5-fold cross-validation approach on 50 human brain FDG PET scans. The ICA-net achieved an average Dice score of 82.18% and an Intersection over Union of 68.54% across all tested scans. Furthermore, the MCIF-net exhibited a minimal root mean squared error of 0.0052. The application of this pipeline to ground truth data for dFDG-PET brain scans resulted in the precise localization of seizure onset regions, which contributed to a successful clinical outcome, with the patient achieving a seizure-free state after treatment. These results underscore the efficacy of the ICA-net and MCIF-net deep learning pipeline in learning the ICA structure's distribution and automating MCIF computation with PV corrections. This advancement marks a significant leap in non-invasive neuroimaging., (Creative Commons Attribution license.)

Objective: Focused ultrasound ablation (FUSA) is an emerging treatment for neurological and psychiatric diseases. We describe the initial experience from a pilot, open-label, single-center clinical trial of unilateral anterior nucleus of the thalamus (ANT) FUSA in patients with treatment-refractory epilepsy., Methods: Two adult subjects with treatment-refractory, focal onset epilepsy were recruited. The subjects received ANT FUSA using the Exablate Neuro (Insightec) system. We determined the safety and feasibility (primary outcomes), and changes in seizure frequency (secondary outcome) at 3, 6, and 12 months. Safety was assessed by the absence of side effects, that is, new onset neurological deficits or performance deterioration on neuropsychological testing. Feasibility was defined as the ability to create a lesion within the anterior nucleus. The monthly seizure frequency was compared between baseline and postthalamotomy., Results: The patients tolerated the procedure well, without neurological deficits or serious adverse events. One patient experienced a decline in verbal fluency, attention/working memory, and immediate verbal memory. Seizure frequency reduced significantly in both patients; one patient was seizure-free at 12 months, and in the second patient, the frequency reduced from 90-100 seizures per month to 3-6 seizures per month., Significance: This is the first known clinical trial to assess the safety, feasibility, and preliminary efficacy of ANT FUSA in adult patients with treatment-refractory focal onset epilepsy., (© 2023 International League Against Epilepsy.)

Objectives: Drug treatment for children with epilepsy should, ideally, be governed by evidence from adequate and well-controlled clinical studies. However, these studies are difficult to conduct, and so direct evidence supporting the informed use of specific drugs is often lacking. The Research Roundtable for Epilepsy (RRE) met in 2020 to align on an approach to therapy development for focal seizures in children age 1 month <2 years of age., Methods: The RRE reviewed the regulatory landscape, epidemiology, seizure semiology, antiseizure medicine pharmacology, and safety issues applicable to this population., Results: After reviewing evidence, the conclusion was that pediatric efficacy trials would be impracticable to conduct but a waiver of the regulatory requirement to conduct any study would lead to an absence of information to guide dosing in a critical population. Review of available data and discussion of RRE attendees led to the conclusion that the requirements for extrapolation of efficacy from older children down to infants from age 1 month to <2 years old appeared to be met. After the RRE, the US Food and Drug Administration (FDA) approved brivaracetam for use in children with focal epilepsy above the age of 1 month in August 2021 and lacosamide in October 2021, both based on the principle of extrapolation from data in older children., Significance: These recommendations should result in more rapid accessibility of antiseizure medications for infants., (© 2022 The Authors. Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Convulsive status epilepticus (SE) is a relatively common emergency condition affecting individuals of all ages. The primary goal of treatment is prompt termination of seizures. Where first-line treatment with benzodiazepine has failed to achieve this, a condition known as established SE (ESE), there is uncertainty about which agent to use next. The Established Status Epilepticus Treatment Trial (ESETT) is a 3-arm (valproate (VPA), fosphenytoin (FOS), levetiracetam (LEV)), phase III, double-blind randomized comparative effectiveness study in patients aged 2 years and above with established convulsive SE. Enrollment was completed in January 2019, and the results are expected later this year. We discuss lessons learnt during the conduct of the study in relation to the following: ethical considerations; trial design and practical implementation in emergency settings, including pediatric and adult populations; quality assurance; and outcome determination where treating emergency clinicians may lack specialist expertise. We consider that the ESETT is already informing both clinical practice and future trial design. This article is part of the Special Issue "Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures"., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: The choice of drugs for patients with status epilepticus that is refractory to treatment with benzodiazepines has not been thoroughly studied., Methods: In a randomized, blinded, adaptive trial, we compared the efficacy and safety of three intravenous anticonvulsive agents - levetiracetam, fosphenytoin, and valproate - in children and adults with convulsive status epilepticus that was unresponsive to treatment with benzodiazepines. The primary outcome was absence of clinically evident seizures and improvement in the level of consciousness by 60 minutes after the start of drug infusion, without additional anticonvulsant medication. The posterior probabilities that each drug was the most or least effective were calculated. Safety outcomes included life-threatening hypotension or cardiac arrhythmia, endotracheal intubation, seizure recurrence, and death., Results: A total of 384 patients were enrolled and randomly assigned to receive levetiracetam (145 patients), fosphenytoin (118), or valproate (121). Reenrollment of patients with a second episode of status epilepticus accounted for 16 additional instances of randomization. In accordance with a prespecified stopping rule for futility of finding one drug to be superior or inferior, a planned interim analysis led to the trial being stopped. Of the enrolled patients, 10% were determined to have had psychogenic seizures. The primary outcome of cessation of status epilepticus and improvement in the level of consciousness at 60 minutes occurred in 68 patients assigned to levetiracetam (47%; 95% credible interval, 39 to 55), 53 patients assigned to fosphenytoin (45%; 95% credible interval, 36 to 54), and 56 patients assigned to valproate (46%; 95% credible interval, 38 to 55). The posterior probability that each drug was the most effective was 0.41, 0.24, and 0.35, respectively. Numerically more episodes of hypotension and intubation occurred in the fosphenytoin group and more deaths occurred in the levetiracetam group than in the other groups, but these differences were not significant., Conclusions: In the context of benzodiazepine-refractory convulsive status epilepticus, the anticonvulsant drugs levetiracetam, fosphenytoin, and valproate each led to seizure cessation and improved alertness by 60 minutes in approximately half the patients, and the three drugs were associated with similar incidences of adverse events. (Funded by the National Institute of Neurological Disorders and Stroke; ESETT ClinicalTrials.gov number, NCT01960075.)., (Copyright © 2019 Massachusetts Medical Society.)

Objective: The long-term efficacy and safety of responsive direct neurostimulation was assessed in adults with medically refractory partial onset seizures., Methods: All participants were treated with a cranially implanted responsive neurostimulator that delivers stimulation to 1 or 2 seizure foci via chronically implanted electrodes when specific electrocorticographic patterns are detected (RNS System). Participants had completed a 2-year primarily open-label safety study (n = 65) or a 2-year randomized blinded controlled safety and efficacy study (n = 191); 230 participants transitioned into an ongoing 7-year study to assess safety and efficacy., Results: The average participant was 34 (±11.4) years old with epilepsy for 19.6 (±11.4) years. The median preimplant frequency of disabling partial or generalized tonic-clonic seizures was 10.2 seizures a month. The median percent seizure reduction in the randomized blinded controlled trial was 44% at 1 year and 53% at 2 years (p < 0.0001, generalized estimating equation) and ranged from 48% to 66% over postimplant years 3 through 6 in the long-term study. Improvements in quality of life were maintained (p < 0.05). The most common serious device-related adverse events over the mean 5.4 years of follow-up were implant site infection (9.0%) involving soft tissue and neurostimulator explantation (4.7%)., Conclusions: The RNS System is the first direct brain responsive neurostimulator. Acute and sustained efficacy and safety were demonstrated in adults with medically refractory partial onset seizures arising from 1 or 2 foci over a mean follow-up of 5.4 years. This experience supports the RNS System as a treatment option for refractory partial seizures., Classification of Evidence: This study provides Class IV evidence that for adults with medically refractory partial onset seizures, responsive direct cortical stimulation reduces seizures and improves quality of life over a mean follow-up of 5.4 years., (© 2015 American Academy of Neurology.)

Benzodiazepine-refractory status epilepticus (established status epilepticus, ESE) is a relatively common emergency condition with several widely used treatments. There are no controlled, randomized, blinded clinical trials to compare the efficacy and tolerability of currently available treatments for ESE. The ESE treatment trial is designed to determine the most effective and/or the least effective treatment of ESE among patients older than 2 years by comparing three arms: fosphenytoin (fPHT) levetiracetam (LVT), and valproic acid (VPA). This is a multicenter, randomized, double-blind, Bayesian adaptive, phase III comparative effectiveness trial. Up to 795 patients will be randomized initially 1:1:1, and response-adaptive randomization will occur after 300 patients have been recruited. Randomization will be stratified by three age groups, 2-18, 19-65, and 66 and older. The primary outcome measure is cessation of clinical seizure activity and improving mental status, without serious adverse effects or further intervention at 60 min after administration of study drug. Each subject will be followed until discharge or 30 days from enrollment. This trial will include interim analyses for early success and futility. This trial will be considered a success if the probability that a treatment is the most effective is >0.975 or the probability that a treatment is the least effective is >0.975 for any treatment. Proposed total sample size is 795, which provides 90% power to identify the most effective and/or the least effective treatment when one treatment arm has a true response rate of 65% and the true response rate is 50% in the other two arms., (Wiley Periodicals, Inc. © 2013 International League Against Epilepsy.)

Background: Epilepsy is a common neurological disorder that affects approximately 50 million people worldwide. Both risk of epilepsy and response to treatment partly depend on genetic factors, and gene identification is a promising approach to target new prediction, treatment, and prevention strategies. However, despite significant progress in the identification of genes causing epilepsy in families with a Mendelian inheritance pattern, there is relatively little known about the genetic factors responsible for common forms of epilepsy and so-called epileptic encephalopathies. Study design The Epilepsy Phenome/Genome Project (EPGP) is a multi-institutional, retrospective phenotype-genotype study designed to gather and analyze detailed phenotypic information and DNA samples on 5250 participants, including probands with specific forms of epilepsy and, in a subset, parents of probands who do not have epilepsy., Results: EPGP is being executed in four phases: study initiation, pilot, study expansion/establishment, and close-out. This article discusses a number of key challenges and solutions encountered during the first three phases of the project, including those related to (1) study initiation and management, (2) recruitment and phenotyping, and (3) data validation. The study has now enrolled 4223 participants., Conclusions: EPGP has demonstrated the value of organizing a large network into cores with specific roles, managed by a strong Administrative Core that utilizes frequent communication and a collaborative model with tools such as study timelines and performance-payment models. The study also highlights the critical importance of an effective informatics system, highly structured recruitment methods, and expert data review.

Objective: Epilepsy is a common neurologic condition with significant personal, societal, medical, and economic burdens. There are considerable gaps in the quality of care delivered. Measuring the quality of care delivered is the first step to its improvement. Performance measures are easily identified and quantitated ways to assess whether specific activities were carried out during a patient encounter. Therefore, epilepsy performance measures were derived through a standardized systematic process and may be the basis for pay-for-performance initiatives and maintenance of certification requirements., Methods: Epilepsy measures were developed through the American Medical Association-convened Physician Consortium for Performance Improvement (PCPI) independent measure development process, which marked the first time a medical specialty society followed this process. Guidelines, measures, and consensus papers reviewed for the period 1998 to 2008 using the National Guidelines Clearinghouse, the National Quality Measures Clearinghouse, PubMed, MEDLINE, and the Cochrane Library were evaluated using a framework to determine the acceptability of each guideline or other evidence review document for measures development. Recommendation statements based on level of evidence, importance, validity, and gap in care were developed into candidate measures. A panel of experts from representative organizations vetted the measures. A period of public comment was followed by approval from the American Academy of Neurology and the PCPI., Results: Literature search identified 160 relevant recommendation statements from 19 guidelines and 2 consensus papers. Systematic assessment resulted in 20 recommendation statements that were refined to 8 candidate measures by the expert panel. The measures are relevant to seizure type and frequency, etiology or epilepsy syndrome, EEG, neuroimaging, antiepileptic drug side effects, safety issues, referral for refractory epilepsy, and issues for women of childbearing potential., Conclusion: There is a reasonable evidence base, and consensus for, deriving performance measures for quality of epilepsy care. It is anticipated that implementation of these performance measures will improve care for patients with epilepsy if adopted by providers.

Purpose: We report a multicenter, double-blind, randomized trial of bilateral stimulation of the anterior nuclei of the thalamus for localization-related epilepsy., Methods: Participants were adults with medically refractory partial seizures, including secondarily generalized seizures. Half received stimulation and half no stimulation during a 3-month blinded phase; then all received unblinded stimulation., Results: One hundred ten participants were randomized. Baseline monthly median seizure frequency was 19.5. In the last month of the blinded phase the stimulated group had a 29% greater reduction in seizures compared with the control group, as estimated by a generalized estimating equations (GEE) model (p = 0.002). Unadjusted median declines at the end of the blinded phase were 14.5% in the control group and 40.4% in the stimulated group. Complex partial and "most severe" seizures were significantly reduced by stimulation. By 2 years, there was a 56% median percent reduction in seizure frequency; 54% of patients had a seizure reduction of at least 50%, and 14 patients were seizure-free for at least 6 months. Five deaths occurred and none were from implantation or stimulation. No participant had symptomatic hemorrhage or brain infection. Two participants had acute, transient stimulation-associated seizures. Cognition and mood showed no group differences, but participants in the stimulated group were more likely to report depression or memory problems as adverse events., Discussion: Bilateral stimulation of the anterior nuclei of the thalamus reduces seizures. Benefit persisted for 2 years of study. Complication rates were modest. Deep brain stimulation of the anterior thalamus is useful for some people with medically refractory partial and secondarily generalized seizures.

Background: Providers are increasingly being held accountable for the quality of care provided. While quality indicators have been used to benchmark the quality of care for a number of other disease states, no such measures are available for evaluating the quality of care provided to adults with epilepsy. In order to assess and improve quality of care, it is critical to develop valid quality indicators. Our objective is to describe the development of quality indicators for evaluating care of adults with epilepsy. As most care is provided in primary and general neurology care, we focused our assessment of quality on care within primary care and general neurology clinics., Methods: We reviewed existing national clinical guidelines and systematic reviews of the literature to develop an initial list of quality indicators; supplemented the list with indicators derived from patient focus groups; and convened a 10-member expert panel to rate the appropriateness, reliability, and necessity of each quality indicator., Results: From the original 37 evidence-based and 10 patient-based quality indicators, the panel identified 24 evidence-based and 5 patient-based indicators as appropriate indicators of quality. Of these, the panel identified 9 that were not necessary for high quality care., Conclusion: There is, at best, a poor understanding of the quality of care provided for adults with epilepsy. These indicators, developed based on published evidence, expert opinion, and patient perceptions, provide a basis to assess and improve the quality of care for this population.

Purpose: The pharmacokinetics of the novel antiepileptic drug (AED) levetiracetam and its major metabolite, ucb L057, were studied in children with partial seizures in a multicenter, open-label, single-dose study., Methods: Twenty-four children (15 boys, nine girls), 6 to 12 years old, received a single dose of levetiracetam (20 mg/kg) as an adjunct to their stable regimen of a single concomitant AED, followed by a 24-h pharmacokinetic evaluation., Results: In children, the half-lives of levetiracetam and its metabolite ucb L057 were 6.0 +/- 1.1 and 8.1 +/-2.7 hours, respectively. The Cmax and area under the curve (AUC) of levetiracetam equated for a 1-mg/kg dose were lower in children (Cmax, norm=1.33 plus minus 0.35 microg/ml; AUCnorm=12.4 +/- 3.5 microg/h/ml) than in adults (Cmax, norm=1.38 +/- 0.05 microg/ml; AUCnorm=11.48 +/- 0.63 microg/h/ml), whereas the renal clearance was higher. The apparent body clearance (1.43 +/- 0.36 ml/min/kg) was approximately 30-40% higher in children than in adults. Levetiracetam was generally well tolerated., Conclusions: On the basis of these data, a daily maintenance dose equivalent to 130-140% of the usual daily adult maintenance dosage (1,000-3,000 mg/day) in two divided doses, on a weight-normalized level (mg/kg/day) is initially recommended. Clinical efficacy trials in children are ongoing with dosages of 20 to 60 mg/kg/day.

Nonconvulsive status epilepticus (NCSE) is often diagnosed based on abolition of rhythmic sharp waves by benzodiazepines. It is possible that sharp waves resulting from metabolic (nonepileptic) encephalopathies may also respond to benzodiazepines and are potentially misdiagnosed as NCSE. The authors hypothesized that triphasic waves (TW) resulting from metabolic encephalopathy are abolished by benzodiazepines. They retrospectively identified patients with TW resulting from metabolic encephalopathy who had EEG recordings before, during, and after benzodiazepine administration. Benzodiazepines were given either because of the possibility of NCSE or for a medically indicated purpose. All patients were diagnosed definitively with a metabolic cause of encephalopathy and not NCSE. Ten patients (mean age, 59 years) met the criteria and were reviewed. TW resolved persistently in four patients and intermittently in six patients. Background activity slowed in five patients and was attenuated in five patients. Unresponsive patients did not arouse and three of five drowsy patients became less responsive. Rhythmic sharp waves resulting from metabolic encephalopathy are abolished by benzodiazepines, similar to NCSE, but without improvement in mental status. This suggests that definitive electrographic diagnosis of primary NCSE should not be based entirely on abolition of sharp waves by benzodiazepines. This also implies that gamma-aminobutyric acid neurotransmission is important in the expression of TW.

Purpose: Previous studies of patient-reported seizure precipitants have not evaluated whether different epilepsy syndromes are differentially affected., Methods: Patients of a tertiary-care epilepsy center were consecutively surveyed with the use of a standardized questionnaire that lists precipitants that might trigger or exacerbate seizures (alcohol, caffeine, fasting, fatigue, fever or illness, flashing lights, heat or humidity, menstrual cycle, sleep, sleep deprivation, emotional stress, unknown, or other). Patients were classified into epilepsy syndromes according to International League Against Epilepsy criteria. Age and gender within groups defined by major precipitants were compared. Pearson's correlation was performed to evaluate common patterns of precipitants., Results: Of 400 patients, 62% cited at least one precipitant. In order of frequency, stress (30%), sleep deprivation (18%), sleep (14%), fever or illness (14%), and fatigue (13%) were noted by at least 10% of patients. Stress, fatigue, and sleep deprivation positively correlated, but sleep tended to negatively correlate with other major precipitants. Rankings of precipitants varied within epilepsy syndromes, with patients with temporal lobe epilepsy citing sleep infrequently compared with patients with other epilepsy syndromes. Menstrual effects were ranked highly within major precipitants among women over age 12 and were especially noted by women with temporal lobe epilepsy (28%)., Conclusions: Most patients with epilepsy identify a precipitant that triggers or exacerbates seizures. The high correlation of stress, sleep deprivation, and fatigue suggests that they act through common mechanisms to worsen seizure control. Through identification of the effect of both endogenous and exogenous precipitants among syndromes, more research and counseling can be directed to specific precipitants.

Status epilepticus is common and associated with significant mortality and complications. It affects approximately 50 patients per 100,000 population annually and recurs in >13%. History of epilepsy is the strongest single risk factor for generalized convulsive status epilepticus. More than 15% of patients with epilepsy have at least one episode of status epilepticus and low antiepileptic drug levels are a potentially modifiable risk factor. Other risks include young age, genetic predisposition, and acquired brain insults. Fever is a very common risk in children, as is stroke in adults. Mortality rates are 15% to 20% in adults and 3% to 15% in children. Acute complications result from hyperthermia, pulmonary edema, cardiac arrhythmias, and cardiovascular collapse. Long-term complications include epilepsy (20% to 40%), encephalopathy (6% to 15%), and focal neurologic deficits (9% to 11%). Neuronal injury leading to temporal lobe epilepsy is probably mediated by excess excitation via activation of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors and consequent elevated intracellular calcium that causes acute necrosis and delayed apoptotic cell death. Some forms of nonconvulsive status epilepticus may also lead to neuronal injury by this mechanism, but others may not. Based on clinical and experimental observations, complex partial status epilepticus is more likely to result in neuronal injury similar to generalized convulsive status epilepticus. Absence status epilepticus is much less likely to result in neuronal injury, and complications because it may be mediated primarily through excess inhibition. Future research strategies to prevent complications of status epilepticus include the study of new drugs (including NMDA antagonists, new drug delivery systems, and drug combinations) to stop seizure activity and prevent acute and delayed neuronal injury that leads to the development of epilepsy.

Generalized convulsive status epilepticus (GCSE) is a medical emergency requiring prompt resolution. Acute treatment is often delayed by difficulty in obtaining intravenous (i.v.) access. Refractory GCSE is often difficult to treat, and traditional therapy with barbiturates induces hypotension and respiratory depression and prolongs recovery. Midazolam is particularly useful for treating acute GCSE because it has an imidazole ring that is open at low pH, allowing it to be dissolved in aqueous solution for intramuscular injection, but closed at physiologic pH, increasing lipophilicity and rendering good intramuscular absorption, brain penetration, and fast onset of action. When given intramuscularly as a 0.2 mg/kg bolus, it has efficacy at least equal to that of i.v. diazepam, is well tolerated, induces little respiratory compromise, and has a shorter latency to onset of action. Therefore, it should be considered for the treatment of acute GCSE when i.v. access is problematic. For refractory GCSE, continuous i.v. midazolam infusion at 0.1-0.6 mg/kg/hr after a 0.2 mg/kg i.v. bolus is effective and has advantages over traditional therapies because it induces less hypotension and cardiorespiratory depression and can be easily titrated. Further prospective studies are needed to define the role of continuous i.v. midazolam compared to other contemporary therapies.

Objective: Disruption of fascicular tracts that connect Wernicke's to Broca's areas is the classic mechanism of conduction aphasia. Later work has emphasised cortical mechanisms., Methods: To determine the distribution of language on dominant cortex, electrical cortical stimulation was performed using implanted subdural electrodes during brain mapping before epilepsy surgery., Results: A transient, isolated deficit in repetition was elicited with stimulation of the posterior portion of the dominant superior temporal gyrus., Conclusion: This finding suggests that cortical dysfunction, not just white matter disruption, can induce conduction aphasia.

Corticosteroids combined with cyclophosphamide are currently recommended for primary angiitis of the CNS. The authors report a 71-year-old man with primary angiitis of the CNS and amyloid angiopathy who responded to cyclophosphamide without steroids, suggesting that corticosteroids may not be needed in all cases of primary angiitis of the CNS.

The limbic/mesial temporal lobe epilepsy syndrome has been defined as a focal epilepsy, with the implication that there is a well defined focus of onset, traditionally centered around the hippocampus. The pathology of the hippocampus in this syndrome has been well described and a number of physiological abnormalities have been defined in this structure in animal models and humans with epilepsy. However, anatomical and physiological abnormalities have also been described in other limbic sites in this form of epilepsy. Previous studies have shown broadly synchronized or multifocal seizure onset within the limbic system of the animal models and human patients. We hypothesized that the epileptogenic circuit for the initiation of seizures was distributed throughout the limbic system with a possible central synchronizing process. In vitro studies showed that multiple limbic sites in epileptic animals (hippocampus, entorhinal cortex, piriform cortex and amygdala) have epileptiform changes with prolonged depolarizations and multiple superimposed action potentials. In vivo studies revealed that thalamic stimulation yields short latency excitatory responses in the entorhinal cortex and hippocampus. In addition, in epileptic animals, thalamic stimulation caused epileptiform responses in the hippocampus. Based on the findings of this study and on previous anatomy and physiology reports, we hypothesize that the process of seizure initiation involves broad circuit interactions involving multiple independent limbic structures, and that the midline thalamus may act as a physiological synchronizer. We offer a new proposal for the functional anatomy of limbic epilepsy that takes widespread hyperexcitability in the limbic system and the potential for thalamic synchronization into consideration.

We investigated whether entorhinal cortex (EC) layer IV neurons are hyperexcitable in the post-selfsustaining limbic status epilepticus (post-SSLSE) animal model of temporal lobe epilepsy. We studied naive rats (n = 44), epileptic rats that had experienced SSLSE resulting in spontaneous seizures (n = 45), and electrode controls (n = 7). There were no differences between electrode control and naive groups, which were pooled into a single control group. Intracellular and extracellular recordings were made from deep layers of EC, targeting layer IV, which was activated by stimulation of the superficial layers of EC or the angular bundle. There were no differences between epileptic and control neurons in basic cellular characteristics, and all neurons were quiescent under resting conditions. In control tissue, 77% of evoked intracellular responses consisted of a short-duration [8.6 +/- 1.3 (SE) ms] excitatory postsynaptic potential and a single action potential followed by gamma-aminobutyric acid-A (GABAA) and GABAB inhibitory post synaptic potentials (IPSPs). Ten percent of controls did not contain IPSPs. In chronically epileptic tissue, evoked intracellular responses demonstrated prolonged depolarizing potentials (256 +/- 39 ms), multiple action potentials (13 +/- 4), and no IPSPs. Ten percent of epileptic responses were followed by rhythmic "clonic" depolarizations. Epileptic responses exhibited an all-or-none response to progressive increases in stimulus intensity and required less stimulation to elicit action potentials. In both epileptic and control animals, intracellular responses correlated precisely in morphology and duration with extracellular field potentials. Severing the hippocampus from the EC did not alter the responses. Duration of intracellular epileptic responses was reduced 22% by the N-methyl--aspartate (NMDA) antagonist (-)-2-amino-5-phosphonovaleric acid (APV), but they did not return to normal and IPSPs were not restored. Epileptic and control responses were abolished by the non-NMDA antagonist 6, 7-dinitroquinoxaline-2-3-dione (DNQX). A monosynaptic IPSP protocol was used to test connectivity of inhibitory interneurons to primary cells by direct activation of interneurons with a stimulating electrode placed near the recording electrode in the presence of APV and DNQX. Using this protocol, IPSPs similar to control (P > 0.05) were seen in epileptic cells. The findings demonstrate that deep layer EC cells are hyperexcitable or "epileptiform" in this model. Hyperexcitability is not due to interactions with the hippocampus. It is due partially to augmented NMDA-mediated excitation. The lack of IPSPs in epileptic neurons may suggest inhibition is impaired, but we found evidence that inhibitory interneurons are connected to their target cells and are capable of inducing IPSPs.

An electroencephalogram (EEG) recorded after sleep deprivation (SDEEG) in epilepsy patients often discloses epileptiform discharges (ED) when routine EEG (REEG) does not, but since sleep alone activates ED, activation during SDEEG may result merely from the induction of sleep. We retrospectively investigated whether SDEEG is useful when REEG containing wakefulness and sleep fails to show ED. Subjects were patients with definite or highly probable epilepsy whose REEG lacked ED and who later underwent SDEEG. All had wakefulness and at least stage II sleep during both REEG and SDEEG. Patients with ED on REEG were specifically excluded to avoid including patients with activation due merely to the occurrence of sleep. Patient and EEG characteristics were studied, including duration of wakefulness and each sleep stage and timing and characteristics of ED. Fifteen of 29 patients (52%) had activation on SDEEG; exclusively during wakefulness in 1, exclusively during sleep in 6 and in both wakefulness and sleep in 8. Activation rates were not significantly different between wakefulness (9, 60%), stage I (11, 74%) and stage II (11, 74%). EEG characteristics were similar for REEG and SDEEG, except that total EEG duration and stage II sleep were longer in SDEEG than in REEG, which did not influence activation by a logistic regression model (p > 0.05). We conclude that sleep deprivation activates ED independent of the activating effects of sleep and therefore is useful in evaluation of suspected epilepsy even when REEG contains sleep.

1. The main purposes of this study are to characterize the intracellular and extracellular responses of cells in superficial layers of entorhinal cortex (EC) in chronically epileptic animals, determine whether their altered physiology is dependent on being connected to hippocampus, and investigate whether there is evidence of augmented excitation and inhibitory interneuron disconnection. 2. Functional connectivity was maintained between the hippocampal area and the EC in vitro in a combined rat hippocampal-parahippocampal slice preparation by slicing with a vibratome at a 30-deg angle to the base of the brain. Three groups of animals were studied: naive animals, animals that had experienced a previous episode of (nonconvulsive) self-sustaining limbic system status epilepticus (SSLSE) induced by electrical stimulation resulting in a chronically epileptic state, and animals in an electrode control group. In chronically epileptic rats and the electrode control group, studies were done on tissue contralateral to the side of electrode implantation. 3. Extracellular and intracellular recordings were made from the superficial layers of EC. Neurons in the superficial layers of the EC were activated by stimulation of the deep layers within the EC or the angular bundle adjacent to the EC, which contains axons from EC neurons. Responses could be elicited by antidromic and synaptic mechanisms by stimulation at either site. In addition, a monosynaptic protocol was used that involved direct activation of interneurons with a stimulating electrode placed near the recording electrode in the presence of the ionotropic glutamate blockers D(-)-2-amino-5-phosphonovaleric acid (APV) and 6,7-dinitroquinoxaline-2-3-dione (DNQX). 4. Responses were collected over a range of stimulus intensities, from very low to high intensities, to construct input/output function (I/O) curves. Amplitudes and durations were measured at the lowest stimulus intensity that elicited a maximum responses. 5. Extracellular field potential responses from electrode controls did not differ from naives qualitatively with respect to morphology of field potential responses or quantitatively with respect to response duration and amplitude. Field potential responses in tissue from post-SSLSE rats differed markedly in morphology from naive and electrode controls, being more complex, significantly longer in duration, and decreased in amplitude. These epileptiform responses were shortened markedly by blockade of N-methyl-D-aspartate (NMDA) receptors with APV, but this manipulation did not convert responses to a normal morphology. These responses were abolished by blockade of non-NMDA mediated ionotropic glutamate receptors with DNQX. 6. During intracellular recordings of neurons in slices from both control and epileptic animals, neurons were quiescent under resting conditions in the absence of electrical stimulation. 7. Intracellular responses in electrode controls were identical to naive, and together were considered "controls." In control tissue, evoked intracellular responses were similar to those previously described and most commonly consisted of an excitatory postsynaptic potential (EPSP) that was blocked partially by the NMDA-receptor antagonist APV, followed by hyperpolarizing potentials, which were identified electrophysiologically and pharmacologically as gamma-aminobuturic acid-A (GABAA)- and GABAB-receptor-mediated inhibitory postsynaptic potentials (IPSPs). EPSPs were blocked completely by DNQX. 8. In chronically epileptic tissue, evoked intracellular responses differed markedly from responses in control animals, exhibiting all-or-none prolonged paroxysmal depolarizing events with multiple superimposed action potentials in response to a single shock. These depolarizing events were reduced in duration and amplitude, but not abolished, in APV. IPSPs were not seen or markedly reduced at all stimulus intensities. These intracellular responses never resembled control responses. Intracellur responss correlated precisely in morphology and duration with extracellular field potentials. (ABSTRACT TRUNCATED)

Early diagnosis is essential for the effective management of primary angiitis of the CNS (PACNS), but the presence of cerebrovascular amyloid angiopathy (CAA) may complicate the pathologic diagnosis since nonvasculitic inflammatory reactions can accompany CAA. We report two patients with PACNS associated with CAA in whom the progression of symptoms ceased during combined corticosteroid/cyclophosphamide therapy. One patient had prominent eosinophilic vasculitis and eosinophilic CSF pleocytosis. Based on review of reported cases, features supporting the diagnosis of symptomatic vasculitis in these patients include subacute progression of mental status changes and multifocal deficits, elevated ESR and CSF protein, and multifocal nonhemorrhagic lesions on imaging studies. We conclude that combined disease (PACNS/CAA) is similar to PACNS and probably occurs more frequently than expected by coincidence. The presence of CAA should not alter the treatment strategy in patients presenting with symptoms and laboratory studies consistent with PACNS.

The cellular and molecular pathophysiology of status epilepticus (SE) provides a conceptual framework for understanding clinical scenarios and prospectively designing logical therapies. SE is a dynamic process that evolves over time in a predictable manner with an established sequence of EEG, motor, physiologic, and cellular changes. Neuronal injury and death are the result of processes intrinsic to the brain, mediated by a complex neurotoxic cascade consisting of multiple serial and parallel processes. The risk of cell injury depends also on the overall pathophysiologic profile, including the presence of alterations resulting from SE and occurring independent of SE. On neurophysiologic grounds, we divide SE into "spike-wave" and "nonspike-wave" forms. Spike-wave "absence" status epilepticus carries a low risk of epileptic brain damage, and therapy should be adjusted accordingly. All nonspike-wave SE has a theoretical basis for epileptic brain damage, but the actual risk is variable. There is a significant known risk of cell injury during generalized convulsive SE, a variety of nonspike-wave SE, so aggressive treatment is warranted to prevent sequelae. There is also a theoretical basis for epileptic brain damage in nonspike-wave nonconvulsive SE, but prospective studies are needed to determine which of these patients warrant aggressive therapy. Based on pathophysiologic principles, future treatment of nonspike-wave SE may use a combination of anti-ictal agents, including gamma-aminobutyric acid agonists and N-methyl-D-aspartate antagonists, as well as various neuroprotectants.