Interictal Epileptiform Activity Research Articles

Multi-day rhythms modulate seizure risk in epilepsy

Epilepsy is defined by the seemingly random occurrence of spontaneous seizures. The ability to anticipate seizures would enable preventative treatment strategies. A central but unresolved question concerns the relationship of seizure timing to fluctuating rates of interictal epileptiform discharges (here termed interictal epileptiform activity, IEA), a marker of brain irritability observed between seizures by electroencephalography (EEG). Here, in 37 subjects with an implanted brain stimulation device that detects IEA and seizures over years, we find that IEA oscillates with circadian and subject-specific multidien (multi-day) periods. Multidien periodicities, most commonly 20–30 days in duration, are robust and relatively stable for up to 10 years in men and women. We show that seizures occur preferentially during the rising phase of multidien IEA rhythms. Combining phase information from circadian and multidien IEA rhythms provides a novel biomarker for determining relative seizure risk with a large effect size in most subjects.

Conectividad funcional derivada del electroencefalograma durante el sueño no REM en los trastornos del espectro autista

To know the differences in the patterns of functional connectivity, the topological characteristics of the network and the relationship between these latter and the interictal epileptiform anomalies in children with primary and secondary autism spectrum disorder (ASD). A retrospective study was conducted with 27 children aged between 3 and 13 years diagnosed with ASD. Subjects were submitted to an electroencephalogram in a functional state of spontaneous sleep. Functional connectivity and the properties of the network were analysed using data obtained from the electroencephalogram during the N2 stage of non-REM sleep. The frequency of discharge of the interictal epileptiform activity (FDIEA) was determined and was correlated with the topological properties of the network. Synchronisation was diminished in patients with secondary ASD for the alpha frequency and increased for the theta and delta frequency compared with patients with primary ASD. Local alpha efficiency was higher in patients who presented interictal epileptiform activity. Additionally, in patients with secondary ASD there was a statistically significant positive and negative correlation between FDIEA and the topological properties of the network. Patients with secondary ASD display patterns of functional connectivity that are weaker for the alpha frequency and stronger for theta and delta than patients with primary ASD. In patients with secondary ASD, the interictal epileptiform activity is related to local and global connectivity of the network for the alpha and beta bands during non-REM sleep.

DETECTING FEATURES OF EPILEPTOGENESIS IN EEG AFTER TBI USING UNSUPERVISED DIFFUSION COMPONENT ANALYSIS.

Epilepsy is among the most common serious disabling disorders of the brain, and the global burden of epilepsy exerts a tremendous cost to society. Most people with epilepsy have acquired forms, and the development of antiepileptogenic interventions could potentially prevent or cure these epilepsies [3, 13]. The discovery of potential antiepileptogenic treatments is currently a high research priority. Clinical validation would require a means to identify populations of patients at particular high risk for epilepsy after a potential epileptogenic insult to know when to treat and to document prevention or cure. We investigate the development of post-traumatic epilepsy (PTE) following traumatic brain injury (TBI), because this condition offers the best opportunity to know the time of onset of epileptogenesis in patients. Epileptogenesis is common after TBI, and because much is known about the physical history of PTE, it represents a near-ideal human model in which to study the process of developing seizures. Using scalp and depth EEG recordings for six patients, the goal of our analysis is to find a way to quantitatively detect features in the EEG that could potentially help predict seizure onset post trauma. Unsupervised Diffusion Component Analysis [5], a novel approach based on the diffusion mapping framework [4], reduces data dimensionality and provides pattern recognition that can be used to distinguish different states of the patient, such as seizures and non-seizure spikes in the EEG. This method is also adapted to the data to enable the extraction of the underlying brain activity. Previous work has shown that such techniques can be useful for seizure prediction [6]. Some new results that demonstrate how this algorithm is used to detect spikes in the EEG data as well as other changes over time are shown. This nonlinear and local network approach has been used to determine if the early occurrences of specific electrical features of epileptogenesis, such as interictal epileptiform activity and morphologic changes in spikes and seizures, during the initial week after TBI predicts the development of PTE.

Electroencephalography abnormalities in generalized epilepsy and their predictors: A multicenter experience.

Background:In spite of the overwhelming significance of knowledge of basic elements of electroencephalography (EEG) in its application to the diagnostic workup and the management of patients with suspected or already established generalized epilepsy (GE), there is a dearth of data on the pattern and utility of clinical variables that can independently determine EEG abnormalities in GE.Objective:The study was designed to evaluate the frequency and pattern of EEG abnormality as well as assess the utility of clinical variables in predicting the likelihood of an abnormal EEG in GE.Methods:It was a cross-sectional study involving the analysis of EEGs of consecutive patients with clinical diagnosis of idiopathic GE from three centers over a 7-year period. Information on sociodemographic and seizure variables was obtained. The International Federation of Societies for Electroencephalography and Clinical Neurophysiology definition of interictal epileptiform discharges (interictal epileptiform activity [IEA]) was adopted in the study.Results:A total of 403 patients comprising 242 (60%) males and 161 (40%) females with clinical diagnosis of GE had EEG. Their age ranged between 2 weeks and 70 years, with a median age of 21 years and an interquartile age of 26 years. Two hundred and thirty-seven (58.8%) and 213 (52.9%) patients had abnormal EEG and IEA, respectively. Before adjustment for confounders, female gender (P = 0.0001), pediatric age group (P = 0.0388), duration of epilepsy of 1–4 years (P = 0.01387), uncontrolled seizure (P = 0.0060), and seizure frequency (P = 0.0001) were significantly associated with the presence of abnormal EEG. However, age, female gender, poor seizure control, and seizure frequencies were the independent predictors of EEG abnormality.Conclusion:The study showed that about 58% of patients with GE patients had abnormal EEG. Age, poor seizure control, and high frequency of seizure were independent predictors of the presence of EEG abnormality.

Early-onset epileptic encephalopathy with de novo SCN8A mutation

Early-onset epileptic encephalopathies (EOEEs) are clinically and genetically heterogeneous disorders characterized by intractable seizures and unremitting interictal paroxysmal epileptiform activity. Consequently, these syndromes impair neurodevelopment during the first year of life. Currently, the etiology of these disorders is largely unknown. In this study, Childhood-Onset Epilepsy Gene Panel Testing (containing 511 epilepsy-related genes) was performed in a parent–offspring trio. In this family, the son had refractory seizures, intellectual disability, and motor abnormalities, and he was diagnosed with EOEE. The boy later died from a sudden unexpected death in epilepsy (SUDEP) at the age of 26 months. In this case, we identified a de novo mutation (c.4423G > A; glycine [Gly]1475 arginine [Arg]) classified as heterozygous missense located in the inactivation gate section of the SCN8A (voltage-gated sodium-channel type VIII alpha subunit) gene. This result strengthens the association between the SCN8A gene and EOEE, and more attention should be given to its high rate of SUDEP. Further studies to determine the pathogenic mechanisms of SCN8A mutations should be warranted at the inactivation gate section of this sodium channel in both neurons and cardiac muscles.

Frequency of post-stroke electroencephalographic epileptiform activity - a systematic review and meta-analysis of observational studies.

Cerebrovascular diseases are the most frequent risk factor for epilepsy in the elderly, and epileptic phenomenon following stroke is known to worsen the prognosis. Although electroencephalography is the gold standard epilepsy biomarker, it is rarely used in post-stroke studies, and the frequency of post-stroke epileptiform activity is still uncertain. We analysed studies indexed to MEDLINE, Embase, Web of Science, PsycINFO and OpenGrey (up to March 2015), reporting post-stroke electroencephalographic epileptiform activity frequency in adults. Epileptiform activity was classified as ictal (electrographic seizures) and interictal (non-periodic spikes and sharp waves). Data selection, extraction and appraisal were done in duplicate. Random-effects meta-analysis was used to pool frequencies. The pooled frequency of post-stroke ictal and interictal epileptiform activity was 7% (95% CI 3%-12%) and 8% (95% CI 4%-13%), respectively. The use of continuous electroencephalogram was not associated with an increased frequency of electrographic seizures (p = 0.05), nor did the management setting (Intensive Care Unit versus non- Intensive Care Unit, p = 0.31). However, studies with continuous electroencephalogram showed a higher frequency of interictal epileptiform activity (p = 0.01). This study provides the best available estimates of the frequency of post-stroke electroencephalographic epileptiform activity. Due to detection bias, it was not possible to correlate clinical and electrographic seizures. The frequency of ictal and interictal epileptiform activity in the electroencephalogram was comparable with previous frequency analyses of clinical seizures. The frequency of ictal epileptiform activity did not change with continuous record or clinical setting, while the frequency of interictal epileptiform activity increased with continuous record.

Diagnostic Yield of Routine Electroencephalography With Concurrent Video Recording in Detecting Interictal Epileptiform Discharges in Relation to Reasons for Request: A Prospective Study of 1,080 Video-Electroencephalograms.

The aim of this study was to prospectively analyze the sensitivity and specificity of routine electroencephalography with concurrent video recording (vEEG) in relation to the reasons for requesting the test and to investigate when routine vEEG should be requested. We prospectively analyzed 1,080 consecutive vEEGs performed between April 2015 and April 2016. The requests for vEEG were classified as requests with a low suspicion of epilepsy (syncope, confusion or delirium, suspicion of psychogenic nonepileptic seizures, and paroxysmal focal neurological deficit) or requests with a high suspicion of epilepsy (first clinical seizure, suspected status epilepticus, follow-up study of a patient with epilepsy, and acute symptomatic seizures). Predominant vEEG findings (ictal and interictal epileptiform activities, diffuse, or focal slowing and triphasic waves) were analyzed, and sensitivity and specificity [ZERO WIDTH SPACE][ZERO WIDTH SPACE]values calculated. The most common indication for vEEG was a follow-up study of patients with epilepsy (38%), followed by first clinical seizure (19.3%) and suspected status epilepticus (11%). The respective specificity and sensitivity values were 93% and 58% for 235 vEEGs performed in children/adolescents (≤18 years), 95% and 40% for 533 vEEGs performed in adults (>18 ≤ 65 years), and 93% and 39% for 312 vEEGs performed in older adults (>65 years). Twenty-four patients with false-positive paroxysms had a clinical diagnosis of confusional state or paroxysmal focal neurological deficit. Neurologists and neuropediatricians with experience in managing epilepsy had higher specificity values than general neurologists or physicians (P = 0.012). In our series, vEEG abnormalities were mainly observed in patients with clinical findings highly suggestive of epilepsy. In confusional states, and paroxysmal focal neurological deficit vEEG could be indicated.

Seizure activity per se does not induce tissue damage markers in human neocortical focal epilepsy.

The contribution of recurring seizures to the progression of epileptogenesis is debated. Seizure-induced brain damage is not conclusively demonstrated either in humans or in animal models of epilepsy. We evaluated the expression of brain injury biomarkers on postsurgical brain tissue obtained from 20 patients with frequent seizures and a long history of drug-resistant focal epilepsy. The expression patterns of specific glial, neuronal, and inflammatory molecules were evaluated by immunohistochemistry in the core of type II focal cortical dysplasias (FCD-II), at the FCD boundary (perilesion), and in the adjacent normal-appearing area included in the epileptogenic region. We also analyzed surgical specimens from cryptogenic patients not presenting structural alterations at imaging. Astroglial and microglial activation, reduced neuronal density, perivascular CD3-positive T-lymphocyte clustering, and fibrinogen extravasation were demonstrated in the core of FCD-II lesions. No pathological immunoreactivity was observed outside the FCD-II or in cryptogenetic specimens, where the occurrence of interictal and ictal epileptiform activity was confirmed by either stereo-electroencephalography or intraoperative electrocorticography. Recurrent seizures do not induce the expression of brain damage markers in nonlesional epileptogenic cortex studied in postsurgical tissue from cryptogenic and FCD patients. This evidence argues against the hypothesis that epileptiform activity per se contributes to focal brain injury, at least in the neocortical epilepsies considered here. Ann Neurol 2017;82:331-341.

Interictal epileptiform activity outside the seizure onset zone impacts cognition.

See Kleen and Kirsch (doi:10.1093/awx178) for a scientific commentary on this article.Cognitive deficits are common among epilepsy patients. In these patients, interictal epileptiform discharges, also termed spikes, are seen routinely on electroencephalography and believed to be associated with transient cognitive impairments. In this study, we investigated the effect of spikes on memory encoding and retrieval, taking into account the spatial distribution of spikes in relation to the seizure onset zone as well as anatomical regions of the brain. Sixty-seven patients with medication refractory epilepsy undergoing continuous intracranial electroencephalography monitoring engaged in a delayed free recall task to test short-term memory. In this task, subjects were asked to memorize and recall lists of common nouns. We quantified the effect of each spike on the probability of successful recall using a generalized logistic mixed model. We found that in patients with left lateralized seizure onset zones, spikes outside the seizure onset zone impacted memory encoding, whereas those within the seizure onset zone did not. In addition, spikes in the left inferior temporal gyrus, middle temporal gyrus, superior temporal gyrus, and fusiform gyrus during memory encoding reduced odds of recall by as much as 15% per spike. Spikes also reduced the odds of word retrieval, an effect that was stronger with spikes outside of the seizure onset zone. These results suggest that seizure onset regions are dysfunctional at baseline, and support the idea that interictal spikes disrupt cognitive processes related to the underlying tissue.

Sudden unexplained death in children

Sudden unexplained death in children

Small temporal pole encephaloceles in children with presumed nonlesional temporal lobe epilepsy

Objective: Temporal lobe epilepsy (TLE) is the one of most common form of focal epilepsy. Children with intractable TLE epilepsy undergo presurgical evaluations for resective treatment. The cases are considered “nonlesional’’ if brain magnetic resonance imaging (MRI) shows no structural abnormality and they sometimes encounter invasive procedures. We describe two patients, initially thought to have “lesion negative” refractory TLE, in whom the recognition of a small anterior temporal encephalocele by close inspection of imaging altered the follow up strategy. Case Presentation: Case 1: 12-year-old girl, focal seizures began at age 10 years, manifesting as no reduced awareness, contractions in the corner of the mouth, and head version. At the time of assessment the patient was having multiple daily attacks. Two antiepileptic drugs in various doses and combinations had failed to control seizures. Early childhood development and schooling were unremarkable. Febrile seizures had not occurred. Video–electroencephalography (EEG) monitoring captured ten typical seizures, all originating from the right temporal region. Prior imaging was reported normal. The current brain MRI has showed small right anterior temporal tip encephalocele through a congenital defect in the sphenoidal bone. She is now a epilepsy surgery candidate. Case 1: 15-year-old girl, discognitive seizures began at age 6 years characterized by a rising abdominal sensation and impaired consciousness. Seizures continued weekly with no evolving to bilateral convulsive seizures, despite trials of two anticonvulsants in various doses and combinations. Febrile seizures had not occurred. Routine EEG showed interictal epileptiform activity in left temporal region. Prior imaging was reported normal. The current brain MRI has showed bilateral temporal tip encephalocele greater on the left. She will be hospitalized for phase I epilepsy surgery evaluations. Conclusion: We would like to present this cases to emphasize the discovery of an occult lesion such as an encephalocele markedly alters treatment opinions in children.

New onset epilepsy in the elderly: clinical, radiological and electroencephalographic features and treatment responses.

Objective:To evaluate new onset epilepsy characteristics, etiology, radiological and electroencephalographic features and to document treatment response in the elderly.Method:This was a retrospective study carried out in King Fahd Medical City, Riyadh, Kingdom of Saudi Arabia, from 2010 to 2013. Medical records were searched to recruit patients. Hundred and nineteen patients were enrolled who fulfill the inclusion criteria. Clinical data with respect to seizure semiology, etiology, electroencephalographic findings, radiological findings, co-morbidities, and anti-epileptic drug (AED) therapy were assessed.Results:Cerebrovascular disease was the most common etiology, followed by occult cerebrovascular disease (oCVD). Focal onset seizures were the most common clinical presentation in this group of cohort. Electroencephalogram (EEG) showed generalized slowing in majority of patients (45.5%), with 21.8% interictal epileptiform activity. Patients required lower doses of AEDs to control seizures, gain better seizure control. Common co-morbidities were hypertension and diabetes mellitus.Conclusion:Patients presenting with LOE, should have search for any other cerebrovascular risk factors. Further research is needed to determine the prevalence of oCVD in LOE, and to investigate whether addressing cerebrovascular risk factors in this cohort of patients can reduce the incidence of stroke.

THE FORMATION OF COGNITIVE AND MENTAL DISORDERS IN EPILEPSY: THE ROLE OF VARIOUS FACTORS ASSOCIATED WITH DISEASE AND TREATMENT (A REVIEW OF LITERATURE AND CASE REPORTS)

Cognitive and mental disorders often occur in patients with epilepsy and significantly reduce the quality of life of patients and their families. Approximately in 35 % of patients, despite treatment, various violations of intelligence, behavior, affective sphere of different degree of seve rity are preserved. In general, mental (affective, anxious and psychotic) disorders occur in epilepsy 2–3 times more often than in the general population. The most common is depression: the occurrence of depression and anxiety in epilepsy varies from 20 to 55 % (and more than 50 % of patients with refractory focal epilepsy, especially epilepsy of the temporal lobe of the brain). Children are a particularly vulnerable category of patients: in addition to persistent intellectual disabilities (mental retardation), they may have specific impairments in the form of mental and speech development delay, learning difficulties, attention deficit hyperactivity disorder. Causes of cognitive and mental disorders in epilepsy can directly be the factor underlying epilepsy (genetic disease, structural brain defect, etc.), epileptic seizures, interictal epileptiform activity, side effects of antiepileptic drugs (AED). In many cases, a patient with epilepsy combines several of these causes, and it is often difficult to determine which one cause is leading. The contribution of specific factors is difficult to estimate, because different factors can have an independent different effect on cognitive impairment. Some of causes underlying cognitive and mental disorders in epilepsy can be influenced and thus reduce the existing risk. Such measures include early diagnosis and effective adequate treatment of epileptic encephalopathy, as early as possible control of seizures, justified appointment of AED in children with cognitive impairment of unknown etiology and frequent epileptiform discharges on the electroencephalogram, careful monitoring of cognitive side effects of AED and assessment of benefit–risk ratio, early surgical treatment of patients with resistance to therapy. Of course, the use of AED with the most favorable profile of influence on cognitive functions plays an important role in the treatment of epilepsy. In the treatment of epilepsy in children, it’s especially important to give preference to AED, which doesn’t negatively influence on the cognitive sphere.

Contralateral interictal and ictal EEG epileptiform activity accentuate memory impairment in unilateral mesial temporal sclerosis patients.

Memory impairment is a recognized complication of mesial temporal sclerosis (MTS). Epileptiform activity may negatively impact on cognition. We evaluated the impact of contralateral EEG involvement on memory in unilateral MTS (uMTS) patients. Retrospective review of 121 right-handed uMTS patients (69 left) evaluated with prolonged video-EEG and verbal and nonverbal memory tests (Rey Auditory Verbal Learning Test and Rey-Osterrieth Complex figure), with additional very delayed trials. Patients were classified according to ictal/interictal EEG findings and MTS side as left or right concordant or discordant. Thirty-nine normal individuals who underwent the same neuropsychological battery served as controls. Demographic, disease, and treatment features did not differ among groups. On the 7-day verbal memory free recall, left discordant performed significantly worse than controls and right concordant, recognized fewer words, and had more recognition errors than all other groups, including left concordant. For nonverbal memory, right discordant performed significantly worse than controls on delayed recall, and attained lower scores than other groups on immediate and 7-day recall, but this difference did not reach statistical significance. Left discordant had higher scores of memory complaints than controls and disclosed a trend toward accentuated memory impairment compared with the other groups over time. Our results suggest that contralateral electrographic involvement in uMTS was associated with more pronounced memory impairment for verbal material in left discordant patients, and to a lesser extent, for nonverbal material in right discordant patients. Left discordant group also had increased memory complaints. (PsycINFO Database Record

An effect of epilepsy on sleep structure

In this review, the authors discuss the problem of management of the patient with epilepsy with regard an impact of epileptic seizures and syndromes on sleep structure. Sleep disorders can lead to worsening of seizure control and general medical condition of the patients. However, seizures themselves and types of epilepsy can affect the sleep architecture. One of the most frequent symptoms of disordered sleep in epilepsy patients is excessive daytime sleepiness, which can be a consequence of poor sleep quality due to frequent nocturnal seizures or excessive interictal epileptiform activity during sleep leading to frequent arousals. is frequently referred to antiepileptic drug side effects. In patients with frontal and temporal lobe epilepsies, which are more associated with sleep, the sleep architecture is significantly different from healthy individuals. They have more frequent arousals, disturbed relationship between sleep phases and stages, in particular inhibited REM-sleep phase. Most recent data on this problem are reviewed. Sleep patterns for different major epileptic syndromes are presented and some general recommendations for patient management, with a special consideration of sleep issues, are given.

Magnetoencephalography and New Imaging Modalities in Epilepsy.

The success of epilepsy surgery is highly dependent on correctly identifying the entire epileptogenic region. Current state-of-the-art for localizing the extent of surgically amenable areas involves combining high resolution three-dimensional magnetic resonance imaging (MRI) with electroencephalography (EEG) and magnetoencephalography (MEG) source modeling of interictal epileptiform activity. Coupling these techniques with newer quantitative structural MRI techniques, such as cortical thickness measurements, however, may improve the extent to which the abnormal epileptogenic region can be visualized. In this review we assess the utility of EEG, MEG and quantitative structural MRI methods for the evaluation of patients with epilepsy and introduce a novel method for the co-localization of a structural MRI measurement to MEG and EEG source modeling. When combined, these techniques may better identify the extent of abnormal structural and functional areas in patients with medically intractable epilepsy.

Deviations from Critical Dynamics in Interictal Epileptiform Activity

Healthy brain dynamics requires a delicate balance between excitatory and inhibitory processes. Several brain disorders, such as epilepsy, are associated with altered excitation-inhibition balance, but assessing this balance using noninvasive tools is still challenging. In this study, we apply the framework of critical brain dynamics to data from epilepsy patients, which were recorded between seizures. We show that metrics of criticality provide a sensitive tool for noninvasive assessment of changes in the balance. Specifically, brain activity of epilepsy patients deviates from healthy critical brain dynamics, particularly during abnormal epileptiform activity. The study offers a novel quantitative perspective on epilepsy and its relation to healthy brain dynamics.

Autosomal-Recessive Mutations in AP3B2, Adaptor-Related Protein Complex 3 Beta 2 Subunit, Cause an Early-Onset Epileptic Encephalopathy with Optic Atrophy

Early-onset epileptic encephalopathy (EOEE) represents a heterogeneous group of severe disorders characterized by seizures, interictal epileptiform activity with a disorganized electroencephalography background, developmental regression or retardation, and onset before 1 year of age. Among a cohort of 57 individuals with epileptic encephalopathy, we ascertained two unrelated affected individuals with EOEE associated with developmental impairment and autosomal-recessive variants in AP3B2 by means of whole-exome sequencing. The targeted sequencing of AP3B2 in 86 unrelated individuals with EOEE led to the identification of an additional family. We gathered five additional families with eight affected individuals through the Matchmaker Exchange initiative by matching autosomal-recessive mutations in AP3B2. Reverse phenotyping of 12 affected individuals from eight families revealed a homogeneous EOEE phenotype characterized by severe developmental delay, poor visual contact with optic atrophy, and postnatal microcephaly. No spasticity, albinism, or hematological symptoms were reported. AP3B2 encodes the neuron-specific subunit of the AP-3 complex. Autosomal-recessive variations of AP3B1, the ubiquitous isoform, cause Hermansky-Pudlak syndrome type 2. The only isoform for the δ subunit of the AP-3 complex is encoded by AP3D1. Autosomal-recessive mutations in AP3D1 cause a severe disorder cumulating the symptoms of the AP3B1 and AP3B2 defects.

Ictal bradyarrhythmias and asystole requiring pacemaker implantation: Combined EEG-ECG analysis of 5 cases.

Seizures can lead to cardiac arrhythmias by a number of mechanisms including activation/inhibition of cortical autonomic centers, increase in vagal tone through activation of brainstem reflex centers, and respiratory failure. Ictal asystole (IA) is a potential mechanism underlying sudden unexpected death in epilepsy (SUDEP). We analyzed the clinical features of 5 patients who developed IA requiring pacemaker implantation. Patients with ictal arrhythmias were identified from the video-telemetry and ambulatory EEG database at Greater Manchester Neurosciences Centre, as well as an independent epilepsy residential care facility. Only those who had IA requiring pacemaker implantation were included in the analysis. A total of 5 patients were identified. Of the 5 patients with IA, 4 were female. All 5 patients had focal epilepsy, and four had temporal lobe epilepsy. Ictal asystole occurred with focal seizures with impairment of awareness. Seizure onset was left-sided in 2 patients, right-sided in one, left-sided onset with switch of lateralization in one, and nonlateralized in one patient. Three patients had hippocampal sclerosis, one of whom had undergone epilepsy surgery, one had traumatic encephalomalacia of the temporal lobe, and one patient had no lesions detected on MRI. Interictal epileptiform activity was more pronounced during sleep in all patients. Asystole occurred in association with sleep-related seizures in 4 of 5 patients. Ictal asystole (IA) occurred in association with sleep-related seizures in 4 out of 5 cases, predominantly in patients with temporal lobe epilepsy. These findings may be of relevance to SUDEP.

Video-EEG results and clinical characteristics in patients with psychogenic nonepileptic spells: The effect of a coexistent epilepsy.

Epilepsy and psychogenic nonepileptic spells (PNES) can coexist, often posing diagnostic and therapeutic challenges. We sought to identify clinical and historical characteristics of two groups of patients, those with coexisting epilepsy and PNES and those with PNES alone, and determine the prevalence of coexisting epilepsy/PNES with strict diagnostic criteria in a large group of epilepsy monitoring unit (EMU) patients. We reviewed the medical records of all consecutive patients admitted to the Vanderbilt University Medical Center Adult EMU between July 1, 2007 and June 30, 2012. We identified patients with recorded PNES and classified them as having coexisting epilepsy/PNES or PNES alone and then systematically compared the clinical characteristics of these two groups. A total of 1567 patient medical records were reviewed. The prevalence rate of coexisting epilepsy/PNES was 5.2% among all EMU admissions (12.3% of all patients with epilepsy and 14.8% of all patients with PNES). These rates were lower when patients with interictal epileptiform activity (IEA) alone and no recorded ictal discharges were not included in the group with epilepsy (2.6%, 6.2%, and 7.4%, respectively). The accuracy of pre-EMU clinical suspicion was significantly higher in the group with PNES-only. Patients with epilepsy/PNES were significantly more likely to require more than one EMU admission for definitive diagnosis. The first PNES event preceded an epileptic seizure (ES) in 94.4% of patients with epilepsy/PNES. The group with PNES-only had significantly higher suggestibility, and the group with epilepsy/PNES had a significantly higher presence of epilepsy risk factors. Abnormal neurological examination and abnormal brain MRI were also significantly more common in the group with epilepsy/PNES. Our study defined the prevalence of coexisting epilepsy/PNES in a large cohort with strict diagnostic criteria and outlined specific clinical and historical characteristics differentiating the two groups of patients with coexisting epilepsy/PNES and PNES-only. These findings should help guide clinicians to reach the correct diagnosis faster and provide appropriate treatment earlier.