Epileptiform EEG Changes Research Articles

Dose-Dependent Induction of Differential Seizure Phenotypes by Pilocarpine in Rats: Considerations for Translational Potential.

Background and Objectives: Pilocarpine is used in experimental studies for testing antiepileptic drugs, but further characterization of this model is essential for its usage in testing novel drugs. The aim of our study was to study the behavioral and EEG characteristics of acute seizures caused by different doses of pilocarpine in rats. Materials and Methods: Male Wistar rats were treated with a single intraperitoneal dose of 100 mg/kg (P100), 200 mg/kg (P200), or 300 mg/kg (P300) of pilocarpine, and epileptiform behavior and EEG changes followed within 4 h. Results: The intensity and the duration of seizures were significantly higher in P300 vs. the P200 and P100 groups, with status epilepticus dominating in P300 and self-limiting tonic-clonic seizures in the P200 group. The seizure grade was significantly higher in P200 vs. the P100 group only during the first hour after pilocarpine application. The latency of seizures was significantly shorter in P300 and P200 compared with P100 group. Conclusions: Pilocarpine (200 mg/kg) can be used as a suitable model for the initial screening of potential anti-seizure medications, while at a dose of 300 mg/kg, it can be used for study of the mechanisms of epileptogenesis.

Intraoperative pediatric electroencephalography monitoring: an updated review.

Intraoperative electroencephalography (EEG) monitoring under pediatric anesthesia has begun to attract increasing interest, driven by the availability of pediatric-specific EEG monitors and the realization that traditional dosing methods based on patient movement or changes in hemodynamic response often lead to imprecise dosing, especially in younger infants who may experience adverse events (e.g., hypotension) due to excess anesthesia. EEG directly measures the effects of anesthetics on the brain, which is the target end-organ responsible for inducing loss of consciousness. Over the past ten years, research on anesthesia and computational neuroscience has improved our understanding of intraoperative pediatric EEG monitoring and expanded the utility of EEG in clinical practice. We now have better insights into neurodevelopmental changes in the developing pediatric brain, functional connectivity, the use of non-proprietary EEG parameters to guide anesthetic dosing, epileptiform EEG changes during induction, EEG changes from spinal/regional anesthesia, EEG discontinuity, and the use of EEG to improve clinical outcomes. This review article summarizes the recent literature on EEG monitoring in perioperative pediatric anesthesia, highlighting several of the topics mentioned above.

Seizure-induced reversible magnetic resonance imaging abnormalities: A retrospective cohort study

PurposeSeizure-induced reversible magnetic resonance imaging (MRI) abnormalities (SRMA) present challenges in seizure management. We sought to investigate the frequency, risk factors, evolution and prognostic value of SRMA. MethodsA retrospective observational cohort study of consecutive seizure patients investigated with an MRI of the brain was conducted. Clinical and MRI data were reviewed to determine the clinical characteristics and imaging findings of SRMA. Outcomes (seizure freedom versus uncontrolled seizures and deaths) were assessed upon the last clinic follow-up. Mann-Whitney U test and chi-square test for independence with Bonferroni correction were used to explore the statistical significance of predictive factors. ResultsThe study included 483 consecutive seizure patients with 7.6% developing SRMA. Patients with SRMA were older (median age 57 years, interquartile range-IQR 52–66, p < 0.001) and experienced longer seizures (median 5 minutes, IQR 2–15, p = 0.002) compared with seizure patients with normal MRI. Seizure type (provoked versus unprovoked), recurrence (first versus recurrent) and epileptiform EEG changes did not demonstrate a significant association. Diffusion restriction and ADC reduction observed in SRMA resolved earlier, while T2, FLAIR hyperintensities and temporal lobes changes persisted longer on follow-up scans. The median time interval from seizure to complete resolution of SRMA was 87 days (IQR 45-225). No statistical difference in outcomes was seen between patients with SRMA and normal MRIs (p = 0.19). ConclusionsSRMA is an uncommon finding following seizures. It is not associated with poor seizure control or mortality. Risk factors associated with SRMA include older age and longer seizure duration including status epilepticus.

A study on the clinical and electrographic profile of Nonconvulsive Status Epilepticus (NCSE) in comatose ICU patients using portable electroencephalography (EEG)

BackgroundComa is one of the frequently encountered clinical conditions in any intensive care unit (ICU), which is responsible for considerable morbidity and mortality. Therefore, this study was designed to look at the clinical and EEG profile of Nonconvulsive Status Epilepticus (NCSE) in comatose ICU patients using portable electroencephalography (EEG). MethodsIn all 102 patients of unresponsive coma (GCS ≤ 8), who remained in poor sensorium despite 48 h of optimum treatment in ICU, were included in the study. All patients underwent 1 h of electroencephalography (EEG) monitoring with a portable EEG machine. All EEGs were screened according to Salzburg Consensus Criteria (SCC) for Nonconvulsive Status Epilepticus (NCSE). Patients with evidence of NCSE were administered parenteral Antiepileptic Drugs (AED). A repeat EEG was done after 24 h of baseline to ascertain the effect of AED. The primary outcome was the recognition of patients with NCSE on the basis of established EEG criteria. The secondary outcome measure was the Glasgow outcome scale (GOS) at the time of discharge. ResultsOut of 102 cases enrolled, 12 (11.8%) cases were detected to have NCSE on portable EEG. The mean age of patients with NCSE was 52.2 years. In terms of gender distribution, 2/12 (17%) were female, and 10/12 (83%) were male (M: F = 5:1). Median GCS was 6 (range 3–8). Looking at CNS infections, 4/12 (33.3%) had evidence of some form of CNS infection in the NCSE group, compared to 16/90 (18%) in the group without NCSE. This difference was statistically significant (P-value < 0.05). The EEG recordings of patients with NCSE showed dynamicity with fluctuating rhythms and ictal-EEG patterns associated with spatiotemporal evolution. All twelve cases showed reversal of EEG changes with AED administration. In 5 out of 12, transient improvement in GCS (>2 points) after administration of AED’ was noted with good clinical outcomes (GOS 5). In five of these 12 cases, death was the final outcome (GOS 1). ConclusionsNSCE should be considered in the differential diagnosis of all unresponsive comatose ICU patients. In resource-limited settings, where continuous EEG monitoring may not be feasible, bedside portable EEG testing can be used to diagnose patients with NCSE. Treating NCSE reverses epileptiform EEG changes and improves clinical outcomes in a subset of comatose ICU patients.

Non-Convulsive Status Epilepticus in Emergency Department: A Diagnostic Challenge

Non-convulsive status epilepticus had always been a diagnostic dilemma to emergency physicians. The challenge falls in its elusive nature and the subtlety of physical findings. Understanding the essence this disease process and the approach to it will result into a rewarding outcome for the patient and the physician. In this brief review we are trying to shed some light on that ambiguous neurological emergency and try to come up with a facilitated way of dealing with this common source of morbidity and mortality. Discussion Non-convulsive status epilepticus (NCSE) is a term used to refer to a prolonged seizure without an overt motor signs. It’s also defined as an altered mental status or change in the behavior from baseline with continuous epileptiform EEG changes. A review of literature showed that till now there is no acceptable definition. [1] NCSE are thought to be responsible for about 25% of the status epilepitcus. [2] De Lorenzo et al conducted a retrospective study in which 164 patients were subjected to a continuous 24 hours EEG monitoring after seizure treatment. He found that 14% of the patients had a NCSE and about 48% of the patient had a persistent seizure activity on EEG. [3] Treiman et al also in a similar manner found that 25% of the patient had NCSE after treatment for GCSE when monitored by EEG in his study that included 384 patients. [23] NCSE diagnosis has always been a diagnostic challenge to emergency physicians as there are no definitive diagnostic criteria, and due to the hectic nature of the emergency department its sound to difficult to do full neurological exam and in-depth medical history. [4] NCSE encompasses a group of syndromes that varies from self-limiting to refractory form. Absence SE and partial complex SE are the 2 major types that are commonly known although some recent data from medical literature had shown other subtypes. Clinical suspicion and EEG findings are mainstay to establish the diagnosis. Clinically, high index of suspicions should be kept in cases of: [5]  Prolonged postictal states  Absence of other clinical explanation for the patients with altered mental status  Stroke patients that seemed worse than expected  Subtle signs (blinking, twitching, fluctuating sensorium. Etc.). www.jmscr.igmpublication.org Impact Factor 5.244 Index Copernicus Value: 83.27 ISSN (e)-2347-176x ISSN (p) 2455-0450 DOI: http://dx.doi.org/10.18535/jmscr/v4i8.103

P92. Electroencephalographic patterns in different types of status epilepticus – Association with specific syndromes and prognostic significance

Objective It was planned to investigate, whether certain electroencephalographic patterns obtained during the treatment of a status epilepticus (SE) were associated with a particular subtype of SE. Methods In a retrospective databank analysis all treatment episodes of a SE between January 1st 2000 and December 31st 2009 in the department of Neurology of the Universitatsmedizin Rostock were identified. The first EEG of each treatment episode, in which an EEG was recorded, was evaluated. Statistical tests (i.e. chi-square-test and Student t -test) were performed in order to find out whether there is an association of a certain EEG pattern with a particular subtype of SE or whether some EEG patterns signify a worse outcome than others. Results In 35 treatment episodes of a SE at least one EEG was obtained during the actual treatment. There was no association of a certain EEG pattern with a particular subtype of SE. Periodic epileptiform discharges were seen more often in Nonlimbic complex partial status epilepticus and Cases of coma due to acute brain injury with epileptiform EEG changes than in Nonconvulsive status epilepticus (NCSE) in the postictal phase of tonic–clonic seizures. These results are at variance with the published literature, where the frequent occurrence of periodic epileptiform discharges in NCSE in the postictal phase of tonic-clonic seizures is reported. Background slowing with a frequency in the theta-range or lower was associated with disability to perform the activities of daily life without any help. On discharge patients with periodic epileptic discharges were more disabled than those without this pattern. Conclusion The concept of different substypes of NCSE needs further evaluation especially with regard to its therapeutic relevance. In adults EEG patterns specific for a particular subtype of SE are rare.

EEG changes in children born to epileptic parents

Epileptiform EEG changes are much more common in children whose parents are epileptic than in the population. There is evidence that subclinical epileptiform activity affects children’s intellect and behavior. These changes need timely detection and therapy. Objective : to determine the specific features and rates of EEG abnormalities in children born to parents with epilepsy. Patients and methods. The brain bioelectrical activity of 47 children born to epileptic fathers, 53 children born to epileptic mothers, and 46 children born to healthy parents (a control group) was evaluated via video EEG monitoring method on an Encephalan 9 apparatus (Medicom MTD, Taganrog, Russia). Results and discussion. Epileptiform EEG activity was significantly more frequently recorded in the children born to epileptic patients than in the control children. There was no significant difference in the detection rate of epileptiform activity in the groups of children, whose parents had epilepsy. EEG changes were significantly more common in children whose parents had idiopathic generalized epilepsy. The children born to epileptic mothers were more often recorded to have impaired bioelectrical activity of organic nature as a regional continued deceleration of basic activity and its deceleration in the background recording. Epileptiform activity was subclinical in the majority of cases. At the same time, it was unaccompanied by clinical manifestations in all the control children. Regional epileptiform activity was predominant in the study and control groups.

EEG Derived Neuronal Dynamics during Meditation: Progress and Challenges.

Meditation advances positivity but how these behavioral and psychological changes are brought can be explained by understanding neurophysiological effects of meditation. In this paper, a broad spectrum of neural mechanics under a variety of meditation styles has been reviewed. The overall aim of this study is to review existing scientific studies and future challenges on meditation effects based on changing EEG brainwave patterns. Albeit the existing researches evidenced the hold for efficacy of meditation in relieving anxiety and depression and producing psychological well-being, more rigorous studies are required with better design, considering client variables like personality characteristics to avoid negative effects, randomized controlled trials, and large sample sizes. A bigger number of clinical trials that concentrate on the use of meditation are required. Also, the controversial subject of epileptiform EEG changes and other adverse effects during meditation has been raised.

Electroencephalographic features of moyamoya in adults

ObjectiveElectroencephalography is useful for evaluating transient neurological events in the setting of moyamoya disease. MethodsEEG findings of adults with moyamoya seen at a large moyamoya referral center are summarized. Patients were identified by retrospective chart review. ResultsEEGs were ordered after cerebral revascularization for altered mental status, aphasia, limb shaking, or facial twitching. Among the study population of 103 patients having EEGs, 24% of adults with moyamoya had a history of clinical seizures. Ischemic or hemorrhagic strokes were associated with a twofold relative risk of seizures. Overall, 90% of EEGs were abnormal, most commonly focally (78%), or diffusely slow (68%). Epileptiform EEG discharges were seen in 24%. Whereas hemispheres with an ischemic stroke had a 19% risk of epileptiform discharges and an 8% risk of seizures on EEG, hemispheres with hemorrhagic stroke had a 35% risk of epileptiform discharges and 19% risk of seizures on EEG. Focal amplitude attenuation was seen in 19%, breach rhythm in 15%, rhythmic delta in 14%, and electrographic seizures in 12%. ConclusionsSeizures and epileptiform EEG changes are common in patients with moyamoya disease. SignificanceTransient events in patients with moyamoya can result from seizures as well as ischemia.

Clinical Signs of Occipital Cortex Dysfunction in Children

Cases with epileptiform EEG-changes, which are not associated with epileptic seizures and clinical signs of epileptic encephalopathy, are frequent in practical child neurology. We present the results of examination 52 children with abovementioned changes. The high frequency of migraine was found in families of these children as well as the association between EEG-changes and earlier traumatic brain injury and other diseases that impact brain maturation.

Risk for developing epilepsy and epileptiform discharges on EEG in patients with febrile seizures

Purpose: The aim of the present study was to investigate the correlation between epileptiform discharges on EEGs after febrile seizures and the prognosis of patients in terms of the development of epilepsy and recurrence of febrile seizures. This study also evaluated the characteristics of epileptiform discharges and EEG changes on follow-up examination. Methods: This study consisted of 36 children who presented to our hospital with febrile seizures and whose electroencephalograms (EEG) showed epileptiform discharges. The development of epilepsy and the recurrence of febrile seizures were compared between the study group (n=36) and the control group (n=87), which included children with febrile seizure but with normal EEG findings. Results: No significant correlation was detected between the recurrence rate of febrile seizures in patients with normal EEG (23 out of 87, 26.4%) findings and that of patients whose EEGs showed epileptiform discharges (12 out of 36, 33.3%) [adjusted OR 0.67 (0.26–1.68)]. However, 9 (25.0%) out of 36 patients with epileptiform discharges on EEG had epilepsy compared to 2 patients (2.3%) in the control group. The correlation was statistically significant [crude OR 10.88 (2.47–47.88) and adjusted OR 8.75 (1.49–51.6)]. Conclusion: Epileptiform discharges on the EEGs of patients with febrile seizures are important predictive risk factors of the development of epilepsy.

Psychogenic seizures and frontal disconnection: EEG synchronisation study

ObjectivePsychogenic non-epileptic seizures (PNES) are paroxysmal events that, in contrast to epileptic seizures, are related to psychological causes without the presence of epileptiform EEG changes. Recent models suggest a multifactorial...

Evidence of brain abnormality in patients with psychogenic nonepileptic seizures

Markers of brain abnormalities in patients with psychogenic nonepileptic seizures (PNES) were studied to explore whether physical brain disorder is associated with an increased risk of PNES. Evidence of epileptiform EEG changes, MRI abnormalities, and neuropsychological (NPS) deficits was obtained from the records of 329 consecutive patients in whom the diagnosis of PNES was established at our center between 1991 and 2001. Two hundred six patients had PNES alone, and 123 PNES and epilepsy (PNES + E). In the PNES-only group, at least one marker of brain disorder was detected in 22.3% of patients (epileptiform potentials in 8.7%, MRI changes in 9.7%, NPS deficits in 9.7%). The actual prevalence of abnormalities is likely to be higher because 54.9% of the patients with only psychogenic seizures did not undergo MRI or neuropsychological testing. Evidence of brain abnormality was found more frequently in the PNES + E group (epileptiform potentials in 70.7%, MRI changes in 60.2%, NPS deficits in 52.8%). Although markers of brain abnormality were detected much less commonly in the PNES than in the PNES + E group, they were still found in a substantial proportion of patients with PNES alone. This suggests that physical brain disease plays a role in the development of PNES. Markers of physical abnormality were not more common in the right hemisphere.

Protective effect of resveratrol against intracortical FeCl3-induced model of posttraumatic seizures in rats.

The present study was carried out to investigate the effect of trans-resveratrol, a potent antioxidant, against FeCl3-induced posttraumatic seizures. Male Wistar rats weighing 200-250 g were implanted with epidural electrodes and allowed to recover After the recording of baseline EEG. FeCl3 (5 microl, 100 mM) was administered intracortically over a period of 5 min and EEG was monitored for 2 h. Subsequently, rats were sacrificed for the estimation of oxidative stress markers, ie., malondialdehyde (MDA) and glutathione in whole brain tissue. A sham group was run parallel with saline (pH adjusted) and similar protocol for EEG recording and estimation of oxidative stress markers was followed FeCl3-treated animals exhibited epileptiform EEG changes thigh amplitude sharp waves of increased frequency and polyspikes) within 15 min, which continued throughout the period of observation. The level of MDA was found to be significantly elevated, whereas insignificant change was observed in the level of glutathione. trans-Resveratrol (20 and 40 mg/kg ip.) administered 30 min before FeCl3 injection delayed the onset of the appearance of epileptiform EEG changes. The brain MDA levels were also significantly reduced in the trans-resveratrol-treated animals as compared to the vehicle-treated FeCl3-injected rats. The findings show the protective effect of trans-resveratrol in the FeCl3-induced seizure model of posttraumatic seizures.

Status epilepticus on the paediatric intensive care unit—the role of EEG monitoring

A pilot study was undertaken of the feasibility of continuous EEG monitoring of patients admitted to a Paediatric Intensive Care Unit (PICU) for management of status epilepticus or its immediate sequelae. Eight children were studied and seizure activity was recorded in four patients. Additional information influencing management was obtained: the bedside nurse considered decerebrate posturing in one patient to be a seizure: there were no epileptiform EEG changes. Another patient was considered to have seizures (clonic movements of both upper limbs) following cardiac arrest; the EEG showed electrocerebral silence, and thiopentone treatment was discontinued. In another patient, continuing epileptiform activity on EEG gave intensivists the confidence to use higher than usual doses of thiopentone. The problems encountered were delays in monitoring, once for a CT scan and once because of two admissions within hours of each other. We conclude that EEG monitoring on a PICU is feasible and provides clinically useful information.

Multiple kainic acid seizures in the immature and adult brain: ictal manifestations and long-term effects on learning and memory.

While there is increasing evidence that the adverse effects of prolonged seizures are less pronounced in the immature than in the mature brain, there have been few investigations of the long-term effects of recurrent seizures during development. This study examined the effects of multiple administrations of the convulsant kainic acid (KA) on seizure characteristics and spatial learning as a function of brain development. To determine the long-term effects of serial KA seizures during ontogeny, saline or convulsant doses of KA were given intraperitoneally 4 times, at 2-day intervals. Immature rats were given KA on P20, P22, P24 and P26; adult rats got KA on P60, P62, P64 and P66. Ictal characteristics and EEGs were recorded. To examine the effects of multiple KA seizures on the retention of spatial learning, water maze testing was performed before (immature group: from P16-19, adult group: from P56-P59) and after (immature: from P60-P63, adult: from P100-P103) KA injections. Finally, histology was performed to compare KA-induced damage at each age. In immature animals, serial KA administration resulted in seizures with a progressively longer onset latency and decreased severity. In contrast, KA serially administered to adult rats caused severe seizures after each of the 4 injections. In immature rats, epileptiform EEG changes were most prominent after the first KA injection, whereas in adults, prolonged paroxysmal EEG patterns were seen after all 4 KA injections. Before KA, both rat pups and adults acquired place learning in the water maze. One month after the final KA injection, there was no deficit in spatial learning retention in the immature group, whereas the adult group had profound impairment compared to age-matched, saline-injected controls. Histology revealed no lesions in immature rats treated multiple times with KA but profound cell loss in hippocampal fields CA4, CA3 and CA1 in rats treated serially with KA as adults. Previous studies have shown that a single KA injection causes prolonged status epilepticus (which persists for several hours), leading to severe histologic and behavioral sequelae in adult rats but not in pups. Our study extends those findings, demonstrating that immature rats are spared the cognitive and pathological sequelae of multiple injections of convulsant doses of KA as well.

Kindling with clozapine: behavioral and molecular consequences.

Clozapine is an 'atypical' neuroleptic that improves symptoms of many patients with schizophrenia whose illness is resistant to treatment with other neuroleptics. Unlike the 'typical neuroleptics (chlorpromazine, haloperidol), clozapine does not induce extrapyramidal symptoms such as Parkinsonism and tardive dyskinesia in humans or catalepsy in the rat. However, clozapine frequently causes epileptiform EEG changes and causes seizures in 3-5% of patients treated with this drug in therapeutic doses. Clozapine also induces dose dependent myoclonus in the partially restrained rat. In the experiments reported here, partially restrained rats were administered repeated alternate day or weekly low, fixed doses of clozapine (1 mg/kg). This dose initially caused no behavioral change. Following the third and subsequent administrations, the same dose elicited an increasing number of myoclonic seizure-like jerks reaching 140/h following the 15th injection in rats receiving the same low dose of clozapine on alternate days and 160/h following the 9th injection in animals that received the same dose once weekly. These effects are consistent with kindling, i.e. a progressive increase of brain excitability following repeated administration of a fixed subconvulsive dose of an excitatory agent. Clozapine kindled animals exhibited a significantly different pattern of early gene expression in ventral tegmental area, origin of the mesolimbic-mesocortical dopamine system and in the anterior thalamic nuclei, compared with saline treated controls subjected to exactly the same recording conditions. The evidence of central nervous system excitation with clozapine may be important to the unique therapeutic effect of this atypical antipsychotic in the treatment of symptoms, especially the deficit symptoms, of schizophrenia.

Clozapine and seizures

Epileptiform EEG changes, myoclonus, and seizures are reported in some patients treated with clozapine. Although these are undesirable side effects, the excitation of specific neuronal networks by clozapine and other neuroleptics may be important for the therapeutic effect of this class of agents. In these experiments, intraperitoneal clozapine 2-16 mg/kg produced dose-related myoclonic jerks in partially restrained rats. Paroxysmal slow waves and spike activity were recorded from implanted electrodes in amygdala, hippocampus, and cortex following higher doses of clozapine, but the EEG abnormalities were not correlated with the myoclonic jerks. Single doses of chlorpromazine (8 and 16 mg/kg) rarely produced myoclonic jerks but provoked generalized tonic seizures in two animals preceded by multiple myoclonic jerks in one. Myoclonus and seizures reflect increased excitability of the central nervous system. It is possible that clozapine and other neuroleptics exert a therapeutic effect by increasing excitability in critical subcortical areas of the brain.

Neurosurgical management of epilepsy: a personal perspective in 1983.

The therapeutic goal in the neurosurgical treatment of medically intractable epilepsy is complete seizure control, for both biologic and psychosocial reasons. Cortical resections are more likely to accomplish this than other surgical alternatives for epilepsy. Although abnormalities on new imaging techniques (CT, positron emission scanning) aid in identifying the epileptic focus, interictal epileptiform EEG changes remain the main indicator of focal origin of the seizures. Where this is equivocal, direct brain recording of spontaneous seizures with subdural electrodes is of value in identifying the side and lobe of seizure onset. The cortical resection is then tailored by the extent of the interictal electrocorticographic abnormalities and functional identification of essential areas such as those for language, using an electrical stimulation mapping technique, under local anesthesia. With this approach, half of the patients with temporal lobe foci are seizure-free since the time of operation, over two-thirds become so with time, and over three-quarters have at least very major reductions in seizure frequency.