Facilitation of epileptic activity during sleep is mediated by high amplitude slow waves

Epileptic discharges in focal epilepsy are frequently activated during non-rapid eye movement sleep. Sleep slow waves are present during this stage and have been shown to include a deactivated ('down', hyperpolarized) and an activated state ('up', depolarized). The 'up' state enhances physiological rhythms, and we hypothesize that sleep slow waves and particularly the 'up' state are the specific components of non-rapid eye movement sleep that mediate the activation of epileptic activity. We investigated eight patients with pharmaco-resistant focal epilepsies who underwent combined scalp-intracerebral electroencephalography for diagnostic evaluation. We analysed 259 frontal electroencephalographic channels, and manually marked 442 epileptic spikes and 8487 high frequency oscillations during high amplitude widespread slow waves, and during matched control segments with low amplitude widespread slow waves, non-widespread slow waves or no slow waves selected during the same sleep stages (total duration of slow wave and control segments: 49 min each). During the slow waves, spikes and high frequency oscillations were more frequent than during control segments (79% of spikes during slow waves and 65% of high frequency oscillations, both P ~ 0). The spike and high frequency oscillation density also increased for higher amplitude slow waves. We compared the density of spikes and high frequency oscillations between the 'up' and 'down' states. Spike and high frequency oscillation density was highest during the transition from the 'up' to the 'down' state. Interestingly, high frequency oscillations in channels with normal activity expressed a different peak at the transition from the 'down' to the 'up' state. These results show that the apparent activation of epileptic discharges by non-rapid eye movement sleep is not a state-dependent phenomenon but is predominantly associated with specific events, the high amplitude widespread slow waves that are frequent, but not continuous, during this state of sleep. Both epileptic spikes and high frequency oscillations do not predominate, like physiological activity, during the 'up' state but during the transition from the 'up' to the 'down' state of the slow wave, a period of high synchronization. Epileptic discharges appear therefore more associated with synchronization than with excitability. Furthermore, high frequency oscillations in channels devoid of epileptic activity peak differently during the slow wave cycle from those in channels with epileptic activity. This property may allow differentiating physiological from pathological high frequency oscillations, a problem that is unresolved until now.Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señale

Facilitation of epileptic activity during sleep is mediated by high amplitude slow waves

Epileptic discharges in focal epilepsy are frequently activated during non-rapid eye movement sleep. Sleep slow waves are present during this stage and have been shown to include a deactivated ('down', hyperpolarized) and an activated state ('up', depolarized). The 'up' state enhances physiological rhythms, and we hypothesize that sleep slow waves and particularly the 'up' state are the specific components of non-rapid eye movement sleep that mediate the activation of epileptic activity. We investigated eight patients with pharmaco-resistant focal epilepsies who underwent combined scalp-intracerebral electroencephalography for diagnostic evaluation. We analysed 259 frontal electroencephalographic channels, and manually marked 442 epileptic spikes and 8487 high frequency oscillations during high amplitude widespread slow waves, and during matched control segments with low amplitude widespread slow waves, non-widespread slow waves or no slow waves selected during the same sleep stages (total duration of slow wave and control segments: 49 min each). During the slow waves, spikes and high frequency oscillations were more frequent than during control segments (79% of spikes during slow waves and 65% of high frequency oscillations, both P ~ 0). The spike and high frequency oscillation density also increased for higher amplitude slow waves. We compared the density of spikes and high frequency oscillations between the 'up' and 'down' states. Spike and high frequency oscillation density was highest during the transition from the 'up' to the 'down' state. Interestingly, high frequency oscillations in channels with normal activity expressed a different peak at the transition from the 'down' to the 'up' state. These results show that the apparent activation of epileptic discharges by non-rapid eye movement sleep is not a state-dependent phenomenon but is predominantly associated with specific events, the high amplitude widespread slow waves that are frequent, but not continuous, during this state of sleep. Both epileptic spikes and high frequency oscillations do not predominate, like physiological activity, during the 'up' state but during the transition from the 'up' to the 'down' state of the slow wave, a period of high synchronization. Epileptic discharges appear therefore more associated with synchronization than with excitability. Furthermore, high frequency oscillations in channels devoid of epileptic activity peak differently during the slow wave cycle from those in channels with epileptic activity. This property may allow differentiating physiological from pathological high frequency oscillations, a problem that is unresolved until now.Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señale

Facilitation of epileptic activity during sleep is mediated by high amplitude slow waves

Epileptic discharges in focal epilepsy are frequently activated during non-rapid eye movement sleep. Sleep slow waves are present during this stage and have been shown to include a deactivated ('down', hyperpolarized) and an activated state ('up', depolarized). The 'up' state enhances physiological rhythms, and we hypothesize that sleep slow waves and particularly the 'up' state are the specific components of non-rapid eye movement sleep that mediate the activation of epileptic activity. We investigated eight patients with pharmaco-resistant focal epilepsies who underwent combined scalp-intracerebral electroencephalography for diagnostic evaluation. We analysed 259 frontal electroencephalographic channels, and manually marked 442 epileptic spikes and 8487 high frequency oscillations during high amplitude widespread slow waves, and during matched control segments with low amplitude widespread slow waves, non-widespread slow waves or no slow waves selected during the same sleep stages (total duration of slow wave and control segments: 49 min each). During the slow waves, spikes and high frequency oscillations were more frequent than during control segments (79% of spikes during slow waves and 65% of high frequency oscillations, both P ~ 0). The spike and high frequency oscillation density also increased for higher amplitude slow waves. We compared the density of spikes and high frequency oscillations between the 'up' and 'down' states. Spike and high frequency oscillation density was highest during the transition from the 'up' to the 'down' state. Interestingly, high frequency oscillations in channels with normal activity expressed a different peak at the transition from the 'down' to the 'up' state. These results show that the apparent activation of epileptic discharges by non-rapid eye movement sleep is not a state-dependent phenomenon but is predominantly associated with specific events, the high amplitude widespread slow waves that are frequent, but not continuous, during this state of sleep. Both epileptic spikes and high frequency oscillations do not predominate, like physiological activity, during the 'up' state but during the transition from the 'up' to the 'down' state of the slow wave, a period of high synchronization. Epileptic discharges appear therefore more associated with synchronization than with excitability. Furthermore, high frequency oscillations in channels devoid of epileptic activity peak differently during the slow wave cycle from those in channels with epileptic activity. This property may allow differentiating physiological from pathological high frequency oscillations, a problem that is unresolved until now.Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señale

Auras in temporal lobe epilepsy with hippocampal sclerosis: Relation to seizure focus laterality and post surgical outcome

We examined the relationship between presence and frequency of different types of auras and side of lesion and post surgical outcomes in 205 patients with medically intractable mesial temporal lobe epilepsy (MTLE) with unilateral hippocampal sclerosis (HS). With respect to the number of auras, multiple auras were not associated with side of lesion (p=0.551). the side of HS was not associated with the type of auras reported. One hundred fifty-seven patients were operated. the occurrence of multiple auras was not associated with post-surgical outcome (p=0.740). the presence of extratemporal auras was significantly higher in patients with poor outcome. in conclusion, this study suggests that the presence of extratemporal auras in patients with MTLE-HS possibly reflects extratemporal epileptogenicity in these patients, who otherwise showed features suggestive of TLE. Therefore, TLE-HS patients undergoing pre-surgical evaluation and presenting clinical symptoms suggestive of extratemporal involvement should bemore extensively evaluated to avoid incomplete resection of the epileptogenic zone. (C) 2012 Elsevier Inc. All rights reserved.Universidade Federal de São Paulo, Dept Neurol & Neurocirurgia, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Diagnost Imagem, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Neurol & Neurocirurgia, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Diagnost Imagem, BR-04024002 São Paulo, BrazilWeb of Scienc

Granule cell dispersion is associated with memory impairment in right mesial temporal lobe epilepsy

Purpose: We analyzed the association of granule cell dispersion (GCD) with memory performance, clinical data and surgical outcome in a series of patients with mesial temporal lobe epilepsy (MILE) and mesial temporal sclerosis (MTS).Method: Hippocampal specimens from 54 patients with MTLE (27 patients with right MILE and 27 with left MTLE) and unilateral MTS, who were separated into CCD and no-GCD groups and thirteen controls were studied. Quantitative neuropathological evaluation was performed using hippocampal sections stained with NeuN. Patients' neuropsychological measures, clinical data, type of MTS and surgical outcome were reviewed.Results: CCD occurred in 28 (51.9%) patients. No correlation between GCD and MTS pattern, clinical data or surgical outcome was found. the presence of GCD was correlated with worse visuospatial memory performance in right MTLE, but not with memory performance in left MTLE.Conclusion: GCD may be related to memory impairment in right MTLE-MTS patients. However, the role of GCD in memory function is not precisely defined. (c) 2012 British Epilepsy Association. Published by Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Instituto Nacional de Neurociencia Translacional (INNT), BrazilUniversidade Federal de São Paulo, Dept Neurol & Neurosurg, Escola Paulista Med, Unidade Pesquisa & Tratamento Epilepsias, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Psychobiol, Escola Paulista Med, BR-04024002 São Paulo, BrazilSanta Casa São Paulo, Dept Pathol, São Paulo, BrazilAFIP, Dept Pathol, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Neurol & Neurosci, Escola Paulista Med, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Neurol & Neurosurg, Escola Paulista Med, Unidade Pesquisa & Tratamento Epilepsias, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Psychobiol, Escola Paulista Med, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Neurol & Neurosci, Escola Paulista Med, BR-04024002 São Paulo, BrazilWeb of Scienc

Outcomes of patients with altered level of consciousness and abnormal electroencephalogram: A retrospective cohort study

<div><p>Introduction</p><p>Nonconvulsive seizures (NCS) are frequent in hospitalized patients and may further aggravate injury in the already damaged brain, potentially worsening outcomes in encephalopathic patients. Therefore, both early seizure recognition and treatment have been advocated to prevent further neurological damage.</p><p>Objective</p><p>Evaluate the main EEG patterns seen in patients with impaired consciousness and address the effect of treatment with antiepileptic drugs (AEDs), continuous intravenous anesthetic drugs (IVADs), or the combination of both, on outcomes.</p><p>Methods</p><p>This was a single center retrospective cohort study conducted in a private, tertiary care hospital. Consecutive adult patients with altered consciousness submitted to a routine EEG between January 2008 and February 2011 were included in this study. Based on EEG pattern, patients were assigned to one of three groups: Group Interictal Patterns (IP; EEG showing only interictal epileptiform discharges or triphasic waves), Group Rhythmic and Periodic Patterns (RPP; at least one EEG with rhythmic or periodic patterns), and Group Ictal (Ictal; at least one EEG showing ictal pattern). Groups were compared in terms of administered antiepileptic treatment and frequency of unfavorable outcomes (modified Rankin scale ≥3 and in-hospital mortality).</p><p>Results</p><p>Two hundred and six patients (475 EEGs) were included in this analysis. Interictal pattern was observed in 35.4% (73/206) of patients, RPP in 53.4% (110/206) and ictal in 11.2% (23/206) of patients. Treatment with AEDs, IVADs or a combination of both was administered in half of the patients. While all Ictal group patients received treatment (AEDs or IVADs), only 24/73 (32.9%) IP group patients and 55/108 (50.9%) RPP group patients were treated (p<0.001). Hospital length of stay (LOS) and frequency of unfavorable outcomes did not differ among the groups. In-hospital mortality was higher in IVADs treated RPP patients compared to AEDs treated RPP patients [11/19 (57.9%) vs. 11/36 (30.6%) patients, respectively, p = 0.049]. Hospital LOS, in-hospital mortality and frequency of unfavorable outcomes did not differ between Ictal patients treated exclusively with AEDs or IVADs.</p><p>Conclusion</p><p>In patients with acute altered consciousness and abnormal routine EEG, antiepileptic treatment did not improve outcomes regardless of the presence of periodic, rhythmic or ictal EEG patterns.</p></div

Granule cell dispersion is not a predictor of surgical outcome in temporal lobe epilepsy with mesial temporal sclerosis

The aim of this retrospective study of a series of patients with mesial temporal lobe epilepsy (MTLE) and mesial temporal sclerosis (MTS) was to analyze the association of granule cell dispersion (GCD) with surgical prognosis, patterns of MTS and clinical data. Hippocampal specimens from 66 patients with MTLE and unilateral MTS and from 13 controls were studied. Quantitative neuropathological evaluation was performed on NeuN-stained hippocampal sections. Patients' clinical data, types of MTS and surgical outcome were reviewed. GCD occurred in 45.5% of cases and was not correlated with clinical variable. More severe neuronal loss was observed in patients with GCD. Except for MTS Type 2 observed only in four no-GCD patients groups did not differ with respect to the types of MTS. Surgical outcome was similar in both groups. in conclusion, GCD was associated with the degree of hippocampal cell loss, but was not a predictor of surgical outcome.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Instituto Nacional de Neurociencia Translacional (INNT), BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Neurol & Neurosurg, São Paulo, BrazilSanta Casa São Paulo, Dept Pathol, São Paulo, BrazilAFIP, Dept Pathol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Neurol & Neurosci, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Neurol & Neurosurg, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Neurol & Neurosci, São Paulo, BrazilWeb of Scienc

EEG recording of a 61-year-old woman in a coma state, after termination of a generalized tonic-clonic seizure.

<p>The EEG reveals continuous epileptiform discharges—sharp waves—over both right and left hemispheres, which in association with the clinical picture constitute a nonconvulsive status epilepticus. The patient was classified into Ictal group.</p