Interictal

SUMMARY Purpose: To better understand the nature of the focal spike-wave discharges (FSWDs) and focally led generalized spike-wave discharges (GSWDs) in typical childhood absence epilepsy (CAE) and by implication their nosologic and taxonomic significance. Methods: Twenty-four abnormal video-electroencephalography (EEG) studies from 13 consecutive children with CAE and good response to appropriate antiepileptic drugs (AEDs) were analyzed. We studied the association between the topography of absence onset and the ictal automatisms, and the topographic correlation between FSWDs and GSWDs and their respective behavior during hyperventilation and the different states of phasic and nonphasic non–rapid eye movement (NREM) sleep. GSWDs were considered as of ''focal'' onset if a lead-in could be visibly recognized at a paper speed of 60 mm/s, and were classified by their topography. Key Findings: (1) Multifocal absences occurred in 10 children; anterior onset was noted in 81 absences (73.6%) from 12 children and posterior in 18 (16.4%) from 7 children; there was no association between topography of absence onset and ictal automatisms; (2) FSWDs occurred in 85% of children and were multifocal in 73% of them; 85% of FSWDs were anterior and 14% posterior; (3) there was good topographic association between FSWDs and the leading spike of GSWDs of ''focal'' onset in all children with FSWDs; (4) both FSWDs and GSWDs increased during hyperventilation; (5) FSWDs occurred mainly during noncyclical NREM sleep and during periods of reduced vigilance of cyclical NREM sleep, whereas GSWDs occurred during the periods of enhanced vigilance of NREM sleep; GSWDs occurred significantly more frequently than FSWDs at the transition from reduced to enhanced vigilance of NREM sleep. Significance: Our findings suggest that in CAE focal EEG paroxysms reflect a system of multifocal nonlocalizing electrically unstable cortical areas that under the facilitatory influence of exogenous or endogenous factors like sleep instability can foster a corticothalamic response of sufficient strength to generate 3-Hz GSWDs that are conditionally sustainable and potentially ictal. FSWDs can be viewed as incomplete forms of the GSWDs; together they define the EEG identity of idiopathic ''generalized'' epileptogenesis.

Epilepsy can cause many different problems such as psychosocial problems except seizures. According to the temporal distribution, the psychiatric disorders which epilepsy caused can be addressed into the two main groups
such as peri-ictal (preictal, ictal, postictal) and interictal. The interictal findings tend to be permanent. This study aimed to reveal interictal psychiatric disorders in detail. Totally 180 patients who are followed by our clinic for at
least two years were evaluated retrospectively. Epileptic seizures are classified according to criterias of International League Against Epilepsy 1981 and Semiological Classification-1998 (Hans Lüders-Soheyl Noachtar),
psychiatric disorders are classified according to criterias of DSM-IV. The cases were divided into two groups according to the presence of psychiatric disorders. The mean age was 35 ± 19 (9-87) years, female / male ratio was105/75, mean age at onset of epilepsy was 25 ± 20 years. Psychiatric disorder ratio was found 43.3% of
cases. They are (in order of frequency); depression, generalized anxiety disorder, psychotic disorder, attention deficit, obsessive-compulsive disorder, panic disorder and affective disorder. Four percent of the patients had a history of attempting suicide. There was no statistical difference between the groups which psychiatric disorders detected and undetected about age, gender, seizure type, antiepileptic drugs and drugs number. Despite, there was no statistical reflection, the ratio of symptomatic epilepsy, frequent seizure and aura was relatively high in
psychiatric disorder group. The most common psychiatric disorders are depression and anxiety disorders in the interictal period. This situations may even cause person commit suicide. It must be considered and measures should be taken that, psychiatric disorders can prepare a ground for several problems such as control of epileptic seizures and some psycho-socio-economic complexities.

Of 47 patients with onset of intractable partial seizures and temporal lobe MRI lesions, subjected to presurgical evaluation and temporal lobe surgery, we identified eight (mean age: 24 years; range: 7-52 years) demonstrating surface interictal and/or ictal EEG features suggestive of an extratemporal localisation. All eight patients underwent surgery aiming to predominantly resect the lesion, without extending to the extratemporal region. The patients were prospectively followed (mean followup duration: 38 months; range: 12-66 months) and all achieved excellent postoperative seizure control. Extratemporal surface interictal/ictalEEGfeaturesweremoreoftenencounteredintumouralandfocalcorticaldysplasia cases, compared with medial temporal sclerosis cases, and were most frequently localised over frontopolar and suprasylvian-pericentral locations. We postulate that propagation of interictal/ictal activity from the epileptogenic region of the temporal lobe to extratemporal neocortical areas, perhaps utilising the temporal pole and insula as intermediary nodes of a common epileptogenic network, accounts for the presence of our cohort’s discordant lesion and EEG features.

A drug-resistant epilepsy patient with premotor type IIb focal cortical dysplasia is described with a positive postoperative outcome followingpartialresectionofthelesionandepileptogeniczone.Presurgical fMRI of the sensorimotor areas showed haemodynamic responses over the posterior border of the lesion and ictal EEG-fMRI revealed activation of both the primary sensorimotor strip and premotor lesion area. Almost continuous 1-2Hz interictal spiking was recorded during a chronic ECoG study over the primary sensorimotor cortex. Following partial resection of the lesion, an acute ECoG revealed marked reduction of epileptic activity over the sensorimotor area. Post-operatively, seizure control was significantly improved (class IV ILAE outcome). Although partial FCD resections predict a worse postoperative outcome, individual patients may still respond favourably. The type of lesion, resected portion, and histopathology maybe included among factors related to successful outcome.

Electroencephalogram (EEG) is a record of ongoing electrical signal to represent the human brain activity. It has great potential for the diagnosis to treatment of mental disorder and brain diseases such as epileptic seizure. Features extraction and classification is a crucial task to detect the stage of ictal (i.e. seizure period) and interictal (i.e. period between seizures) EEG signals for the treatment and precaution of the patient. However, existing seizure and non-seizure feature extraction techniques are not good enough for the classification of ictal and interictal EEG signals considering their non-abrupt phenomena and inconsistency in different brain locations. In this paper, we present new approaches for feature extraction using high-frequency components from discrete cosine transformation (DCT) and intrinsic mode function (IMF) extracted from empirical mode decomposition (EMD). These features are then used as an input to least square-support vector machine (LV-SVM) to cla...

The EEG in childhood absence epilepsy (CAE) may contain focal and generalised spike-wave discharges (SWDs) with focal, mainly frontal, "lead-in". The term "frontal absence" has been used to imply fast, secondary, 3-Hz generalisation from occult frontal foci with potential impact on clinical EEG interpretation and syndrome classification. The aim of this study was to investigate the relationship between focal and generalised SWDs. We studied five children with CAE and examined a sufficient number of focal ("interictal") and generalised SWDs in order to obtain reliable analysis. All generalised SWDs with focal lead-in were "decomposed" into their "pre-generalisation" focal and "generalised" constituents, which were studied separately. Two types of focal SWD ("interictal" and "pre-generalisation") and generalised SWD were visually clustered into groups, waveform-averaged, and plotted in the 2D-electrode spa...

We propose a new integrative approach to characterize the structure of seizures in the space, time, and frequency domains. Such characterization leads to a new technical development of ictal source analysis for the presurgical evaluation of epilepsy patients. The present new ictal source analysis method consists of three parts. First, a three-dimensional source scanning procedure is performed by a spatio-temporal FINE source localization method to locate the multiple sources responsible for the time evolving ictal rhythms at their onsets. Next, the dynamic behavior of the sources is modeled by a multivariate autoregressive process (MVAR). Lastly, the causal interaction patterns among the sources as a function of frequency are estimated from the MVAR modeling of the source temporal dynamics. The causal interaction patterns indicate the dynamic communications between sources, which are useful in distinguishing the primary sources responsible for the ictal onset from the secondary sources caused by the ictal propagation. The present ictal analysis strategy has been applied to a number of seizures from five epilepsy patients, and their results are consistent with observations from either MRI lesions or SPECT scans, which indicate its effectiveness. Each step of the ictal source analysis is statistically evaluated in order to guarantee the confidence in the results.

We propose a new integrative approach to characterize the structure of seizures in the space, time, and frequency domains. Such characterization leads to a new technical development of ictal source analysis for the presurgical evaluation of epilepsy patients. The present new ictal source analysis method consists of three parts. First, a three-dimensional source scanning procedure is performed by a spatio-temporal FINE source localization method to locate the multiple sources responsible for the time evolving ictal rhythms at their onsets. Next, the dynamic behavior of the sources is modeled by a multivariate autoregressive process (MVAR). Lastly, the causal interaction patterns among the sources as a function of frequency are estimated from the MVAR modeling of the source temporal dynamics. The causal interaction patterns indicate the dynamic communications between sources, which are useful in distinguishing the primary sources responsible for the ictal onset from the secondary sources caused by the ictal propagation. The present ictal analysis strategy has been applied to a number of seizures from five epilepsy patients, and their results are consistent with observations from either MRI lesions or SPECT scans, which indicate its effectiveness. Each step of the ictal source analysis is statistically evaluated in order to guarantee the confidence in the results.

There is currently a lack of knowledge about electroencephalography (EEG)-functional magnetic resonance imaging (fMRI) specificity. Our aim was to define sensitivity and specificity of blood oxygen level dependent (BOLD) responses to interictal epileptic spikes during EEG-fMRI for detecting the ictal onset zone (IOZ). We studied 21 refractory focal epilepsy patients who had a well-defined IOZ after a full presurgical evaluation and interictal spikes during EEG-fMRI. Areas of spike-related BOLD changes overlapping the IOZ in patients were considered as true positives; if no overlap was found, they were treated as false-negatives. Matched healthy case-controls had undergone similar EEG-fMRI in order to determine true-negative and false-positive fractions. The spike-related regressor of the patient was used in the design matrix of the healthy case-control. Suprathreshold BOLD changes in the brain of controls were considered as false positives, absence of these changes as true negatives. Sensitivity and specificity were calculated for different statistical thresholds at the voxel level combined with different cluster size thresholds and represented in receiver operating characteristic (ROC)-curves. Additionally, we calculated the ROC-curves based on the cluster containing the maximal significant activation. We achieved a combination of 100% specificity and 62% sensitivity, using a Z-threshold in the interval 3.4-3.5 and cluster size threshold of 350 voxels. We could obtain higher sensitivity at the expense of specificity. Similar performance was found when using the cluster containing the maximal significant activation. Our data provide a guideline for different EEG-fMRI settings with their respective sensitivity and specificity for detecting the IOZ. The unique cluster containing the maximal significant BOLD activation was a sensitive and specific marker of the IOZ.