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Objective We hypothesized that the extensive epileptic network in patients with tuberous sclerosis complex (TSC) manifests as clustered and scattered distributions of magnetoencephalography spike sources (MEGSS). Methods We retrospectively analyzed pre-surgical MEG in 15 patients with TSC. We performed single moving dipole analysis to localize and classify clustered and scattered MEGSS. We compared the number of electrodes within the resected area (RA) and the proportions of clustered and scattered MEGSS within RA with the seizure outcome. Results The number of electrodes within RA ranged from 29 to 83 (mean = 51). The MEGSS were distributed over multiple lobes (3–8; mean = 5.9) and bilaterally in 14 patients. Clusters of MEGSS ranged from 1 to 4 (mean = 1.4). The number of MEGSS ranged in total from 28 to 139 (mean = 70); in the clusters, 10–128 (mean = 49); and in the scatters, 0–45 (mean = 21). Four patients achieved an Engel class I surgical outcome, four, a class II outcome; five, a class III outcome; and two, a class IV outcome. The proportion of MEGSS ranged in total from 0 to 92% (mean = 57%) within RA; 0–100% (mean = 67%) in the resection hemisphere; 0–100% (mean = 63%) in the clusters; and 0–81% (mean = 28%) in the scatters. Univariate ordinal logistic regression analyses showed that the proportion of scattered MEGSS within RA (p = 0.049) significantly correlated with seizure outcomes. Multivariate analyses using three covariates (number of electrodes, proportions of clustered and scattered MEGSS within RA) showed that only the proportion of scattered MEGSS within RA significantly correlated with seizure outcomes (p = 0.016). Significance MEG data showed a wide distribution of multilobar MEGSS in patients with TSC. The seizure outcome was not related to the clustered MEGSS within RA, since the grids were essentially planned to cover and resect the clustered MEGSS surrounding tubers. The maximal possible resection of scattered MEGSS correlated with improved seizure outcome in TSC. Some parts of the epileptogenic zone disrupted by multiple tubers did not have a sufficiently large area to produce clustered MEGSS. Although the wide distribution of scattered MEGSS is not interpreted as epileptogenic, they might be interrelated with clustered MEGSS to project a complex epilepsy network and be part of the extensive epileptogenic zones found in TSC.

Occipital lobe epilepsy (OLE) poses a diagnostic challenge to clinicians. Here, we present our experience in the surgical management of OLE in children using magnetoencephalography (MEG) in the pre-operative evaluation.Retrospective chart review was performed from 2000 to 2010 to identify patients with OLE. Patients were analyzed in two categories: isolated OLE (11 patients) and extended OLE (parietooccipital, temporooccipital, and temporoparietooccipital; 30 patients). Survival analysis and multivariate Cox proportional hazards regression were used to identify independent predictors of seizure outcome.Forty-one patients with a mean follow-up of 3.1 years were identified with an overall 68% rate of satisfactory seizure outcome. Patients with extended OLE had younger ages at seizure onset and different seizure semiologies compared with those with isolated OLE. None of the latter underwent insertion of subdural grid electrodes for localization of the epileptogenic zone compared with 77% of the former (p0.001). On multivariate analysis, the strongest independent predictor of unsatisfactory outcome was MEG dipoles in the occipital lobe contralateral to resection.Here, we find similar seizure outcomes for isolated and extended OLE foci despite the use of less invasive strategies for the former. Furthermore, we describe the role of MEG in evaluation, surgical planning and prognostication of children with OLE.

Summary Objectives To elucidate the pathophysiology of intractable epileptic spasms in older children by describing the interictal magnetoencephalography spike sources (MEGSSs), intracranial EEG ictal-onset zones (IOZs) and their ictal high-frequency oscillations (HFOs) and surgical outcomes. Methods We studied five patients (4.5–14 years) who underwent surgery following intracranial video-EEG (VEEG) monitoring. We analyzed clinical profiles, MRIs, scalp and intracranial VEEGs, and MEGSSs. We localized ictal HFOs using a sampling rate of 1000 Hz and multiple band frequency analysis (MBFA). Results Seizure onset ranged from 0.4 to 8 years. Three patients presented with asymmetrical spasms. Interictal scalp VEEG recorded predominantly unilateral epileptiform discharges in four; generalized and multifocal in one. Ictal scalp VEEG showed generalized high-amplitude slow waves with superimposed fast waves in four patients; hemispheric electrodecremental episodes in one. MRI findings were normal in three, hemispheric polymicrogyria and periventricular heterotopia in one each. All patients had unilateral MEGSS clusters. Ictal HFOs, ranging from 150 to 250 Hz, localized over Rolandic and frontal regions in four, with one also having extensive temporo-occipital HFOs. After cortical resection, three patients were seizure free; one had >90% reduction in seizure frequency. One patient experienced residual seizures after resection of the hemispheric ictal HFO region. Conclusion Unilateral clusters of MEGSSs overlapped regional IOZs in older patients with epileptic spasms. High spatio-temporal MBFA before and during spasms revealed the regional ictal HFOs. Seizure-free outcomes following resection of zone with MEGSS clusters and ictal HFOs suggested that a subset of epileptic spasms was focal-onset seizures.

Summary Introduction Paroxysmal fast activity (FA) has been proposed as a marker for epileptic networks. We explore the presence and significance of ictal FA on scalp video EEG seizures (EEG Sz) recorded in neonates. Methodology Forty two babies had 159 EEG Szs. The seizures were analysed for ictal FA, using a low frequency filter of 30Hz. We explored the relationship of ictal FA to the occurrence of electroclinical and electrographic seizures, the use of phenobarbitone and to neurodevelopmental outcomes. Results Ictal FA occurred in 62 (39%) of the 159 EEG Szs. In the 62 seizures with ictal FA, 34 (55%) were electroclinical seizures (ECSz) and 28 (45%) were electrographic (ESz). In the remaining 97 seizures without ictal FA, 27 (28%) were ECSz and 70 (72%) ESz. There was a significant correlation ( p =0.0006) between ictal FA and electroclinical seizures. There was no relationship between phenobarbitone and presence of ictal FA. There was no significant difference in the background EEG, neuroimaging abnormalities, neurodevelopmental impairment or post neonatal seizures between those with and without ictal FA. Conclusions Ictal FA is highly correlated to the occurrence of clinical features during an EEG seizure. The presence of ictal FA does not appear to influence neurodevelopmental outcomes.

We present a child with myoclonic seizures, epileptic spasms and generalized epileptiform discharges on scalp EEG. Magnetoencephalography and coherence-phase analysis for scalp EEG suggested focal onset in the left hemisphere. Intracranial video EEG confirmed seizure onset in the left frontal lobe with ictal high-frequency oscillations. Left frontal lobectomy suppressed his seizures. Subsets of myoclonic seizures can be focal in origin despite bilaterally synchronized epileptiform discharges on scalp EEG.

Summary Purpose To characterize very early onset symptomatic epilepsies electroclinically, to identify meaningful factors to delineate epilepsy syndromes under this category, and to test validity of the current syndromic organization of these epilepsies by the International League Against Epilepsy (ILAE). Methods Subjects were 38 epileptic patients with seizure onset before 3 months of age. We investigated the age of seizure onset, seizure types, myoclonus, EEG features, neuroimaging studies, outcome of seizures and development. We performed multiple correspondence analysis (MCA) to reveal associations among these characteristics and to find important characteristics to divide this epilepsy group into subgroups. Results Very early onset epilepsies were characterized by partial seizures and epileptic spasms, especially occurring in combination as a single ictal event (combined seizures), and poor outcome. Suppression-burst (SB), hypsarrhythmia, EEG asymmetry and structural brain abnormalities were common. MCA demonstrated that presence or absence of SB was the most meaningful factor to separate this group into subgroups. MCA on the subgroup with SB revealed a subset with early-onset spasms, partial seizures with single focus, no myoclonus, SB during wakefulness and sleep, no EEG asynchrony, hypsarrhythmia and combined seizures, and another subset with late-onset spasms, partial seizures with multiple foci, myoclonus, EEG asynchrony, no combined seizures, SB during sleep only, no EEG asymmetry, no structural abnormality and no hypsarrhythmia. These corresponded to Ohtahara syndrome and early myoclonic encephalopathy, respectively. Conclusions Very early onset symptomatic epilepsies have the electroclinical characteristics distinct from those with later onset. This study supported the current ILAE organization on this epilepsy group from statistic approach.

The purpose of this study is to clarify the usefulness and problems of the newly proposed classification of epilepsies (International League Against Epilepsy: ILAE, 2001) in the epidemiological studies of epilepsy. We previously conducted an epidemiological study in Okayama Prefecture, Japan, in 1999, using the ILAE 1989 classification. Among 250,997 children under 13 years of age, 2220 epileptic patients were ascertained. In this study, we reclassified them according to the ILAE 2001 classification, focusing on axes 2 (seizure types) and 3 (syndromes). We were able to classify 1803 (95.0%) seizure types out of 1899 with detailed clinical information. In focal seizures, the most common were secondarily generalized seizures (88.6%), which generally do not represent a unique anatomic substrate. In generalized seizures, topic-clonic seizures (40.7%) and spasms (21.0%) were the most common. We identified only 269 (12.1%) patients with specific epilepsy syndromes out of the 2220. We classified 1761 patients without specific syndromic diagnoses only by axis 2, but the new concept of epileptic seizure types, representing a unique pathophysiologic mechanism and anatomic substrate, was not very meaningful in most cases, even in those with focal seizures.