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Refractory convulsive status epilepticus in infancy and childhood is a rare emergency situation. Metabolic disorders frequently underlie this condition, in particular Alpers' disease caused by POLG1 mutations. Status epilepticus may be the first symptom. A pathognomonic electroencephalography (EEG) signature may facilitate diagnosis of Alpers' disease and allow timely avoidance of valproic acid, which is contraindicated in this disorder because it may trigger fatal liver failure. We present five patients with Alpers' disease caused by mutations in POLG1. Age of onset ranged from 7 months to 10 years. Three of the five children died after 3 to 12 months after onset of status epilepticus. Two of these had liver failure associated with use of valproic acid; liver transplantation in one child did not prevent a fatal neurologic outcome. Convulsive status epilepticus was the first obvious sign of Alpers' disease in all children. All had focal clonic and complex-focal seizures; four of them developed epilepsia partialis continua. In four children, initial EEG showed unilateral occipital rhythmic high-amplitude delta with superimposed (poly)spikes (RHADS). Magnetic resonance imaging (MRI) revealed cortical and thalamic involvement in all, although there were only discrete abnormalities in one child. Metabolic investigations remained normal in three children. Alpers' disease is an important differential diagnosis in childhood refractory convulsive status epilepticus. Its EEG hallmark of RHADS is important for timely diagnosis, management, and counseling. [ABSTRACT FROM AUTHOR]

Purpose: Simultaneous interictal EEG and magnetoencephalography (MEG) recordings were used for noninvasive analysis of epileptogenicity in focal cortical dysplasia (FCD). The results of two different approach methods (multiple source analysis of averaged spikes and single dipole peak localization of single spikes) were compared with pre- and postoperative anatomic magnetic resonance imaging (MRI). Patients: We studied nine children and adolescents (age, 3.5–15.9 years) with localization-related epilepsy and FCD diagnosis based on MRI. Five patients underwent epilepsy surgery, two of them after long-term recording with subdural grid electrodes, and one after intraoperative electrocorticography. Methods: The 122-channel whole-head MEGs and 33-channel EEGs were recorded simultaneously for 25 to 40 min. Interictal spikes were identified visually and used as templates to search for similar spatiotemporal spike patterns throughout the recording. With the BESA program, similar spikes ( r > 0.85) were detected, averaged, high-pass filtered (5 Hz) to enhance spike onset, and subjected to multiple spatiotemporal source analysis with a multishell spherical head model. Peak activity from single spikes was modeled by single dipoles for the same subset of spikes. Source localization was visualized by superposition on T1-weighted MRI and compared with the lesion identified in T1- and T2-weighted MRI. In the five cases undergoing epilepsy surgery, the results were correlated with invasive recordings, postoperative MRI, and outcome. Results: In all cases, the analysis of averaged spikes showed a localization of onset- and peak-related sources within the visible lesion for both EEG and MEG. Of the single spikes, 128 (45%; total 284) were localizable at the peak in MEG, and 170 (60%) in EEG. Of these, 91% localized within the lesion with MEG, and 93.5% with EEG. In three of five patients operated on, the resected area included the onset zones of averaged EEG and MEG spike activity. These patients had excellent postoperative outcome, whereas the others did not become seizure free. Conclusions: Consistent MEG and EEG spike localization in the lesional zone confirmed the hypothesis of intrinsic epileptogenicity in FCD. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: Multiple source analysis of interictal EEG and MEG spikes was used to identify irritative zones in polymicrogyria (PMG). Spike onset times and source localization were compared between both modalities. PMG is characterized by a marked loss of deep cortical fissures. Hence, differences between EEG and MEG were expected since MEG signals are predominantly generated from tangentially orientated neurons in fissures. Patients: We studied 7 children and young adults (age 7.5 to 19 years) with localization-related epilepsy and unilateral polymicrogyria (PMG) as defined from anatomical MRI. Methods: 122-channel whole-head MEG and 32-channel EEG were recorded simultaneously for 25 to 40 min. Using the BESA program, interictal spikes were identified visually and used as templates to search for similar spatio-temporal spike patterns throughout the recording. Detected similar spikes (r > 0.85) were averaged, high-pass filtered (5 Hz) to enhance spike onset, and subjected to multiple spatio-temporal source analysis. Source localization was visualized by superposition on T1-weighted MRI and compared to the lesion. Results: Nine spike types were identified in seven patients (2 types in 2 patients). Eight out of nine EEG sources and seven MEG sources modeling spike onset were localized within the visible lesion. EEG spike onset preceded MEG significantly in two spike types by 19 and 25 ms. This was related to radial onset activity in EEG while MEG localized propagated activity. In one case, the earliest MEG spike activity was localized to the normal hemisphere while the preceding radial EEG onset activity was localized within the lesion. Distances between EEG and MEG onset sources varied markedly between 9 and 51 mm in the eight spike types with concordant lateralization. Conclusion: Interictal irritative zones were localized within the lesion in PMG comparable to other malformations, e.g., FCD. Discrepancies in MEG and EEG were related to the lack of deep fissures in PMG. In two cases, MEG was blind to the onset of radial interictal spike activity and localized propagated spike activity. In two other cases, MEG localized to the more peripheral parts of the irritative zone. Simultaneous EEG recordings with MEG and multiple source analysis are required to avoid problems of MEG interpretation. [Copyright &y& Elsevier]