From cryogenic to on-scalp magnetoencephalography for the evaluation of paediatric epilepsy

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Miller Fisher syndrome associated with respiratory failure

Miller Fischer syndrome (MFS) is a rare clinical variant of GuillainBarre syndrome. The diagnosis suspected primarily on clinical trial of areflexia, ophtalmoplegia and ataxia, is confirmed by the mandatory presence of antiganglioside antibodies (anti GQ1b). An acute onset is typical of MFS, beginning with neurological symptoms following a respiratory or digestive infectious illness. The therapeutic options are either the plasmapheresis or the administration of intravenous immunoglobulin (IVIG). Although rare, in certain cases the patients present with respiratory symptoms needing intensive care. We report the case report of a patient which presented with the classical triad of MFS but also with rapid progressive respiratory failure due to bilateral vocal cords palsy and general muscle weakness. He needed respiratory mechanical support. The patient received a treatment by IVIG without any improvement in symptomatology. Eventually he completely recovered and he was discharged from the hospital 3 month later

Where do we stand exactly with on-scalp magnetoencephalography in the presurgical evaluation of refractory focal epilepsy?

SCOPUS: le.jinfo:eu-repo/semantics/publishe

On-scalp magnetoencephalography for the diagnostic evaluation of epilepsy during infancy

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Diagnostic and therapeutic approaches in refractory insular epilepsy

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On-Scalp Optically Pumped Magnetometers versus Cryogenic Magnetoencephalography for Diagnostic Evaluation of Epilepsy in School-aged Children

Background Magnetoencephalography (MEG) is an established method used to detect and localize focal interictal epileptiform discharges (IEDs). Current MEG systems house hundreds of cryogenic sensors in a rigid, one-size-fits-all helmet, which results in several limitations, particularly in children. Purpose To determine if on-scalp MEG based on optically pumped magnetometers (OPMs) alleviates the main limitations of cryogenic MEG. Materials and Methods In this prospective single-center study conducted in a tertiary university teaching hospital, participants underwent cryogenic (102 magnetometers, 204 planar gradiometers) and on-scalp (32 OPMs) MEG. The two modalities for the detection and localization of IEDs were compared. The t test was used to compare IED amplitude and signal-to-noise ratio (SNR). Distributed source modeling was performed on OPM-based and cryogenic MEG data. Results Five children (median age, 9.4 years [range, 5-11 years]; four girls) with self-limited idiopathic (n = 3) or refractory (n = 2) focal epilepsy were included. IEDs were identified in all five children with comparable sensor topographies for both MEG devices. IED amplitudes were 2.3 (7.2 of 3.1) to 4.6 (3.2 of 0.7) times higher (P < .001) with on-scalp MEG, and the SNR was 27% (16.7 of 13.2) to 60% (12.8 of 8.0) higher (P value range: .001-.009) with on-scalp MEG in all but one participant (P = .93), whose head movements created pronounced motion artifacts. The neural source of averaged IEDs was located at approximately 5 mm (n = 3) or higher (8.3 mm, n = 1; 15.6 mm, n = 1) between on-scalp and cryogenic MEG. Conclusion Despite the limited number of sensors and scalp coverage, on-scalp magnetoencephalography (MEG) based on optically pumped magnetometers helped detect interictal epileptiform discharges in school-aged children with epilepsy with a higher amplitude, higher signal-to-noise ratio, and similar localization value compared with conventional cryogenic MEG. Online supplemental material is available for this article. © RSNA, 2022 See also the editorial by Widjaja in this issue

On-Scalp Magnetoencephalography Based On Optically Pumped Magnetometers Can Detect Mesial Temporal Lobe Epileptiform Discharges.

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Ictal EEG source imaging and connectivity to localize the seizure onset zone in extratemporal lobe epilepsy

Purpose To evaluate the yield of Functional Connectivity (FC) in addition to low-density ictal Electrical Source Imaging (ESI) in extratemporal lobe epilepsy (ETLE), using an automated algorithm for analysis. Method Long-term EEG monitoring of consecutive ETLE patients who underwent surgery was reviewed by epileptologists, and seizure onsets characterized by rhythmical activity were identified. A spectrogram-based algorithm was developed to select objectively the parameters of ESI analysis. Two methods for SOZ localization were compared: i) ESI power, based on LORETA exclusively; ii) ESI + FC, including a Granger causality-based connectivity analysis. Results were determined at a sublobar level. The resection zone, in relation to 1-year follow-up surgical outcome, was considered as reference standard for diagnostic accuracy analyses. Results Ninety-four seizures from 24 patients were analyzed. At seizure-level, ESI power showed 36 % sensitivity and 72 % specificity (accuracy: 45 %). ESI + FC significantly improved the accuracy, with 52 % sensitivity and 84 % specificity (accuracy: 61 %, p = 0.04). Results of ESI + FC were equally valuable in patients with lateralized or bilateral/generalized visual interpretation of ictal EEG. In a patient level sub-analysis, upon blinded clinical interpretation, ESI + FC showed a correct localization in 67 % of patients and substantial inter-rater agreement (kappa = 0.64), against 27 % achieved by ESI power, with fair inter-rater agreement (kappa = 0.37). Conclusion FC significantly improves SOZ localization compared to ESI solely in ETLE. Ictal ESI + FC could represent a novel option in the armamentarium of presurgical evaluation, aiding also in patients with visually non-localizable scalp ictal EEG. Prospective studies evaluating the clinical added value of automated low-density ictal ESI may be justified

Ictal EEG source imaging and connectivity to localize the seizure onset zone in extratemporal lobe epilepsy

Purpose To determine the diagnostic accuracy of ictal Electrical source imaging (ESI) and subsequent Functional connectivity (FC) to localize the seizure onset zone from classical 19-21 electrodes scalp EEG, in a cohort of extratemporal lobe epilepsy (ETLE) patients. Methods STARD guidelines were adopted for reporting the present study. The epilepsy surgical database of St.Luc Hospital, Brussels, Belgium was retrospectively screened for consecutive patients with: (1) resective surgery for ETLE (2) availability of structural MRI and scalp EEG monitoring (3) 1-year follow-up available. The epileptologist marked seizure onsets characterized by: (1) rhythmical discharges in the delta, theta or alpha band (2) rhythmical spiking activity, (3) fast paroxysmal low voltage activity. Spasms and seizures presenting a non-rhythmic or electrodecremental pattern were excluded. We developed a semi-automated analysis of rhythmic ictal EEG. First, a spectrogram-based algorithm was applied to automatically select the epoch length and the frequency of interest. For ESI power method, we considered as SOZ the source with the highest power (SPOW). For ESI+FC, we used the source with the highest out-degree (SCONN) based on Granger causality FC analysis. Sublobar concordance was determined between SPOW, SCONN and the resection zone, used as reference standard, and diagnostic accuracy was evaluated based on surgical outcome. Results We could analyze 98 seizures from 25 patients. At a seizure level, the overall accuracy was 42% for ESI power (C.I. 17-53%) and 66% for ESI+FC (C.I. 54-78%), at p = 0,0042 (chi-square test). Sensitivity was 36% for ESI power and 54% for ESI+FC. Test specificity was 57% for ESI power and 86% for ESI+FC. Positive predictive value reached 90,2% for ESI+FC. Conclusion Ictal FC analysis may be a valuable tool in the pre-surgical evaluation of ETLE cases. FC significantly improves SOZ localization compared to ESI solely, and is readily applicable on a classic 19-21 channel EEG