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Author Spotlight: Advancing Pediatric Epilepsy Surgery in Children Through Novel Biomarkers and Enhanced Localization
Published on: September 20, 2024
Magnetoencephalographic Characteristics of Cortical Dysplasia in Children
Nitin Agarwal1, Balu Krishnan2, Richard C Burgess2
1Epilepsy Center, Cleveland Clinic, Cleveland, Ohio; Division of Pediatric Epilepsy, Minnesota Epilepsy Group, P.A., St. Paul, Minnesota; Department of Pediatric Neurology, Children's Hospitals and Clinics of Minnesota, St. Paul, Minnesota.
Insights
Magnetoencephalography (MEG) aids in localizing epilepsy sources in children with focal cortical dysplasia. MEG findings, particularly spikes and clusters, differ across dysplasia subtypes, informing surgical planning for improved seizure outcomes.
Area of Science:
- Pediatric Neurology
- Epileptology
- Neuroimaging
Background:
- Magnetoencephalography (MEG) is increasingly utilized for preoperative evaluation in pediatric epilepsy cases.
- Focal cortical dysplasia (FCD) is a common cause of intractable epilepsy in children.
- Understanding MEG characteristics in FCD subtypes is crucial for surgical decision-making.
Purpose of the Study:
- To investigate magnetoencephalography (MEG) characteristics in different subtypes of focal cortical dysplasia (FCD) in children.
- To correlate MEG findings with postoperative seizure outcomes following epilepsy surgery.
- To assess the utility of MEG in localizing seizure onset zones in pediatric FCD.
Main Methods:
- Retrospective review of 33 pediatric patients (≤18 years) with FCD who underwent preoperative MEG and epilepsy surgery.
- Analysis of patient demographics, MRI, video electroencephalography, and MEG data.
- Categorization of postoperative seizure outcomes based on International League Against Epilepsy (ILAE) definitions.
Main Results:
- FCD types I, II, and III were diagnosed in 52%, 39%, and 9% of patients, respectively.
- Thirty patients (91%) showed positive MEG dipoles, with all FCD type II/III and 82% of FCD type I patients affected.
- Favorable postoperative seizure outcomes were achieved in 48% of patients who underwent resection of MEG dipoles.
Conclusions:
- Magnetoencephalography is valuable for localizing seizure onset in pediatric FCD, supplementing scalp EEG.
- MEG spikes and clusters are more prevalent in FCD types II and III compared to FCD type I.
- While MEG aids localization, factors like MRI lesions and resection completeness did not significantly impact seizure outcome in this cohort, possibly due to patient selection bias.
Background And Rationale:
Magnetoencephalography has emerged as a tool for preoperative evaluation in children. We studied magnetoencephalography characteristics in subtypes of focal cortical dysplasia and correlated the findings with postoperative seizure outcome.
Methods:
Inclusion criteria were children ≤18 years who underwent magnetoencephalography during the preoperative evaluation followed by epilepsy surgery and a histopathologic diagnosis of focal cortical dysplasia between February 2008 and February 2013. Patient demographics, MRI, video electroencephalography, and magnetoencephalography data were reviewed. Postoperative seizure outcome data were categorized per International League against Epilepsy definitions.
Results:
Of 178 magnetoencephalography studies performed in children during the study period, 33 patients met inclusion criteria. Focal cortical dysplasia type I, II, and III were found on histopathology in 52%, 39%, and 9% of patients, respectively. Thirty patients had positive magnetoencephalography dipoles, including all patients with focal cortical dysplasia type II and III and 82% of patients with focal cortical dysplasia type I. Three patients had magnetoencephalography unique spikes. Brain MRI lesions were noted preoperatively in 21 patients (64%). Twenty-three patients (77%) had surgical resection of magnetoencephalography dipoles and 11 (48%) of them achieved favorable outcome.
Conclusions:
Magnetoencephalography supplemented scalp electroencephalography data in spike source localization and showed unique spikes in 10% of the focal cortical dysplasia patients. Magnetoencephalography spikes and tight magnetoencephalography clusters were found more frequently in patients with focal cortical dysplasia type II and III as compared with focal cortical dysplasia type I. Presence of an MRI lesion and complete versus incomplete resection of magnetoencephalography cluster did not result in significant difference in postoperative seizure outcome, likely reflecting selection bias of doing magnetoencephalography in only difficult-to-localize epilepsies.
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