Abstracts

Rationale: Structural brain abnormalities in epileptic patients (epileptogenic lesion) carry higher risk of becoming drug resistant and are more suitable candidates for epilepsy surgery. Epileptogenic lesions in the pediatric brain carry negative outcomes for seizure control and neuro-development. The most common challenges in children are age-dependent visualization of the MRI lesion and the variability of the video EEG (vEEG) and semiological features related to brain maturation.  Significant gaps still exist identifying clinical, EEG, and radiological features that will predict poor outcomes in children with lesional DR. The aim of our study is to describe the most common brain MRI lesions and vEEG features found in children with DRE and their relationship with the seizure onset.   Methods: A total of 91 children with drug-resistant epilepsy are followed in the comprehensive epilepsy clinic at Children’s Hospital/ LHSC. Among those we retrospectively identified 51 (56 %) with brain MRI lesions.  A board certified pediatric neuroradiologist (MJ) reviewed their brain MRIs describing lesion type, location, and extension. We defined discrete lesions as the ones confined within one lobe versus extensive ones, when more than one lobe was involved. We defined early seizure onset as one year or younger versus late onset as older than 1 year.  Available vEEG recording were also reviewed to identify topographic concordance between the lesions, EEG features, and seizure semiology.   Results: From the 51 children, 29 were males (56.8%), the age at seizure onset ranged from 0 to 15 years (median 2). Twenty-one children (41.1%) had MCD with seizure onset from 0 to 12 years (median 3).  Nine (17.6%) had vascular lesions with seizure onset from 0 to 5 years (median 0.5 years).  Six children (11.7%) had neurocutaneous syndromes (tuberous sclerosis and Sturge Weber) with seizure of onset from 0.16 to 8 (median 3 years). Four children (7.8%) had neoplastic lesions with seizure onset from 7 to 15 years (median 7), and 11 (21.5%) children had other lesion types (including post-infectious, mesial temporal sclerosis) with seizure onset from 0 to 11 years (median 1.8). In terms of localization/extension of the lesion, 22 (43.1%) had discrete lesion vs. 29 (56.8%) who had extensive lesions.  Early seizure onset is more frequent in those with extensive lesions (29.4%) vs. those with discrete lesions (7.8%) (p=0.014). From 51 patients, 48 had vEEG available as part of their clinical work up. Interictal EEG was concordant in 21/48 (43.7%), Ictal EEG in 10/48 (20.8%), seizure semiology 21/48 (43.7%).  Conclusions: Malformations of cortical development are the most common brain lesion in children with DRE. Extensive lesions are associated with an early seizure onset. Poor concordance between vEEG findings and MRI lesions in children with DRE makes the surgical evaluation process more challenging compared to adults, requiring more advanced testing and invasive monitoring strategies to localize the epileptogenic zone.   Funding: No funding