Abstracts

Rationale: Focal cortical dysplasia (FCD) is one of the most frequent causes of drug resistant epilepsy, especially in children. The detection of FCD in the first year of life is challenging because the brain MRI may fail to show a lesion due to evolving maturation-related imaging changes. Some studies have suggested that the FCD location/extension in this age group may be associated with age of seizure onset. If true, such a relationship may provide a helpful clinical tool to guide with epilepsy localization. The objective of this study is to explore in detail the relationship between FCD localization and age at onset in a well-characterized patient cohort.Methods: We retrospectively reviewed 49 patients aged under 18 years old who underwent epilepsy surgery and had a pathological diagnosis of isolated FCD at our institution from 2006 to 2014. Clinical characteristics, FCD location and extension and seizure outcome were evaluated. FCD location/extension and age of seizure onset were analyzed, as were age of onset and seizure types.Results: Twenty-six of 49 (53%) patients were male. Mean age at onset was 7.4 months. Mean age at surgery was 58.1 months. Forty-three percent of patients were FCD type 2b according to ILAE classification. Twenty-seven children had focal seizures, 12 had infantile spasm (IS) and eight had generalized seizures. Neuroimaging was normal in four patients, showed a unilateral lobar lesion in 29 patients, unilateral multi-lobar in 12 patients and bilateral lobar in four patients. Surgical resection was frontal lobe plus [frontal lobe (FL), frontotemporal (FT), frontoparietal (FP), frontoinsular (FI), or frontotemporoparietal (FTP)] in 26 patients, occipital lobe plus [occipital lobe (OL), temporoparietooccipital (TPO), parietooccipital (PO), or temporooccipital (TO)] in 16 and temporal lobe plus [temporal lobe (TL), parietal lobe (PL) or temporoparietal (TP)] in seven. Twenty-eight of 49 (58.3%) patients were seizure free at one year, 48% were remained seizure free after three years. There was a gradient towards an increasing mean age of seizure onset between these various regions: (4.0 months old with occipital plus vs. 8.6 months with frontal plus vs.10.9 months with the temporal lobe plus group(p=0.05). The age of onset of patients with multi-lobar FCD was 5.0 months versus 9.5 months for lobar FCD (p=0.03)Conclusions: Our study showed that the age of seizure onset in patients with FCD can predict the FCD location and extension with earlier onset for children with posterior quadrant FCD and more extensive lesions. Seizure outcome in this group of patients was similar to the one described for patients with FCD.