Multi-centre Epilepsy Lesion Detection (MELD) Project: Predictors of lesion location and postsurgical seizure freedom in focal cortical dysplasia

Background Drug-resistant focal epilepsy is often caused by focal cortical dysplasia (FCD). The impact of FCD location on clinical presentation and surgical outcome is largely unknown. We created a large neuroimaging cohort of patients with individually mapped FCDs to determine predictors of lesion location and postsurgical seizure freedom to aid presurgical decision-making. Methods The Multi-centre Epilepsy Lesion Detection (MELD) project collated a retrospective cohort of 580 patients with epilepsy due to FCD from 20 epilepsy centres worldwide. MRI-based maps of individual FCD lesions with accompanying demographic, clinical and surgical information were collected for each patient. We mapped the distribution of FCD lesions across the cerebral cortex and examined for associations between clinical factors and lesion location. Findings FCDs were non-uniformly distributed across the brain, concentrating in the superior frontal sulcus, frontal pole and temporal pole. Age of epilepsy onset was typically before age 10. Earlier epilepsy onset was associated with lesions in primary sensory areas while later epilepsy onset was associated with lesions in association cortices. Lesions in temporal and occipital lobes tended to be larger than frontal lobe lesions. Seizure freedom rates varied with FCD location, being around 30% in visual, motor and premotor areas to 75% in superior temporal and frontal gyri. These differences are likely attributable to reduced resection volumes due to neurosurgical caution around eloquent cortex. Interpretation The MELD project has gathered the largest neuroimaging cohort of patients with FCD to date. The location of the FCD is non-uniformly distributed across the cerebral cortex and is an important determinant of its size, the age of epilepsy onset and the likelihood of seizure freedom post-surgery. Using an open-science collaborative initiative, we have characterised the spatial distribution of a focal pathology to identify data-driven, patient-specific predictors of lesion location and postsurgical seizure freedom to inform clinical decision-making.