KCNQ2 mutations cause approximately 13% of unexplained NEE. Patients present with a wide spectrum of severity and, although rare, infantile epilepsy onset is possible.
Focal cortical dysplasia (FCD) causes drug‐resistant epilepsy and is associated with pathogenic variants in mTOR pathway genes. How germline variants cause these focal lesions is unclear, however a germline + somatic “2‐hit” model is hypothesized. In a boy with drug‐resistant epilepsy, FCD, and a germline DEPDC5 pathogenic variant, we show that a second‐hit DEPDC5 variant is limited to dysmorphic neurons, and the somatic mutation load correlates with both dysmorphic neuron density and the epileptogenic zone. These findings provide new insights into the molecular and cellular correlates of FCD determining drug‐resistant epilepsy and refine conceptualization of the epileptogenic zone.
Objective:To determine if one-stage, limited corticectomy controls seizures in patients with MRI-positive, bottom-of-sulcus dysplasia (BOSD).Methods:We reviewed clinical, neuroimaging, electrocorticography (ECoG), operative and histopathology findings in consecutively operated patients with drug-resistant focal epilepsy and MRI-positive BOSD, all of whom underwent corticectomy guided by MRI and ECoG.Results:38 patients with median age at surgery of 10.2 (IQR: 6.0-14.1) years were included. BOSDs involved eloquent cortex in 15 patients. 87% of patients had rhythmic spiking on pre-resection ECoG. Rhythmic spiking was present in 22/24 patients studied with combined depth and surface electrodes, being limited to the dysplastic sulcus in 7 and involving the dysplastic sulcus and gyral crown in 15. 68% of resections were limited to the dysplastic sulcus, leaving the gyral crown. Histopathology was FCDIIb in 29 patients and FCDIIa in 9. Dysmorphic neurons were present in the bottom of the sulcus but not the top or the gyral crown in 17/22 patients. Six (16%) patients required reoperation for postoperative seizures and residual dysplasia; reoperation was not correlated with ECoG, neuroimaging or histological abnormalities in the gyral crown. At median 6.3 (IQR: 4.8-9.9) years follow-up, 33 (87%) patients are seizure-free, 31 off antiseizure medication.Conclusion:BOSD can be safely and effectively resected with MRI and ECoG guidance, corticectomy potentially being limited to the dysplastic sulcus, without need for intracranial EEG monitoring and functional mapping.Classification of Evidence:This study provides Class IV evidence that one-stage, limited corticectomy for BOSD is safe and effective for control of seizures.
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