Abstracts

Rationale: Though relatively rare, genetic causes of epilepsy such as channelopathies can co-exist with structural epileptogenic lesions. Mutations in SCN1A encoding the sodium channel alpha 1 subunit have been associated with a broad spectrum of disease severity ranging from GEFS+ to Dravet syndrome. Neuroimaging in children with SCN1A mutations is typically normal or shows non-specific abnormalities. However, several patients have been reported with co-existing SCN1A mutations and structural epileptogenic lesions including focal cortical dysplasia (FCD). In past reports, these patients have not responded well to resective epilepsy surgery of the lesion. We present a child with SCN1A mutation and FCD who had significant improvement in seizure control with resection of the lesion. Methods: We retrospectively reviewed the history of a seven-year-old boy with Dravet syndrome due to pathological SCN1A mutation (variant L221P) and FCD. He initially presented at six months of age with prolonged generalized convulsions in the setting of fever. His first afebrile seizure occurred at 18 months of age. At approximately five years of age he developed focal motor seizures consisting of right head and eye deviation with rhythmic eye blinking. MRI revealed a FCD approximately 1 cm in size in the left posterior medial part of the superior frontal gyrus anterior to the pre central sulcus (Figure 1). Results: A non-invasive presurgical evaluation was undertaken and four focal seizures were recorded on long term video EEG telemetry, all arising from the left frontal region. A PET scan and source localization were concordant with the MRI lesion. Due to ongoing seizures resistant to multiple antiepileptic medications and poor tolerance to other medications he underwent surgical resection with intra-operative functional mapping and electrocorticography. Post-operatively he had transient right hemiparesis but later recovered his pre-operative function. He had a single breakthrough seizure in the setting of high fever and lower antiepileptic medication level while at rehabilitation. Overall he has had a dramatic reduction in seizure burden after surgery. Conclusions: To our knowledge, this is the first report of good seizure outcome with resection of a focal epileptogenic lesion in patients with SCN1A mutation. Traditionally, genetic epilepsy has been considered as a relative contraindication to focal resective epilepsy surgery. Given the continued risk of breakthrough seizures in genetic epilepsies, focal resective surgery is considered as a palliative option. However, our case suggests that when clinical, neuroimaging, and electrographic data are concordant with an epileptogenic lesion, focal resection can offer improvement in seizure control in patients with genetic epilepsies. Conversely, an effective treatment for the genetic epilepsy may not be sufficient when there is a con-existing focal epileptogenic lesion, and additional treatment such as resection of the epileptic foci may be necessary to improve seizure control. Funding: None