Initial negative imaging in GATOR1-associated genetic epilepsy does not preclude the existence of a focal, resectable epileptogenic zone: illustrative cases.

backgroundFamilial focal epilepsy with variable foci (FFEVF) is a genetic epilepsy disorder in which affected family members experience different focal seizures. Focal cortical dysplasia (FCD) is a frequent cause of drug-resistant epilepsy in the pediatric population. Patients with focal epilepsy are less frequently referred for presurgical evaluation when FCD is not identified on MRI or when they have genetic epilepsy. The authors describe the successful surgical management of 3 drug-resistant FFEVF patients who initially had either negative or inconclusive MRI studies. OBSERVATIONS: All 3 patients carried the same germline pathogenic variant in NPRL3, a GATOR1 complex gene. In patient 1, an ill-defined signal abnormality on MRI raised the suspicion for FCD and suggested that similar occult lesions might underlie the epilepsy of her relatives, whose scan results were initially reported as negative. Each patient was thus referred for comprehensive presurgical evaluation. Through the use of advanced neuroimaging, epileptogenic zones were identified in all 3 patients, allowing for targeted resection. At the last follow-up, all had remained seizure free for more than 5 years. LESSONS: When a genetic alteration is associated with FCD, such patients warrant imaging reexamination and exhaustive presurgical evaluation with advanced neuroimaging, as eventual lesion detection and subsequent resection can lead to long-term seizure freedom. https://thejns.org/doi/10.3171/CASE26127.