Interictal pattern on scalp electroencephalogram predicts excellent surgical outcome of epilepsy caused by focal cortical dysplasia

Abstract

Objective Focal cortical dysplasia (FCD) represents an essential cause of drug‐resistant epilepsy with surgery as an effective treatment option. This study aimed to identify the important predictors of favorable surgical outcomes and the impact of the interictal scalp electroencephalogram (EEG) patterns in predicting postsurgical seizure outcomes. Methods We retrospectively evaluated 210 consecutive patients between 2015 and 2019. They were diagnosed with FCD by pathology, underwent resection, and had at least one year of postsurgical follow‐up. Predictors of seizure freedom were analyzed. Results Based on the information at the latest follow‐up, seizure outcome was classified as Engel Class I (seizure‐free) in 81.4% and Engel Class II‐IV (non‐seizure‐free) in 18.6% of patients. There were 43, 105, and 62 cases of FCD type I, type II, and type III, respectively. The interictal EEG showed a repetitive discharge pattern (REDP) in 87 (41.4%) patients, polyspike discharge pattern (PDP) in 41 (19.5%), and the coexistence of REDP and PDP in the same location in 32 (15.2%) patients. The analyzed patterns in order of frequency were repetitive discharges lasting 5 seconds or more (32.4%); polyspikes (16.7%); RED type 1 (11.4%); continuous epileptiform discharges occupying >80% of the recording (11.4%); RED type 2 (6.2%); brushes (3.3%); focal, fast, continuous spikes (2.4%); focal fast rhythmic epileptiform discharges (1.43%); and frequent rhythmic bursting epileptiform activity (1.4%). The coexistence of REDP and PDP in the same location on scalp EEG and complete resection of the assumed epileptogenic zone (EZ) was independently associated with favorable postsurgical prognosis. Significance Resective epilepsy surgery for intractable epilepsy caused by FCD has favorable outcomes. Interictal scalp EEG patterns were revealed to be predictive of excellent surgical outcomes and may help clinical decision‐making and enable better presurgical evaluation.

Analysis of clinical characteristics and histopathological transcription in 40 patients afflicted by epilepsy stemming from focal cortical dysplasia

“…Scalp EEG patterns in patients with FCD are characterized by low‐amplitude fast activity, spike or sharp wave activity, and slow wave activity 23,24 . These findings align with our current study, which examined 10 patients with bottom‐of‐sulcus FCD experiencing stereotypical seizures.…”

Association of Lateralized Interictal Epileptiform Discharges with Postsurgical Seizure Outcomes in Patients with Tuberous Sclerosis Complex: A 10-Year Retrospective Study at a Single Center

“…Ictal scalp video-EEG and intracranial video-EEG can be used to localize the epileptic foci and predict the prognosis of resective epilepsy surgery, and interictal EEG is usually used to define the irritation zone [16,[18][19][20]. Previous study highlighted the value of scalp video-EEG, particularly interictal EEG, in predicting the surgical outcome of epilepsy patients, and the present study supported this conclusion [12,21,22]. Our study showed that IEDs were associated with postsurgical seizure outcomes, and patients with lateralized IEDs had better surgical effects at the 10-year follow-up than patients with focal, multifocal, and generalized epileptic discharges.…”

Lesion volume and spike frequency on EEG impact perfusion values in focal cortical dysplasia: a pediatric arterial spin labeling study

“…Thus, voxel-wise approaches of AI calculation highlighting perfusion asymmetries between the hemispheres have been increasingly implemented in the latest ASL studies 25 , 31 to obtain observer-independent results and increase confidence in image reporting. The recent observation that specific interictal spike patterns in presurgical EEG are predictive of postsurgical seizure freedom in FCD-associated epilepsy 51 , gives additional weight to the link between ASL and interictal spikes substantiated for the first time in our study, pointing to exciting avenues of ASL application beyond the obvious benefits for image reporting and lesion detection.…”