Objective:

To characterize the EEG patterns of type-1 and type-2 FCD with refractory epilepsy, correlate with clinic-radiological features and determine predictors of surgical outcome.

Background:

Focal cortical dysplasia (FCD) is the most common malformation of cortical development (MCD) causing drug refractory epilepsy(DRE) requiring surgical evaluation. Precise characterisation of the FCD and associated epileptogenic zone (EZ) with multimodal evaluation is crucial for surgical success

Design/Methods:

Retrospective analysis data of 188 consecutive patients with FCD operated for DRE and at least two years post-surgery follow-up was analyzed. The clinical features, MRI and interictal and ictal EEG patterns were studied for all patients

Results:

Average age of patients was 17.31±11.26 (2 – 64) years with 48.9% women. Interictal EEG showed regional pattern in 66% of FCD2 patients (p=0.04), while generalised interictal discharges were commonly associated with persistent seizures after surgery (p=0.016). Ictal beta rhythm was significantly associated with FCD2 (p=0.05). Generalised ictal onset was significantly seen in patients with persistent seizures after surgery (p=0.48). MRI showed clear cut FCD in 72.3% patients. At last follow-up 66.0% were seizure free. Patients with FCD type-1 had earlier age at onset (p=0.029) of epilepsy and had multiple seizure patterns (0.034). Patients with FCD type-2 commonly reported aura (p=0.019) and had clear-cut lesion on MRI (p=0.021) and high seizure freedom(p=0.004). Patients with FCD type-1 more often were detected on PET-MRI, underwent multilobar resections and had higher rate of acute postoperative seizures, while complete resection was more frequent in type-2 FCD

Conclusions:

FCD type-1 had early onset of seizures with multiple seizure semiologies, subtle MRI, multi-lobar resection and poor surgical outcome. FCD2 had clear-cut MRI lesion, regional inter-ictal discharges, ictal beta at onset with complete resection at surgery hence favorable post-surgical outcome