Background: Although surgical resection has been an important alternative treatment for patients with intractable epilepsy related to focal cortical dysplasia (FCD), the prognostic relevance of the degree of pathologic severity is controversial and there has been only limited information regarding the prognostic factors involved in the surgical treatment of refractory epilepsy in patients with FCD.

Methods: We undertook the present study to assess whether the pathologic subtypes of FCD affect surgical outcomes in patients with drug-resistant epilepsy. We also studied the prognostic roles of clinical factors and various diagnostic modalities in the surgical treatment.

Results: A total of 166 consecutive patients were included. By univariate analysis, incomplete resection of epileptogenic area (p < 0.001), mild pathologic features (p = 0.01), and the presence of secondary tonic clonic seizures (2GTCS) (p = 0.05) were associated with poor surgical outcomes. There was a strong tendency for patients with severe pathologic features to have MRI abnormalities (p < 0.001). Incomplete resection of epileptogenic area (p < 0.001) and mild pathologic features (p = 0.02) were poor independent outcome predictors on multivariate analysis. The results of MRI, scalp EEG, fluorodeoxyglucose–PET, and ictal SPECT were not associated with surgical outcomes.

Conclusions: Our study shows that there is a strong tendency for patients with severe pathologic features to have MRI abnormalities, and patients with incomplete resection, mild pathologic features, or the presence of secondary tonic clonic seizures have a high chance of a poorer surgical outcome.