Preoperative clinical, neuropsychological, EEG, and imaging features and surgical outcomes of focal cortical dysplasias (FCD) types I and II were compared in 40 children with refractory epilepsy and histopathologically confirmed FCD subtypes, in a study at Charles University, Prague, Czech Republic and centers in Germany. FCD type I was identified in 24 and FCD type II in 16 patients. Seizure types were secondarily generalized tonic-clonic in 54% of FCDI and 37% FCDII; and infantile spasms in 21% of FCDI and 12% FCDII patients. Status epilepticus occurred in 4% of FCDI and 12% of FCDII patients. Multilobar involvement was found in 92% patients with FCDI and in 50% of FCDII patients. FCD type I MRI findings include white matter signal changes on T2 images and/or FLAIR, and reduction of white matter volume. FCD type II MRI showed increased cortical thickness, transmantle sign, gray-white matter junction blurring, fluid-attenuated inversion recovery (FLAIR) and proton density (PD) gray and white matter signal changes. Hippocampal atrophy occurred in only 1 patient of each type. Patients with FCD type I showed EEG continuous slowing more commonly; they had lower IQ levels and more behavioral disorders. Postsurgical seizure freedom occurred in 21% FCD type I and in 75% FCD type II patients (P<0.001). 
COMMENT. FCD is reported in up to 25% of surgical patients with intractable epilepsy and 5-10% of epilepsies. FCD Ia and Ib, and FCD IIa and IIb are classified histopathologically. Type IIa is distinguished by dysmorphic, and IIb by balloon cells. FCD type I patients present within the first year of life, and have multilobar involvement, high seizure frequency, more complications, and a worse prognosis than FCD type II patients. FCDI is more frequently associated with mental retardation and behavioral disorders, more difficult to localize by EEG and MRI, and has less favorable surgical outcome. The authors consider surgery except for hemispherectomy is frequently palliative in FCDI cases. FCD type I should be considered a distinct entity.