Focal cortical dysplasia is a malformation of cortical development, which is the 
most common cause of medically refractory epilepsy in the pediatric population 
and the second/third most common etiology of medically intractable seizures in 
adults.Both genetic and acquired factors are involved in the pathogenesis of 
cortical dysplasia. Numerous classifications of the complex structural 
abnormalities of focal cortical dysplasia have been proposed - from Taylor et 
al. in 1971 to the last modification of Palmini classification made by Blumcke 
in 2011. In general, three types of cortical dysplasia are recognized.Type I 
focal cortical dysplasia with mild symptomatic expression and late onset, is 
more often seen in adults, with changes present in the temporal lobe.Clinical 
symptoms are more severe in type II of cortical dysplasia usually seen in 
children. In this type, more extensive changes occur outside the temporal lobe 
with predilection for the frontal lobes.New type III is one of the above 
dysplasias with associated another principal lesion as hippocampal sclerosis, 
tumor, vascular malformation or acquired pathology during early life.Brain MRI 
imaging shows abnormalities in the majority of type II dysplasias and in only 
some of type I cortical dysplasias.THE MOST COMMON FINDINGS ON MRI IMAGING 
INCLUDE: focal cortical thickening or thinning, areas of focal brain atrophy, 
blurring of the gray-white junction, increased signal on T2- and FLAIR-weighted 
images in the gray and subcortical white matter often tapering toward the 
ventricle. On the basis of the MRI findings, it is possible to differentiate 
between type I and type II cortical dysplasia. A complete resection of the 
epileptogenic zone is required for seizure-free life. MRI imaging is very 
helpful to identify those patients who are likely to benefit from surgical 
treatment in a group of patients with drug-resistant epilepsy.However, in type I 
cortical dysplasia, MR imaging is often normal, and also in both types the 
lesion seen on MRI may be smaller than the seizure-generating region seen in the 
EEG. The abnormalities may also involve vital for life brain parts, where 
curative surgery will not be an option. Therefore, other diagnostic imaging 
techniques such as FDG PET, MEG, DTI and intra-cranial EEG are widely used to 
establish the diagnosis and to decide on management.With advances in both 
genetics and neuroimaging, we may develop a better understanding of patients 
with drug-resistant epilepsy, which will help us to provide more successful 
pharmacological and/or surgical treatment in the future.