Focal cortical dysplasia

Focal cortical dysplasia is a congenital abnormality of brain development in which neurons in one area of the brain fail to migrate into their proper formation before birth. The word focal means the disorganized zone is limited to a region of one lobe. It is a common cause of intractable epilepsy in children and a frequent cause of epilepsy in adults. The condition is grouped into three types with subtypes: type 1 shows subtle changes in the layering of the cortex, type 2 shows enlarged dysmorphic neurons and, in type 2b, balloon cells with complete loss of layered structure, and type 3 is cortical disorganization that accompanies another lesion such as hippocampal sclerosis, a tumor, a vascular malformation or scarring. Types 2a and 2b result from somatic mutations in genes of the mTOR pathway, while no causative genes are known for types 1 and 3. Seizures are treated with medication, and surgery to remove the affected area is an option for suitable candidates.