|Classification and external resources|
Cortical dysplasia is a congenital abnormality where the neurons in an area of the brain failed to migrate in the proper formation in utero. Occasionally neurons will develop that are larger than normal in certain areas. This causes the signals sent through the neurons in these areas to misfire, which sends an incorrect signal. It is commonly found near the cerebral cortex and is associated with seizures. Medication is used to treat the seizures that may arise due to cortical dysplasia. Increasingly, surgery has become a viable treatment option for appropriate candidates.
Focal cortical dysplasia is a common cause of intractable epilepsy in children and is a frequent cause of epilepsy in adults. All forms of focal cortical dysplasia lead to disorganization of the normal structure of the cerebral cortex. Focal cortical dysplasia associated with enlarged cells is known as FCDIIB. The enlarged cells are called balloon cells for their large elliptical shape, displaced nucleus, and lack of dendrites or axons. The developmental origin of balloon cells is currently attributed to HPV16 infection, they are believed to be derived from neuronal or glial progenitor cells. Balloon cells are similar in structure to giant cells in the disorder tuberous sclerosis complex. Other large cells known as cytomegalic neurons or dysplastic neurons exhibit an enlarged cell body but clear axons and dendrites. It is widely hypothesized that balloon cells and dysplastic neurons contribute to seizures in patients with cortical dysplasia.
No specific treatment is required for cortical dysplasia, and all treatment is aimed at the resulting symptoms (typically seizures). When a cortical dysplasia is a cause of epilepsy, then seizure medications (anticonvulsants) are a first line treatment. If anticonvulsants fail to control seizure activity, neurosurgery may be an option to remove or disconnect the abnormal cells from the rest of the brain (depending on where the cortical dysplasia is located and the safety of the surgery relative to continued seizures). Neurosurgery can range from removing an entire hemisphere (hemispherectomy), a small lesionectomy, or multiple transsections to try to disconnect the abnormal tissue from the rest of the brain (multiple subpial transsections). Physical therapy should be considered for infants and children with muscle weakness. Educational therapy is often prescribed for those with developmental delays, but there is no complete treatment for the delays.