Cortical dysplasia is a malformation of the cerebral cortex due to a congenital disorder where the neurons in a region of the cerebrum did not migrate in the proper cortical order during development of the embryo and fetus. Put it in other words, cortical dysplasia occurs when developing brain cells (neurons) in an embryo or fetus fail to reach the parts of the brain's cortex for which they are genetically destined. As a result, those areas of the cortex lack the appropriate synaptic connections between nerve cells to function properly. The affected cortical areas can be small and defined or can include an entire brain hemisphere.
Cortical dysplasia can lead to seizures and developmental retardation. During the embryological stage, sometimes nerve cells develop into larger than normal in certain areas, causing the neuronal electrochemical signals to misfire. The normal cortex has a very specific and complex architecture with 6 primary layers of neurons. In some children this process of development does not occur properly in some parts of the brain. As a result the cortex in that area develops abnormally, often without the normal layers, architecture and connections that are required for the normal functioning of the brain.
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. Neurosurgery can range from removing an entire hemisphere (hemispherectomy), a small lesionectemy, or multiple transections to try and disconnect the abnormal tissue from the rest of the brain (multiple subpial transections). Physical therapy should be considered for infants and children with muscle weakness.