The corpus callosum is a band of tissue made up of around 300 million nerve fibers that transmit signals between the two hemispheres of the brain. It helps to share and integrate information processed by the brain, but in children with epilepsy, the corpus callosum allows the abnormal brain activity occurring in one hemisphere to travel and influence the other.
In generalized seizures, neurons fire in abnormal patterns and at elevated rates across both hemispheres of the brain. Because of the corpus callosum’s role in distributing activity between the two sides of brain, it often plays an active part in generalized seizures, particularly in cases where the child is experiencing seizures due to bilaterally synchronous brain discharges.
What Is a Corpus Callosotomy?
In order to reduce or eliminate seizures, the corpus callosum is either partially or completely severed. This stops most of the activity related to a child’s seizures from traveling between the two hemispheres and disrupts synchronous brain discharges.
Not all activity between cerebral hemispheres is stopped, even in a complete corpus callosotomy, though the activity is diminished. Seizures may sometimes persist after a corpus callosotomy, though they are typically less severe.
How Does a Corpus Callosotomy Work?
A comprehensive pre-surgical evaluation will be conducted by the pediatric neurologist to ensure that the child is a good candidate for the procedure. Typically, less invasive approaches such as anti-epileptic medication or vagal nerve stimulation will be tried first.
In some cases, the corpus callosotomy may be performed in two stages. During the first surgery, only the front portion of the corpus callosum is cut, leaving the back section intact. If the child’s seizures continue, then a second corpus callosotomy is performed to cut the remaining connection.
Because a corpus callosotomy requires general anesthesia, a period of fasting needs to be observed beforehand and part or all the child’s head will be shaved. Children typically spend a couple days in the intensive care unit after the procedure, and around a week at the hospital.
Side effects of a corpus callosotomy depend on the parts of the brain affected by seizures and the extent to which the callosum was severed. In patients that have a received a complete corpus callosotomy, there is a risk of developing problems with coordination or information processing. However, the risk of these problems is reduced in children and many symptoms can be treated with regular physical and occupational therapy.
Who Benefits from Receiving a Corpus Callosotomy?
When developing a treatment for a child with epilepsy, the pediatric neurologist will most often first attempt treatment with medication. However, if the child’s seizures persist for at least two years after treatment with medication begins, and if a single source for the seizures in the brain cannot be identified, then a corpus callosotomy may be necessary.
The corpus callosotomy is particular effective in treating atonic seizures, also called “drop attacks” due the loss of muscle tension that causes the child’s body to go limp, often causing them to drop to the ground. However, this procedure can also be used to treat tonic-clonic or other generalized seizures.