Split-brain or callosal syndrome is a type of disconnection syndrome when the corpus callosum connecting the two hemispheres of the brain is severed to some degree. It is an association of symptoms produced by disruption of, or interference with, the connection between the hemispheres of the brain. The surgical operation to produce this condition (corpus callosotomy) involves transection of the corpus callosum, and is usually a last resort to treat refractory epilepsy. Initially, partial callosotomies are performed; if this operation does not succeed, a complete callosotomy is performed to mitigate the risk of accidental physical injury by reducing the severity and violence of epileptic seizures. Before using callosotomies, epilepsy is instead treated through pharmaceutical means. After surgery, neuropsychological assessments are often performed.
After the right and left brain are separated, each hemisphere will have its own separate perception, concepts, and impulses to act. Having two "brains" in one body can create some interesting dilemmas. There was a case in which, when one split-brain patient would dress himself, sometimes he pulled his pants up with one hand (the side of his brain that wanted to get dressed) and down with the other (the side that did not). He was also reported to have grabbed his wife with his left hand and shook her violently, at which point his right hand came to her aid and grabbed the aggressive left hand (a phenomenon sometimes occurring, known as alien hand syndrome). However, such conflicts are very rare. If a conflict arises, one hemisphere usually overrides the other.
