Callosotomy or Corpus Callosotomy is sometimes called split-brain surgery or callosal sectioning. It is a palliative surgical operation severing all or only a part of the corpus callosum. It aims to reduce the rapid spread of seizure from one hemisphere of the corpus callosum to the other in individuals with intractable epilepsy. It also controls the frequency of "drop attacks" in children with generalized seizure (atonic seizure). The first procedures of callosotomy were performed in the 1940's by Dr. William van P. Wagener. Oftentimes, callosal sectioning is done in stages. The anterior two-thirds of the corpus callosum is sectioned first. Then, if necessary, the posterior one-third is sectioned in a second surgical procedure.