Explaining hemispherectomy

The rare, radical surgery known as hemispherectomy, in which half of the brain is removed, was first tried on humans in the mid-1920s. However, not until the 1950s was it performed successfully, mostly for cases of severe childhood epilepsy. Its use increased in the 1990s as surgeons, including Ben Carson, developed more sophisticated techniques that produced improved outcomes.

It is done almost entirely on children, whose brains have more neuroplasticity than adults', meaning that neurons in the remaining half can more easily assume the tasks of neurons in the missing half.

Christina Santhouse underwent an anatomic hemispherectomy, in which the entire cerebral hemisphere was removed. Increasingly, though, doctors perform what is called a functional hemispherectomy, in which some tissue in the damaged hemisphere is left in place but its connections to other brain centers are cut so that it no longer functions.

During both procedures, the patient's head is shaved and a portion of the skull removed. After all tissue has been cut and removed and all bleeding is stopped, the underlying tissues are sutured and the skull and scalp are replaced.