There are several different types of surgery for Parkinson's disease. The first surgical procedures developed were destructive, or brain lesioning, procedures. Examples of lesioning surgery include thalamotomy and pallidotomy. Lesioning surgery involves the precisely controlled destruction, using a heat probe, of a small region of brain tissue that is abnormally too active. It produces a permanent effect on the brain. In general, it is not safe to perform lesioning on both sides of the brain due to potential side effects. In most centers, lesioning has been largely replaced by deep brain stimulation (DBS). DBS surgery involves placing a thin metal electrode (about the diameter of an spaghetti) into one of several possible brain targets and attaching it to a computerized pulse generator or battery, which is implanted under the skin in the chest (much like a heart pacemaker). All parts of the stimulator system are internal; there are no wires coming out through the skin. To achieve maximal relief of symptoms, the electrical stimulation can be adjusted during a routine office visit by a physician or nurse using a programming computer held next to the skin over the pulse generator. Unlike lesioning, DBS does not destroy brain tissue. Instead, it reversibly alters the abnormal function of the brain tissue in the region of the stimulating electrode. Although deep brain stimulation is a major new advance, it is a relatively complicated therapy that may demand considerable time and patience before its effects are optimized. Restorative therapies, such as transplantation of fetal cells or stem cells, growth factor infusion, or gene therapy, attempt to correct the basic chemical defect of Parkinson's disease by increasing the production of dopamine in the brain. These procedures are currently experimental but hopefully in the future, restorative therapies will emerge as effective and possibly curative interventions for Parkinson's disease.