While medications, such as propranolol, primidone, levodopa, dopamine agonists, botulinum toxin, and other drugs are helpful, many patients with Parkinson’s disease (PD), tremor, dystonia and other movement disorders continue to experience embarrassing, troublesome or even disabling symptoms. Patients who do not obtain satisfactory response from optimal medical therapy may be considered candidates for surgical intervention. In the past, the neurosurgical treatments consisted chiefly of procedures that produced lesions to selected areas of the brain in order to control the movement disorder (“ablative surgery”). These procedures involve an incision in the scalp and drilling a hole through the skull. The surgeon than uses a “probe” (electrode) and advances it into the portion of the brain that is thought to be functioning abnormally. An electrical current is then used to heat the tip of the electrode which results in a lesion in the target brain area (nucleus). This is usually associated with a reduction of the abnormal or involuntary movement on the opposite side of the body. Although effective in most cases, there is a risk of stroke resulting in weakness on the opposite side of the body, numbness, poor coordination, speech disturbance and other complications. These potential risks are compounded when the procedure is performed bilaterally (on both sides).