Types of Surgery

There are two surgical procedures—lesioning and deep brain stimulation—and three target locations in PD surgery: thalamus, globus pallidum internus (GPi), and subthalamic nucleus (STN). Other surgery-based procedures—cell transplants, gene therapy, and neurotrophic factor delivery—remain experimental procedures for the treatment of PD.

Lesion procedures (i.e., pallidotomy, thalamotomy) deliver radio-frequency energy to heat and ablate (destroy) a pea-sized region within the target, where there is abnormal activity related to the movement problems.

Deep brain stimulation (DBS) uses implanted electrodes to stimulate one or another of these same regions. The electrical stimulation interferes with the abnormal activity, creating the same effect as a lesion. The effect lasts as long as the stimulation continues, but ceases when it is shut off.

During needle-guided (stereotaxic) brain surgery, the patient remains awake. This is for two reasons. The first is that the brain itself has no pain sensors, and once the initial incision is made (using a local anesthetic like Novocain), there is no pain. The second is that patients must be able to respond to the surgical team's questions about what they are experiencing during the surgical procedure. The pathway to the target lies close to several other important structures in the brain that may be inadvertently stimulated during the procedure. This may cause unusual sensations such as flashing lights, tingling, or experience of emotions. Patients then report these sensations to the surgeon during the procedure. Avoiding these areas is crucial for successful surgery.

Because surgery requires very precise placement of surgical instruments, a three-dimensional frame is attached to the patient's head to guide the surgeon. The frame may be uncomfortable and local anesthetic is used to ease the discomfort. Before surgery, patients will also undergo several imaging procedures, in order to identify the target and other landmarks within the brain. Depending on the center, the procedures may include magnetic resonance imaging (MRI) scans, computerized tomography (CT), or ventriculography.

	Pallidotomy