Surgical Procedure
Once a physician has determined that deep brain stimulation will be the best effective treatment for a Parkinson’s patient and has chosen a site for the stimulator, the candidate must undergo two surgeries.
First the stimulator is inserted in the subthalamic nucleus, globus pallidus, or the thalamus. After that procedure is a second one to place a pacemaker-like device under the skin over the patient’s chest.
Before brain surgery, MRI and CT scans are used to locate the target brain structure. Once an internal map is drawn, this map is matched with external landmarks so surgeons can make an accurate incision.
Surgery is performed through a hole in the skull about the size of a quarter. A microelectrode guided by a microdriver is passed through into the brain. The microelectrode measures the neural signals and can be used to find the exact location of the target.
Signals picked up from the microelectrode are displayed on a computer monitor and as audio signals. Analysis of electrode recordings allows for a high degree of precision for stimulator placement. Once the appropriate structure is found, the microelectrode is replaced with a permanent electrode.
The patient is awake during the surgery to allow the surgical team to assess the patient’s brain function. While the electrode is being advanced, the patient does not feel any pain because of the brain’s unique nature and its inability to generate pain signals due to an absence of nociceptors or pain receptors. A local anesthetic is administered when the surgeon makes the opening in the skull.
Once the patient has successfully recovered from the brain surgery a lead is connected from the brain electrode to a pulse generator device. During this procedure the patient is once again placed under general anesthesia. The “pacemaker” is surgically implanted under the chest, just below the collarbone. The programmed stimulator is turned on for the first time a few weeks post-operation. Programming does not require any further surgery.
There are risks associated with deep brain stimulation therapy but the results can be dramatic.
Sources: WebMD interview with Dr. Erwin Montgomery, MD; New York–Presbyterian Neuroscience; Wake Forest Neurosurgery; Iacono Neuroscience Clinic; The Cleveland Clinic