Deep Brain Stimulation for Parkinson's Disease
Deep brain stimulation (or DBS) is a way to inactivate parts of the brain that cause Parkinson's disease and its associated symptoms without purposefully destroying the brain. In deep brain stimulation, electrodes are placed in the thalamus (to treat essential tremor and multiple sclerosis) or in the globus pallidus (for Parkinson's disease).
In deep brain stimulation electrodes are connected by wires to a type of pacemaker device (called an impulse generator, or IPG) implanted under the skin of the chest, below the collarbone. Once activated, the device sends continuous electrical pulses to the target areas in the brain, blocking the impulses that cause tremors. This has the same effect as thalamotomy or pallidotomy surgeries without actually destroying parts of the brain.
The IPG can easily be programmed using a computer that sends radio signals to the device. Patients are given special magnets or other devices so they can externally turn the IPG on or off.
Depending on use, the stimulators may last three to five years. The IPG replacement procedure is relatively simple.
How Does Deep Brain Stimulation Work?
Experts are unclear how deep brain stimulation works.
How Is Deep Brain Stimulation Performed?
Patients who are having stimulators placed on both sides of the brain will have their surgery divided into two parts. Most people with Parkinson's disease will require the surgery be done on both sides of the brain. During the first surgery, the electrodes are placed into the brain, but left unconnected.
There are several ways in which the electrodes are placed into the target areas of the brain. First these areas must be located. One way to locate the target areas is to rely only on a computed tomography (CT) or magnetic resonance imaging (MRI) scan. While some surgeons stop there, others use an electrode recording technique to map and target the specific areas that they will need to reach.
Once the correct location is identified, the permanent electrodes are implanted. The loose ends are placed underneath the skin of the head and the incision is closed with sutures. The patient receives general anesthesia for the placement of the impulse generator in the chest and the positioning of extension wires that connect the electrodes to the impulse generators. It may take a few weeks until the simulators and medications are adjusted sufficiently for patients receive adequate symptom relief. But, overall, DBS causes very few side effects.
What Is Subthalamic Nucleus Deep Brain Stimulation?
Subthalamic nucleus stimulation is a new application of the original deep brain stimulation technique. After extensive clinical trials, stimulation of the part of the brain called the subthalamic nucleus has been recognized as the most effective surgical treatment for Parkinson's disease, addressing not only tremors, but the full range of the disease's symptoms, including: rigidity, slowness of movement, stiffness, and walking concerns.
Successful stimulation of the subthalamic nucleus allows patients to consistently reduce their medication while improving all of their other disease-related symptoms. In addition, the surgery to place the stimulator in the subthalamic nucleus is generally easier than surgeries for the thalamus or globus pallidus.