Deep Brain Stimulation As Treatment for Parkinson's Disease

Deep brain stimulation (DBS) is a relatively new development in the treatment of Parkinson's disease (PD). Neurosurgeons in the 1950s began the use of lesioning procedures to correct movement disorders. This was an irreversible procedure that destroyed the target area in the brain. It was not until 1987 that a pilot study was conducted by a French neurosurgical team to test the theory that tremors could be controlled by an implanted system. In 1995, Medtronic stimulation therapy was approved in Europe, Canada and Australia; and in 1997 in the United States. 

The DBS device consists of two insulated wires called leads which are surgically implanted in precise targets of the brain to deliver electrical stimulation.  This stimulation blocks the abnormal nerve signals that cause the involuntary movements and tremors associated with Parkinson's disease. The device is powered by a neurostimulator surgically implanted in the chest below the collarbone. The neurostimulator is about two inches wide and 1/2 inch and contains a small battery and computer chip programmed to send electrical pulses. An insulated wire called an extension is tunnelled under the scalp, behind the ear, down the neck, and into the chest to connect the neurostimulator with the leads in the brain.

The stimulator is customized for each patient. A neurosurgical nurse with intensive training in DBS technology programs the neurostimulator after the surgery. Frequent follow up visits for testing and fine tuning are necessary for the rest of the patient's life. Patient education is crucial. Hazards that can interfere with the functioning of the system include MRI scans, defibrillation, and strong magnetic devices such as airport screenings and the theft control devices used by many retailers. Even the magnetic strips on credit cards have been known to interfere with the neurostimulator when carried in a pocket close to the chest implant.

I had a DBS device implanted in 2008 in Winnipeg, Manitoba (Canada) by a team that has been doing this surgery for about ten years. Two surgical procedures are needed for this treatment. The first surgery is to install the leads in the brain. The neurosurgeon chooses one of two areas to target: either the subthalamic nucleus (STN) or the internal globus pallidus (GPi). This surgery generally takes at least eight hours, mine took about eleven hours. The patient needs to be awake for this surgery in order to answer questions and follow directions so that the surgeon can place the leads where they will provide the most benefit and the least side effects. About a week later, they do a second surgery to install the neurostimulator and tunnel in the extension. For this procedure, general anesthetic can be used. After the surgeries, the patient is sent home for eight weeks to heal before returning to have the device turned on.

Deep brain stimulation is not a cure for Parkinson's disease, nor does it slow the progression of the disease. It can increase the benefits and reduce the side effects of levodopa and other Parkinson's medications. There are serious risks involved with brain surgery and with stimulation therapy. It is also an extremely expensive procedure, which in Canada is covered by our medicare system. The screening process ensures that the patients who will benefit the most receive the procedure. Follow up visits to test and adjust the device are extremely important. 

DBS therapy is reversible. If a cure for PD is developed within my lifetime, the therapy can be turned off and the system can be removed.