August - December 2007 Issue
Surgical Implant Can Improve Symptoms of Parkinson’s, Other Disorders
Bradley C. Hiner, MDMedical College of Wisconsin Neurologist
For people with movement disorders like Parkinson’s disease, shakiness and other difficult symptoms can make everyday activities next to impossible. Now, a new implant technique called deep brain stimulation can help many of these patients enjoy a major improvement in symptoms. Dr. Bradley Hiner explains the amazing possibilities.
Q. What challenges do people with Parkinson’s disease face?Parkinson’s disease is characterized by four major problems. The first is a specific type of tremor called a resting tremor. Even when a patient is just sitting and relaxing, his or her hands will shake. The second problem is rigidity, or a particular type of stiffness of the muscles that feels like a funny kind of ratcheting. The third is called bradykinesia, which simply means slowness of movement. The patient has trouble doing even simple activities like getting up out of a chair or rolling over in bed. The fourth problem is trouble with balance and walking.
All four of these things can range in severity from fairly mild to quite severe. In fact, we are recognizing more and more that some patients never get bad with Parkinson’s. Unfortunately, the rule of thumb is that all four major problems typically get worse as time goes on.
Q. What is the usual treatment for Parkinson’s?Parkinson’s disease is known to be the result of a deficiency of dopamine, which is a chemical produced naturally by the brain. Fortunately, we have a variety of different options to boost that brain dopamine level, with the best one still being a medication called levodopa. Unfortunately, as time goes on (typically, once you hit the five-year mark) the medications begin to lose their effect. The struggle becomes more pills, less and less benefit, and more side effects. It’s not uncommon to see patients who are taking 10, 15, 20 pills a day. These are the patients for whom deep brain stimulation, or DBS, is a wonderful new option.
Q. How does deep brain stimulation work?In patients with Parkinson’s disease, the area of the brain called the subthalamic nucleus is hyperactive. When you stimulate that area of abnormal hyperactivity with a very small amount of electricity, it actually has a calming effect. The result is an improvement in symptoms.
The DBS device is basically a pacemaker for the brain. It consists of a battery pack that is almost identical in size and appearance to a heart pacemaker.
This pack is placed under the skin at the collarbone and it is connected by a wire (again, under the skin) to a fine probe. This probe is implanted in the patient’s brain — guided to the target region with a great degree of sub-millimeter accuracy. The surgery is done under local anesthesia. The patient needs to be awake because we have to be able to talk to him or her during the procedure.
Q. How effective is it?In properly selected patients, we’re looking at a 70 percent improvement. For example, yesterday morning we saw a patient who had the implantation surgery performed a few weeks back a patient who had done the implantation surgery a few weeks back and was now coming in for us to activate the stimulator for the first time. When he came in, he was essentially unable to walk. We turned on his stimulator, and literally within minutes he could stand up and walk, albeit with a walker. His daughter and son were just astounded. We took a walk out in the hallway, and their mouths were hanging open.
It really can be quite remarkable in the right patients. We are often able to cut medications in half or more. We recently had a patient who went from a dozen pills a day down to just three.
I should point out that following the implantation, the stimulator needs to be programmed. We do that with a wand held over the battery pack. The initial programming may take a handful of visits, but once we have the stimulator tuned in, most folks don’t need to come in except for a couple of times a year.
Q. Who is a good candidate for DBS?We do not advocate DBS for everybody. Certainly if someone’s Parkinson’s disease is well-controlled with medication, there is no reason necessarily to jump in there and do this. Also, we don’t recommend DBS for patients with “end stage” Parkinson’s disease.
We do a very thorough pre-operative evaluation to make sure that if we’re going to offer DBS, it runs a very high probability of providing significant benefits. Our most remarkable successes are those Parkinson’s patients who are in the middle stages but are starting to slide down hill — they’re starting to have to take more medications and they’re starting to experience more side effects.
Q. What other conditions can DBS help?There is a condition called essential tremor. It’s the most common cause of shakiness and it is actually just as common as Parkinson’s disease or even more so. For patients with essential tremor, the tremor is not present at rest, but with use or movement, for example, when trying to drink a cup of coffee or use a screwdriver.
The DBS target for essential tremor is a structure of the brain called the thalamus. When we implant the probe into the thalamus, the improvement is literally within seconds. We can watch tremors stop almost immediately in the operating room. It’s one of the most remarkable things that you ever want to see. For essential tremor, our success rate with DBS is 90 percent or greater.
DBS can also help people with a movement disorder called dystonia, which causes patients to experience involuntary twisting, writhing and pulling movements. The procedure can also be an effective treatment for epilepsy — one or our patients experienced a significant reduction in seizures.
Q. Could DBS be a treatment for other disorders in the future?If you have a neurologic or psycho-neurologic disorder for which you can identify an area of abnormal function in the brain, and if you can modulate the activity of that area with a low level of electricity, then that disorder could potentially be treated with DBS.
There’s a really severe type of headache called cluster headache, and in some Italian studies DBS has shown tremendous promise. Also, some time in the next year or so, there may be a DBS trial for severe depression and obsessive-compulsive disorder.
These are things that I certainly never would have dreamt of as a medical student or even as a neurologic resident. It’s just been remarkable, and it’s been wonderful to be in this field. We think the future is bright for this mode of treatment.
Source: Every Day
Date: Aug - Dec 2007 Issue