Dr. Michael Okun 00:00:16
When you take your Parkinson's disease medications, you can get periods where you're on and you're feeling quite good. But when you're off, you may be stiff and rigid and, in some cases, tremulous and may have difficulty walking. When Parkinson's patients are having a difficult time keeping that good quality on time, those are the types of patients that we begin to think about for deep brain stimulation. Deep brain stimulation is a therapy that's really designed to improve the Parkinson's patient's quality of life. The way that it does that is it increases or extends the amount of good on time.
In most centers, you'll come in the day before and be screened by an anesthesiologist. They'll make sure that you're a suitable candidate for the DBS operation and that you're going to be able to tolerate it. In some centers, they'll even get a specialized MRI scan of your brain the day before the operation. In most centers, you'll actually stay awake during the operation, and it's important to understand that. In fact, if you have some fear of being awake, we may want to have some counseling for you before you end up in the operating suite so that you understand how it's going to happen.
On the day of the operation, you'll come in and they'll put a heavy hat called a head frame, and they'll attach it to certain aspects of your skull. They're either going to get another scan called a CT scan or another MRI with this heavy hat on. They're going to turn your brain into a virtual reality space. They'll find a spot in the brain. They'll point to it, and then the neurologist or the neurophysiologist will pass a tiny little electrode called a microelectrode into the brain. The tip of that electrode is about the size of a hair.
What we'll do is drive that electrode down and listen to the cells. As we go through different brain regions, every brain region has a different language. As you cross from the border from one area to another, we'll decode that and try to create a three-dimensional map of where the structures are in your brain. Once we know where the right location is, we'll put an electrode in, and the electrode is about a millimeter in diameter. This is small and has four little contacts on it, and those contacts we can stimulate with thousands of different combinations to try to improve your symptoms of Parkinson's.
Dr. Michael Okun 00:03:03
Once the electrode's in place, they'll test it in the operating room, so you may even see some results during the operation. In some cases, we don't see tremendous benefits or side effects in the operation, but that doesn't necessarily mean that you don't do well if that structure's been mapped properly. Once the operation is complete, you'll get a battery pack right up underneath your collarbone and attached to a wire that goes up underneath your skin to control that device, and it's like a pacemaker. Once that pacemaker's in place, and once the brain has had a chance for a few weeks after that operation to cool down, your neurologist will start programming you.
Usually, you’ll program once a month on average for about the first six months. Once they find the right stimulation parameters, they'll also adjust your medications around and find the right mix for you. It's an ongoing process. It's not a light switch, although if the right patients are chosen for this operation, the results can really be quite dramatic, and they can improve the symptoms that the patient wanted improved as long as the education has happened and the patients are completely informed about what the risks and benefits of the operation are.
This operation is not completely risk-free. In 90% of patients who undergo deep brain stimulation, they don't have many problems. But it's very important for you to understand that there are complications and there are risks. Whenever we pass these little microelectrodes and these little DBS leads into the brain, we can collide with blood vessels or we can damage some of the brain structures, and you can get things like strokes or bleeds. Certain side effects can happen in patients, like weakness or numbness, changes in vision, and changes in speech. Infection is a very real risk, which can happen in 5% or more of the cases.
What happens when we see infections? Sometimes we have to take the hardware out, treat the infection, and then reimplant it. We also worry about worsening thinking, worsening the cognitive function of patients. If you have any pre-existing depression or anxiety, we want to make sure that's treated and stable because we don't want to make you worse with the operation. These are hardware parts, so they can break. You may need to get a wire replaced or a box replaced at some point during the course of your therapy, so it's important to have regular follow-up visits with your doctors. The risk-benefit ratio in well-selected patients is very good.