Managing Parkinson's disease with surgery
- [Voiceover] So, we know that when the movement symptoms of Parkinson's disease start to interfere with a person's day-to-day living, that's when we would normally try to find some medications that can help manage, help minimize the problems, right? But we also know that the most effective medication that we currently have, L-DOPA, can cause some side effects after several years of use that also need to be managed, like dyskinesia and "wearing off," and because Parkinson's disease is a progressive disease, because it continues to worsen over the years following diagnosis, sometimes medications just can't keep up with how bad the symptoms get, and as a result, they just can't manage the symptoms anymore. So, if our person with Parkinson's disease gets to the point where their quality of life is just too impacted by the disease itself, or by the side effects of medications that they have to be on, well, that's when surgery to help manage the symptoms might be considered, and the particular operation that's often useful in Parkinson's disease is called "deep brain stimulation," or DBS, and DBS is actually really interesting. It's kind of like a pacemaker. You know, those electronic implants that help you regulate your heartbeat, but instead of being for your heart, DBS is like a pacemaker for your brain, so what it does is, it's actually kind of interesting, because we don't really know how it works. This is just what's been observed over the past 20-odd years or so, but what it does is it helps to reduce the movement symptoms of Parkinson's disease, the bradykinesia and the tremor, and the rigidity, and it can also help with the dyskinesia that can result from the long-term use of L-DOPA. So, let's actually take a quick look at how this procedure is carried out here. So, a DBS operation is actually done in two main steps. The first step is kinda like a surveying step. So, what happens is that a little wire called an electrode is very skillfully and carefully inserted into the brain, into the area of the basal ganglia. We can think of this initial set of electrodes as like our undercover agents, right? They're gonna keep their ears to the ground, so to speak, and find out where all those misbehaving neurons are, where they're hanging around in the brain, because it's one thing to, say, look at a textbook or a nice drawing and see exactly where our nuclei are, but it's an entirely different thing to be able to accurately find these areas in live human beings in surgery. So, good thing we have our undercover agent electrodes here to help us out, right? I said that they keep their ears to the ground, and I almost literally mean that. They actually work by analyzing the activity patterns of neurons that are around them, and then what they do is, they translate what they find into distinct sounds, sounds that we can hear, so the surgeons that are doing the procedure can hear these sounds and say, "Aha, this is the spot!" when they've actually reached the right place in the brain, and this can take quite a while to do. It can take several hours per hemisphere of the brain, depending on the person. Okay, step two now. Our undercovers have done a really great job at mapping out the important areas that we need, figuring out where we need to go, so we pull them out, and in goes some permanent electrodes to those areas, so let's draw that here on our guy, and we can also see what that looks like on an MRI. So, here's an MRI, kind of the same sort of view that we're looking at, and you can see those electrodes here on both sides of the brain. So, the idea is that these electrodes, they stay in the person's brain permanently now, on maybe just one side of the brain, or maybe on both sides of the brain, depending on the person's symptoms and the severity of those symptoms, and in case you're wondering about a power supply, they're actually connected to a battery-powered pacemaker down here, that's normally put below the collarbone. So, now we have the ability to continually send electrical signals to the part of the brain where those electrodes are, the part that's causing the movement problems, and the electrical signals that are sent, what do they do? Well, they adjust the activity of the neurons here, so this is kinda like adjusting the knobs on a radio, right? We tune in to the station that we want, in this case, movement, and we do this by placing those first electrodes, our undercover agents, in some of the movement areas, like parts of the basal ganglia, and now what we're doing is we're adjusting the volume. We're turning it down to turn down the activity of the trouble-making neurons in these areas of the brain, and that's actually part of the beauty of DBS. This is actually a reversible setup that allows us to fine-tune how much these neurons are turned down, and what's extra-great about that is that it means this setup can be adjusted to individualize it for different patients. Now, let me just make two clarifications here. So, just from when you look at the name, "deep brain stimulation," you're thinking, "Okay, deep brain. "Well, where is that?" So, in the case of someone with Parkinson's disease, our target is the basal ganglia area, which is pretty deep in the brain, right? So that's that, and the second thing is that the second half of this name is "stimulation," but I just told you that we're turning down the activity of these neurons, so I think an analogy that I'll give you is think about when your dog is barking uncontrollably. Well, you tell him to quiet down, right? You're talking to him. It still counts as stimulation, even though the end result is that you're turning his volume down, so that's kinda the idea with our electrodes in our basal ganglia here. Even though we're stimulating the brain, the end result is that the activity of the neurons is turned down, and let's actually look at where in the basal ganglia we're talking about here with Parkinson's disease. So, in order to figure out where we wanna go, let's think back to how the basal ganglia control our movements. Remember that in Parkinson's disease, our thalamus is not able to talk to our motor cortex as much as it needs to, and so we end up with a reduction in movement, right? Remember that this happens because the subthalamic nucleus gets too active, and when it's too active, it over-excites the globus pallidus internal, and when the globus pallidus internal is too excited, it's what inhibits our thalamus too much, so that it can't talk to the motor cortex properly. So, right away we can probably see that the globus pallidus internal is definitely one of those problem-causing areas in Parkinson's disease because it's too active. It's inhibiting the thalamus too much, and another area that we can probably see as a problem-causing area is the subthalamic nucleus, because it's the one that's getting too active and over-exciting the globus pallidus internal in the first place. So, it turns out that these are indeed the main areas that we target with DBS for someone who has Parkinson's disease, so we use DBS to turn down the activity of the neurons in these areas, these areas that are too active, and that allows us to restore the balance in our direct and indirect pathways. I mentioned this already, but how DBS works is still a bit of a mystery. We haven't quite figured out how targeting these areas with DBS manages to reduce the movement problems that we get from Parkinson's disease and long-term use of L-DOPA. We just know that it consistently works, and one added bonus of DBS is that it often allows the person with Parkinson's disease to reduce or discontinue some of their medications, So, that's a really good thing, because we know that some of those medications can bring on some bad side effects. So, for example, remember how L-DOPA is kinda like a pendulum that wants to bring our patient from too little movement to normal, but after a few years it can kinda overshoot and cause too much movement. Well, we want to avoid that if we can, so with DBS, helping to manage the movement problems in the first place, the patient can often get away with taking less L-DOPA, which can maybe help our pendulum here from swinging a little too far and causing too much movement. Good, that's surgical intervention. So, now we know that we have medications, and if needed later on, surgery that can help manage some of the symptoms of Parkinson's disease, but we have another category that we'll quickly touch on, and that's lifestyle management options. So, for example, exercise and physiotherapy, well, they won't stop or slow down the movement signs. They can help to alleviate some of the associated muscle and joint pain that can result from things like rigidity, and the postural changes that can happen over time with Parkinson's disease. Another thing that can be really helpful is speech therapy, and that's because a lot of people with Parkinson's disease, they tend to develop a really soft speaking voice due to a lack of coordination of muscles in the voice box, so speech therapy can help train them to increase their speaking volume, and that allows them to continue to converse with the people around them. One last example is emotional and psychological support. This can be really important for someone with Parkinson's disease. This can be really helpful early on, when the person is kinda just learning about the disease and starting to cope with it, and it can also be really helpful later on, because remember that the disease can start to affect the person's mood. It can cause problems with depression and anxiety, so this support can be really helpful if this happens for someone with Parkinson's disease.