WEBVTT - How Does Myasthenia Gravis Work? 0:00:01.890 --> 0:00:08.010 Welcome to BrainStuff, a production of iHeartRadio. Hey BrainStuff, Lauren 0:00:08.030 --> 0:00:12.410 Vogelbaum here. For many of us, a lot of purposeful 0:00:12.470 --> 0:00:17.430 motions feel automatic. Our gait when we walk, our posture 0:00:17.470 --> 0:00:20.530 when we sit, a smile when a friend enters the room. 0:00:21.590 --> 0:00:25.140 Some can even feel compulsive. Like, have you ever known 0:00:25.320 --> 0:00:30.300 or been an emphatic gesticulator? I've accidentally smacked people during 0:00:30.360 --> 0:00:35.450 excited conversations. But all of our purposeful motions are actually 0:00:35.490 --> 0:00:39.690 the result of an incredibly complex chain of electrochemical actions 0:00:39.729 --> 0:00:42.510 in our bodies, from our nervous system to our muscles 0:00:42.570 --> 0:00:46.379 and back again, that tell us from experience that we're 0:00:46.659 --> 0:00:49.349 on steady ground to take our next step, or that 0:00:49.380 --> 0:00:52.180 we're sitting up straight, or that our smile is warm 0:00:52.220 --> 0:00:55.480 and welcoming, or that we've just flailed into someone and 0:00:55.520 --> 0:00:59.300 need to apologize. It takes a lot of things in 0:00:59.360 --> 0:01:03.270 our bodies going right just to blink. So what happens 0:01:03.330 --> 0:01:07.250 when something goes wrong? Today, let's look at a condition 0:01:07.390 --> 0:01:14.080 called myasthenia gravis. In myasthenia gravis, the communication between your 0:01:14.140 --> 0:01:18.180 nerves and your muscles breaks down, resulting in muscle weakness 0:01:18.400 --> 0:01:22.280 and easy fatigue in areas like the eyes, face, neck, 0:01:22.380 --> 0:01:26.730 and limbs, making it difficult to control your vision and expressions, 0:01:27.130 --> 0:01:30.710 to move around, and sometimes even to swallow or breathe. 0:01:31.680 --> 0:01:34.860 The term comes from ancient Greek words for muscle and weakness, 0:01:35.120 --> 0:01:39.160 along with the Latin for severe or grave. It was 0:01:39.220 --> 0:01:43.070 coined in the late 1800s. Physicians have been describing these 0:01:43.110 --> 0:01:46.530 types of muscle fatigue since the 1600s, but it wasn't 0:01:46.610 --> 0:01:49.990 until around the 1960s that we began understanding what we 0:01:50.010 --> 0:01:53.860 were looking at. It turns out that myasthenia gravis is 0:01:53.920 --> 0:01:57.960 an autoimmune condition. We've talked before on the show about 0:01:58.060 --> 0:02:00.760 how the immune system works and what can go wonky 0:02:00.820 --> 0:02:04.760 when it isn't working as expected. It's meant to clear 0:02:04.900 --> 0:02:08.440 out dead or damaged cells and fight off germs and 0:02:08.560 --> 0:02:11.769 remember how to fight them again in the future. But 0:02:12.150 --> 0:02:15.950 for reasons we don't understand very well, sometimes your immune 0:02:15.970 --> 0:02:19.670 system makes a mistake and attacks healthy cells in your body. 0:02:20.930 --> 0:02:24.270 In arthritis, it attacks your joints. In psoriasis, it can 0:02:24.310 --> 0:02:28.380 attack your skin. In myasthenia gravis, your immune system attacks 0:02:28.530 --> 0:02:32.910 the points of communication between your nerves and muscles. It's 0:02:33.030 --> 0:02:36.049 sort of like in a horror flick or thriller, where 0:02:36.110 --> 0:02:38.650 the bad guy cuts the phone line or power line 0:02:38.690 --> 0:02:41.210 going to a house, leaving the heroes in the dark, 0:02:41.690 --> 0:02:46.700 literally or figuratively. The signal, or electricity, may still be 0:02:46.760 --> 0:02:50.929 coming through the wire, but it can't be received. It's 0:02:51.060 --> 0:02:53.889 a little more complicated in our bodies because we are 0:02:53.990 --> 0:02:57.150 electrochemically driven meat. We'll have to do a whole episode 0:02:57.230 --> 0:02:59.530 on how your nerves tell your muscles to do stuff, 0:02:59.910 --> 0:03:04.910 and we will. But very basically, our muscle fibers are 0:03:04.950 --> 0:03:08.830 all connected to our nervous system via tiny junctions with 0:03:08.910 --> 0:03:13.970 motor neurons. When we want to, say, blink, nerve impulses 0:03:14.110 --> 0:03:18.000 travel to the motor neurons in our eyelids. Our muscles 0:03:18.169 --> 0:03:21.489 can't receive the signal directly. Our motor neurons have to 0:03:21.810 --> 0:03:25.390 translate or transform the signal into something that the muscles 0:03:25.450 --> 0:03:30.299 can get. So the motor neurons give off chemicals that 0:03:30.380 --> 0:03:37.720 transmit the neural signal, aka neurotransmitters. Okay, so the junction 0:03:37.800 --> 0:03:41.210 in question here is a tiny gap between the motor 0:03:41.250 --> 0:03:45.270 neuron and the muscle fibers that it's communicating with. To 0:03:45.310 --> 0:03:49.350 pass along the signal, the motor neuron releases neurotransmitters into 0:03:49.400 --> 0:03:53.280 that gap. They'll be caught by receptors on the surface 0:03:53.380 --> 0:03:57.440 of the muscle fibers, which, again, very basically, can then 0:03:57.760 --> 0:04:00.920 recognize that a request for movement has been made and 0:04:00.960 --> 0:04:06.000 can trigger muscle contraction. So, you blink. This can happen 0:04:06.060 --> 0:04:11.050 very quickly. Now, in vertebrates like humans, the main neurotransmitter 0:04:11.150 --> 0:04:16.570 involved in muscle stimulation is called acetylcholine. In the condition 0:04:16.630 --> 0:04:22.120 Myasthenia gravis, your immune system attacks your acetylcholine receptors on 0:04:22.150 --> 0:04:26.279 your muscle fibers. Or, in some cases, the immune system 0:04:26.460 --> 0:04:29.960 also or instead attacks other proteins that are involved with 0:04:30.020 --> 0:04:35.660 maintaining these neuromuscular junctions. This effectively causes the same breakdown 0:04:35.680 --> 0:04:43.219 in communication. But, okay, why? Good question. Let's talk about 0:04:43.339 --> 0:04:47.659 the immune response. When your immune system is working normally, 0:04:47.900 --> 0:04:52.720 it's constantly scanning for invaders, you know, viruses, bacteria, and 0:04:52.980 --> 0:04:56.000 other things that might pose a threat. It does this 0:04:56.110 --> 0:05:00.330 by looking for identifying molecules called antigens on the surface 0:05:00.410 --> 0:05:03.470 of germs and your cells and anything else that it 0:05:03.529 --> 0:05:07.210 comes across. If the thing in question is from your 0:05:07.290 --> 0:05:11.310 own body and thus belongs there, your immune system should 0:05:11.600 --> 0:05:16.500 recognize that. But If your immune system identifies those antigens 0:05:16.640 --> 0:05:20.260 as being not from your body, and therefore potentially unsafe, 0:05:20.660 --> 0:05:25.540 it will launch an attack. It attacks by developing invader-specific 0:05:25.640 --> 0:05:30.010 proteins called antibodies that can destroy the antigen and anything 0:05:30.029 --> 0:05:33.450 attached to it, or tag it for destruction by immune 0:05:33.490 --> 0:05:38.550 system cells. After the battle, your immune system will stockpile 0:05:38.589 --> 0:05:42.750 that antibody, and remember how to identify that antigen. in 0:05:42.890 --> 0:05:47.510 most cases, forever. So if your immune system encounters antigens 0:05:47.550 --> 0:05:49.770 of the same type later on, it can fight the 0:05:49.790 --> 0:05:54.300 disease off fast. This immune response is really great when 0:05:54.310 --> 0:05:57.520 it comes to chickenpox, or the variant of the flu 0:05:57.580 --> 0:06:00.779 going around this year. It means that you won't get 0:06:00.839 --> 0:06:03.620 chickenpox again, and that you might be able to take 0:06:03.660 --> 0:06:06.560 a vaccine to teach your immune system about this flu 0:06:06.600 --> 0:06:11.370 variant and thus avoid getting sick from it. But sometimes, Again, 0:06:11.589 --> 0:06:16.050 for reasons we don't really understand, your immune system misidentifies 0:06:16.210 --> 0:06:19.120 some of your own cells as a threat and produces 0:06:19.279 --> 0:06:24.480 antibodies to attack them. In myasthenia gravis, your immune system 0:06:24.600 --> 0:06:29.700 creates antibodies that stuff up, block, damage, or otherwise impair 0:06:29.720 --> 0:06:35.140 the function of those acetylcholine receptors on your muscle fibers. So, 0:06:35.690 --> 0:06:39.330 Your motor neurons are releasing the neurotransmitter that should tell 0:06:39.350 --> 0:06:42.230 the muscle fibers in your eyes to, for example, blink, 0:06:42.730 --> 0:06:46.190 but the muscle fibers can't receive the signal. It's not 0:06:46.250 --> 0:06:49.240 exactly like the line is cut, more like the signal 0:06:49.300 --> 0:06:53.140 is coming through real patchy. In our thriller metaphor, it's 0:06:53.240 --> 0:06:56.960 like if the bad guy is jamming the frequency. Because 0:06:57.339 --> 0:06:59.780 all of this doesn't mean that your muscles will never work. 0:07:00.360 --> 0:07:04.440 but they can become less reliable or stop responding after 0:07:04.500 --> 0:07:08.980 periods of activity. I picked blinking as an example here 0:07:09.180 --> 0:07:13.290 because myasthenia gravis often first presents as muscle weakness around 0:07:13.310 --> 0:07:16.530 the eyes. You might notice one or both of your 0:07:16.650 --> 0:07:21.470 eyelids drooping, have difficulty moving your eyes, or experience blurriness 0:07:21.550 --> 0:07:24.270 or double vision because your eyes are basically out of 0:07:24.310 --> 0:07:28.750 sync If symptoms don't progress beyond the eye muscles, that's 0:07:28.810 --> 0:07:33.150 called ocular myasthenia gravis. It affects around 10% of people 0:07:33.190 --> 0:07:37.060 with the condition. More commonly, you'll start to notice muscle 0:07:37.080 --> 0:07:39.780 weakness around the rest of the face and neck and 0:07:39.880 --> 0:07:44.520 down into the limbs. This is called generalized myasthenia gravis. 0:07:45.540 --> 0:07:48.360 It can make you feel very fatigued. It can become 0:07:48.420 --> 0:07:51.700 difficult to stand up or lift objects, and you might 0:07:51.900 --> 0:07:55.620 tire quickly or get wobbly when walking. Your hands might 0:07:55.640 --> 0:07:59.760 feel clumsy. Depending on exactly what muscles are affected, your 0:07:59.880 --> 0:08:04.270 speech might sound different, softer or more nasal or garbled. 0:08:05.130 --> 0:08:08.790 Your face might be less expressive. Chewing and swallowing can 0:08:08.830 --> 0:08:11.910 become a chore, and you might even find yourself choking easily. 0:08:11.930 --> 0:08:16.570 In some cases, the respiratory muscles become weak too, and 0:08:16.650 --> 0:08:20.800 you might experience shortness of breath. That symptom in particular 0:08:20.860 --> 0:08:23.800 can be life-threatening if your muscles tire out and you 0:08:23.880 --> 0:08:27.900 can't get enough air. This is called a myasthenic crisis, 0:08:28.170 --> 0:08:30.390 and about a fifth of people with the condition will 0:08:30.450 --> 0:08:34.890 experience it at least once. Definitely tell your healthcare provider 0:08:34.929 --> 0:08:37.250 about any shortness of breath that you or a loved 0:08:37.309 --> 0:08:40.190 one experienced so that you can monitor the situation, and 0:08:40.450 --> 0:08:44.540 always get emergency care if you're struggling to breathe. All 0:08:44.559 --> 0:08:47.319 of this can be scary, and to Even if it's 0:08:47.380 --> 0:08:50.939 not physically scary, it can be really frustrating to feel 0:08:51.140 --> 0:08:55.800 out of control of your movement, expressions, and stamina. The 0:08:55.820 --> 0:08:59.480 muscle weakness experienced is typically made worse by activity and 0:08:59.610 --> 0:09:04.829 better by rest. There's unfortunately no cure for myasthenia gravis yet, 0:09:05.570 --> 0:09:09.010 but there are lots of treatment options to help manage symptoms. 0:09:10.309 --> 0:09:14.950 The first step is diagnosis. Anyone can develop myasthenia gravis, 0:09:15.170 --> 0:09:17.950 though it most commonly first appears in adult women ages 0:09:17.950 --> 0:09:20.569 30 to 50 and adult men over the age of 60. 0:09:20.570 --> 0:09:24.530 It doesn't usually run in families, but does pop up 0:09:24.570 --> 0:09:27.490 more often in people who already have an autoimmune disorder. 0:09:27.510 --> 0:09:31.290 A healthcare provider will talk through your symptoms, give you 0:09:31.350 --> 0:09:33.710 a physical exam to see how your muscles are behaving 0:09:34.010 --> 0:09:37.770 or misbehaving, and may perform one or a few tests. 0:09:38.850 --> 0:09:41.910 A blood test can look for telltale antibodies that your 0:09:41.929 --> 0:09:45.390 immune system has produced that are misguidedly built to attack 0:09:45.450 --> 0:09:50.110 those acetylcholine receptors or the proteins that help neuromuscular junctions work. 0:09:51.210 --> 0:09:54.290 An electrical activity test can be used to measure your muscles' 0:09:54.350 --> 0:09:58.070 responses to signals from nerves, and they might have you 0:09:58.130 --> 0:10:01.340 undergo some kind of imaging scan. like an MRI or 0:10:01.380 --> 0:10:06.060 CT scan, to check out your thymus. The thymus is 0:10:06.100 --> 0:10:08.420 an immune system gland in your chest where some of 0:10:08.460 --> 0:10:13.380 your specialized attack cells, called T-cells, mature. The thymus is 0:10:13.440 --> 0:10:16.660 usually active during our childhoods and then phases out as 0:10:16.700 --> 0:10:20.460 we get older. If something unusual is going on with it, 0:10:20.710 --> 0:10:23.380 that can be a solid sign of an autoimmune disorder. 0:10:24.710 --> 0:10:26.809 Once you've got a diagnosis, you can look at what 0:10:26.870 --> 0:10:30.770 treatments might be most helpful for you. Your healthcare provider 0:10:30.809 --> 0:10:35.010 might talk to you about different medications, including immunosuppressants, that is, 0:10:35.330 --> 0:10:38.949 drugs like steroids that can suppress an overactive immune system, 0:10:39.550 --> 0:10:44.510 or what's called acetylcholine esterase inhibitors. These help prevent the 0:10:44.530 --> 0:10:47.650 breakdown of acetylcholine in your body, leaving you with more 0:10:47.670 --> 0:10:51.150 of it for your muscle fibers to receive. So the 0:10:51.170 --> 0:10:55.550 medication basically boosts the signals from your motor neurons. Both 0:10:55.600 --> 0:10:57.880 of these types of medications might be taken by mouth 0:10:58.200 --> 0:11:02.120 or injection. There are also a few types of infusions 0:11:02.200 --> 0:11:06.720 that may be prescribed. Donor antibodies can help remove or 0:11:06.780 --> 0:11:11.370 replace harmful antibodies in your system. There's also a class 0:11:11.390 --> 0:11:15.580 of treatments called monoclonal antibodies, which are antibodies produced in 0:11:15.640 --> 0:11:19.339 labs to target something specific and bind to it, thus 0:11:19.559 --> 0:11:23.980 accomplishing something. It's a clever concept because you can basically 0:11:24.040 --> 0:11:27.179 build a monoclonal antibody to target anything in our bodies. 0:11:28.210 --> 0:11:30.949 There are a few different ones used in myasthenia gravis 0:11:31.050 --> 0:11:34.550 that target different cells or proteins that are involved in 0:11:34.590 --> 0:11:38.510 the immune response that's preventing communication from your motor neurons 0:11:38.590 --> 0:11:42.350 to your muscle fibers. In cases where there is something 0:11:42.450 --> 0:11:45.470 weird with the thymus gland, like maybe there's a tumor there, 0:11:45.950 --> 0:11:49.890 surgery to remove the gland might be recommended. Of course, 0:11:50.130 --> 0:11:52.170 there's also a lot you can do at home to 0:11:52.250 --> 0:11:55.640 help boost muscle strength and alleviate some of that fatigue. 0:11:56.679 --> 0:11:59.540 People often feel fresher in the morning and tire as 0:11:59.580 --> 0:12:02.880 the day goes on. Work with that instead of against it, 0:12:03.260 --> 0:12:05.680 and take on more difficult tasks when you feel up 0:12:05.740 --> 0:12:09.540 for it. Make sure to avoid overheating, which can make 0:12:09.580 --> 0:12:13.469 symptoms worse. Take breaks or naps as you need to 0:12:13.550 --> 0:12:17.030 help restore some function. Be sure to get enough protein 0:12:17.080 --> 0:12:21.220 and carbs in your diet to fuel you. And regular exercise, 0:12:21.580 --> 0:12:23.840 though it may wear you out in the immediate moment, 0:12:24.320 --> 0:12:26.880 can help strengthen your muscles and give you more energy 0:12:26.940 --> 0:12:30.209 down the line. It really can help improve your mood, 0:12:30.400 --> 0:12:35.689 which is earnestly very annoying, but true. Your healthcare provider 0:12:35.710 --> 0:12:38.990 might recommend physical therapy and or a support group to 0:12:39.170 --> 0:12:42.830 help you figure out what works best. The symptoms of 0:12:42.880 --> 0:12:46.589 myasthenia gravis can be more or less severe. They can 0:12:46.710 --> 0:12:50.130 change by the day, week, or month. They can even 0:12:50.170 --> 0:12:54.050 go into remission for months or for years. Again, there 0:12:54.150 --> 0:12:57.770 is no cure, but with treatment, most people lead full 0:12:57.870 --> 0:13:01.870 and active lives. New research is improving our understanding of 0:13:01.910 --> 0:13:05.300 the condition all the time and leading to more effective treatments. 0:13:06.200 --> 0:13:09.790 But hey, I'm just a podcaster. If you or a 0:13:09.840 --> 0:13:13.520 loved one has been experiencing symptoms of muscle weakness, talk 0:13:13.540 --> 0:13:16.220 to a health care provider about it. And take care 0:13:16.260 --> 0:13:24.699 of yourself, okay? Today's episode was written by me, Lauren Vogelbaum. 0:13:25.500 --> 0:13:28.120 BrainStuff is a production of iHeart Podcasts and is produced 0:13:28.179 --> 0:13:31.720 by Tyler Klang. For more shows from iHeart Podcasts, visit 0:13:31.740 --> 0:13:35.240 the iHeart Radio app, Apple Podcasts, or wherever you listen 0:13:35.280 --> 0:13:36.140 to your favorite shows.