Just Breathe: Life with Charcot Marie Tooth Disease and Neuromuscular Respiratory Failure
Updated: Jan 18, 2021
When I was diagnosed with Charcot Marie Tooth Disease at 29, they said it was not life altering. I was fortunate to have as my physician the world’s foremost authority on the disease. Even he was adamant that the disease is not life-altering. It’s been 18 years since being diagnosed. While they still say that, despite all of the advances, the disease is not life-altering, life is exactly what the disease alters, and the disease changes everything. Everything. The most recent manifestation is my breathing and respiratory impairment. This one has completely changed life as I knew it. And, this is the one that ticks me off.
Throw It All Away Throw out everything you know about breathing and respiratory issues. Conventional wisdom of respiratory issues does not apply to me or others like me. Let me explain how and why. My breathing is such that I run out of air easily in mid-sentence, and mid-word if I keep on pushing. I struggle to get a full breath, and I especially struggle to expel. The most remedial of tasks destroys my breathing, and it can take hours to recover. Laying down causes a significant reduction in my respiratory function. My voice gets weak quickly. This causes my articulation to disappear, and I can have difficulty having the muscle strength to form and speak words. This further erodes my breathing issues because my vocal cords essentially collapse, thereby affecting airflow. My CMT has caused CMT related respiratory failure, or what is referred to as neuromuscular respiratory failure. The mechanics of breathing, in a nutshell, are such that the diaphragm contracts and moves downward, causing a low-pressure area within the chest. Because air moves from high pressure to low pressure, and the pressure outside the chest is now higher than inside the chest, air moves in and fills the lungs. To facilitate the lungs filling and expanding, the intercostal muscles (the rib cage), contract and this expands the rib cage. We know this simply as inhaling, inhalation, or inspiration. To exhale, the intercostals and diaphragm relax, causing the air to be pushed out, and the abdominal muscles help. This is also referred to as expiration. The mechanism by which this takes place is referred to as the respiratory pump.This is an oversimplified explanation, but it’s essentially how breathing occurs. Conventional wisdom tells us that when we experience shortness-of-breath during exertion, physical activity, speaking, etc., the lungs and/or bronchial tree are/is trash, as in COPD or chronic bronchitis, for example. The solution is to hit the inhalers to open the inflamed/restricted/obstructed airways, and monitor O2/give O2 therapy as needed. Continue treatment and management, and move on. This is not the case though when neuromuscular disease is causing the respiratory failure. Breathing occurs because of the actions of muscles. All muscles do their thing at the command of the brain via motor neurons and nerves. The nervous system is made up of two structural components - the Central Nervous System (brain, brain stem, spinal cord) and the Peripheral Nervous System (every nerve that’s outside the spinal cord and brain, for the most part). The most important muscle for breathing, the diaphragm, is controlled by the phrenic nerve. Other components, such as larynx, pharynx, and ancillary respiratory muscles are controlled by branches of the vagus nerve, which is the longest cranial nerve. CMT affects these nerves, thereby affecting the breathing muscles. Charcot Marie Tooth Disease causes damage to the Peripheral Nervous System. I have CMT1A. The damage to the nerves that my subtype causes results in the speed at which signals travel through the nerves to be slowed. In my case, as is the typical with CMT1A, the speeds are 1/3 of normal (normal is understood to be between 50 and 60 meters/sec, mine is 19 m/sec). This reduction causes muscles to weaken and to atrophy, and this atrophy is progressive over time. What does all of this mean though?
When the Lungs are Good Remember me saying to throw out the conventional wisdom? With me, my lungs and bronchial tree are top-notch. Test after test after test indicates and confirms that I have no signs of lung disease. Despite having been a smoker (I’m one-year totally clean), all tests indicate I dodged a bullet. My issues are that the muscles used for breathing are weakened, and they get weaker with use - the more/faster/harder I try to breath, the weaker the respiratory muscles get. Testing confirms this. Inhalers don’t fix it. O2 remains tip-top, and giving O2 would make things worse by causing oxygen induced hypercapnia. My shortness-of-breath does not cause coughing, like one would expect. My lungs and airways aren’t restricted - airway and/or lung restriction/obstruction is what causes the coughing with shortness-of-breath. When I’m having breathing difficulties, it’s because my muscles are weakened, they are tired (fatigable weakness), and they just can’t do their job. Conventional wisdom does not apply. My diaphragm is weak and does not move well. Because our bodies compensate automatically for impairments, my other breathing muscles are activated in ways that they normally would not be. But, they, too, are already weakened, and they get more weakened from the fatigability of operating in ways they normally wouldn’t. When my voice weakens, the muscles at the top of the airway that control the vocal cords and keep the airway open can’t do their job, and the vocal cords collapse, thereby closing off the airway. Inhalers do not fix this muscle problem. Because I frequently struggle to take a full breath, I can’t always accomplish a good enough gas exchange to filter out everything we need to expel, like CO2 and CO. We can only expel the volume we inhale. If my inspiratory volume is low, then I can’t expel enough volume for filtering CO2. This causes CO2 levels to rise, and can get kind of bad. O2 levels stay good though. When physical activity requires an increase in respiration rate, I don’t have the muscle strength and endurance to keep up with demand. Again, my lungs are top-notch, but the muscles used for breathing are not. Breathing becomes a huge struggle. Not because of restrictions/obstructions, but because the muscles can’t do their job properly. The only thing I can do about it is rest, or throw on the ventilator if it’s bad enough. And, it’s bad enough way more than I care for it to be. Why do these things tick me off though? Just Add Water
There is no viable treatment or cure for CMT. There is only trying to manage its presentations. The disease is only progressive. Things will only get worse. There is no way to stop it. There’s no way to forecast or predict either. The variability in presentation amongst the patient population is mind boggling. A year ago, my breathing wasn’t too bad. Comparatively though, today, it’s a difference of night and day.
There are many with CMT whose diaphragm is paralyzed, whether partially or fully. I’m fortunate that I still have some use of mine. How long before I lose it is anybody’s guess. What is this crap really like though? The only comparison I’ve come up with to accurately depict what the breathing issues feel like is a fairly simply one.
Lay down flat on the floor with no pillow. Have somebody gently place on your chest a 32ct case of bottled water, and breathe normally. For most, this shouldn’t be too bad. Now, have your somebody gently place a second 32ct case of bottled water across your abdomen, and breathe normally. Most are going to be struggling a little within a couple of minutes. Lay there, until it gets a little bit difficult for you and you have to get the cases of water off of you in order to catch your breath. Now, imagine that those cases of water are always there, and that difficulty is always there, and gets worse with system demand. That is what my normal is. Now, imagine that that’s what it’s like when you’re standing, but then you lay down and add the cases of water.
Things could always be worse. There are people who are significantly more severely affected than I am. However, that doesn’t mean that I have to like where I’m at with mine or that I have to be ok with where mine’s at. Because, you know what? I’m not. I hate it and it ticks me off. It’s rude and uncalled for.