Myasthenia gravis, or MG is an autoimmune disease, which means that the body’s immune system mistakenly attacks it. In the case of myasthenia gravis, the immune system attacks the muscles and the nerves that control them. These muscles are under the person’s control, such as the muscles that move the arms and legs. Though it is like other autoimmune diseases in that it is found more often in women, MG also affects men. Myasthenia gravis usually strikes women under 40 and men over 60 and occurs in 20 per 100,000 people. As of 2018 there is no cure for myasthenia gravis.
The nerves that control the muscles are in turn controlled by a neurotransmitter called acetylcholine. A neurotransmitter is a chemical that sends messages to and from the nerve cells. In the case of myasthenia gravis, the body produces antibodies that destroy the acetylcholine receptors in the nerves. Some doctors believe these antibodies are made in the patient’s thymus gland, which is found in the chest. This gland is usually small and sometimes nonexistent in adults, but in people with myasthenia gravis it’s large and might contain benign tumors. Sometimes, when the thymus is removed the symptoms and signs of myasthenia gravis resolve.
1. Muscle Weakness
When muscles are weak, the patient feels like they don’t have the strength to do ordinary tasks such as walking, writing or even picking up lightweight objects. Since the muscles in the face are affected, the patient may be expressionless. The muscle weakness of myasthenia gravis gets worse the more the patient uses their muscles but improves when they rest. At first, the muscle weakness is intermittent, but it gets worse over time. Muscle weakness and other symptoms are at their very worst a few years after the person starts complaining of the signs and symptoms of myasthenia gravis.
2. Eyelid Drooping
This is called ptosis and occurs when the disease affects the muscles that control the eyelids. This symptom is one of the first to appear when the patient contracts myasthenia gravis. The upper eyelid droops, sometimes to the point where it completely or partially covers the eye and interferes with vision. Ptosis also makes it difficult to blink. The extent of the droop sometimes seems to depend the time of day. If the condition persists, it may lead to lazy eye in children and a decreased field of vision in adults. The patient may also suffer headaches from this sign of myasthenia gravis.
3. Arm Weakness
Myasthenia gravis tends to affect the arms more severely than it affects the legs. When it attacks the arms the patient finds it hard to hold their arms up. As with other muscle groups, the weakness in the arm gets worse the more the patient tries to use their arms. Strength returns, at least temporarily, when they rest. Weakness in the arms is not the same as fatigue in the arms. A person who has arm weakness simply can’t get their arms to move what they used to be able to move with ease. There are also periods when the arm weakness is gone, and the patient’s strength is almost normal. Conversely, there are times when the arms are weaker than ever. This is called an exacerbation.
4. Difficulty Swallowing
When myasthenia gravis attacks the muscles that control swallowing, the patient finds that eating and drinking are difficult and even painful. The muscles of the mouth, throat and esophagus are involved. The patient drools, chokes on their food or has a coughing fit while they are trying to eat. Food and liquid may come out of the patient’s nose. They may feel like something is stuck half-way down their throat, or they may feel a sensation of pressure in the middle of their chest. If the problem persists, the patient may develop bad breath and may even become malnourished and dehydrated because they can’t take in enough nutrition.
5. Double Vision
Double vision, when the patient sees two images of the same thing, is called diplopia. The patient may see double in the vertical or the horizontal plane, and the problem goes away for a while when they close one eye. Double vision happens because MG affects the muscles of the eye. In order for a person to see normally, the eyes have to align precisely, which means that the muscles that control them need to work correctly. If the eyes align, the brain then creates a single image. If the eyes are not aligned, the brain can’t create a single image out of what the two eyes are looking at.
6. Fatigue
Fatigue is a feeling of exhaustion that won’t let up, even after the person sleeps. Fatigue robs the person of their motivation and their desire to either start a project or an action and to see it through to the end. Some medical researchers believe that the fatigue specific to myasthenia gravis is a result of how the disease affects the autonomic nervous system. This is the part of the nervous system that controls bodily functions that the patient doesn’t consciously control, unlike their arms, legs and eyes. These functions include the heartbeat and the digestion. Researchers believe that this is because the acetylcholine receptors that control both the muscles and the nervous system are similar and come under attack by the immune system.
7. Shortness Of Breath
The struggle of the MG patient to catch their breath is a result of the disease affecting the respiratory muscles that help the lungs take in and expel air. Some patients have a fluctuating shortness of breath or have dyspnea whether they are exerting themselves or resting. Other patients have such shortness of breath that they cannot finish a sentence. If the dyspnea of myasthenia gravis becomes very severe, it must be considered a medical emergency, and the patient needs to see a doctor as soon as possible. This is called a myasthenia crisis.
8. Impaired Voice
Since the muscles that control the vocal cords are attacked by myasthenia gravis, the patient may have an altered voice, or dysphonia. The speech may become slurred, which is dysarthria. The voice may so soft that a person has to come close to hear what the patient is saying. Their voice may simply wear out, or the patient can no longer control its tone or pitch. The voice can also have a nasal quality. What happens to the voice depends on which muscles in the patient’s throat, lungs or face are affected. Impaired speech may seem less serious than the other symptoms of MG, but it can affect the patient’s social life and self-esteem.
