Myasthenia gravis is a disease that causes periods of muscle weakness.
Myasthenia is an autoimmune disease that keeps your nerves from passing signals to your muscles
Myasthenia gravis happens most often in women ages 20 to 40 and men ages 50 to 80, but it can happen at any age
Your muscles become unusually tired and weak after exercise
You have drooping eyelids and double vision
Doctors prescribe medicines that temporarily strengthen your muscles and help you feel better
Medicines that slow down your immune system often help
Myasthenia gravis is an autoimmune disease. Your immune system is your body's defense system. It helps protect you from illness and infection. But in an autoimmune disease, your immune system attacks parts of your own body.
Your nerves send signals to your muscles to move. Proteins called receptors in your nerves and muscles receive the signals. In myasthenia gravis, your immune system attacks a receptor in your muscles and the signals to move the muscle can’t get through.
Doctors don’t know exactly why this happens, but they think it may involve a problem with the thymus gland. The thymus gland, located in your chest, is part of your immune system. Many people with myasthenia gravis have an unusually large thymus gland or a benign tumor in it.
You're more likely to have myasthenia gravis if you have another autoimmune disease, such as:
Myasthenia gravis may start after:
Sometimes, babies born to mothers with myasthenia gravis have muscle weakness for a few days or weeks after birth.
The main symptom of myasthenia gravis is:
Your muscles work normally when you start to use them but then get weaker as you keep using them. For example, if you try to blink rapidly, at first you’ll be able to. Then after about 10 seconds, your blinking gets slower and slower.
Other symptoms of weakness include:
Double vision because of weak eye muscles
Weakness in your arms or legs, hands, or neck
Extreme tiredness after using your muscles
Weakness that's worse when it's hot out, less severe in cool weather
Problems talking, chewing, swallowing, or talking
Sometimes, problems breathing
Myasthenia affects only your muscles. Even though you're weak, you still have all the feeling in your body and your mind is clear.
Doctors will ask about your symptoms and do an exam.
If you're weak, doctors may see how your symptoms respond to things that can make myasthenia better. For example, if you have droopy eyelids, doctors may:
If doctors suspect myasthenia after this, they do other tests such as:
Electromyography involves putting small needles in nerves (usually in your arm). The needles record the electrical activity of your muscles. They also record how your muscles and nerves respond to a mild electric shock.
Doctors may give you medicines to:
Medicines to improve your strength act like the chemicals your nerves use to send signals to your muscles. But these medicines work for only a few hours. Also, the medicines don't stop the disease, they just help your symptoms. Doctors adjust the dose based on how you feel. But getting too much medicine can make you weaker. So it's sometimes hard for doctors to tell whether your disease is worse and you need more medicine or whether you're having side effects and need less medicine.
Treatments that slow down your immune system include:
If you have a tumor in your thymus gland, doctors remove the gland. This often helps the myasthenia. Taking out the thymus sometimes helps even if there isn't a tumor.