Myasthenia Gravis

Myasthenia gravis is a disease that causes periods of muscle weakness Weakness Weakness is a loss of muscle strength. If you have weakness, you can’t move a muscle normally, even when you’re trying as hard as you can. Weakness is different than being tired ( fatigued)... read more .

Myasthenia gravis is an autoimmune disease Autoimmune Diseases "Auto" is a medical term for "self." The immune system is your body's defense system. It helps protect you from illness and infection. The immune system usually attacks invading bacteria, viruses... read more . 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:

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.

If you're diagnosed with myasthenia gravis, doctors will do imaging tests such as an MRI Magnetic Resonance Imaging (MRI) MRI is a test that uses a machine with a powerful magnet to make pictures of the inside of your body. A computer records changes in the magnetic field around your body. The computer then uses... read more (magnetic resonance imaging) or CT scan Computed Tomography A CT scan uses a large machine shaped like a large donut to take x-rays from many angles. A computer then takes the x-rays and creates many detailed pictures of the inside of your body. Each... read more to check for problems with your thymus gland.

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.