How does myasthenia gravis affect muscle contraction

What research is being done? Where can I get more information? Myasthenia gravis is a chronic autoimmune, neuromuscular disease that causes weakness in the skeletal muscles that worsens after periods of activity and improves after periods of rest. These muscles are responsible for functions involving breathing and moving parts of the body, including the arms and legs. Available treatments can control symptoms and often allow people to have a relatively high quality of life.

Most individuals with the condition have a normal life expectancy. The hallmark of myasthenia gravis is muscle weakness that worsens after periods of activity and improves after periods of rest.

Certain muscles such as those that control eye and eyelid movement, facial expression, chewing, talking, and swallowing are often but not always involved in the disorder. The onset of the disorder may be sudden, and symptoms often are not immediately recognized as myasthenia gravis. The degree of muscle weakness involved in myasthenia gravis varies greatly among individuals.

Sometimes the severe weakness of myasthenia gravis may cause respiratory failure, which requires immediate emergency medical care. A myasthenic crisis is a medical emergency that occurs when the muscles that control breathing weaken to the point where individuals require a ventilator to help them breathe. It may be triggered by infection, stress, surgery, or an adverse reaction to medication. Approximately 15 to 20 percent of people with myasthenia gravis experience at least one myasthenic crisis.

However, up to one-half of people may have no obvious cause for their myasthenic crisis. Certain medications have been shown to cause myasthenia gravis.

However, sometimes these medications may still be used if it is more important to treat an underlying condition. Myasthenia gravis is an autoimmune disease, which means the immune system—which normally protects the body from foreign organisms—mistakenly attacks itself.

Myasthenia gravis is caused by an error in the transmission of nerve impulses to muscles. It occurs when normal communication between the nerve and muscle is interrupted at the neuromuscular junction—the place where nerve cells connect with the muscles they control.

Neurotransmitters are chemicals that neurons, or brain cells, use to communicate information. Normally when electrical signals or impulses travel down a motor nerve, the nerve endings release a neurotransmitter called acetylcholine that binds to sites called acetylcholine receptors on the muscle.

The binding of acetylcholine to its receptor activates the muscle and causes a muscle contraction. This is most often caused by antibodies to the acetylcholine receptor itself, but antibodies to other proteins, such as MuSK Muscle-Specific Kinase protein, also can impair transmission at the neuromuscular junction.

The goal of treatment is to manage symptoms and control the activity of your immune system. Corticosteroids and immunosuppressants can be used to suppress the immune system. These medications help minimize the abnormal immune response that occurs in MG.

Additionally, cholinesterase inhibitors, such as pyridostigmine Mestinon , can be used to increase communication between nerves and muscles. Removal of the thymus gland, which is part of the immune system, may be appropriate for many patients with MG. Once the thymus is removed, patients typically show less muscle weakness. According to the Myasthenia Gravis Foundation of America , between 10 and 15 percent of people with MG will have a tumor in their thymus.

Tumors, even those that are benign, are always removed because they may become cancerous. Plasmapheresis is also known as a plasma exchange.

This process removes harmful antibodies from the blood, which may result in an improvement in muscle strength. Plasmapheresis is a short-term treatment. The body continues to produce the harmful antibodies and weakness may recur. Plasma exchange is helpful before surgery or during times of extreme MG weakness. Intravenous immune globulin IVIG is blood product that comes from donors. These treatments cannot cure MG. Some individuals may go into remission, during which treatment is not necessary.

Tell your doctor about any medications or supplements you take. Some drugs can make MG symptoms worse. One of the most dangerous potential complications of MG is myasthenic crisis. This consists of life-threatening muscle weakness that can include breathing problems.

Talk with your doctor about your risks. If you start to have trouble breathing or swallowing, call or go to your local emergency room immediately. Individuals with MG are at a higher risk of developing other autoimmune disorders such as lupus and rheumatoid arthritis. The long-term outlook for MG depends on a lot of factors.

Some people will only have mild symptoms. Others may eventually become confined to a wheelchair. Talk to your doctor about what you can do to minimize the severity of your MG. An EMG can detect abnormal electrical muscle activity due to diseases and neuromuscular conditions. Single-fiber EMG. This is a very special EMG. It records the transmission of nerve to muscle.

Treatment will depend on your symptoms, age, and general health. It will also depend on how severe the condition is. There is no cure for myasthenia gravis. But the symptoms can often be controlled. Myasthenia gravis is a lifelong health problem. It may go into remission for extended periods. Early detection is the key to managing the condition. The goal of treatment is to increase muscle function and prevent swallowing and breathing problems. Most people with this condition can improve their muscle strength and lead normal or near normal lives.

In more severe cases, help may be needed for breathing and eating. This is surgical removal of the thymus gland. The role of the thymus gland in myasthenia gravis is not fully understood.

They also tend to have fewer problems, such as needing a hospital stay, within 3 years after the surgery. This procedure removes abnormal antibodies from the blood and replaces the blood with normal antibodies from donated blood.

It is given intravenously IV. The most serious complications of myasthenia gravis is myasthenic crisis. This is a condition of extreme muscle weakness, particularly of the diaphragm and chest muscles that support breathing. Breathing may become shallow or ineffective. The airway may become blocked because of weakened throat muscles and a build up of secretions. Myasthenic crisis may be caused by a lack of medicine or by other factors, such as a respiratory infection, emotional stress, surgery, or some other type of stress.

In severe crisis, a person may have to be placed on a ventilator to help with breathing until muscle strength returns with treatment.