Myasthenia Gravis Causes, Symptoms, Diagnosis, Treatment, Prevention, Home Remedies

Myasthenia Gravis Causes, Symptoms, Diagnosis, Treatment, Prevention


What is myasthenia gravis?


Myasthenia gravis is a chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal (voluntary) muscles of the body. The name myasthenia gravis, which is Latin and Greek in origin, literally means "grave muscle weakness." With current therapies, however, most cases of myasthenia gravis are not as "grave" as the name implies. In fact, for the majority of individuals with myasthenia gravis, life expectancy is not lessened by the disorder.

Myasthenia Gravis Causes, Symptoms, Diagnosis, Treatment, Prevention, Home Remedies
Myasthenia Gravis


The hallmark of myasthenia gravis is muscle weakness that increases during 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 muscles that control breathing and neck and limb movements may also be affected.

Causes of Myasthenia Gravis


Antibodies


Myasthenia Gravis Causes, Symptoms, Diagnosis, Treatment, Prevention, Home Remedies

Your nerves communicate with your muscles by releasing chemicals (neurotransmitters) that fit precisely into receptor sites on the muscle cells at the nerve-muscular junction.

In myasthenia gravis, your immune system produces antibodies that block or destroy many of your muscles' receptor sites for a neurotransmitter called acetylcholine (as-uh-teel-KOH-leen). With fewer receptor sites available, your muscles receive fewer nerve signals, resulting in weakness.

Antibodies may also block the function of a protein called a muscle-specific receptor tyrosine kinase (TIE-roh-seen KIE-nays). This protein is involved in forming the nerve-muscular junction. When antibodies block the function of this protein, it may lead to myasthenia gravis. Research continues to study how the antibodies inhibiting this protein are related to the development of myasthenia gravis.

Thymus gland


Researchers believe that the thymus gland, a part of your immune system situated in the upper chest beneath your breastbone, may trigger or maintain the production of the antibodies that block acetylcholine.

Large in infancy, the thymus is small in healthy adults. In some adults with myasthenia gravis, however, the thymus is abnormally large. Some people with myasthenia gravis also have tumors of the thymus (thymomas). Usually, thymomas aren't cancerous (malignant).

Other causes


Some people may have myasthenia gravis that isn't caused by antibodies blocking acetylcholine or the muscle-specific receptor tyrosine kinase. This type of myasthenia gravis is called antibody-negative myasthenia gravis. Antibodies against another protein, called lipoprotein-related protein 4, may play a part in the development of this condition.

Genetic factors also may be associated with myasthenia gravis.

Rarely, mothers with myasthenia gravis have children who are born with myasthenia gravis (neonatal myasthenia gravis). If treated promptly, children generally recover within two months after birth.

Some children are born with a rare, hereditary form of myasthenia, called congenital myasthenic syndrome.

Factors that can worsen myasthenia gravis


  • Fatigue
  • Illness
  • Stress
  • Extreme heat
  • Some medications — such as beta blockers, quinidine gluconate, quinidine sulfate, quinine (Qualaquin), phenytoin (Dilantin), certain anesthetics and some antibiotics

What is the role of the thymus gland in myasthenia gravis?


The thymus gland, which lies in the upper chest area beneath the breastbone, plays an important role in the development of the immune system in early life. Its cells form a part of the body's normal immune system. The gland is somewhat large in infants, grows gradually until puberty, and then gets smaller and is replaced by fat with age. In adults with myasthenia gravis, the thymus gland is abnormal. It contains certain clusters of immune cells indicative of lymphoid hyperplasia - a condition usually found only in the spleen and lymph nodes during an active immune response. Some individuals with myasthenia gravis develop thymomas or tumors on the thymus gland. Generally thymomas are benign, but they can become malignant.

The relationship between the thymus gland and myasthenia gravis is not yet fully understood. Scientists believe the thymus gland may give incorrect instructions about the production of the acetylcholine receptor antibodies, thereby setting the stage for the attack on neuromuscular transmission.

Symptoms and Complications of Myasthenia Gravis


The most common symptoms of myasthenia gravis are double vision (diplopia), drooping eyelids (ptosis), and muscle weakness that usually gets worse after exercise or at the end of the day and improves with rest.

The muscles around the eyes are particularly likely to be affected by myasthenia gravis, and eye problems are the first sign of the disease in about 40% of cases. Eventually, almost everyone with myasthenia gravis will experience eye symptoms. About 15% of people experience symptoms only around the eyes and nowhere else - this is called ocular myasthenia gravis.

Other common symptoms of this disease include:


  • blurred vision
  • difficulty chewing or swallowing
  • inability to stand up without using hands
  • unstable or unusual gait
  • weakness in the arms, legs, hands, and fingers
  • weakness in the muscles of facial expression
Many people find that their symptoms rise and fall in intensity many times in the course of a single day. Often, they follow a similar pattern each day, with muscle fatigue at its worst in the evening.

People who find it temporarily impossible to eat may have to be admitted to hospital and be fed intravenously. Of more immediate danger is when the disease causes difficulty in breathing. This is called a myasthenic crisis, and it's responsible for most of the small number of deaths due to myasthenia gravis. People with breathing problems must go to a hospital immediately.

When to see a doctor


Talk to your doctor if you have difficulty:

  • Breathing
  • Seeing
  • Swallowing
  • Chewing
  • Walking
  • Using your arms or hands
  • Holding up your head

Who gets myasthenia gravis?


Myasthenia gravis occurs in all ethnic groups and both genders. It most commonly affects young adult women (under 40) and older men (over 60), but it can occur at any age.

In neonatal myasthenia, the fetus may acquire immune proteins (antibodies) from a mother affected with myasthenia gravis. Generally, cases of neonatal myasthenia gravis are transient (temporary) and the child's symptoms usually disappear within few weeks after birth. Other children develop myasthenia gravis indistinguishable from adults. Myasthenia gravis in juveniles is common.

Myasthenia gravis is not directly inherited nor is it contagious. Occasionally, the disease may occur in more than one member of the same family.

Rarely, children may show signs of congenital myasthenia or congenital myasthenic syndrome. These are not autoimmune disorders, but are caused by defective genes that control proteins in the acetylcholine receptor or in acetylcholineterase.

How is myasthenia gravis diagnosed?


Because weakness is a common symptom of many other disorders, the diagnosis of myasthenia gravis is often missed or delayed (sometimes up to two years) in people who experience mild weakness or in those individuals whose weakness is restricted to only a few muscles.

The first steps of diagnosing myasthenia gravis include a review of the individual's medical history, and physical and neurological examinations. The physician looks for impairment of eye movements or muscle weakness without any changes in the individual's ability to feel things. If the doctor suspects myasthenia gravis, several tests are available to confirm the diagnosis.

A special blood test can detect the presence of immune molecules or acetylcholine receptor antibodies. Most patients with myasthenia gravis have abnormally elevated levels of these antibodies. Recently, a second antibody -- called the anti-MuSK antibody -- has been found in about 30 to 40 percent of individuals with myasthenia gravis who do not have acetylcholine receptor antibodies. This antibody can also be tested for in the blood. However, neither of these antibodies is present in some individuals with myasthenia gravis, most often in those with ocular myasthenia gravis.

The edrophonium test uses intravenous administration of edrophonium chloride to very briefly relieve weakness in people with myasthenia gravis. The drug blocks the degradation (breakdown) of acetylcholine and temporarily increases the levels of acetylcholine at the neuromuscular junction. Other methods to confirm the diagnosis include a version of nerve conduction study which tests for specific muscle "fatigue" by repetitive nerve stimulation. This test records weakening muscle responses when the nerves are repetitively stimulated by small pulses of electricity. Repetitive stimulation of a nerve during a nerve conduction study may demonstrate gradual decreases of the muscle action potential due to impaired nerve-to-muscle transmission.

Single fiber electromyography (EMG) can also detect impaired nerve-to-muscle transmission. EMG measures the electrical potential of muscle cells when single muscle fibers are stimulated by electrical impulses. Muscle fibers in myasthenia gravis, as well as other neuromuscular disorders, do not respond as well to repeated electrical stimulation compared to muscles from normal individuals.

Diagnostic imaging of the chest, using computed tomography (CT) or magnetic resonance imaging (MRI), may be used to identify the presence of a thymoma.

Pulmonary function testing, which measures breathing strength, helps to predict whether respiration may fail and lead to a myasthenic crisis.

Treatments and drugs for Myasthenia Gravis


Doctors use a variety of treatments, alone or in combination, to relieve symptoms of myasthenia gravis.

Medications for Myasthenia Gravis


Cholinesterase inhibitors

Medications such as pyridostigmine (Mestinon) enhance communication between nerves and muscles. These medications don't cure the underlying condition, but they may improve muscle contraction and muscle strength.

Possible side effects may include gastrointestinal upset, nausea, and excessive salivation and sweating.

Corticosteroids

Corticosteroids such as prednisone inhibit the immune system, limiting antibody production.

Prolonged use of corticosteroids, however, can lead to serious side effects, such as bone thinning, weight gain, diabetes and increased risk of some infections.

Immunosuppressants

Your doctor may also prescribe other medications that alter your immune system, such as azathioprine (Imuran), mycophenolate mofetil (CellCept), cyclosporine (Sandimmune, Neoral) or tacrolimus (Prograf).

Side effects of immunosuppressants can be serious and may include nausea, vomiting, gastrointestinal upset, increased risk of infection, liver damage and kidney damage.

Therapy for Myasthenia Gravis


Plasmapheresis (plaz-muh-fuh-REE-sis)

This procedure uses a filtering process similar to dialysis. Your blood is routed through a machine that removes the antibodies that block transmission of signals from your nerve endings to your muscles' receptor sites. However, the beneficial effects usually last only a few weeks.

After repeated treatments, it may be difficult for doctors to gain access to your vein. They may need to implant a long, flexible tube (catheter) into your chest to conduct the procedure.

Other risks associated with plasmapheresis include a drop in blood pressure, bleeding, heart rhythm problems or muscle cramps. Some people may also develop an allergic reaction to the solutions used to replace the plasma.

Intravenous immunoglobulin (IVIg)

This therapy provides your body with normal antibodies, which alters your immune system response.

IVIg has a lower risk of side effects than do plasmapheresis and immune-suppressing therapy. However, it may take about a week to start working, and the benefits usually last no more than three to six weeks.

Side effects, which usually are mild, may include chills, dizziness, headaches and fluid retention.

Surgery for Myasthenia Gravis


About 15 percent of the people with myasthenia gravis have a tumor in their thymus gland, a gland under the breastbone that is involved with the immune system. If you have a tumor, called a thymoma, doctors will conduct surgery to remove your thymus gland (thymectomy).

If you don't have a tumor in the thymus gland, surgery to remove the thymus gland may improve your myasthenia gravis symptoms. It may eliminate your symptoms, and you may be able to stop taking medications for your condition. However, you may not notice the benefits of a thymectomy for several years, if at all.

A thymectomy may be performed as an open surgery or as a minimally invasive surgery.

In an open surgery, your surgeon splits the central breast bone (sternum) to open your chest and remove your thymus gland.

Surgeons may perform minimally invasive surgery to remove the thymus gland, which uses smaller incisions. Minimally invasive thymectomy may include:

  • Video-assisted thymectomy. In one form of this surgery, surgeons make a small incision in your neck and use a long thin camera (video endoscope) and small instruments to visualize and remove the thymus gland through your neck.

Alternatively, surgeons may make a few small incisions in the side of your chest. Doctors use a video scope and small instruments to conduct the procedure and remove the thymus gland through these incisions.

  • Robot-assisted thymectomy. In a robot-assisted thymectomy, surgeons make several small incisions in the side of your chest. Surgeons conduct the procedure to remove the thymus gland using a robotic system, which includes a camera arm and mechanical arms.
Benefits of these procedures may include less blood loss, less pain, lower mortality rates and shorter hospital stays compared with open surgery.

Your doctor will determine which treatment may be most appropriate for you based on several factors, including:

  • Your age
  • Severity of your condition
  • Location of muscles affected
  • Other existing medical conditions

Prevention for Myasthenia Gravis


Because the cause of myasthenia gravis is unknown, there is no way to prevent it. However, once the disease has developed, there may be ways to prevent episodes of worsening symptoms or flare-ups:

  • Give yourself plenty of rest.
  • Avoid strenuous, exhausting activities.
  • Avoid excessive heat and cold.
  • Whenever possible, avoid exposure to any kind of infection, including colds and influenza (flu). You should be vaccinated against common infections, such as influenza.
  • Work with your doctor to monitor your reactions to prescription medications. Some drugs commonly prescribed for other problems, such as infections, heart disease or hypertension, may make myasthenia gravis worse. You may need to choose alternative therapies or avoid some medications entirely.

Lifestyle and home remedies for Myasthenia Gravis


Supplementing your medical care with these approaches may help you make the most of your energy and cope with the symptoms of myasthenia gravis:

Adjust your eating routine


Try to eat when you have good muscle strength. Take your time chewing your food, and take a break between bites of food. Small meals eaten several times a day may be easier to handle. Also, try eating mainly soft foods and avoid foods that require more chewing, such as raw fruits or vegetables.

Use safety precautions at home


Install grab bars or railings in places where you may need support, such as next to the bathtub or next to steps. Keep your floors clean, and move any loose rugs out of areas where you may walk. Outside your home, keep paths, sidewalks and driveways cleared of leaves, snow and other potential debris that could cause you to stumble.

Use electric appliances and power tools


You may lose energy quickly when conducting tasks. Try using an electric toothbrush, electric can openers and other electrical tools to perform tasks when possible.

Wear an eye patch


Consider wearing an eye patch if you have double vision, as this can help relieve the problem. Try wearing the eye patch while you write, read or watch television. Periodically switch the eye patch to the other eye to help reduce eyestrain.

Plan


If you have chores, shopping or errands to do, plan the activity to coincide with the time at which you have the most energy. Also, try to reduce extra walking in your house when working on projects, as it may reduce your energy.


What are myasthenic crises?


A myasthenic crisis occurs when weakness affects the muscles that control breathing, creating a medical emergency and requiring a respirator for assisted ventilation. In patients whose respiratory muscles are weak, crises - which generally call for immediate medical attention - may be triggered by infection, fever, an adverse reaction to medication, or emotional stress.

What is the prognosis?


With treatment, the outlook for most patients with myasthenia gravis is bright: they will have significant improvement of their muscle weakness and they can expect to lead normal or nearly normal lives. Some cases of myasthenia gravis may go into remission temporarily and muscle weakness may disappear completely so that medications can be discontinued. Stable, long-lasting complete remissions are the goal of thymectomy. In a few cases, the severe weakness of myasthenia gravis may cause a crisis (respiratory failure), which requires immediate emergency medical care.