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Myasthenia Gravis (MG)

Questions

What is Myasthenia Gravis (MG)?

Myasthenia gravis (MG) is a neuromuscular disorder that causes weakness in the skeletal muscles that our body uses for movement. It occurs when communication between nerve cells and muscles becomes impaired. This impairment prevents crucial muscle contractions from occurring, resulting in muscle weakness.

Myasthenia gravis is characterized by weakness and rapid fatigue of any of the muscles under voluntary control. There’s no cure for myasthenia gravis, but treatment can help relieve signs and symptoms, such as weakness of an arm or leg muscles, double vision, drooping eyelids, and difficulties with speech, chewing, swallowing, and breathing. Though this disease can affect people of any age, it's more common in women younger than 40 and in men older than 60.

What are the Symptoms of Myasthenia Gravis?

The main symptom of MG is a weakness in the voluntary skeletal muscles, which are muscles under our control. The failure of muscles to contract normally occurs because they can’t respond to nerve impulses. Without proper transmission of the impulse, the communication between nerve and muscle is blocked and weakness results. Weakness associated with MG typically gets worse with more activity and improves with rest. Symptoms of MG can include:

 

  • Trouble talking
  • Problems walking up stairs or lifting objects
  • Facial paralysis
  • Difficulty breathing due to muscle weakness
  • Difficulty swallowing or chewing
  • Fatigue
  • Hoarse voice
  • Drooping of eyelids
  • Double vision

 

Not everyone will have every symptom, and the degree of muscle weakness can change from day today. The severity of the symptoms typically increases over time if left untreated.

What are the Causes of Myasthenia Gravis?

Antibodies

 

In myasthenia gravis, the immune system produces antibodies that block or destroy many of the muscles' receptor sites for a neurotransmitter called acetylcholine. With fewer receptor sites available, the muscles receive fewer nerve signals, resulting in weakness. Antibodies can also block the function of a protein called a muscle-specific receptor tyrosine kinase. This protein is involved in forming the nerve-muscular junction. Antibodies that block this protein can lead to myasthenia gravis.

 

Other causes

 

Some people 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, can play a part in the development of this condition. 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.

Diagnosis of Myasthenia Gravis.

Your doctor will perform a complete physical exam, as well as take a detailed history of your symptoms. They’ll also do a neurological exam. This may consist of:

 

  • Checking your reflexes
  • Looking for muscle weakness
  • Checking for muscle tone
  • Making certain your eyes move properly
  • Testing sensation in different areas of your body
  • Testing motor functions, like touching your finger to your nose

 

Other tests that can help your doctor diagnose the condition include:

  • Repetitive nerve stimulation test
  • Blood testing for antibodies associated with MG
  • Edrophonium (Tensilon) test: a drug called Tensilon (or a placebo) is administered intravenously, and you’re asked to perform muscle movements under doctor observation
  • Imaging of the chest using CT scans or MRI to rule out a tumor

Treatment Overview.

Many patients find, adequate sleep and rest, helpful in carrying on with their normal routine. Some Medications including some steroids are also prescribed by the doctors.

For patients with severe or life-threatening symptoms, Plasmapheresis and Immunoglobulin therapy can be administered in the hospital.

 

Physical Therapy

 

Rehabilitation alone or in combination with other forms of treatment can relieve or reduce symptoms for some people with MG. Studies show a clear benefit of strength training exercise program for a group of patients with mild to moderate MG. MG patients should find the optimal balance between physical activity and rest. Physical activity and physical training of low to medium intensity is recommended.

Physical exercise is well tolerated in patients with well-regulated Myasthenia Gravis. Aerobic Exercises and Mild Strength Training can be advised and should be supervised. Physical therapy interventions usually include exercises targeting balance, strength, and endurance impairments in a functional and progressively challenging manner. Throughout the course of physical therapy treatment, the patient can make meaningful improvements in imbalance, strength, and gait, stair climbing, and overall functional mobility of the body.