Myasthenia Gravis

Myasthenia Gravis is an immune system disorder. It cause damage to the neuromuscular system. The body's immune system attacks the muscle receptors that communicate with nerve signals. The damaged receptors are no longer able to respond to the neurotransmitter acetylcholine. This results in chronic muscle weakness in different parts of the body.

Causes

The cause of Myasthenia Gravis is unknown. However, genetics play a role. Some newborns of mothers with Myasthenia Gravis are born with symptoms of the disease that usually disappear within a few weeks of birth.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.
  • Sex: Women
  • Age: onset between 20 and 40
  • History of other autoimmune diseases
  • Family history of myasthenia gravis

Symptoms

The main symptom of Myasthenia Gravis is chronic, fluctuating muscle weakness. This muscle weakness worsens with activity and improves with rest. Over time, the muscle weakness tends to get worse.
This muscle weakness can lead to:
  • Drooping eyelids
  • Blurred or double vision
  • Loss of normal facial expressions
  • Difficulty swallowing
  • Difficulty speaking clearly
  • Arm and leg impairment
Less common symptoms include:
  • Paralysis (usually temporary)
  • Difficulty breathing

Diagnosis

The doctor will ask about your symptoms and medical history, and perform a physical exam. This will include an evaluation of the nervous system. Initial diagnosis is based on the symptoms and exam findings.
One or more of the following is used to confirm the diagnosis:
  • Blood tests – to detect antibodies to acetylcholine receptors
  • Edrophonium test – a drug test that often temporarily relieves symptoms
  • Electromyography or other nerve stimulation tests
  • CT scan or MRI scan – to look for problems with the thymus gland, which can play a role in myasthenia gravis
  • Lung function tests – used in severe cases involving respiration

Treatment

There is no cure for Myasthenia Gravis. Treatment is aimed at controlling symptoms.
Treatments include:
Medication - to control the symptoms of myasthenia gravis. Careful monitoring is required since they tend to produce side effects and lose their effectiveness overtime. Medications include:

  • Pyridostigmine or neostigmine – controls symptoms by increasing the level of acetycholine
  • Corticosteroids or other immunosuppressive drugs – reduces damage to muscle receptors by suppressing the immune system
Plasmapheresis – removes toxic substances from the blood including abnormal antibodies that cause myasthenia gravis
Respirator – artificial ventilation to support the breathing of patients whose respiratory muscles are significantly involved.
Surgery – to remove the thymus gland. This tends to be most effective in younger patients with generalized weakness.

Prevention

There are no guidelines for preventing Myasthenia Gravis because the cause is unknown.