Myasthenia Gravis

Myasthenia gravis is a neuromuscular disorder that causes weakness and fatigue in the muscles that control voluntary movement in the body. The weakness is caused by a disruption in the communication between the muscles and the nerves that control them. Because the communication interference is caused by the patient’s own antibodies, myasthenia gravis is considered an autoimmune disease.

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Symptoms

While myasthenia gravis can affect any voluntary muscles in the body, most patients will first notice its effects in the muscles that control the movement of the eyes and eyelids. The weakening of these muscles can result in droopy eyelids, double vision and partial paralysis of eye movements. Every patient is different, however, and the symptoms can vary from person to person.

Other symptoms include:

  • Changes in facial expression
  • Fatigue in the neck and jaw
  • Difficulty swallowing
  • Impaired speech
  • Shortness of breath
  • Weakness in extremities (arms, legs, hands, feet)


Causes and Risk Factors

Myasthenia gravis occurs among people of all ethnicities and in both genders. While myasthenia gravis can affect people of all ages, adult women younger than 40 and men older than 60 appear to be the most commonly affected groups.

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Diagnosis

Diagnosis of myasthenia gravis generally starts with a physical and neurological examination, which may include testing for impaired eye movement, muscle weakness, poor coordination, difficulty with balance and altered muscle tone and strength.

The patient's physician may follow up with blood tests and other physical and neurological exams such as electrodiagnostics, which uses small electrical impulses applied along the leg, arm or face to measure the muscle reaction. Electromyography (EMG) allows doctors to observe the nerve-to-muscle communication disruption by inserting a thin wire electrode into the muscle and monitoring the electrical activity.

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Treatments

Symptoms of myasthenia gravis can be successfully controlled through a variety of treatments under the care of experienced physicians, such as those who make up Cedars-Sinai’s Neuromuscular Disorders Program team. Most patients with the condition have a normal life expectancy.

Patients may be prescribed medications from a group of drugs that work to reduce the antibodies within the patient’s body while increasing the presence of the neurotransmitter acetylcholine. The patient also might be prescribed an immunosuppressant medication, which can address the cause of the disease at its source by slowing down the body’s immune system.

Other treatments may include plasmapheresis, which moves the patient’s blood through a filtering system to remove the antibodies causing the communication disruption between the nerves and muscles. Intravenous immunoglobulin (IVIg) is another therapy that may control the symptoms of myasthenia gravis.

Patients with myasthenia gravis often have an abnormal thymus gland, and their physician may determine that removing the thymus gland surgically could help successfully control the symptoms of the disease. This surgery, known as a thymectomy, may successfully treat a patient’s symptoms to the point that they no longer need to take medication. Sometimes, however, the benefits of the surgery may not become noticeable until several years later, if at all.