A look at symptoms, diagnosis, treatments and current MDA-supported research into this complex autoimmune disorder
In recognition of June being National Myasthenia Gravis Awareness Month, MDA is examining the disease from several perspectives. This article offers an overview of signs, symptoms, diagnosis and treatments for myasthenia gravis (MG), as well as information on drugs that people with MG should avoid.
MDA’s commitment to MG research over the past five years includes 41 research grants with a total funding commitment of more than $8.5 million. Currently, MG is the focus of six MDA-funded research projects. These projects, described below, range from identification of genetic causes and molecular underpinnings to development of potential new treatments.
MG is part of a large class of diseases known as "autoimmune," or "self-immune," disorders, in which the body's immune system deploys antibodies (proteins that identify and attack bacteria and other foreign substances) to attack its own tissues.
In MG, the attack occurs at the neuromuscular junction (NMJ) — the connection between muscle and nerve.
In most cases of MG, the immune system targets the acetylcholine receptor (AchR), the part of a muscle cell that receives signals from a nerve cell. The receptors are destroyed faster than the body can replace them. Another form of the disease is characterized by an attack on muscle-specific tyrosine kinase (MuSK), a protein that helps organize acetylcholine receptors on the muscle cell.
It remains unclear what triggers the disease, but the list of possibilities includes autoimmune responses to viruses or bacteria, and tumors or hyperactivity in the thymus gland, located in the upper chest.
Signs and symptoms
Some 10 to 15 out of every 100,000 Americans have MG, which most commonly affects women between the ages of 30 and 40, and men in their 50s or 60s. In some cases, it affects children. Symptoms vary in type and severity, but generally involve weakness and fatigue of the body's voluntary muscles.
Early symptoms often include weakness in the muscles that control movement of the eyes and eyelids, sometimes leading to partial paralysis of eye movements, double vision and droopy eyelids.
Weakness in the neck and jaw, called "bulbar" weakness, also can occur early in MG. Such weakness can make it difficult to talk, chew, swallow and hold up the head. It also may affect speech, cause choking, and make eating unpleasant or difficult.
Typically, as the disease progresses, weakness spreads from the face and neck to the upper limbs, the hands and then the lower limbs. People with MG may find it difficult to raise their arms over their head or stand up from a sitting position. They may lose the ability to walk long distances and climb stairs, and weakness in the arms and hands often leads to an inability to grip or hold on to heavy objects.
In severe cases, weakness may spread to the muscles in the chest that control breathing. This can lead to respiratory distress or failure ("myasthenic crisis"), and the need for assisted ventilation.
Diagnosis of the disease is made via review of the individual's medical history, and physical and neurological examinations. Confirmatory tests may include:
There are a number of medications designed to help control MG, and with treatment many experience significant improvement of their muscle weakness. In some cases, MG may go into temporary remission and muscle weakness may disappear, allowing for the discontinuation of medication.
People with MG also should be aware that many prescription drugs can worsen their disease. Those with MG should avoid:
Current MDA-funded research
MDA currently funds six worldwide research projects focused on MG. These projects, listed below, are helping to reveal numerous facets of the disease, from the identification of genetic causes and molecular underpinnings to a number of specific treatment strategies.
MG clinical trials and advocacy
For information about MG-related clinical trials, visit ClinicalTrials.gov, click on "Search for Clinical Trials," and enter "myasthenia gravis" in the search box. You always should discuss any interest in participation in a clinical trial with your MDA physician.
To find out how you can help raise awareness for MG, learn about key legislative issues that may affect you or family members with MG, or get involved in the search for a cure, visit MDA's advocacy home page or contact your local health care service coordinator by using MDA’s office locator.