Myasthenia gravis is one of the rarest and most concerning muscular disorders. Here's why.
When it comes to muscular diseases, most of us have heard of especially common ones like muscular dystrophy and Lou Gehrig's disease. But one of the rarest muscular disorders is also one of the most concerning. It's called myasthenia gravis and affects only about 37 out of every 100,000 people in the United States.
Despite being so rare, "improved awareness and diagnostic techniques have led to more frequent diagnoses and better care," says Sharon Hesterlee, chief research officer of the Muscular Dystrophy Association in Chicago.
Here's what myasthenia gravis is, what causes it, and what treatment options exist if you or someone you love is affected.
What is myasthenia gravis?
Myasthenia gravis, or MG, is "a chronic autoimmune neuromuscular disorder that causes muscle weakness and fatigue," says Hesterlee. It occurs "when a person’s immune system is essentially attacking their own body," adds Sara Weidmayer, a practicing physician at the LTC Charles S. Kettles VA Medical Center in Michigan, who has co-authored MG research. The disease disrupts communication between nerves and muscles, she explains, by interfering with a neurotransmitter called acetylcholine, which travels between nerves and muscles and affects muscle contraction.
Because of this, Hesterlee says the disorder "can affect voluntary muscles − particularly those that control eye and eyelid movement, facial expressions, swallowing and breathing." It can cause vision problems, drooping eyelids, and difficulty walking, talking, chewing tough food, and even limit your ability to lift your arms above their head.
Severe cases of MG can also affect breathing muscles, which Weidmayer says can lead to shortness of breath or difficulty breathing and may become a medical emergency.
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What causes myasthenia gravis?
Because MG is an autoimmune disorder, it's caused by dysfunction within the immune system − though the source of the dysfunction is not entirely known or understood. Still, it's thought that "genetic predisposition and environmental factors may contribute," says Hesterlee. Some such environmental triggers could include infections, chronic stress, or taking certain medications.
In some cases, abnormalities in a small organ called the thymus gland "also appear to play a role in triggering or exacerbating MG," Hesterlee adds.
No matter what's behind the disorder, it's known that MG is not contagious, nor are there any known ways it can be prevented.
What treatment is there for myasthenia gravis?
Hesterlee explains that MG is diagnosed through physical and neurological exams, electromyography evaluations that look at issues with the connection between muscles and nerves, and CT or MRI scans that are capable of detecting neurological dysfunction associated with the disorder. Blood tests are also often used to identify associated antibodies. "About 80% of patients with MG are positive" for the antibody behind the immune system dysfunction, says Weidmayer.
While there is no cure for MG, once the chronic disorder is diagnosed, it's often treated by administering one of five FDA-approved medications.
Hesterlee says that intravenous treatments are also sometimes recommended to remove or neutralize associated antibodies; and some patients undergo the surgical removal of the thymus gland in an operation called a thymectomy. Weidmayer says that some patients also receive steroids, immunosuppressants, and plasma exchange, as recommended by a specialist.
"Treatment options focus on managing symptoms and improving quality of life," says Hesterlee. "With appropriate treatment, many people with myasthenia gravis can manage their symptoms effectively and can still lead active lives."
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