Myasthenia Gravis: What You Need To Know

Myasthenia gravis is a rare, chronic neuromuscular disorder that can cause a person’s muscles to weaken, affecting their face muscles, diaphragm and throat. The disorder can affect people’s ability to make facial expressions, chew, talk clearly, swallow, lift their arms and walk. 

While myasthenia gravis is rare—about 20 people per 100,000 in the United States have the disorder—symptoms can look like those associated with other conditions. Because of the apparent similarities, myasthenia gravis is underdiagnosed, meaning it’s most likely more common than estimated. 

“There are no clear-cut risk factors or lifestyle choices that cause myasthenia gravis, and it’s not inherited or contagious,” said Mary Vo, M.D. assistant professor of neurology and assistant attending neurologist at NewYork-Presbyterian/Weill Cornell Medical College. “We do know this is an autoimmune condition that manifests in adulthood. Women under 40 and men over 60 are typically diagnosed, but it can occur at any age, including childhood. As the population ages, we're noticing more men are affected than women.” 

Symptoms commonly associated with myasthenia gravis include: 

  • Blurred or double vision 
  • Changes in facial expressions 
  • Difficulty swallowing 
  • Drooping eyelids or eye muscle weakness 
  • Impaired speech 
  • Shortness of breath 
  • Weakness in the arms, hands, fingers, legs and neck 

Additionally, myasthenia gravis can cause the muscles that control breathing to weaken to the point where a person needs a ventilator. Known as a myasthenic crisis, this medical emergency requires immediate medical care. Between 15% to 20% of people with myasthenia gravis experience a myasthenic crisis at least one time in their lives. 

The Promise of a Healthier Future  

Researchers continue to gain a better understanding of myasthenia gravis, its causes, and the structure and function of the neuromuscular junction. Technological advances have led to more timely and accurate diagnosis. And new and enhanced therapies have improved treatment options. Researchers are developing new tools to diagnose patients with undetectable antibodies and identify potential biomarkers (biological signs of disease) to predict an individual's response to medications that suppress the immune system’s function. 

Myasthenia Gravis and Stroke 

Some of the symptoms of myasthenia gravis are similar to the symptoms of a stroke. But they’re not the same.  

“The main difference is that myasthenia is much more gradual than stroke,” Dr. Vo says. “In a stroke, the weakness or neurological deficit is there right at the onset, and everything can happen in an instant. With myasthenia, there’s a repetitive pattern of more subtle weakness that’s better in the morning and gradually gets worse over the course of the day.” 

Myasthenia can affect different areas of the body. The most common noticeable symptoms are eye drooping and double vision, particularly at the end of the day or after a very fatiguing activity. Over time, other muscles can be involved. In 10% of cases, one can develop arm or leg weakness. 

Treating Myasthenia Gravis 

The treatment for myasthenia gravis involves two main components. First, a medication called pyridostigmine blocks the enzymes from breaking down the neurotransmitter. Although this treatment is a great symptomatic quick fix, it doesn't change the underlying cause of the disease. 

That’s where the second component of treatment comes in: immunosuppression. A number of long-term treatments can suppress the immune system and the symptoms of myasthenia gravis, allowing the muscles to function more normally. Steroids are tried-and-true options that can help most patients feel better within a few weeks. But while effective, long-term use of steroids can bring on undesired side effects. 

To avoid those side effects, doctors may choose to use a number of steroid-sparing medications. Some are oral, including medications that have been around for quite some time—azathioprine and mycophenolate. The oral medications are typically taken daily to treat the disease and suppress symptoms.  

If someone has more difficulty controlling their condition, there are more potent intravenous medications available. These immunosuppressants don't have the same side effects as steroids, so they can be used on a longer-term basis to keep the immune system working right. 

Exciting Developments in Myasthenia Care 

“For patients living with myasthenia, this is a very fortunate time in the sense that there are so many new treatment options available to us that we didn't have even two years ago.,” Dr.  Vo says. “And, there are a number of new treatments in the pipeline that are more potent and have less side effects than traditional agents. So I think we’re looking at more streamlined and tailored approaches for myasthenia control.” 

Two medications that directly impact myasthenia gravis without the side effects of much broader immunosuppression have recently been approved: Efgartigimod and a new long-acting complement inhibitor.  

Because there are well-tolerated and effective treatments to keep the condition at bay, Dr. Vo encourages patients developing new symptoms, including repetitive weakness that gets worse at the end of the day, to see a neuromuscular specialist sooner rather than later, to obtain a diagnosis and get started on treatment.  

Concerned with symptoms you’re experiencing? Find a doctor at Weill Cornell Medicine to help manage your health.