Myasthenia gravis (MG) is a rare, chronic autoimmune disease where neuromuscular junction transmission is disrupted, producing painless weakness in the skeletal muscles throughout the body. Skeletal muscles are ones that are voluntary controlled, such as those in the limbs, face, tongue and muscles that move eyes.
The name myasthenia gravis comes from Greek and Latin words meaning “grave muscular weakness.” However, with current treatments, the disease can be managed much better than when first attempted, just a half century ago.
Today, at any given time, 100 - 150 people out of 1 million live with MG. Women younger than 40 and men older than 60 are most commonly diagnosed. Recent studies suggest an increasing incidence of MG in the elderly of both genders. Because the symptoms can be similar to other diseases, MG may be underdiagnosed. As awareness of the disease grows, the number of cases diagnosed also has increased.
What Causes Myasthenia Gravis?
MG is an autoimmune disease that causes the immune system to attack healthy cells in the body. With MG, antibodies inhibit the receptors at the neuromuscular junction and interfere with the transmission of nerve signals to your muscles, making them weaker. An abnormal thymus gland is found frequently in patients with myasthenia gravis and is more common in younger-onset MG.
Fatigue and weakness are the hallmark symptoms of MG, as are fluctuations in strength or stamina. One of the first symptoms is an isolated drooping eyelid and blurry or double vision. Most patients develop generalized limb muscle weakness and chewing or swallowing difficulties. Fatigable voice and speech also are common. Breathing involvement mainly on exertion or when lying down flat usually occurs with the progression of the disease.
Various factors — such as exercise, warm weather, systemic infections, pregnancy, surgical procedures and emotional stress — may make fatigue and weakness more evident.
Patients with MG may have a myasthenic crisis, which is a complication of MG symptoms that results in a severe worsening of muscle weakness. Because this can affect breathing, MG patients may need hospitalization and a ventilator until their respiratory muscles recover. A myasthenic crisis can be caused by missing doses of medicine, surgery, emotional stress or a respiratory infection.
Symptoms of MG are similar to several other conditions. If you notice increased difficulty breathing, seeing, swallowing, chewing, walking, using your arms or hands, or holding up your head, talk with your doctor. If your symptoms are severe, seek emergency medical treatment, because this could signal other serious medical conditions, including stroke.
To diagnose MG, your doctor likely will use laboratory testing and electrodiagnostic and imaging studies. Timely recognition of early symptoms of MG is essential to reach an accurate diagnosis and start management.
Treatment of MG
Although there currently is no cure for MG, the disease can go into remission. In addition, current treatments and new research offer promising options in managing the disease. Treatment options for MG include treating the symptoms as they occur, immunotherapy, and in selected cases, surgical removal of the thymus gland. Treatment regimens are individualized depending on the severity of the symptoms, patient’s age and any underlying conditions.
A discussion about expected benefit of medication, the time course, and how to monitor for side effects is essential. Primary care or other prescribing physicians should review the list of medications that should be avoided, such as magnesium, beta blockers, calcium channel blockers, and antibiotics including aminoglycosides, macrolides and fluoroquinolones.
Outlook for MG
Managing MG requires patients to form a diligent partnership with their medical team, and combined with ongoing treatment, this can help to control symptoms long-term and maintain good quality of life. Recent advances in therapies that are directed to specific components of the immune response will expand and improve our management options.
Treatment for Myasthenia Gravis
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