Myasthenia Gravis

What is Myasthenia Gravis?

Myasthenia gravis is an autoimmune disease that causes muscle weakness and fatigue. The immune system mistakenly attacks the communication points between nerves and muscles. This blocks the signals that tell your muscles to move.

The condition gets its name from Latin words meaning muscle weakness. In myasthenia gravis, your immune system creates antibodies that damage acetylcholine receptors. These receptors help muscles receive signals from nerves. When they stop working properly, muscles become weak and tire easily.

Myasthenia gravis can affect people of any age, but it most commonly appears in women under 40 and men over 60. The weakness typically gets worse with activity and improves with rest. Some people experience mild symptoms that affect only certain muscles, while others have more widespread weakness.

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Symptoms

Drooping of one or both eyelids
Double vision or blurred vision
Difficulty swallowing or choking easily
Trouble chewing, especially with hard foods
Slurred speech or nasal voice quality
Weakness in arms, hands, legs, or neck
Shortness of breath or difficulty breathing
Facial weakness or difficulty making expressions
Fatigue that worsens throughout the day
Difficulty holding up your head

Symptoms often fluctuate in severity throughout the day. Most people notice their muscles feel strongest in the morning and weakest in the evening. Some people experience symptoms that affect only the eyes, while others develop generalized weakness affecting multiple muscle groups.

Causes and risk factors

Myasthenia gravis happens when the immune system produces antibodies that attack the neuromuscular junction. This is the area where nerve cells connect with muscles. Most people with myasthenia gravis have antibodies that block, alter, or destroy acetylcholine receptors. Some have antibodies against other proteins like MuSK or LRP4. These antibodies prevent normal muscle contraction signals.

The thymus gland often plays a role in myasthenia gravis. This gland is part of the immune system and sits in the upper chest. About 75% of people with myasthenia gravis have thymus abnormalities. Some have an enlarged thymus, while about 10% to 15% have a thymus tumor called a thymoma. Certain medications, infections, surgery, or stress can trigger symptom flares. Genetic factors may increase susceptibility, but the condition itself is not directly inherited.

How it's diagnosed

Doctors diagnose myasthenia gravis through a combination of physical examination, medical history, and specialized tests. A neurologist will assess muscle weakness patterns and how symptoms change with activity and rest. Blood tests check for specific antibodies that attack the neuromuscular junction. These include acetylcholine receptor antibodies, MuSK antibodies, and LRP4 antibodies. Different antibody types indicate different subtypes of myasthenia gravis.

Additional diagnostic tests may include electromyography, which measures electrical activity in muscles, and nerve conduction studies. Some doctors perform an ice pack test or edrophonium test to see if symptoms temporarily improve. Imaging tests like CT or MRI scans of the chest help identify thymus abnormalities. Talk to a doctor about specialized antibody testing if you experience unexplained muscle weakness or vision problems.

Treatment options

Medications called cholinesterase inhibitors that improve nerve-to-muscle communication
Immunosuppressive drugs to reduce antibody production and calm the immune system
Corticosteroids to decrease inflammation and immune response
Plasmapheresis, a procedure that removes harmful antibodies from blood
Intravenous immunoglobulin therapy to block damaging antibodies
Thymectomy, surgical removal of the thymus gland in certain cases
Rest periods throughout the day to prevent muscle fatigue
Avoiding triggers like stress, illness, extreme temperatures, and certain medications
Physical therapy to maintain muscle strength without overexertion
Dietary adjustments for people with swallowing difficulties

Frequently asked questions

Myasthenia gravis is caused by an autoimmune response where your body produces antibodies that attack the neuromuscular junction. These antibodies block or destroy receptors that muscles need to receive signals from nerves. The thymus gland often plays a role, with many people showing thymus abnormalities. While the exact trigger is unknown, genetics and environmental factors may contribute to the immune system malfunction.

Myasthenia gravis is typically a chronic condition that requires ongoing management. However, symptoms can fluctuate significantly over time. Some people experience periods of remission where symptoms improve or disappear temporarily. Treatment with medications and sometimes surgery can help many people achieve good symptom control. Working closely with a neurologist helps manage the condition and maintain quality of life.

The first signs often involve the muscles around the eyes, causing drooping eyelids or double vision. About 15% of people experience only eye symptoms, called ocular myasthenia gravis. Other early signs include difficulty swallowing, slurred speech, or facial weakness. Symptoms typically worsen with activity and improve with rest. Many people notice their symptoms are worse later in the day.

Doctors use several tests to diagnose myasthenia gravis. Blood tests detect specific antibodies like acetylcholine receptor antibodies, MuSK antibodies, or LRP4 antibodies. Electromyography measures muscle electrical activity and can show characteristic patterns. A physical exam assesses muscle weakness and how it changes with repeated use. Imaging tests of the chest check for thymus gland abnormalities.

Myasthenia gravis can be serious if it affects breathing muscles, causing a potentially life-threatening situation called myasthenic crisis. This requires immediate emergency medical care. However, with proper treatment, most people with myasthenia gravis can manage their symptoms effectively. Modern treatments have greatly improved outcomes, and many people live full, active lives with appropriate medical management.

Several factors can trigger symptom flare-ups in people with myasthenia gravis. Common triggers include infections like colds or flu, emotional or physical stress, and extreme temperatures. Certain medications, including some antibiotics and heart medications, can worsen symptoms. Surgery, pregnancy, and menstrual periods may also trigger flares. Identifying and avoiding your personal triggers helps prevent symptom worsening.

Exercise requires a careful balance with myasthenia gravis. Gentle, moderate activity can help maintain muscle strength and overall health. However, overexertion can worsen muscle weakness and trigger fatigue. Physical therapy with a therapist familiar with myasthenia gravis can help develop a safe exercise plan. Rest periods are essential, and activities should be scheduled when medication is most effective.

These are different subtypes based on which antibodies are present. AChR-positive means acetylcholine receptor antibodies are present, which is the most common type affecting about 85% of people. MuSK-positive means antibodies target a protein called muscle-specific kinase, affecting about 5% to 8% of people. MuSK-positive myasthenia gravis often causes more severe symptoms affecting face, throat, and breathing muscles and may respond differently to treatments.

There is no specific diet required for myasthenia gravis, but some adjustments may help. People with swallowing difficulties may need softer foods or thicker liquids to prevent choking. Eating smaller, frequent meals can help if chewing becomes tiring. Some people find that timing meals when medication is most effective makes eating easier. Maintaining good nutrition supports overall health and energy levels.

Women with myasthenia gravis can have successful pregnancies, but careful planning and monitoring are essential. Symptoms may improve, worsen, or stay the same during pregnancy. Some medications used to treat myasthenia gravis need to be adjusted during pregnancy and breastfeeding. Babies born to mothers with myasthenia gravis may temporarily have muscle weakness due to maternal antibodies, but this usually resolves within weeks. Work closely with both a neurologist and obstetrician.