Myasthenia gravis is an autoimmune disorder that affects nerve-muscle communication and leads to muscle weakness. This condition often begins with drooping eyelids or double vision and progresses to difficulty standing, lifting, speaking, or swallowing. While there’s no cure, medications and surgery can alleviate symptoms of this chronic illness.
Understanding Myasthenia Gravis
Myasthenia gravis causes skeletal muscle weakness, impacting muscles connected to bones that help with movement. It commonly affects muscles in the eyes, face, neck, arms, and legs, impairing abilities such as:
- Moving or blinking your eyes
- Keeping eyes open
- Making facial expressions
- Chewing, swallowing, and talking
- Raising arms and lifting objects
- Walking upstairs or getting up from a chair
Muscle weakness worsens with physical activity and improves with rest, with symptoms appearing suddenly.
Types of Myasthenia Gravis
- Autoimmune Myasthenia: The most common type, caused by antibodies disrupting nerve-muscle communication.
- Neonatal Myasthenia: This condition occurs in infants who inherit antibodies from a parent with myasthenia gravis. Symptoms usually resolve within three months.
- Congenital Myasthenia: A genetic, non-autoimmune form of the condition.
There are two subtypes of autoimmune myasthenia:
- Ocular: Affects muscles moving the eyes and eyelids, often the first sign of myasthenia.
- Generalized: It involves the eye muscles and other muscles in the face, neck, arms, legs, and throat.
Prevalence
Myasthenia gravis affects about 20 in 100,000 people worldwide. In the U.S., approximately 60,000 people are affected at any given time.
Symptoms and Causes
Symptoms
- Muscle weakness in arms, hands, fingers, legs, and neck
- Fatigue
- Droopy eyelids (ptosis)
- Blurry or double-vision
- Limited facial expressions
- Difficulty speaking, swallowing, or chewing
- Trouble walking
Symptoms often worsen with activity and improve with rest. Severe cases may involve respiratory muscles, causing breathing problems.
Causes
Autoimmune myasthenia gravis occurs when the immune system mistakenly attacks itself. Researchers believe issues in the thymus gland may play a role. Congenital myasthenia results from genetic changes, while neonatal myasthenia is caused by antibodies passed from parent to fetus.
Impact on the Body
Myasthenia gravis disrupts communication between nerves and muscles. Normally, nerves release acetylcholine to trigger muscle contraction. In myasthenia gravis, antibodies destroy acetylcholine receptors, hindering communication and causing muscle weakness.
Inheritance
While rare, congenital and neonatal myasthenia can be inherited. Autoimmune myasthenia gravis is not typically inherited.
Risk Factors
- Women around age 40 and men around age 60 are most commonly affected.
- Other autoimmune conditions or thyroid disease may increase risk.
- Medications for malaria and heart arrhythmias, surgery, or infections can trigger symptoms.
Complications
Severe cases may lead to a myasthenic crisis, a life-threatening respiratory muscle weakness requiring immediate medical attention. Myasthenia gravis can also lead to stress and depression due to activity limitations.
Diagnosis and Treatment
Diagnosis
- Blood tests: Check for high levels of acetylcholine receptor antibodies.
- Imaging scans: MRI or CT scans detect thymus gland issues.
- Electromyography (EMG): Measures electrical activity of muscles and nerves.
Treatment
While there is no cure, treatments include:
- Medications: Cholinesterase inhibitors and immunosuppressants reduce symptoms and inflammation.
- Monoclonal antibodies: IV or SQ infusions suppress the immune system.
- Plasma exchange (plasmapheresis): Removes harmful antibodies from the blood.
- IV or SQ immunoglobulin (IVIG or SCIG): Provides donor antibodies to treat myasthenic crisis or generalized myasthenia.
- Surgery: Thymectomy removes the thymus gland.
Living with Myasthenia Gravis
Managing myasthenia gravis involves lifestyle adjustments:
- Exercise regularly to strengthen muscles and boost energy.
- Avoid heat, which can worsen symptoms.
- Eat protein and carbohydrates for energy.
- Schedule exhausting tasks early in the day.
- Take naps and rest breaks.
Prognosis
Most people with myasthenia gravis live full, active lives with treatment. Symptoms can range from mild to severe, and some individuals may experience remission, where symptoms temporarily or permanently stop.
Pregnancy and Myasthenia Gravis
Pregnancy may trigger symptoms for the first time or worsen existing ones. Certain treatments may be unsafe during pregnancy or breastfeeding, so consult your healthcare provider.
When to Seek Medical Help
Contact your healthcare provider if you experience blurred vision, difficulty walking, talking, eating, or extreme muscle fatigue. Seek emergency help for breathing difficulties.
Questions for Your Healthcare Provider
- What caused my symptoms?
- What’s the best treatment option for me?
- What are the side effects of treatment?
- What lifestyle changes should I make?
- What signs of complications should I watch for?
- Can I safely start an exercise program?
- Are there patient support groups or research projects I can join?
