Myasthenia Gravis: Causes, Symptoms, and Management

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