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Overview

What Is Myasthenia Gravis?

Myasthenia gravis is an autoimmune disorder that affects communication between nerves and voluntary muscles. The immune system interferes with signals that tell muscles to contract, causing weakness that typically worsens with activity and improves with rest. It can affect people of any age, including children and adults. This myasthenia gravis definition explains why strength may change throughout the day rather than disappear permanently.

Symptoms

Myasthenia Gravis Symptoms

Myasthenia gravis symptoms may vary during the day and often become more noticeable after repeated muscle use. Weakness may improve after rest, so a person can feel stronger at one time and weaker later. The muscles around the eyes are often affected, but weakness can also involve the face, throat, neck, arms, legs, or breathing muscles.

  • Drooping eyelids (ptosis).
  • Double vision (diplopia).
  • Difficulty chewing, especially after eating for some time.
  • Difficulty swallowing (dysphagia).
  • Slurred or nasal-sounding speech.
  • Facial weakness that may make smiling or making facial expressions difficult.
  • Neck weakness that can make it hard to hold up the head.
  • Arm weakness, particularly after repeated use.
  • Leg weakness that may cause trouble climbing stairs or walking.
  • Shortness of breath or difficulty taking a deep breath.

Causes

Myasthenia Gravis Causes

In myasthenia gravis, the immune system produces antibodies that interfere with proteins involved in nerve-to-muscle signaling. These antibodies may block or damage acetylcholine receptors or other signaling proteins, so nerve messages do not produce a strong, reliable muscle contraction. This autoimmune problem is the main focus when clinicians discuss myasthenia gravis pathophysiology.

The thymus, an immune-system gland in the chest, may contribute to the condition. Some people with myasthenia gravis have an enlarged thymus, and a smaller number have a thymoma, or tumor of the thymus. However, the precise reason autoimmunity develops is not always known, and a thymus abnormality is not present in every person.

Risk Factors

Myasthenia Gravis Risk Factors

  • Age: Myasthenia gravis can occur at any age, with different patterns in younger adults and older adults.
  • Sex-related patterns: The condition is more common in females earlier in adulthood and more common in males at older ages, although anyone can develop it.
  • Personal or family history of autoimmune disease may be associated with a higher likelihood of myasthenia gravis.
  • Thymus abnormalities, including thymus enlargement or thymoma, are associated with some cases.
  • Rare inherited forms can affect newborns temporarily or cause congenital muscle weakness because of gene changes affecting neuromuscular signaling.
  • A newborn may rarely develop temporary neonatal myasthenia when antibodies pass from a mother with myasthenia gravis during pregnancy.

Myasthenia gravis is not contagious and cannot be spread from person to person. Having a risk factor does not mean someone will develop gravis, and many people with the condition have no clear family history or preventable cause.

Complications

Myasthenia Gravis Complications

Seek emergency care

Recognize myasthenic crisis

Myasthenic crisis is a medical emergency in which severe weakness affects breathing or swallowing muscles. Call emergency services immediately for serious trouble breathing, choking, inability to swallow saliva, or rapidly worsening weakness.

  • Swallowing weakness can allow food or liquid to enter the airway, causing aspiration or pneumonia.
  • Severe weakness of the breathing muscles can lead to respiratory failure and the need for urgent hospital support.
  • Weakness in the arms or legs can increase the risk of falls, accidents, and injuries.
  • Chewing and swallowing problems may lead to inadequate nutrition, dehydration, or weight loss.
  • Persistent weakness may reduce independence with work, self-care, mobility, or other daily activities.
  • Medicines used for myasthenia gravis can cause complications or side effects, so treatment requires monitoring and medication review.

Diagnosis

How Is Myasthenia Gravis Diagnosed?

Myasthenia gravis diagnosis begins with the pattern of fatigable weakness and a neurologic examination. A clinician may assess the eye, facial, speech, swallowing, neck, arm, and leg muscles, including how strength changes with repeated use. The examination also helps distinguish myasthenia from other causes of fluctuating weakness.

  • Blood tests can look for antibodies against acetylcholine receptors and MuSK, although not every person has detectable antibodies.
  • Repetitive nerve stimulation or single-fiber electromyography (EMG) can assess how reliably nerves activate muscles.
  • Pulmonary function testing may be used when weakness of the breathing muscles is suspected.
  • Chest imaging, such as CT or MRI, can evaluate the thymus for enlargement or thymoma.

Treatment & Management

Myasthenia Gravis Treatment and Management

Myasthenia gravis treatment is individualized to improve muscle strength, control abnormal immune activity, prevent myasthenic crises, and preserve daily function. A neurologist considers the muscles affected, symptom severity, other health conditions, and response to treatment when creating a plan.

SYMPTOM RELIEF

Pyridostigmine can improve communication between nerves and muscles and may provide symptom relief. The dose and timing are tailored to the person’s symptoms and medical needs.

IMMUNE CONTROL

Corticosteroids and steroid-sparing immunosuppressants can reduce the immune attack on nerve-to-muscle signaling. They require regular monitoring because they can have important side effects.

RAPID TREATMENT

Intravenous immunoglobulin (IVIG) or plasma exchange may be used for severe worsening, before certain procedures, or when a rapid improvement is needed. These treatments are generally provided under specialist or hospital care.

THYMUS SURGERY

Thymectomy, or removal of the thymus, may be appropriate for some people, including those with a thymoma and selected people without one. The decision depends on age, antibody status, symptoms, and overall health.

Long-term management and safety

Regular neurology follow-up helps monitor strength, breathing, swallowing, and medicine effects. Rehabilitation or supportive therapies may help with speech, swallowing, mobility, or daily activities; energy conservation and infection prevention can also be useful. Ask the care team to review any new medicine before starting it, and keep a personalized emergency plan for worsening weakness. Do not stop myasthenia gravis medication without medical guidance.

Outlook and Prognosis

Outlook and Prognosis for Myasthenia Gravis

Myasthenia gravis is usually a long-term condition rather than a contagious or steadily degenerative disease. Many people improve substantially with appropriate treatment, although symptoms can vary and may require ongoing management. The condition may affect the eyes alone or involve several muscle groups, including those used for swallowing and breathing.

  • The muscles affected and whether symptoms remain limited to the eyes or become generalized can influence outlook.
  • The severity of weakness, especially swallowing or breathing weakness, affects the level of monitoring and support needed.
  • Response to treatment helps determine symptom control and daily function over time.
  • Age at onset may be associated with different disease patterns and treatment considerations.
  • Thymus disease, including thymoma, can affect evaluation and management.
  • Other health conditions may influence treatment choices, recovery from flares, and overall function.
  • Access to ongoing specialist care can help identify changes early and reduce the risk of serious complications.

When Should You See a Doctor

When Should You See a Doctor?

Call emergency services

Breathing or swallowing emergency

Call emergency services immediately for severe trouble breathing, inability to swallow saliva, choking, rapidly worsening weakness, or inability to speak because of weakness. These may be signs of myasthenic crisis and require urgent care.

If you have an established diagnosis, contact your care team promptly when symptoms change or worsen. Ask a clinician or pharmacist to review medicines before starting them, because some drugs may worsen neuromuscular weakness.

Symptoms

1 topic

  • Myasthenia Gravis

    Fatigue