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Myasthenia gravis
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Myasthenia gravis

Myasthenia gravis is an autoimmune disorder that causes weakness of the skeletal muscles, often fluctuating with activity and improving with rest.

Overview

Myasthenia gravis affects the skeletal muscles used for movement. It is most commonly diagnosed in women younger than 40 and men older than 60. While uncommon in children, some infants born to affected mothers may experience temporary symptoms known as transient neonatal myasthenia gravis.

Symptoms

Weakness often begins in the eye muscles, leading to drooping eyelids (ptosis) and blurred or double vision. In ocular myasthenia, weakness is confined to the eyes, but most individuals experience broader muscle involvement, including:

  • Facial and neck weakness: Unusual facial expressions, difficulty holding up the head, speech impairment (dysarthria), and chewing or swallowing problems (dysphagia).
  • Limb weakness: Difficulty lifting objects, climbing stairs, or rising from a seated position.
  • Respiratory distress: Weakness of the chest wall and diaphragm can lead to a myasthenic crisis, a life-threatening complication where breathing is severely impaired.

Causes

Myasthenia gravis is an autoimmune disorder where the immune system produces antibodies that attack the body's own tissues. These antibodies target proteins essential for nerve signal transmission, specifically the acetylcholine receptor (AChR) or muscle-specific kinase (MuSK). This attack reduces the signaling between nerve and muscle cells, resulting in muscle weakness.

About 75 percent of affected individuals have an abnormally large or overactive thymus gland, which may contain noncancerous tumors called thymomas. The condition is also associated with an increased risk of other autoimmune disorders, such as systemic lupus erythematosus and autoimmune thyroid disease.

Inheritance

In most cases, myasthenia gravis is not inherited. Only 3 to 5 percent of affected individuals have family members with the disorder or other autoimmune conditions, and the specific inheritance pattern remains unknown.

Frequently Asked Questions

Several commonly prescribed drugs can severely worsen neuromuscular transmission and trigger acute weakness. Patients should avoid or use extreme caution with fluoroquinolone antibiotics (such as ciprofloxacin and levofloxacin), macrolides (such as azithromycin), aminoglycosides, beta-blockers, calcium channel blockers, and intravenous magnesium. Always inform any treating physician, dentist, or anesthesiologist of the diagnosis before starting new medications.
n ordinary flare typically involves increased generalized fatigue, worsening double vision, or limb heaviness after exertion that improves with rest. A myasthenic crisis is a life-threatening emergency characterized by severe weakness of the diaphragm and intercostal muscles, making breathing difficult, along with severe choking, inability to swallow saliva, and profound neck weakness preventing head elevation. Anyone experiencing progressive shortness of breath or inability to clear secretions must seek emergency medical care immediately.
Even in the absence of a thymoma, surgical removal of the thymus gland has been shown in clinical trials to improve clinical outcomes in patients with acetylcholine receptor (AChR) antibody-positive generalized myasthenia gravis. The procedure can significantly reduce the severity of symptoms, decrease the required doses of corticosteroids and immunosuppressive medications over several years, and increase the likelihood of achieving long-term symptom-free remission.
Timing meals to coincide with peak medication effectiveness is key, typically 30 to 45 minutes after taking an oral dose of pyridostigmine. Eating smaller, more frequent meals consisting of soft, moist foods reduces jaw fatigue. Sitting upright with the chin tilted slightly downward when swallowing can help prevent aspiration, and drinking liquids between mouthfuls rather than simultaneously reduces choking risks.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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