A myasthenic crisis is a serious complication of myasthenia gravis. It causes respiratory failure, which is a life threatening condition.

Myasthenia gravis is an autoimmune condition that causes weakness in your voluntary muscles. These are the muscles that attach to your bones and control movement in your body, including those that help you breathe.

Read on to learn more about myasthenic crisis, including prevention, diagnosis, and management.

Myasthenic crisis is a medical emergency

Myasthenic crisis can be life threatening. If you experience difficulty breathing, call 911 or contact your local emergency services.

A myasthenic crisis is a life threatening complication of myasthenia gravis. It happens when muscles that control your breathing weaken to the point that you need medical intervention.

The National Institute of Neurological Disorders and Stroke reports that an estimated 15–20% of people with myasthenia gravis will have at least one myasthenic crisis. Myasthenic crisis is more likely in older adults.

The following factors may increase your risk of a myasthenic crisis:

  • myasthenia gravis that is severe or untreated
  • a history of myasthenic crisis
  • weakness that affects your throat (oropharynx)
  • positive test results for muscle-specific kinase (MuSK) antibodies
  • thymoma, a type of tumor that can develop in your chest

Additionally, some people may not know they have myasthenia gravis until they experience a myasthenic crisis.

A myasthenic crisis usually develops over days or weeks. But it sometimes progresses more quickly.

Potential signs and symptoms of a myasthenic crisis include:

  • difficulty breathing
  • shallow breathing
  • weak cough
  • general muscle weakness
  • weakness in your limbs

Bulbar weakness

Myasthenic crisis can also cause bulbar weakness, a condition that affects your jaw and throat. Symptoms of bulbar weakness include:

  • drooling
  • lip trembling
  • loss of gag reflex
  • tongue or jaw weakness
  • difficulty swallowing or talking
  • nasal or hoarse voice

Seek medical help right away if you think you may be developing or experiencing a myasthenic crisis. Early treatment is important to improve your outcome.

Myasthenic crisis is often caused by a trigger, with respiratory infections being the most common.

Other potential triggers include:

  • an adverse reaction to medication
  • surgery
  • injury
  • pregnancy
  • childbirth
  • stress

About 30% to 40% of myasthenic crises have an unknown trigger.

Following your treatment plan for myasthenia gravis can help reduce your risk of a myasthenic crisis. This may include medication and other treatments your doctor prescribes.

Taking steps to avoid or manage potential triggers may also reduce your risk of a myasthenic crisis, such as:

  • Preventing respiratory infections: This includes getting recommended vaccinations, avoiding close contact with people who are sick, and sanitizing your hands regularly with soap and water or an alcohol-based hand gel.
  • Preparing for stressful events: Ask your doctor how to lower your risk of myasthenic crisis before changing medications, undergoing a scheduled surgery, becoming pregnant, or giving birth.
  • Limiting injuries: Take steps to limit preventable injuries.

Seeking early treatment for symptoms of a myasthenic crisis may help improve your outlook.

Your doctor will diagnose a myasthenic crisis by:

  • considering your symptoms
  • conducting a physical exam
  • ordering tests to evaluate your respiratory function

They may also order tests to help rule out other potential causes, like a blood clot in your lungs, heart failure, or acute respiratory distress syndrome (ARDS).

Most people who develop a myasthenic crisis already know they have myasthenia gravis. However for some people, a myasthenic crisis may be the first sign they have the condition.

Your doctor can diagnose myasthenia gravis by ordering blood tests and electrical tests of your nerves and muscles. They may also order tests to check for additional signs of myasthenia gravis or rule out other conditions.

Treatment for a myasthenic crisis will likely involve a stay in a hospital intensive care unit. Your visit may include:

  • intubation, or insertion of a tube into your windpipe
  • breathing support from a machine known as a ventilator
  • breathing exercises to help improve lung function
  • airway suctioning to remove mucus and other secretions from your airways
  • medication to open your airways or manage symptoms
  • immune suppressing medications
  • immune therapies like plasma exchange or intravenous immunoglobulin
  • fluids and dietary supplements for hydration and nutrition

After your hospital stay, your doctor may recommend rehabilitation therapy or other treatments to support your recovery. These can include referral to a respiratory therapist, psychological counselor, or other specialists.

Your care team will monitor for signs of complications that may require additional treatments. They can help you and your loved ones understand your outlook and treatment options.

A myasthenic crisis is a complication of myasthenia gravis that causes serious breathing difficulties.

It may be triggered by a respiratory infection, adverse reaction to medication, or other physical or emotional stress. The trigger is not always known.

If you have myasthenia gravis, following your treatment plan can help reduce your risk of a myasthenic crisis. This can include taking medication as your doctor prescribes, managing potential triggers, and other treatments.

A myasthenic crisis is a medical emergency. Seek immediate care if you experience breathing difficulties or other symptoms of a myasthenic crisis.