What is a myasthenic crisis?

crisis myasthenic

ANSWER A myasthenic crisis is when you have trouble breathing on your own and problems swallowing. Myasthenic crisis occurs when myasthenic weakness affects the respiratory muscles and breathing is dangerously impaired. In this situation the volume of air in the lung decreases, a situation known as atelectasis. By definition, a patient in myasthenic crisis has respiratory failure requiring intubation (the passage of a tube into the patient’s airway to keep it patent) and mechanical ventilation. Crisis can be produced by infection (40%) or can occur spontaneously (30%). Other causes of myasthenic crisis include aspiration, pregnancy, medications, and surgery. About one quarter of patients can be taken off the respirator within a week, 50% within two weeks, and 75% within a month. About one third of the patients experiencing a myasthenic crisis will experience a second crisis.


A myasthenic crisis occurs when weakness affects the muscles that control breathing. This can create a medical emergency requiring either a respirator to help the person breathe or measures to prevent a person from taking too much air into their lungs. Weak respiratory muscles, infection, fever, or a bad reaction to medication can also trigger a crisis. The treatments described above—in particular, intravenous immune globulin and plasma exchange—can reverse the severe weakness of a myasthenic crisis.