Myasthenic and Cholinergic Crises: What You Need to Know

If you or your loved one is living with myasthenia gravis (MG), you may have questions about complications. One serious complication that can develop is called a myasthenic crisis. Another less-common complication that may feel similar is a cholinergic crisis. Some of the symptoms are similar, but they happen for different reasons.

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What are the symptoms of a myasthenic crisis?

When a myasthenic crisis happens, the muscles that control breathing and swallowing become extremely weak. It can be life-threatening. People in myasthenic crisis may need a machine called a ventilator to help them breathe.^1,2

What causes it?

MG is a chronic autoimmune disease. It is caused by the body’s immune system destroying key parts of how nerves and muscles interact. This results in muscle weakness.^2,3

A myasthenic crisis happens when the muscles related to breathing become extremely weak. The person in crisis has great difficulty breathing and swallowing without help.^2,3

What are the triggers?

A few different conditions can trigger a myasthenic crisis, such as:^1,2

• Infection
• Reaction to medicine(s)
• Surgery
• Pregnancy
• Childbirth

Myasthenic crises can also be caused by taking lower and lower doses of immunosuppressive medicines. They can also happen in the natural course of MG.^1,2,4

Who is affected?

A myasthenic crisis can only occur in someone who has MG. As few as 1 or 2 people out of every 10 people with MG will experience a myasthenic crisis. Many episodes occur in the first few years after someone’s illness with MG begins.^1,5,6

People with MG may first notice an overall weakening. This may be a warning. The annual risk of myasthenic crisis among people with MG is low at just 2 to 3 percent.^1,5,6

If you have MG plus another condition or an infection, your myasthenic crisis might last longer. But with proper medical care, more than 95 percent of MG will survive their crisis.^4,6,7

What are the symptoms of a cholinergic crisis?

There is another condition that can feel similar. While a cholinergic crisis is rarer than a myasthenic crisis in someone with MG, it is still a possibility. People with MG should also know about this condition.

Someone who is having a cholinergic crisis may experience:^8,9

• Trouble breathing
• Blurry vision or water eyes
• Nausea, vomiting, and diarrhea
• A slower-than-normal heartbeat
• More saliva than usual
• A frequent urge to urinate
• Muscle twitches involving fine muscle fibers

Why does it happen?

Cholinergic crisis happens because of toxicity in 2 cholinergic receptors, muscarinic and nicotinic.⁸

Muscarinic receptors work in both the peripheral and central nervous systems. Nictonic receptors work in the central nervous system and at the neuromuscular junction. They play a role in helping organs in the chest work properly.¹⁰

A cholinergic crisis develops from an excess of a particular kind of medicine or exposure to certain chemical compounds.⁸

Who is at risk?

A cholinergic crisis can happen to someone with or without MG. For example:⁸

• People who received general anesthesia and high doses of drugs to reverse the effects of nerve-blocking agents
• Children and adults who were exposed to specific chemicals, such as nerve gases,
• pesticides, and insecticides
• People with MG who are taking very high doses of acetylcholinesterase inhibitors

When someone with MG develops a cholinergic crisis, it happens because of taking too much of an acetylcholinesterase inhibitor.⁹

This causes toxicity in the muscarinic and nicotinic receptors. But with proper dosing, most people with MG do not develop this complication.⁹

Knowing the difference

It is extremely rare for someone with MG to have a cholinergic crisis. For example, 1 study found that of 53 people admitted to a hospital for 73 episodes of myasthenic crisis over a 12-year period, none had a cholinergic crisis.¹⁰

But because both types of crises can lead to trouble breathing, knowing the symptoms of each is important. It may help you describe your symptoms, or your loved one’s, to a doctor.