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Glossary of Myasthenia Gravis Terms

Reviewed by: HU Medical Review Board | Last reviewed: May 2021

Like many health conditions, myasthenia gravis (MG) has a language of its own that you will need to learn. Here are some of the most common words you may see and hear as you talk with your healthcare team.1-5


Acetylcholine (ACh)

A chemical that occurs naturally in the body. Nerves release ACh to tell muscles to contract (move).

AChR antibody

AChR stands for acetylcholine receptor. AChR antibodies are the most common type of MG antibody. These antibodies keep nerves and muscles from communicating properly. This causes the muscle weakness of MG.


Antibodies are chemicals that the body makes to fight infection, germs, or cancer. If a person has an autoimmune disease, the person’s antibodies are attacking healthy cells and tissue.

Autoimmune disease

A disease in which the immune system attacks the body’s healthy cells and tissues by mistake. Myasthenia gravis is an autoimmune disease that attacks the neuromuscular junction.


Cholinergic crisis

A reaction to taking high doses of an acetylcholinesterase inhibitor, a type of drug prescribed for people with MG. A cholinergic crisis causes weakness in breathing muscles similar to a myasthenic crisis.

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Double vision.


The medical term for problems speaking or a change in the quality of a person’s voice. In MG, a person may sound nasal, breathy, monotone, or have trouble controlling pitch or talking for long periods.


Slurred speech.


Problems swallowing.



A time when muscle weakness happens more often or is more severe than usual. Also known as a flare. Exacerbations may lead to a myasthenic crisis.


Generalized MG

The most common type of myasthenia gravis in which muscles of the eyes, face, neck, arms, and legs are affected.


LRP4 antibody

LRP4 stands for low-density lipoprotein receptor-related protein 4. The LRP4 protein, a chemical in the body, helps nerves communicate with muscles.


MuSK antibody

MuSK stands for muscle-specific kinase. MuSK antibodies bind to the MuSK protein. The MuSK protein, a chemical in the body, helps nerves communicate with muscles.

Myasthenic crisis

A period when weakness of the breathing muscle gets much much much worse. If the breathing muscles become too weak, the person may need help breathing, usually in the hospital. This is a medical emergency.

Myasthenia gravis

An autoimmune condition in which the body turns on itself and attacks the areas where nerves and muscles communicate.


Neonatal MG

A type of myasthenia gravis that appears in babies born to women with MG. Symptoms are temporary and usually go away in a few weeks.


A doctor who specializes in treating diseases of the nervous system, including myasthenia gravis.

Neuromuscular junction

Places on the muscle that “read” nerve signals, telling it to move. These places include receptors, such as the acetylcholine receptor (AChR), that receives chemical signals from the nerves.


Ocular MG

A less common form of myasthenia gravis in which only the eye muscles are affected.



Also known as plasma exchange. An MG treatment in which antibodies are removed from the blood.


Drooping eyelid.


Refractory MG

MG that does not get better despite using all the normal treatments.


A period of time when MG symptoms go away completely, either with less treatment or no treatment.


Seronegative myasthenia gravis

A form of MG in which none of the usual MG antibodies are found in the blood.



A gland that sits just over the heart behind the breast bone. The thymus is part of the immune system that often does not work properly in people with myasthenia gravis.


Thymectomy is a surgery to remove the thymus gland. This is a common treatment for some types of myasthenia gravis.


A tumor on the thymus gland that may be cancerous or non-cancerous in people with myasthenia gravis.