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Myasthenia Gravis

A disease in which antibodies made by a person's immune system prevent certain nerve-muscle interactions. It causes weakness in the arms and legs, vision problems, and drooping eyelids or head.

PubMed Health Glossary
(Source: NIH - National Cancer Institute)

About Myasthenia Gravis

Myasthenia gravis is a chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal (voluntary) muscles of the body. The name myasthenia gravis, which is Latin and Greek in origin, literally means "grave muscle weakness." With current therapies, however, most cases of myasthenia gravis are not as "grave" as the name implies. In fact, most individuals with myasthenia gravis have a normal life expectancy.

The hallmark of myasthenia gravis is muscle weakness that increases during periods of activity and improves after periods of rest. Certain muscles such as those that control eye and eyelid movement, facial expression, chewing, talking, and swallowing are often, but not always, involved in the disorder. The muscles that control breathing and neck and limb movements may also be affected.

What causes myasthenia gravis?

Myasthenia gravis is caused by a defect in the transmission of nerve impulses to muscles. It occurs when normal communication between the nerve and muscle is interrupted at the neuromuscular junction—the place where nerve cells connect with the muscles they control. Normally when impulses travel down the nerve, the nerve endings release a neurotransmitter substance called acetylcholine. Acetylcholine travels from the neuromuscular junction and binds to acetylcholine receptors which are activated and generate a muscle contraction...Read more about Myasthenia Gravis NIH - National Institute of Neurological Disorders and Stroke

What works? Research summarized

Evidence reviews

Surgical removal of the thymus for myasthenia gravis that is not caused by a tumour of the thymus

Myasthenia gravis is a disorder that causes muscle weakness and excessive muscle tiredness. In most people with myasthenia gravis, muscles throughout the body are affected in the first two years after the onset of symptoms, although there is also a form of the disease that affects only the eyes (ocular myasthenia). Myasthenia gravis occurs when the person’s own immune system attacks the vital structures that transmit impulses from nerves to muscle, the neuromuscular junctions. A tumour affecting an immune system organ called the thymus (a thymoma) is sometimes the underlying cause; this is known as thymomatous myasthenia gravis. Thymomatous myasthenia gravis was not the subject of this systematic review as the thymoma should be treated on its own merit, independently of the myasthenia gravis.

Acetylcholinesterase inhibitor treatment for myasthenia gravis

We reviewed the evidence about the effect of aceytlcholinesterase inhibitor drugs in people with myasthenia gravis.

Ephedrine treatment for myasthenia gravis, neonatal myasthenia and congenital myasthenic syndromes

We reviewed the evidence about the effect of ephedrine in adults and children with myasthenia gravis (MG), neonatal myasthenia and the congenital myasthenic syndromes (CMSs).

See all (32)

Summaries for consumers

Surgical removal of the thymus for myasthenia gravis that is not caused by a tumour of the thymus

Myasthenia gravis is a disorder that causes muscle weakness and excessive muscle tiredness. In most people with myasthenia gravis, muscles throughout the body are affected in the first two years after the onset of symptoms, although there is also a form of the disease that affects only the eyes (ocular myasthenia). Myasthenia gravis occurs when the person’s own immune system attacks the vital structures that transmit impulses from nerves to muscle, the neuromuscular junctions. A tumour affecting an immune system organ called the thymus (a thymoma) is sometimes the underlying cause; this is known as thymomatous myasthenia gravis. Thymomatous myasthenia gravis was not the subject of this systematic review as the thymoma should be treated on its own merit, independently of the myasthenia gravis.

Acetylcholinesterase inhibitor treatment for myasthenia gravis

We reviewed the evidence about the effect of aceytlcholinesterase inhibitor drugs in people with myasthenia gravis.

Ephedrine treatment for myasthenia gravis, neonatal myasthenia and congenital myasthenic syndromes

We reviewed the evidence about the effect of ephedrine in adults and children with myasthenia gravis (MG), neonatal myasthenia and the congenital myasthenic syndromes (CMSs).

See all (11)

Terms to know

Antibodies
A protein produced by the immune system in response to a foreign substance such as a virus or bacterium.
Autoimmune Disease
Disease that results when the immune system mistakenly attacks the body's own tissues. Examples include multiple sclerosis, type 1 diabetes, rheumatoid arthritis, and systemic lupus erythematosus.
Immune System
The body's system for protecting itself from viruses and bacteria or any foreign substances.
Muscles
Muscles function to produce force and motion. They are primarily responsible for maintaining and changing posture, locomotion, as well as movement of internal organs, such as the contraction of the heart and the movement of food through the digestive system.
Nerve Impulse
The signal transmitted along a nerve fibre, either in response to a stimulus (such as touch, pain or heat), or as an instruction (such as causing a muscle to contract).
Nerves
A bundle of fibers that receives and sends messages between the body and the brain. The messages are sent by chemical and electrical changes in the cells that make up the nerves.
Receptors
A molecule inside or on the surface of a cell that binds to a specific substance and causes a specific effect in the cell.
Thymus Gland
An organ that is part of the lymphatic system, in which T lymphocytes grow and multiply. The thymus is in the chest behind the breastbone.

More about Myasthenia Gravis

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Other terms to know: See all 8
Antibodies, Autoimmune Disease, Immune System

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