Myasthenia Gravis (MG) is a chronic, autoimmune disorder caused by a breakdown in the communication between nerves and muscles in the neuromuscular junction. At the junction, nerve and muscle communicate via a neurotransmitter known as acetylcholine.
In MG, antibodies block or destroy receptors at the junction, affecting transmission. This results in fatigue and muscle weakness.
MG affects voluntary muscles in the body. Weakness may come and go, become more prominent as the affected muscle is used repeatedly, and improves with rest.
Signs may be generalised or localised:
Common signs include:
Not all signs occur at the same time or are always present. The signs usually occur slowly but may develop suddenly with generalised weakness and rapid weakening of swallowing and breathing muscles. This is termed myasthenic crisis and needs immediate medical attention.
MG affects all ages, sex and ethnic groups. It is most common in young adult women under 40 and older men over 60. It may affect newborns when a mother with MG passes the abnormal antibodies to the foetus. In adults, it is usually not hereditary. MG is not contagious.
A consult with a neurologist is needed to confirm the diagnosis. Tests include:
Download the Myasthenia Gravis brochure.