The name myasthenia gravis (MG) comes from Latin and Greek and means 'grave muscle
For our muscles to work, electrical signals are sent from the brain to
the nerve ending. When these signals reach the nerve ends they trigger the release
of a neurotransmitter chemical called acetylcholine, which acts on receptor cells
on the muscle causing it to contract.
A different chemical then breaks down the acetylcholine
so the muscle relaxes again.
MG is one of the autoimmune diseases where, for an unknown
reason, the body attacks itself. In MG the body makes antibodies that destroy some
of our muscle receptors. When this happens the muscle contractions are weak. Symptoms
of Myasthenia Gravis
Affected muscles suffer varying degrees of weakness. Only the muscles under conscious
(or voluntary) control are affected, whereas those of the heart and intestine aren't.
muscles controlling the eyelids are usually affected first, causing them to droop
and creating the appearance of looking tired. The muscles controlling eye movements
are also commonly involved, causing double vision.
Next the facial muscles may become
weak, so any facial expression appears as a grimace. If the jaw and muscles of the
gullet are affected then eating and swallowing become difficult. In severe cases,
people find themselves unable to speak, lift their arms or walk, and they have difficulty
Most people find rest and a good night's sleep relieves their symptoms
initially. Symptoms may become worse as the day progresses. Any stress worsens the
muscle weakness, and women often find their symptoms are more severe during their
Although it's usually a progressive disease this isn't always thecase. Some
people find their symptoms disappear spontaneously and don't return for many years.
Just how weak the muscles are when symptoms do persist also varies from person to
The condition tends to affect men later in life, usually after the age of 60, and
under the age of 40. In the UK, it's estimated one in 10,000 people has MG.
For some people, surgical removal of the thymus gland may cure, or at least lessen,
the problem. Other people are treated with drugs to stop the breakdown of the chemical
neurotransmitter, increasing its level in the body.
In certain situations steroids
or other immunosuppressant drugs are used to damp down the immune response.
are very severe a process called plasmaphoresis is performed. This involves routing
the person's blood supply through a machine to remove the harmful antibody-containing
plasma and replace it with antibody-free plasma.
Extremes of temperature, stress,
infection and overtiredness can all make symptoms worse and should be avoided.
current treatments, people with MG are expected to live a relatively normal life
and to have a normal life expectancy.