2. What are the
Odds?
Myasthenia Gravis affects
approximately 2 out of every
100,000 people and can
occur within any age, race, or
sex. According to these odds
this is more likely to happen
than
•Finding a four-leaf clover on
the first try
•Being murdered
•Being considered possessed
by Satan.
3. A chronic autoimmune neuromuscular disease characterized
by varying degrees of weakness of the skeletal (voluntary)
muscles of the body.
The hallmark of myasthenia gravis is muscle weakness that
increases during periods of activity and improves after
periods of rest. Muscles that control eye and eyelid
movement, facial expression, chewing, talking, and
swallowing are often, but not always, involved in the
disorder. (muscles that control breathing and neck
movements also may be affected.)
4. What causes myasthenia
gravis…
MG is caused by a defect in the transmission of
nerve impulses to muscles, occurring when
normal communication between the nerve and
the muscle is interrupted at the neuromuscular
junction, the place where nerve cells connect
with the muscles they control.
Impulses travel down the nerve and the nerve
endings normally release a neurotransmitter
substance called acetylcholine. Acetylcholine
travels through the neuromuscular junction and
binds to the acetylcholine receptors which are
activated and generate a muscle contraction.
In MG, antibodies block, alter, or destroy the
receptors for acetylcholine at the
neuromuscular junction which prevents the
muscle contraction from occurring.
5. With MG, normal communication between the nerve
and muscle is stopped at the place where nerve
endings connect with the muscles they control—the
nerve muscle junction. Normally, the nerve endings
release a substance called acetylcholine, which binds
the muscle tissue at the nerve-muscle junction, causing
the muscle to contract. In someone with MG, the
body’s own immune system makes antibodies that
block the binding of acetylcholine to the muscle.
6. The role of the thymus
gland in myasthenia
The thymus gland lies in the upper chest
gravis… area beneath the breastbone and plays
an important role in the development of
the immune system in early life. It’s
somewhat large in infants, grows
gradually until puberty, and then gets
smaller and is replaced by fat with age. In
adults with MG, the thymus is abnormal.
Some individuals with MG develop
thymomas, or tumors of the thymus gland,
which are generally benign, but could
become malignant. Although the
relationship between the thymus gland
and MG is not yet fully understood,
scientists believe that it gives incorrect
instructions to developing immune cells,
ultimately resulting in autoimmunity and
the production of the acetylcholine
receptor antibodies, thereby setting the
stage for the attack on the neuromuscular
transmission.
7. •Drooping of one or both eyelids (ocular myasthenia gravis/ptosis)
•Blurred or double vision (diplopia)
•Problems walking (unstable or waddling gait)
•Weakness in arms, hands, fingers, legs, and neck
•Change in facial expression
•Having a hard time swallowing
(which leads to difficulty eating and ultimately extreme weight loss)
•Impaired speech (dysarthria)
•Shortness of breath (feeling like you can’t get enough air)
The onset of the disorder may be sudden. Symptoms often are not
immediately recognized as myasthenia gravis. In most cases the most
noticeable symptom is weakness of the eye muscles. In others, difficulty
in swallowing and slurred speech may be the first signs. The degree of
muscle weakness in MG varies greatly among patients, ranging from a
localized form, limited to eye muscles, to a severe or generalized form in
which many muscles-sometimes including those that control breathing-
are affected.
8. Myasthenia gravis occurs in all ethnic groups and both
genders. It most commonly affects young adult women
(under 40) and older men (over 60), but it can occur at
any age.
MG in juveniles is common and is not directly inherited
nor is it contagious. However, the disease may
occasionally occur in more than one member of the
same family.
9. Diagnosis
It’s not uncommon in cases of MG for a delay in
diagnosis. The first step of diagnosis includes a
review of the individual’s medical history, and
physical and neurological examinations. If the doctor
suspects MG several tests are available to confirm
the diagnosis.
•Antibody blood tests: Blood tests detect the
presence of high levels of abnormal antibodies that
prevent normal nerve-to-muscle transmission.
•Edrophonium test: Drug is injected and weak eye
muscles will be temporarily strengthened.
•Nerve conduction test/repetitive stimulation: A
nerve linked with a specific muscle is stimulated to
see if the muscle action is weakened.
•Single fiber electromyography (EMG): Singe muscle
fibers are stimulated by electrical impulses. Muscle
fibers of people with MG do not respond to repeated
electrical stimulation as well as muscles that
function normally. Can detect problems with nerve-to-
muscle transmission.
•Computed Tomography (CT) or Magnetic Resonance
Imaging: Test shows if there is an abnormal thymus
gland or a thymus gland tumor.
10. There is no cure for MG, however there are several therapies that can
help strengthen the muscles of someone with MG.
•Medications: Drugs used including cholinesterase inhibitors, such as
pyridostigmine. These drugs help improve nerve signals to muscles and
increase muscle strength. Immunosuppressive drugs are used to
suppress the production of abnormal antibodies.
•Thymectomy: The surgical removal of the thymus gland, which is
abnormal in most persons with MG. The procedure is done for people
with MG who have tumors, as well as for some who don’t have tumors.
•Plasmapheresis: Procedure removes abnormal antibodies from the
blood, providing relief for MG symptoms for a few weeks.
•High-dose intravenous immune globulin: This treatment keeps the
immune system from damaging the nerve-muscle junction for a short
time. Provides relief from MG symptoms in many patients for weeks to
months.
11. Myasthenic Crises
Occurs when the muscles that control breathing
weaken to the point that ventilation is inadequate,
creating a medical emergency and requiring a
respirator for assisted ventilation. In patients whose
respiratory muscles are weak, crises-which generally
call for immediate medical attention-may be triggered
by infection, fever, or an adverse reaction to
medication.
12. Much has been learned about myasthenia gravis in recent years and,
with treatment, the outlook for most patients with myasthenia gravis is
bright. They will have significant improvement of their muscle weakness
and they can expect to lead normal or nearly normal lives. Some cases
of MG go into remission temporarily and muscle weakness may
disappear completely so that medications can be discontinued. Stable,
long-lasting complete remissions are the goal of Thymectomy. Though
much has been learned, there is still much more knowledge to gain. The
ultimate goal of myasthenia gravis research is to increase scientific
understanding of the disorder. Researchers are seeking to learn what
causes the autoimmune response in MG, and to better define the
relationship between the thymus gland and MG. Today’s research
includes a broad spectrum of studies conducted and supported by
NINDS (National Institute of Neurological Disorders and Stroke)
scientists, who are evaluating new and improving current treatments for
the disorder. The objective of the study is to expand current knowledge
of the function of receptors and to apply this knowledge to the treatment
of MG.
13. In July of this past year, I was diagnosed with
Myasthenia Gravis and immediately admitted to the
pediatric oncology unit of the Florida Hospital. By the
time of my diagnosis I had lost over 50 pounds and
reached crisis status. So much of my digested foods
had been inhaled into my lungs that I was beginning to
develop pneumonia. Since my diagnosis, I’ve been
undergoing treatment for the condition and have been
extremely satisfied with the results. I’ve never felt better
and couldn’t be happier.
