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What
is MG?
Myasthenia Gravis
is an autoimmune disease.
That
means that your bodies immune system which is supposed to fight bacteria
and viruses has gone a little crazy and has decided to attack itself.
- With
MG your body makes a protein called an antibody which attacks a small
piece of your muscle called the acetylcholine receptor. This receptor
needs to be activated in order for the muscle to contract.
-
With MG, as the attack on the acetylcholine receptor continues, the
number of receptors decreases and people are left with the inability
to move their muscles repeatedly.
- Often
a person with MG can have relatively normal strength in the mornings
or after brief rest, but then the symptoms worsen with repeated activity.
- Weakness
usually affects proximal muscles, such as upper arms and upper thighs
first. In many people the symptoms also involve the eyes with drooping
eyelids and double vision.
- Pain
is not a common symptom of MG and numbness and tingling is never a symptom
of MG.
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How is MG diagnosed?
There are two ways to make the diagnosis. These two tests detect 98% of
patients with MG.
- The
most sensitive and specific way to make the diagnosis is with a blood
test looking for the presence of the antibodies against the acetylcholine
receptor. If these are present you have MG. 10-15% of patients with
MG can still have antibodies that are not detected by our tests. For
these people an EMG/NCS should be performed. This is a test of the way
our nerves and muscles work. This has to be performed with "repetitive
stimulation" if one is concerned about MG. This also needs to be performed
by a person with special training in the test.
- If
one still suspects MG then a very special test called a "single fiber
EMG" can be performed. This is highly sensitive, meaning everyone with
MG will have an abnormal test. However, it is not very sensitive, meaning
that it can be abnormal for reasons other than MG. This test is done
by only a few very specially trained neurologists.
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What
Treatments are there?
-
Since myasthenia is caused by an abnormal protein in the blood, the
acteylcholine receptor antibody (AchR Aby) the best way to treat MG
is to get rid of this antibody. This can be done most rapidly by a process
called plasmaphresis, which is a form of dialysis or blood washing.
This actually removes the AchR Aby from your blood. However, it does
not prevent the antibody from being made again. Plasmaphresis is therefore
used for people who are very sick from their MG and need to get better
quickly.
- The
second line of treatments then are drugs we use to prevent the antibodies
from being made. This involves medications which suppress our immune
system, since antibodies are made by our immune system. There are many
choices of medications but the most widely effective choice is steroids.
Other drugs such as immuran, cyclosporine, or cellcept are used as well.
All of these medications have serious side effects and therefore should
only be used by a neurologist familiar with treating this disease.
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What
is the thymus?
The
thymus is a gland in our chests which allows our immune system to mature
correctly. Some people with MG have a tumor of the thymus gland called
a thymoma. Other people with MG have an overgrowth of their thymus. For
the last twenty years neurologists have believed that removing the thymus
gland, even if it is not cancerous makes the long term treatment of the
disease much easier. There is a well designed trial about to begin to
test this theory. Currently , thymectomy is still considered a very good
option for anyone with moderate or severe disease who is a good surgical
candidate.
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Do we know what causes our bodies to produce antibodies
to attack our muscles?
There is no known cause for MG. There is a link to other autoimmune diseases
such as thyroid disease or diabetes. There may also be a link to the thymus
gland, but as of yet there is no answer to why some people make antibodies
to the acetylcholine receptor.
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How do our muscles recover their strength with no medication
if we rest?
MG is caused when the number of receptors for acetylcholine on the muscle
falls below a certain level. We need acetylcholine to interact with the
receptors to make our muscles move. These receptors are destroyed by the
antibodies which are produced in MG. In some people with MG there are
enough receptors to make your muscles move once or twice but then the
muscles fatigue because the receptors have not gotten ready to be stimulated
again. With rest the acetylcholine receptors can prepare themselves to
be restimulated so symptoms seem better but then there is fatigue again.
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Why do my symptoms come and go?
Symptoms come and go for the reasons mentioned above
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Can Certain Foods trigger MG exacerbation i.e.: salty foods?
There are no foods which we know of that can trigger MG exacerbation.
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Why does daylight or bright light cause my eyelids to "shut
down"?
There should not be any change in symptoms with daylight, although some
people notice a change with temperature. There is another disease cause
blepharospasm which causes involunary forced eye closure and this is triggered
by sunlight. If the eyelids seem to be forced down as opposed to being
weak, then you should consider the possibility of blepharospasm.
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Why does excess Mestinon exacerbate my symptoms and make
my muscles weaker than they had been without it.
Excess Mestinon can make MG worse because it will cause over stimulation
of the acetylcholine receptors which can lead to muscle weakness. If you
believe that excess Mestinon is causing your muscle weakness you should
discuss this with your doctor because this can be serious. Usually if
you have too much Mestinon you will also be sweaty, nauseated, and have
diarrhea.
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I'm now on 3 grams Cellcept and 125 mg Cyclosporine/day;
they seem to control my MG symptoms but my overall strength seems to have
diminished over what it had been when I was first diagnosed. Is this MG
related or just a coincidence?
The main symptom of MG is muscle weakness, so if you are weak I would
be concerned that your MG symptoms are not completely controlled. You
should discuss this with your doctor.
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Sometimes my tongue feels fat and swollen as well as my
throat and everything seems to be closing up and trouble breathing. Am
I really swelling or does it only feel that way? If it is really swelling,
then why wouldn't physicians be able to prescribe drugs such as anti allergy
drugs to fight this problem?
In MG the tongue and throat can feel thick or swollen because they do
not move well. This can be a serious medical problem and so I would say
you need to discuss this with your doctor.
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Are there any known links or research regarding any kind
of connection between MG and Fibromyalgia Syndrome?
There are no known links between Fibromyalgia and MG. MG has a known cause
and treatment. Fibromyalgia has not yet been shown to have a known cause
or a specific pathology or treatment. Some people that I have seen who
have been diagnosed with fibromyalgia are in fact significantly weak and
with the correct diagnostic tools are shown to have MG. So i would say
if there is a lot of weakness then one should look aggresively for MG.
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What do you think about sero-negative MG? Is this widely
accepted or not in the neuro community? What would finally get a neuro
to give an MG diagnosis, with tests being negative but with MG signs/symptoms?
Sero-negative MG is widely accepted. It is believed approximately
10% of patients with MG are seronegative. However new antibodies are being
discovered so this number will decline over the next few years. If you
believe someone has MG but has normal blood tests then you need to do
a good EMG/NCS including repetitive nerve stimulation and possibly single
fiber EMG. If all of these are negative than I don't believe you can make
a diagnosis of MG.
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When I eat a meal, I notice that my sinuses seem to clog
up and I have to blow my nose constantly. I just assumed that it was me,
until I read of another Myasthenic who has the same problem. Is this a
common problem?
In MG if your swallowing muscles are weak then eating or drinking can
cause the food to come out of the nose. This is also a serious problem
because it can be a sign that your breathing muscles are weak. You should
discuss this with your doctor
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Can
I become pregnant if I have MG?
Pregnancy
is complicated by MG but not impossible. There can be problems with the
medications people take for MG in terms of fetal development. MG can also
be made worse by pregnancy. It is still possible to have a healthy baby
with MG but it is best to discuss this with your neurologist BEFORE you
get pregnant
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If
I am pregnant, should I continue using Imuran and Mestinon?
Mestinon
is probably safe in pregnancy. However; other than tylenol and codeine
the FDA does not declare any medicine SAFE in pregnancy. Imuran can suppress
the immune system and we do not know how it affects the fetus. These issues
should be discussed with your doctor.
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Will
my baby be born with MG just because I have it?
Many
babies that are born to mothers with MG have a 4-6 week period right after
they are born where the mothers acetylcholine receptor antibodies get
into the baby and cause weakness. This can be severe and end up with the
baby going on a breathing machine. After the 4-6 weeks the antibodies
from the mother are cleared out of the babies system and the baby is normal.
It is important for the OB doctors and pediatrician to know the mother
has MG so they can be prepared at the time of delivery.
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Is
MG hereditary?
There
are a few rare forms of MG which are hereditary. These are called congenital
myasthenia. In autoimmune myasthenia where people have antibodies, it
is not genetic.
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What
are the statistics on thymectomy outcomes; ie: full remission, partial
medicated remission, no response etc.?
There
are no good data on thymectomy. The largest trial was done out of Duke
University in the 1970's and suggested that after thymectomy MG is easier
to control. But there are no data on number of remissions, cures etc.
In general in young healthy people with generalized myasthenia we believe
the benefits are greater than the risks. There is a large trial getting
started to ask this question.
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I
do not want to try any medication to treat my MG until I try alternative
methods of treatment. Can you recommend any forms of treatment that MG
patients can try to control MG on their own without using medication?
There
are no alternative treatments which have ever been shown to be effective.
Treated, all patients with MG should lead a normal life and have a normal
life span. Untreated, MG can be fatal.
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Do
I have to continue taking cellcept and cyclosporine "forever", or will
I someday be able to taper off them, without the MG symptoms returning?
Some
patients can be cured, but most patients require treatment of some form
for their lifetime.
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Mestinon
is non specific, that is, it acts upon normal, healthy muscle receptors
as well as antibody damaged receptors. What, if any, are the long term
effects of mestinon on normal, healthy muscle receptors?
We
do not know of ny long term effects of taking mestinon on healthy muscle.
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What
are the best methods for myasthenics to maintain their muscle tone?
Repeated
exercise weakens our muscles as opposed to normal non myasthenic muscles,
which strengthen with exercise. Is there a solution to this "catch 22"?
Knowing what type of exercise to suggest to people with MG is difficult
and there are several studies investigating this question. In general
I suggest that people do what is comfortable but not to the point of exhaustion.
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If
a myasthenic has a thymoma does age play a part in whether to have it
removed or not?
If
you don't have it removed for age reasons how do you know if it is cancerous
or not? Since the benefits of thymectomy takes years to see, doing it
in people over 80 makes little sense but if someone is expected to live
more than 10 years it is reasonable to do. If the thymus appears enlarged
on CT or MRI (thymoma) it should always come out because cancers are possible.
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