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Myasthenia Gravis
(MG) is a chronic neuromuscular autoimmune
disease that manifests itself by varying weakness of the voluntary muscles
of the body. Myasthenia Gravis occurs in all races, both sexes and at any age.
However MG is most common in young adult women and older men. Myasthenia Gravis is not directly
inherited nor is contagious, but does occasionally occur in more than one member
of the same family. Myasthenia Gravis may affect any muscle that is under
voluntary control, and certain muscles are more often involved, which are the
ones that control eye movements, eyelids, chewing, swallowing, coughing and
facial expressions. Muscles that control breathing and movements of the arms and
legs may also be affected by Myasthenia Gravis, and the weakness of the muscles needed for breathing may
cause shortness of breath and difficulty in taking a deep breath and coughing.
The muscle weakness of Myasthenia Gravis
increases with continuous activity and improves after periods of rest. The
muscles involved in MG vary greatly from one patient to the next. Weakness may
be limited to the muscles controlling eye movements and the eyelids, which is
the mildest form of Myasthenia Gravis and is called ocular MG. In its severest form,
MG
involves many of the voluntary muscles of the body, including those needed for
breathing. The degree and distribution of muscle weakness for many patients
falls in between these two extremes. When the muscle weakness is severe and
involves breathing hospitalization is usually necessary.
It is recommended that Transfer
Factor Advanced Formula to be used in autoimmune conditions.
Transfer Factor Plus is generally preferred for
conditions caused by infection. Transfer Factors
suppress over acting immune system
to ease autoimmune conditions.
Causes of
Myasthenia Gravis
The voluntary muscles of the entire body are
controlled by nerve impulses arising from the brain.
These nerve impulses travel down the nerves to the place where the nerves meet
the muscle fibers. However nerve fivers do not actually connect with muscle fibers.
There is a space between the nerve ending and muscle fiber and this area is
called the neuromuscular junction.
When the nerve impulse, originating in the brain,
arrives at the nerve ending it releases a chemical called "acetylcholine". The
acetylcholine travels across the space to the muscle fiver side of the
neuromuscular junction where it attaches to receptor sites. There are many
receptor sites on the muscle side of the neuromuscular junction. The muscle
contracts when enough of the receptor sites have been activated by the
acetylcholine. In Myasthenia Gravis there is a reduction in the number of these
receptor sites, as much as 80%. This is responsible for the muscle weakness. The
reduction of the receptor sites is caused by an antibody that destroys or blocks
the receptor site at the neuromuscular junction (autoimmune
condition).
Antibodies are proteins that play an important
role in our immune system. They are normally directed at foreign proteins called
antigens that attack the body. Such foreign proteins include viruses and
bacteria. The antibodies help the body to protect itself from these foreign
proteins. For reasons which we do not understand, the
immune system of the
patient with MG makes antibodies against the receptor sites of the neuromuscular
junction. These abnormal antibodies can be measured in the blood of patients
with MG. These antibodies destroy the receptor sites more rapidly than they can
be replaced by the body. The muscle weakness occurs when acetylcholine cannot
activate enough receptor sites at the neuromuscular junction.
It is recommended that Transfer
Factor Advanced Formula to be used in autoimmune conditions.
Transfer Factor Plus is generally preferred for
conditions caused by infection. Transfer Factors
suppress over acting immune system
to ease autoimmune conditions.
Diagnosis of
Myasthenia Gravis
There are many disorders that may cause muscle
weakness. In evaluating the problem the doctor will carry out a neurological
evaluation that includes testing muscles and checking reflexes. There are
several tests that may be used in establishing a diagnosis of Myasthenia Gravis.
The edrophonium (Tensilon) test is performed by
injecting this chemical into a vein. Improvement of strength immediately after
the injection provides strong support or the diagnosis of MG. EMG studies
including repetitive electrical stimulation of nerves can also provide support
for the diagnosis of MG when characteristic patterns are present. A blood test
for the abnormal antibodies can be performed to see if they are present.
Myasthenia Gravis Treatment
There have been major advances in the treatment of Myasthenia Gravis in recent
years. Although there is no known cure for MG, the available treatments are
sufficiently effective that most patients will show excellent improvement and
can lead normal lives. The various forms of treatment include medications, thymectomy and plasmapheresis. Medications
are most frequently used in treatment. Anticholinesterase agents (such as
Mestinon) allow the acetylcholiac to remain at the neuromuscular junction a
little longer than usual so that more receptor sites can be activated.
Prednisone, a cortisone-like drug, and azathioprine (Imuran) may be used to
suppress the abnormal action of the immune system that occures in
MG.
Thymectomy (the surgical removal of the thymus
gland) is another treatment used. The thymus gland lies behind the breast bone
and is an important part of the immune system. When there is a tumour in the
thymus gland is also removed because of the risk of malignancy. The thymectomy
usually, but not always, lessens the severity of the muscle weakness after some
months. In some patients the muscle weakness may completely disappear and thus
is called remission. The degree to which the thymectomy helps varies with each
patient. Plasmapheresis may also be useful
in the treatment of Myasthenia Gravis. This procedure removes the abnormal antibodies from the
plasma of the blood in patients with MG. The improvement in muscle strength may
be striking but is usually short-lived since the abnormal antibodies continue to
be formed. When plasmapheresis is used it may, therefore, require repeated use.
Plasmapheresis may be especially helpful during the period of MG arisisi or
before thymectomy. Which of these various
treatments are used in a Myasthenia Gravis patient depends upon the severity of the weakness,
which muscles are weak, the patients age and other associated medical problems.
The doctor will determine which of these treatments are the best for each
patient.
It is recommended that Transfer
Factor Advanced Formula to be used in autoimmune conditions.
Transfer Factor Plus is generally preferred for
conditions caused by infection. Transfer Factors
suppress over acting immune system
to ease autoimmune conditions.
Special Issues of
Myasthenia Gravis
Most Myasthenia Gravis women experience no change or an improvement
in their weakness during pregnancy. A few may note worsening in weakness during
some point in the pregnancy or following the delivery. This is usually
temporary. In approximately 10-15% of the newborn baby of MG mothers there is a
temporary type of MG weakness that lasts from several days to weeks. The
weakness is due to the transfer of the abnormal antibodies from the mother to
the fetus before the baby is born. Why the weakness occur in only a minority of
the infants is not known. This weakness in the newborn requires proper treatment
and once it clears does not recur in later life.
Certain drugs may make the weakness in the Myathenia Graivs
patient worse. Some antibiotics (especially the amino-glycosides), narcotics, penicillamine, magnesium, muscle relaxants, cardiac anti-arrhythmia agents and
anaesthetics may increase the weakness. Prednisone when used in the treatment of
MG, may temporarily worsen the patient's weakness before improvement occurs. It
is important that the patient inform any physician or dentist who is consulted
for other problems that he/she has Myasthenia Gravis that help the doctor avoid the drugs that
may aggravate the weakness. Sometimes it is still very important to use such
drugs. In that case they should be used with care. Occasionally, the weakness in an Myasthenia
Gravis patient may
be come rapidly worse. When the patient has difficulty breathing or maintaining
an open windpipe, the patient and doctor are faced with a critical situation.
this is referred to as Myasthenia Grivis Crisis. |
