Myasthenia gravis is a neuromuscular disorder that causes weakness in the skeletal muscles, which are the muscles your body uses for movement. It occurs when communication between nerve cells and muscles become impaired. This impairment prevents crucial muscle contractions from occurring, resulting in muscle weakness. Most common primary disorder of neuromuscular transmission.

2. INTRODUCTION
 Myasthenia gravis is a neuromuscular disorder that
causes weakness in the skeletal muscles, which are the
muscles your body uses for movement.
 It occurs when communication between nerve cells
and muscles become impaired.
 This impairment prevents crucial muscle contractions
from occurring, resulting in muscle weakness.
 Most common primary disorder of neuromuscular
transmission.

3.  Most commonly affected muscles are those of the eyes,
face and swallowing.
 It can result in double vision, drooping eyelids, trouble
talking, trouble walking.
 Those affected often have a large thymus gland or
develop thymoma.

4.  Rarely an inherited genetic defect in the
neuromuscular junction results in a similar condition
known as congenital myasthenia.
 Though myasthenia gravis can affect people of any age,
it is more common in younger women and older men.

5. Symptoms
 The main symptom of MG is weakness in the voluntary
skeletal muscles, which are muscles under your control.
 trouble talking
 problems walking up stairs or lifting objects
 facial paralysis
 difficulty breathing because of muscle weakness
 difficulty swallowing or chewing
 fatigue
 hoarse voice
 drooping of eyelids
 double vision

6. Eye muscles
 In more than half the people who develop myasthenia
gravis, their first signs and symptoms involve eye
problems, such as:
 Drooping of one or both eyelids (ptosis).
 Double vision (diplopia), which may be horizontal or
vertical, and improves or resolves when one eye is
closed.

8. Face and throat muscles
 In about 15 percent of people with myasthenia gravis, the first
symptoms involve face and throat muscles, which can cause:
 Altered speaking. Your speech may sound very soft or nasal,
depending upon which muscles have been affected.
 Difficulty swallowing. You may choke very easily, which makes it
difficult to eat, drink or take pills. In some cases, liquids you're
trying to swallow may come out your nose.
 Problems chewing. The muscles used for chewing may wear out
halfway through a meal, particularly if you've been eating
something hard to chew, such as steak.
 Limited facial expressions. Your family members may comment
that you've "lost your smile" if the muscles that control your
facial expressions have been affected

10. Neck and limb muscles
 Myasthenia gravis can cause weakness in your neck,
arms and legs, but this usually happens along with
muscle weakness in other parts of your body, such as
your eyes, face or throat.
 The disorder usually affects arms more often than legs.
However, if it affects your legs, you may waddle when
you walk. If your neck is weak, it may be hard to hold
up your head.

11. Causes
 MG is a neuromuscular disorder that’s usually caused
by an autoimmune problem.
 Autoimmune disorders occur when your immune
system mistakenly attacks healthy tissue.
 In this condition, antibodies, which are proteins that
normally attack foreign, harmful substances in the
body, attack the neurotransmitter substance
acetylcholine, which is a crucial substance for
communication between nerve cells and muscles. This
results in muscle weakness.

13.  The exact cause of this autoimmune reaction is unclear
to scientists.
 According to the Muscular Dystrophy Association, one
theory is that certain viral or bacterial proteins may
prompt the body to attack acetylcholine.

15. Diagnosis
 Neurological examination:
 Reflexes
 Muscle strength
 Muscle tone
 Senses of touch and sight
 Coordination
 Balance

16.  Edrophonium test
 Injection of the chemical edrophonium chloride
(Tensilon) may result in a sudden, although
temporary, improvement in your muscle strength. This
is an indication that you may have myasthenia gravis.
 Edrophonium chloride blocks an enzyme that breaks
down acetylcholine, the chemical that transmits
signals from your nerve endings to your muscle
receptor sites.

17.  Ice pack test
 If you have a droopy eyelid, your doctor may conduct an ice
pack test. In this test, a doctor places a bag filled with ice
on your eyelid. After two minutes, your doctor removes the
bag and analyzes your droopy eyelid for signs of
improvement. Doctors may conduct this test instead of the
edrophonium test.
 Blood analysis
 A blood test may reveal the presence of abnormal
antibodies that disrupt the receptor sites where nerve
impulses signal your muscles to move.

18. TreatmentMedications
Cholinesterase inhibitors. Medications such as pyridostigmine
(Mestinon) enhance communication between nerves and muscles. These
medications don't cure the underlying condition, but they may improve
muscle contraction and muscle strength.
Possible side effects may include gastrointestinal upset, nausea, and
excessive salivation and sweating.
Corticosteroids. Corticosteroids such as prednisone inhibit the immune
system, limiting antibody production.
Prolonged use of corticosteroids, however, can lead to serious side effects,
such as bone thinning, weight gain, diabetes and increased risk of some
infections.

19. 
Immunosuppressants. Your doctor may also prescribe
other medications that alter your immune system,
such as azathioprine (Imuran), mycophenolate mofetil
(CellCept), cyclosporine (Sandimmune, Neoral),
methotrexate (Trexall) or tacrolimus (Prograf).
Side effects of immunosuppressants can be serious and
may include nausea, vomiting, gastrointestinal upset,
increased risk of infection, liver damage and kidney
damage.

20.  Intravenous therapy
 Plasmapheresis :This procedure uses a filtering process
similar to dialysis. Your blood is routed through a machine
that removes the antibodies that block transmission of
signals from your nerve endings to your muscles' receptor
sites. However, the beneficial effects usually last only a few
weeks.
 After repeated treatments, it may be difficult for doctors to
gain access to your vein. They may need to implant a long,
flexible tube (catheter) into your chest to conduct the
procedure.

21. Surgery
 About 15 percent of the people with myasthenia gravis
have a tumor in their thymus gland, a gland under the
breastbone that is involved with the immune system.
 If you have a tumor, called a thymoma, doctors will
conduct surgery to remove your thymus gland
(thymectomy).
 If you don't have a tumor in the thymus gland, surgery to
remove the thymus gland may improve your myasthenia
gravis symptoms.

22.  It may eliminate your symptoms, and you may be able
to stop taking medications for your condition.
However, you may not notice the benefits of a
thymectomy for several years, if at all.
 A thymectomy may be performed as an open surgery
or as a minimally invasive surgery.
 In an open surgery, your surgeon splits the central
breast bone (sternum) to open your chest and remove
your thymus gland.

23. Complications
 Myasthenic crisis
 Myasthenic crisis is a life-threatening condition that
occurs when the muscles that control breathing
become too weak to do their jobs. Emergency
treatment is needed to provide mechanical assistance
with breathing. Medications and blood-filtering
therapies help people to again breathe on their own.

24.  Thymus tumors
 About 15 percent of people with myasthenia gravis
have a tumor in their thymus, a gland under the
breastbone that is involved with the immune system.
Most of these tumors, called thymomas, aren't
cancerous (malignant).

26. Other disorders
 People with myasthenia gravis are more likely to have the
following conditions:
 Underactive or overactive thyroid. The thyroid gland,
which is in the neck, secretes hormones that regulate your
metabolism.
 If your thyroid is underactive, you may have difficulties
dealing with cold, weight gain and other issues.
 An overactive thyroid can cause difficulties dealing with
heat, weight loss and other issues.
 Autoimmune conditions: People with myasthenia gravis
may be more likely to have autoimmune conditions, such
as rheumatoid arthritis or lupus.