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This website aims to provide information about Myasthenia Gravis. Please consult your doctor for individual treatment. The information presented here is for education only. Although we have tried our best to provide accurate information in the pages published here, we are in no way responsible if they are out-of-date or incorrectly presented. However, we would like to hear from you in case you would like to know more about Myasthenia Gravis or have any suggestions on making this site better. Your contributions are most welcome. Please send us an email at myestin@myestin.com 

What is Myasthenia Gravis?
Myasthenia gravis is a chronic auto-immune disorder. It is characterized by weakness of the skeletal (voluntary) muscles of the body. 

What are Voluntary Muscles?
Skeletal muscles - also known as striated or voluntary muscles are the muscles that are attached to parts of the skeleton and are involved with voluntary movement like walking and talking. Contraction and relaxation of the skeletal muscles are important for our smooth movement. Walking, talking and even breathing requires muscular contraction. The cerebral and cerebeller system controls and co-ordinates the movements through spinal cord and the peripheral nervous system. The motor unit is the final common pathway.

Cardiac muscles - the muscles of the heart and smooth muscles such as the muscles in the walls of the digestive tract are not under conscious control, and are therefore not affected by Myasthenia Gravis.

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 movements, facial expression, chewing, talking, and swallowing are often, but not always, involved. The muscles that that control breathing and neck and limb movements may also be affected. Myasthenia gravis is caused by a defect in the transmission of nerve impulses to muscles.

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What are the symptoms of Myasthenia Gravis?

Ocular Symptoms 
About 30-50 % of Myasthenia Gravis patients develop ocular symptoms as the first symptoms of MG. About 10% of all patients experience only ocular problems - referred to as ocular MG. However, ptosis ( drooping of the eyelid ) and diplopia, (double vision ) increase towards the end of the day as one uses these muscles throughout the day for a long period of time for day-today activities.  

Oral Symptoms 
Weakness of the muscles of the Pharynx is a very common symptom in Myasthenia Gravis. Pharynx is the passageway for air from the nasal way to the larynx and for food from mouth to the oesophagus. It also acts as a resonating cavity. Naturally when the muscles of the pharynx become weak, one would have difficulty in swallowing, chewing, or breathing. The speech may become slurred. Eating or talking continuously for a long time may cause fatigue to these muscles and may lead to a nasal sound. 

Head, Neck and Arms
Weakness of these muscles is observed in about 10% of patients only. Although any of the limbs can be affected, the arms are usually weaker than the legs. The weakness progresses throughout the day as the patient uses muscles for long period of time during day-today activities.

The symptoms often fluctuate, and the patient may have periods of weakness mixed with periods of normal health. Appropriate treatment may lead to a good control over symptoms such as fatigue and help the patient do routine activities with ease. In some patients, however, deterioration can be abrupt and may lead to breathing problems. This may require the patient being put on a respirator. There are many factors that can trigger episodes of weakness in patients with MG, including other illnesses (e.g. viral respiratory infections), drugs that affect the neuromuscular junction, hot weather, pregnancy, and emotional upset.

The first noticeable symptoms of myasthenia gravis may be weakness of the eye muscles, difficulty in swallowing, or slurred speech. Symptoms vary in type and severity. Myasthenia gravis is not directly inherited nor is it contagious. The first steps in diagnosing myasthenia gravis include a review of the individual's medical history and physical and neurological examinations. If the doctor suspects myasthenia gravis, several diagnostic tests are available to confirm the diagnosis, including a special blood test that can detect the presence of immune molecules or acetylcholine receptor antibodies.

Presentation and progression of Myasthenia Gravis

1. Extra Ocular Eye Muscles - Muscles of the eyeball and those which hold the      eyelids open, are often but not always involved. This results in drooping of the upper eyelid ( ptosis ) and double vision (diplopia )due to weakness and fatigue in the Extra Ocular Muscles.
2. The muscles of facial expression, smiling, chewing, talking, or swallowing can be selectively affected in some people with MG.
3. Muscles of the neck and limbs may be affected.
4. Generally MG is painless, however, if muscles of the neck are in spasm, one may feel pain at the back of the neck.
5. Any muscle of a limb may be affected. More common is shoulder girdle muscles involvement. In that case, the patient may find it difficult to comb hair without frequent rest.

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What are the Contributory Causative Factors of Myasthenia Gravis?

Myasthenia Gravis is mostly idiopathic in nature. It means the disease may occur without recognizable causative factors and  may occur spontaneously. The exact causes remain largely unknown. However, a genetic factor has been implicated in family studies. Other causative factors could be;

HLA: Presence of some types of Human Leucocyte Antigens (HLA), increase the likelihood of the disease appearing.

Gender: Females appear to be more susceptible than males, hinting at a hormonal link.

Thymoma: About 15 % patients, mainly of late onset, have an encapsulated or locally invasive thymoma. A thymoma is a tumor originating in the epithelial tissue of the thymus. Thymus plays an important role in the development of immune response in the newborn.  At birth the average weight of the thymus is about 13 gms. It grows very rapidly in first 2 years, then slows down attaining a weight of about 30 gms at puberty. Then it begins to reduce in size. In adults, thymus is largely believed to have a diminished role.

Majority of patients, have one of a number of thymic abnormalities. The younger patients have a marked personal and familial relationship with other auto-immune diseases and may have inherited an immuno-reactive gene. This has been linked to some of the HLA haplotypes as mentioned above. The inheritance of this gene is not necessary for Myasthenia and not much is known about possible triggering factors responsible for the spontaneous disease.

Drugs: A number of  drugs can exacerbate symptoms of Myasthenia Gravis. Antibiotics (eg, aminoglycosides, ciprofloxacin, erythromycin, and ampicillin)

Penicillamine, a drug sometimes used in the treatment of Rheumatoid Arthritis, is known to induce various autoimmune disorders, including Myasthenia Gravis. About 90% of patients who develop Myasthenia Gravis secondary to penicillamine exposure show presence of Actylcholine Receptor Antibodies.

Beta-adrenergic receptor blocking agents such as  propranolol, a drug used in the treatment of hypertension and oxprenolol.

Lithium used as its salt, invariably, Lithium Carbonate which is indicated in the treatment of manic depressive psychosis.

Magnesium , Procainamide , Verapamil , Quinidine , Chloroquine , Prednisone , Timolol (i.e. a topical beta-blocking agent used for glaucoma) , Anticholinergics (e.g. trihexyphenidyl) and Neuromuscular blocking agents.

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Myasthenia Gravis - A Historical Perspective.

Thomas Willis, the English physician, first described a woman with myasthenia gravis (MG), in his book named De anima brutorum(1) published in 1672 (1. (1) De anima brutorum quae hominis vitalis ac sensitiva est, exercitationes duae by Thomas Willis, Amstelodami, Apud Joannem Blaeu, 1672. Written in latin. ). Myasthenia gravis is an acquired autoimmune disorder characterized clinically by weakness of skeletal muscles. The distinctive feature of MG is fluctuating weakness of voluntary or striated muscles, which is made worse by use of those muscles and improved at least partially by rest of these muscles. Thus weakness increases during the day and improves with rest. The involuntary muscles e.g. those of heart and smooth muscles of the gut, blood vessels, and uterus are not involved in MG. Myasthenia gravis is probably under-diagnosed and the prevalence is probably higher. Previous studies had showed women to be more often affected than men. However, with longer life expectancy now the male to female ratio with MG is almost 1:1.

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Treatment options for Myasthenia Gravis

Myasthenia gravis can be controlled. Some medications improve neuromuscular transmission and increase muscle strength, and some suppress the production of abnormal antibodies. These medications must be used with careful medical followup because they may cause major side effects. Thymectomy, the surgical removal of the thymus gland, improves symptoms in certain patients and may cure some individuals. Other therapies include plasmapheresis, a procedure in which abnormal antibodies are removed from the blood, and high-dose intravenous immune globulin, which temporarily modifies the immune system and provides the body with normal antibodies from donated blood .

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