shiva Kumar

INTRODUCTION Myasthenia gravis (MG) is a complex, autoimmune

disorder in which antibodies destroy neuromuscular connections.

Causes problems with the nerves that communicate with muscles.

Affects the voluntary muscles of the body, especially the eyes, mouth, throat, and limbs.

Characterized by weakness and rapid fatigue of any of the muscles under the voluntary control.

The cause of myasthenia gravis is a breakdown in the normal communication between nerves and muscles.

No cure for myasthenia gravis, but treatment can help relieve signs and symptoms – such as weakness of arm or leg muscles, double vision, drooping eyelids, and difficulties with speech, chewing, swallowing and breathing.

While myasthenia gravis can affect people of any age from neonatal to above 60 and more common in women younger than 40 and in men older than 60.

TYPES OF MYASTHENIA GRAVISThree types of MG in children:

Congenital MG - Very rare non-immune form of MG that is inherited as an autosomal recessive disease. This means that both males and females are equally affected and that two copies of the gene, one inherited from each parent, are necessary to have the condition. Symptoms of congenital MG usually begin in the baby's first year and are life-long.

Transient neonatal MG - Between 10 and 20 percent of babies born to mothers with MG may have a temporary form of MG. This occurs when antibodies common in MG cross the placenta to the developing fetus. Neonatal MG usually lasts only a few weeks, and babies are not at greater risk for developing MG later in life.

Juvenile MG - This auto-immune disorder develops typically in female adolescents - especially Caucasian females. It is a life-long condition that may go in and out of remission. About 10 percent of MG cases are juvenile-onset.

SYMPTOMS Babies with neonatal MG may be weak, with a poor suck,

and may have respiratory difficulty. A few babies may need the help of a mechanical breathing machine if their respiratory muscles are too weak to breathe on their own. Symptoms go away as the maternal antibodies disappear over time.

Congenital MG symptoms may begin in the first year, with generalized weakness in the arms and legs, and delays in motor skills such as crawling, sitting, and walking. Babies may have difficulty feeding and may have weak eyelids and poor head control.

Juvenile MG symptoms may begin gradually over weeks or months. The child may become excessively tired after very little activity, and begin to have problems chewing and swallowing. Drooping eyelids may be so severe that the child cannot see.

Eye muscles

In more than half the people who develop MG, their first signs and symptoms involve eye problems:

Drooping of one or both eyelids (ptosis)

Double vision (diplopia), which may be horizontal or vertical

Blurred vision, which may come and go

Face and throat muscles

In about 15 percent of people with myasthenia gravis, the first symptoms involve face and throat muscles, which can cause difficulties with:

Speaking. The speech may be very soft or sound nasal, depending upon which muscles have been affected.

Swallowing. May choke very easily, which makes it difficult to eat, drink or take pills. In some cases, liquids may come out of the nose.

Chewing. The muscles used for chewing may wear out halfway through a meal, particularly if eating

something hard to chew, such as sugarcane.

Facial expressions. Family members may

note "lost smile" if the muscles that control

facial expressions are affected.

Arm and leg muscles

Myasthenia gravis can cause weakness in arms and legs, but this usually happens in conjunction with muscle weakness in other parts of the body – such as eyes, face or throat.

The disorder usually affects arms more often than legs.

If it affects legs, may waddle when walking.

Normal dumbbell Weakness dumbbell

When to see a doctorIf having trouble with:

Breathing

Seeing

Swallowing

Chewing

Walking

CAUSES Myasthenia gravis may be inherited as a rare,

genetic disease, acquired by babies born to mothers with MG, or the disorder may develop spontaneously later in childhood.

Nerves communicate with the muscles by releasing chemicals, called neurotransmitters, which fit precisely into receptor sites on the muscle cells.

In myasthenia gravis, immune system produces antibodies that block or destroy many of the muscles' receptor sites for a neurotransmitter called acetylcholine.

With fewer receptor sites available, muscles receive fewer nerve signals, resulting in weakness.

Chemicals messengers, called neurotransmitters, fit precisely into receptor sites on your muscle cells. In myasthenia gravis, certain receptor sites are blocked or destroyed, causing muscle weakness.

It's believed that the thymus gland, a part of the immune system located in the upper chest beneath the breastbone, may trigger or maintain the production of these antibodies.

Large in infancy, the thymus is small in healthy adults. But, in some adults with myasthenia gravis, the thymus is abnormally large.

Some people also have tumors of the thymus.

Usually, thymus gland tumors are noncancerous.

Thymus gland, a part of your immune system located in the upper chest beneath the breastbone, may trigger or maintain the production of antibodies that result in the muscle weakness common in MG.

Factors worsening MG

Fatigue

Illness

Stress

Extreme heat

Medications – such as beta blockers, calcium channel blockers, quinine and some antibiotics

COMPLICATIONS Myasthenic crisis: A life-threatening condition,

which 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 recover from myasthenic crisis, so they can again breathe on their own.

Thymus tumors: About 15 percent of the people who have myasthenia gravis have a tumor in their thymus, a gland under the breastbone that is involved with the immune system. Most of these tumors are noncancerous.

Other disorders

Underactive or overactive thyroid. The thyroid gland, located in the neck, secretes hormones that regulate metabolism. If thyroid is underactive, body uses energy more slowly. An overactive thyroid makes body use energy too quickly.

Lupus. Disease of immune system. Common symptoms include painful or swollen joints, hair loss, extreme fatigue and a red rash on the face.

Rheumatoid arthritis. Caused by problems with immune system. It is most conspicuous in the wrists and fingers, and can result in joint deformities that make it difficult to use hands.

TESTS AND DIAGNOSIS Diagnosis is made after the sudden or gradual onset

of specific symptoms and after diagnostic testing.

It is confirmed with a Tensilon test. With this test, a small amount of medicine (Tensilon) is injected into the child, if the child has MG, an immediate, but brief, increase in muscle tone is noted.

Other diagnostic tests

Blood tests

Genetic tests - diagnostic tests that evaluate for conditions that have a tendency to run in families.

Electromyogram (EMG) - a test that measures the electrical activity of a muscle or a group of muscles. An EMG can detect abnormal electrical muscle activity due to diseases and neuromuscular conditions.

Muscle biopsy - a small sample of the muscle is removed and examined to determine and confirm a diagnosis or condition.

Reflexes

Muscle strength

Muscle tone

Senses of touch and sight

Coordination

Balance

Edrophonium test: Injection of the chemical edrophonium (Tensilon) may result in a sudden, although temporary, improvement in muscle strength — an indication that you may have myasthenia gravis. Edrophonium acts to block an enzyme that breaks down acetylcholine, the chemical that transmits signals from nerve endings to muscle receptor sites.

Blood analysis: A blood test may reveal the presence of abnormal antibodies that disrupt the receptor sites where nerve impulses signal muscles to move.

Repetitive nerve stimulation: Is a type of nerve conduction study, in which electrodes are attached to skin over the muscles to be tested. Small pulses of electricity are sent through the electrodes to measure the nerve's ability to send a signal to muscle. To diagnose MG, the nerve will be tested many times to see if its ability to send signals worsens with fatigue.

Single-fiber electromyography (EMG): EMG measures the electrical activity traveling between brain and muscle. It involves inserting a very fine wire electrode through skin and into a muscle. In single-fiber EMGs, a single muscle fiber is tested.

Imaging scans: CT scan or an MRI to confirm a tumor or other abnormality in thymus.

CT Chest

Thymoma

Single-fiber EMG

TREATMENTS & DRUGS Specific treatment to age, overall health, and

medical history and extent of the condition

No cure for MG, but the symptoms can be controlled.

MG is a life-long medical condition and the key to medically managing MG is early detection.

The goal of treatment is to prevent respiratory problems and provide adequate nutritional care to the child since the swallowing and breathing muscles are affected by this condition.

Medications

Cholinesterase inhibitors. Drugs like pyridostigmine (Mestinon) enhance communication between nerves and muscles. These drugs don't cure, but improves muscle contraction and strength.

Corticosteroids. These types of drugs inhibit the immune system, limiting antibody production. Prolonged use of corticosteroids, can lead to serious side effects, like bone thinning, weight gain, diabetes, increased risk of some infections, and increase and redistribution of body fat.

Immunosuppressants. Doctor may also prescribe other medications that alter immune system, like azathioprine (Imuran), cyclosporine (Sandimmune, Neoral) or mycophenolate (CellCept).

How antibodies against acetylcholine receptor

block impulse conduction in synapse

Therapy

Plasmapheresis. This procedure uses a filtering process similar to dialysis. Blood is routed through a machine that removes the antibodies that are blocking transmission of signals from nerve endings to muscles' receptor sites. However, the beneficial effects usually last only a few weeks.

Intravenous immune globulin. This therapy provides body with normal antibodies, which alters immune system response. It has a lower risk of side effects than do plasmapheresis and immune-suppressing therapy, but it can take a week or two to start working and the benefits usually last less than a month or two.

Surgery

Thymectomy - surgical removal of the thymus gland. The role of the thymus gland in MG is not fully understood, and the thymectomy may or may not improve a child's symptoms.

Plasmapheresis - a procedure that removes abnormal antibodies from the blood and replaces the child's blood with normal antibodies through donated blood.

Extent of the problems is dependent on the severity of the condition and the presence of other problems that could affect the child.

In severe cases, a breathing machine may be required to help the child breathe easier.

The healthcare team educates the family after hospitalization on how to best care for their child at home and outlines specific clinical problems that require immediate medical attention by their physician.

A child with MG requires frequent medical evaluations throughout his/her life.

It is important to allow the child as much independent function and self care, especially with juvenile MG, as possible and to promote age-appropriate activities to ensure a sense of normalcy.

About 15 percent of the people who have MG have a tumor in their thymus, a gland under the breastbone that is involved with the immune system, thymus will be removed.

For people with MG who don't have a tumor in the thymus, it's unclear whether the potential benefit of removing the thymus outweighs the risks of surgery.

This is an individualized decision between patient and the doctor, but most doctors don't recommend surgery if:

Symptoms are mild

Symptoms involve only the eyes

Patients over 60 years old

Myasthenia Gravis through yoga

Help to stretch the body which increase the flexibility as well as strengthen the muscles of the body, which become weak due to MG.

Improve blood circulation and remove carbondioxide from the body & provide oxygenated blood to every part of the body.

Yoga Exercises

Pranayama – yoga breathing

Helpful because the onset of MG often lead to mild depression but the practice of breathing exercises like,

Nadi- Shodhan,

Anulom-Vilom,

Deep breathing and

Mild Kapalbhati

Helps to remove depression and relax the mind as well as the body.

Meditation also brings more positive thinking.

Nutrition

Along with exercises & breathing practices eating habits should also be altered.

Simple, nourishing, no stimulating foods, including plenty of fresh fruits & lightly cooked vegetable, particularly greens.

Asparagus is considered excellent since it contains certain natural steroid-like nutritious elements, which help strengthen the weakened muscles caused by MG.

Whole meal grains, sprouts & pulses in places eggs and meats.

Food should have a blend of all necessary vitamins.

Research Study in NIMH Background – Juvenile myasthenia gravis (JMG) is

an uncommon disease. Unlike adults, clinical characteristics and outcomes of myasthenia gravis (MG) are not well studied in children.

Patients and methods – Case records of 77 patients with MG who were 15 years of age or less at disease onset, evaluated over a period of 34 years at the National Institute of Mental Health and Neurosciences, Bangalore, India, were reviewed. Their clinical characteristics and response to therapy was compared with 290 patients with MG onset after 15 years of age.

Results – Median age at onset was 8 years and mean period of follow-up was 6.2 years (range 6 months to 25 years).

At presentation, 30% of patients had ocular myasthenia and the rest had generalized disease.

Twenty-one patients (27%) had disease confined to ocular muscles throughout the course and three had limb girdle myasthenia.

Familial myasthenia was more common than adult onset disease, 10 patients had positive family history.

Unlike adults, none of the patients had associated autoimmune disease. Fifty-two patients (67%) received corticosteroids, and azathioprine was

added in five patients. Thymectomy was performed in 11 patients, six below the age of 15 years. Thymic histology was normal in one and showed hyperplasia in eight and

thymoma in one. Four patients had crisis. At the end of follow-up, 25 patients were asymptomatic, 28 had partial

improvement, and nine remained unchanged or worsened and two died. Ten patients achieved complete stable remission.

Conclusions – This study shows some distinctive characteristics of JMG, such as higher frequency of ocular myasthenia, benign course, better long-term outcome and lack of association of thymoma and other autoimmune disorders.

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