mysthenia gravis

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MYASTHENIA GRAVIS
shiva Kumar
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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.

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• 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.

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TYPES OF MYASTHENIA GRAVIS

• Three 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.

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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.

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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

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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.

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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
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When to see a doctor

• If having trouble with
• Breathing
• Seeing
• Swallowing
• Chewing
• Walking

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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.

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• 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.

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• 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.

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• 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.

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Factors worsening MG

• Fatigue
• Illness
• Stress
• Extreme heat
• Medications such as beta blockers, calcium
  channel blockers, quinine and some antibiotics

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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.

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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.

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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.

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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.

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• Reflexes
• Muscle strength
• Muscle tone
• Senses of touch and sight
• Coordination
• Balance

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• 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.

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• 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.

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CT Chest
Single-fiber EMG
Thymoma
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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.

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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).

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How antibodies against acetylcholine receptor
block impulse conduction in synapse
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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.

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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.

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• 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.

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• 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

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Myasthenia Gravis through yoga
Yoga Exercises

• 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.

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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.

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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.

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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.

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• 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.

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• 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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