Myasthenia Gravis


Published on

Published in: Health & Medicine
  • Be the first to comment

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Myasthenia Gravis

  1. 1. Phylicia Allen Honors Biology Professor Hunnicutt
  2. 2. What are the Odds? Myasthenia Gravis affects approximately 2 out of every 100,000 people and can occur within any age, race, or sex. According to these odds this is more likely to happen than •Finding a four-leaf clover on the first try •Being murdered •Being considered possessed by Satan.
  3. 3. A chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal (voluntary) muscles of the body. 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 movement, facial expression, chewing, talking, and swallowing are often, but not always, involved in the disorder. (muscles that control breathing and neck movements also may be affected.)
  4. 4. What causes myasthenia gravis… MG is caused by a defect in the transmission of nerve impulses to muscles, occurring when normal communication between the nerve and the muscle is interrupted at the neuromuscular junction, the place where nerve cells connect with the muscles they control. Impulses travel down the nerve and the nerve endings normally release a neurotransmitter substance called acetylcholine. Acetylcholine travels through the neuromuscular junction and binds to the acetylcholine receptors which are activated and generate a muscle contraction. In MG, antibodies block, alter, or destroy the receptors for acetylcholine at the neuromuscular junction which prevents the muscle contraction from occurring.
  5. 5. With MG, normal communication between the nerve and muscle is stopped at the place where nerve endings connect with the muscles they control—the nerve muscle junction. Normally, the nerve endings release a substance called acetylcholine, which binds the muscle tissue at the nerve-muscle junction, causing the muscle to contract. In someone with MG, the body’s own immune system makes antibodies that block the binding of acetylcholine to the muscle.
  6. 6. The role of the thymus gland in myasthenia The thymus gland lies in the upper chest gravis… area beneath the breastbone and plays an important role in the development of the immune system in early life. It’s somewhat large in infants, grows gradually until puberty, and then gets smaller and is replaced by fat with age. In adults with MG, the thymus is abnormal. Some individuals with MG develop thymomas, or tumors of the thymus gland, which are generally benign, but could become malignant. Although the relationship between the thymus gland and MG is not yet fully understood, scientists believe that it gives incorrect instructions to developing immune cells, ultimately resulting in autoimmunity and the production of the acetylcholine receptor antibodies, thereby setting the stage for the attack on the neuromuscular transmission.
  7. 7. •Drooping of one or both eyelids (ocular myasthenia gravis/ptosis) •Blurred or double vision (diplopia) •Problems walking (unstable or waddling gait) •Weakness in arms, hands, fingers, legs, and neck •Change in facial expression •Having a hard time swallowing (which leads to difficulty eating and ultimately extreme weight loss) •Impaired speech (dysarthria) •Shortness of breath (feeling like you can’t get enough air) The onset of the disorder may be sudden. Symptoms often are not immediately recognized as myasthenia gravis. In most cases the most noticeable symptom is weakness of the eye muscles. In others, difficulty in swallowing and slurred speech may be the first signs. The degree of muscle weakness in MG varies greatly among patients, ranging from a localized form, limited to eye muscles, to a severe or generalized form in which many muscles-sometimes including those that control breathing- are affected.
  8. 8. Myasthenia gravis occurs in all ethnic groups and both genders. It most commonly affects young adult women (under 40) and older men (over 60), but it can occur at any age. MG in juveniles is common and is not directly inherited nor is it contagious. However, the disease may occasionally occur in more than one member of the same family.
  9. 9. Diagnosis It’s not uncommon in cases of MG for a delay in diagnosis. The first step of diagnosis includes a review of the individual’s medical history, and physical and neurological examinations. If the doctor suspects MG several tests are available to confirm the diagnosis. •Antibody blood tests: Blood tests detect the presence of high levels of abnormal antibodies that prevent normal nerve-to-muscle transmission. •Edrophonium test: Drug is injected and weak eye muscles will be temporarily strengthened. •Nerve conduction test/repetitive stimulation: A nerve linked with a specific muscle is stimulated to see if the muscle action is weakened. •Single fiber electromyography (EMG): Singe muscle fibers are stimulated by electrical impulses. Muscle fibers of people with MG do not respond to repeated electrical stimulation as well as muscles that function normally. Can detect problems with nerve-to- muscle transmission. •Computed Tomography (CT) or Magnetic Resonance Imaging: Test shows if there is an abnormal thymus gland or a thymus gland tumor.
  10. 10. There is no cure for MG, however there are several therapies that can help strengthen the muscles of someone with MG. •Medications: Drugs used including cholinesterase inhibitors, such as pyridostigmine. These drugs help improve nerve signals to muscles and increase muscle strength. Immunosuppressive drugs are used to suppress the production of abnormal antibodies. •Thymectomy: The surgical removal of the thymus gland, which is abnormal in most persons with MG. The procedure is done for people with MG who have tumors, as well as for some who don’t have tumors. •Plasmapheresis: Procedure removes abnormal antibodies from the blood, providing relief for MG symptoms for a few weeks. •High-dose intravenous immune globulin: This treatment keeps the immune system from damaging the nerve-muscle junction for a short time. Provides relief from MG symptoms in many patients for weeks to months.
  11. 11. Myasthenic Crises  Occurs when the muscles that control breathing weaken to the point that ventilation is inadequate, creating a medical emergency and requiring a respirator for assisted ventilation. In patients whose respiratory muscles are weak, crises-which generally call for immediate medical attention-may be triggered by infection, fever, or an adverse reaction to medication.
  12. 12. Much has been learned about myasthenia gravis in recent years and, with treatment, the outlook for most patients with myasthenia gravis is bright. They will have significant improvement of their muscle weakness and they can expect to lead normal or nearly normal lives. Some cases of MG go into remission temporarily and muscle weakness may disappear completely so that medications can be discontinued. Stable, long-lasting complete remissions are the goal of Thymectomy. Though much has been learned, there is still much more knowledge to gain. The ultimate goal of myasthenia gravis research is to increase scientific understanding of the disorder. Researchers are seeking to learn what causes the autoimmune response in MG, and to better define the relationship between the thymus gland and MG. Today’s research includes a broad spectrum of studies conducted and supported by NINDS (National Institute of Neurological Disorders and Stroke) scientists, who are evaluating new and improving current treatments for the disorder. The objective of the study is to expand current knowledge of the function of receptors and to apply this knowledge to the treatment of MG.
  13. 13. In July of this past year, I was diagnosed with Myasthenia Gravis and immediately admitted to the pediatric oncology unit of the Florida Hospital. By the time of my diagnosis I had lost over 50 pounds and reached crisis status. So much of my digested foods had been inhaled into my lungs that I was beginning to develop pneumonia. Since my diagnosis, I’ve been undergoing treatment for the condition and have been extremely satisfied with the results. I’ve never felt better and couldn’t be happier.