2. Myasthenia Gravis

• Myasthenia Gravis is a relatively rare neuromuscular disease in which the voluntary muscles easily become tired and weak, caused by a problem with how the nerves stimulate the contraction of muscles.
• Myasthenia Gravis means grave muscle weakness.
• Usually, patients with Myasthenia Gravis have a mild life expectancy.
• Pathophysiology of Myasthenia Gravis involves antibodies blocking or destroying muscle receptor cells, resulting in fewer available muscle fibers resulting in muscles not contracting properly and they easily feel tired and weak.
• The reason for Myasthenia Gravis is unknown, but the Thymus Gland, located in the upper chest beneath the breastbone, plays a key role.
• The Thymus gland is located behind the sternum and between the lungs.
• The Thymus gland is only active until puberty; after, the thymus starts to slowly shrink and become replaced by fat.
• Thymosin, a hormone produced by the Thymus gland, stimulates the development of disease-fighting T-cells.
• The Thymus gland is at its largest in children.
• By 15 y/o, the thymus is little more than fatty tissue.
• Patients with Myasthenia Gravis usually have an abnormally large thymus gland and about 1 in 10 patients with Myasthenia Gravis have benign tumors in the thymus gland.
• Medications that cause Myasthenia Gravis:

  1. Beta blockers
  2. Calcium Channel blocker
  3. Quinine
  4. Some antibiotics.
• General factors that can worsen symptoms of Myasthenia Gravis include emotional or mental stress, illness, tiredness or high fever.
• Neonatal myasthenia affects newborns if they acquire antibodies from a mother who has MG.
• Symptoms of Neonatal Myasthenia Gravis usually disappear in two to three months and MG in infants and children is rare.
• Signs and symptoms of Myasthenia Gravis include:

  • fatigue
  • ocular myasthenia gravis
  • swallowing difficulties
  • speaking problems
  • facial expression changes
  • chewing problem
  • limb weakness
  • difficulty in breathing
• MG is suspected if a patient has drooping eyelids but no problem feeling things or if they are prone to muscle weakness that improves after rest.
• Tests for Myasthenia Gravis include

  • Edrophonium test
  • blood tests
  • repetitive nerve stimulation
  • single fine electromyography (EMG)
  • imaging test
  • pulmonary function test or spirometry
  • muscle biopsy.
• Treatment for Myasthenia Gravis include MEDICATIONS:

  • cholinesterase inhibitors
  • steroids (Prednisone) or immunosuppressants (Azathioprine)
• Cholinesterase inhibitors improve communication between nerves and muscles and are effective in patients with mild symptoms of MG.
• steroids or immunosuppressants alter the body's immune system so that it produces fewer of the antibodies.
• It takes four meds to take effect (steroids); 3 to 6 months (immunosuppressants).
• Short term treatment for MG includes Thymectomy: Removal of thymus gland in the case of a tumor, Plasmapheresis, and Intravenous immunoglobulin therapy.
• Patients with MG are at risk for aspiration pneumonia because they have difficulty swallowing food and liquids.
• The most common cause of death during a myasthenic crisis is respiratory failure due to weakness of the diaphragm, intercostal muscles, or both.
• Thymosin stimulates development of disease fighting T-cells.
• Treatment for Myasthenia Gravis includes SHORT TERM TREATMENT:

  • Thymectomy
  • Plasmapheresis
  • Intravenous immunoglobulin therapy.
• Cholinesterase inhibitors improve communication between nerves and muscles and are effective in patients with mild symptoms of Myasthenia Gravis.
• Steroids takes 4 weeks to take effect; and immunosuppressants takes from 3 to 6 months.