Myasthenia Gravis

Myasthenia Gravis
By:
* Cathie Rohleder
* Sydnee Jacobson
* Ashley Cox

Pathology
* A chronic Autoimmune Disease
* Affects the Neuromuscular junction
* Postsynaptic acetylcholine receptors on muscle cells plasma membrane are no longer recognized as ‘self’ and elicit the generation of auto antibodies.
* IgG antibody is produced against the acetylcholine receptors and fixes to receptor sites, blocking the binding of acetylcholine.
* Diminished transmission and lack of muscular depolarization results.
* Several Types of Myasthenia Gravis
o Neonatal Myasthenia Gravis: A transient condition in 10% to 15% of infants born to mothers with MG.
o Congenital Myasthenia
o Juvenile Myasthenia: Onset is around 10 years of age.
o Ocular Myasthenia
o Generalized Autoimmune Myasthenia

Clinical Manifestations
* Insidious onset
o May first appear during pregnancy, during the postpartum period, or in combination with the administration of anesthetic agents.
* Complaints
o Most individuals complain of fatigue and progressive weakness.
o The person usually has a history of frequent respiratory tract infections.
* Muscles affected
o First muscles affected
+ Muscles of the eyes, mouth, face, throat and neck.
+ The most affected muscles are the extra ocular (eye) muscles and levator muscles.
o Second most affected muscles
+ Muscles of mastication, swallowing, facial expression, and speech.
o Less frequently affected muscles
+ Neck, shoulder girdle, and hip flexors
o All muscles are weak in the advanced stage of the disease.
* Other occurrences
o Myasthenic Crisis happens when extreme muscle weakness causes quadriparesis or quadriplegia, difficulty swallowing, and shortness of breath. A person in this state is in danger of respiratory arrest.
o Cholinergic Crisis occurs from anticholinesterase drug toxicity. This is similar to Myasthenic Crisis, but also includes increased intestinal motility with diarrhea and complaints of cramping, fasciculation, bradycardia, constriction of the pupils, increased salvation, and sweating. A person in this state may also be in danger of respiratory arrest.

Treatment
* Surgery
o Thymectomy: removal of the thymus gland
o A tumor is usually present in the thymus gland

* Medication
o Cholinesterase inhibitors
+ These include neostigmine and pyridostigmine
+ Helps improve neuromuscular transmission and increase muscle strength
o Immunosuppressive drugs
+ These include prednisone, cyclosporine, and azathioprine
+ Improves muscle strength by suppressing the production of abnormal antibodies
o Corticosteroids
+ Inhibits the immune system
+ Limits antibody production.
* Plasmapheresis
o remove abnormal antibodies from the blood
o Used for more serious conditions.
o Benefits last around a few weeks
* High-dose of Intravenous Immune Globulin (IVIG)
o Modifies immune system temporarily
o Provides the body with normal antibodies from donated blood
o Less risk of side effects
o Benefits last 1-2 months and takes a couple weeks to start working

Treatment
* One or more of the treatments may be used to alleviate symptoms caused by Myasthenia Gravis

Resources
Myasthenia Gravis.ppt