Myasthenia Gravis.ppt
- 1. Neurology Chapter of IAP Myasthenia Gravis • Disease of the neuromuscular junction characterized by fluctuating weakness of certain skeletal muscle groups.
- 2. Neurology Chapter of IAP Myasthenia Gravis(MG) • Acetycholine (ACh) is an important neurotransmitter that stimulates muscle tissue to contract. • MG is an autoimmune disease in which antibodies are formed against ACh and a reduction in ACh receptor sites at the neuromuscular junction.
- 3. Neurology Chapter of IAP •
- 4. Neurology Chapter of IAP Pathophysiology • Loss of muscle strength. • There is no single cause identified, however, thymic tumors and viral infections have been found in a certain number of patients.
- 5. Neurology Chapter of IAP Clinical manifestations • Primary s/s= easy fatigability of skeletal muscle during activity. • Muscles involved: eyes and eyelids, chewing, swallowing, speaking, and breathing. • Fluctuating weakness: usually strong in the a.m., progressively weaker with activity.
- 6. Neurology Chapter of IAP Clinical Manifestations • 90% of patients have eye involvement • Facial mobility may be impaired • Muscles of limb and trunk less often affected. • No sensory or reflex loss; muscle atrophy is rare.
- 7. Neurology Chapter of IAP Clinical manifestations • Variable course • May be precipitated by emotional stress, pregnancy, menses, secondary illness, trauma, temperature extremes, hypokalemia, ingestion of drugs with neuromuscular blocking agents, surgery.
- 8. Neurology Chapter of IAP Complications • Aspiration, respiratory insufficiency, and respiratory infection • Acute exacerbation called myasthenic crisis. • The opposite of this is a cholinergic crisis and results from overdose of cholinergic drugs.
- 9. Neurology Chapter of IAP Diagnostic studies • Assessment: – Have pt look up for 2-3 minutes; if MG, patient will have increased droop of eyelids. – EMG may show muscle fatigue – Tensilon test- in MG reveal improved muscle contractility after IV anticholinesterase agent edrophonium chloride (tensilon) – Also diagnosis cholinergic crisis- muscle weakness gets worse – Keep atropine on hand to counteract effects of tensilon
- 10. Neurology Chapter of IAP Therapeutic management • Anticholinesterase inhibitors- prevents anticholinestersase from breaking down ACh; helps neurotransmission. Monitor dose! – Mestinon, Prostigmine Corticosteroids- decrease immune response Prednisone Plasmapheresis- removes ACh antibodies and short-term improvement.