1. Neurology Chapter of IAP
Myasthenia Gravis
Disease of the neuromuscular junction characterized by fluctuating weakness of certain skeletal muscle groups.
Neurology Chapter of IAP

2. 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.
Neurology Chapter of IAP

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.
Neurology Chapter of IAP

5. 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.
Neurology Chapter of IAP

6. 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.
Neurology Chapter of IAP

7. 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.
Neurology Chapter of IAP

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.
Neurology Chapter of IAP

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
Neurology Chapter of IAP

10. 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.
Neurology Chapter of IAP