1. MYASTHENIA GRAVIS (MG)

2. CASE STUDY 66 year male Physical exam revealed Ice pack test
Healthy and active entire life
Presents with 4 month history of gradually progressive diplopia
Physical exam revealed
Moderate ptosis of both eyelids
Limitation of R/L ocular movement
Ice pack test
Improved ptosis

4. CASE STUDY Radiology Laboratory CT of chest was normal Tests Results
ANA Negative
RF Negative
Anti-AChR Positive
Anti-MuSK Negative

5. CASE STUDY Prescription for pyridostigmine (Mestinon)
6 tablets (60 mg) daily
Dose reduced to 3 tablets daily
Nausea, vomiting and diarrhea
Two years later following severe influenza
Diplopia, dysphagia, dysarthria, dyspnea
Admitted to hospital and treated with
Azathioprine (Imuran)

6. MYASTHENIA GRAVIS (MG)
Chronic autoimmune neuromuscular disease
Hallmark
Skeletal muscle weakness and fatigue
Increases with activity and improves with rest
Muscles affected
Eye and eyelid movement, facial expression, chewing, swallowing and talking
Most common primary disease of neuromuscular transmission

7. EPIDEMIOLOGY OF MYASTHENIA GRAVIS
Prevalence of 50,000 cases in US
All ethnic groups and both genders
Female to male ratio
20 to 40 years (females 1.5:1)
50 to 70 years (males 1.5:1)
Etiology is unknown

8. SYMPTOMS OF MYASTHENIA GRAVIS
Ptosis
Diplopia
Dysphagia
Dysarthria
Change in facial expression
Weakness of arms, hands, fingers, legs

12. DIAGNOSIS OF MYASTHENIA GRAVIS
Physical examination for muscle fatigue
Edrophonium Test
IV administration of Edrophonium chloride (Tensilon)
Blocks degradation of acetylcholine
Brief relief of eye weakness
Single fiber electromyography (EMG)
CT of thymus gland

13. LABORATORY DIAGNOSIS OF MG
Acetylcholine receptor antibody (Anti-AChR)
Binding
Blocking
Modulating
Muscle-specific tyrosine kinase antibody
Anti-MuSK
45% of seronegative MG

14. LABORATORY DIAGNOSIS OF MG
Acetylcholine receptor antibody, binding
90% generalized
70% ocular
Acetylcholine receptor antibody, blocking
50% generalized
20% ocular
Acetylcholine receptor antibody, modulating

15. IMMUNOPATHOLOGY OF MYASTHENIA GRAVIS
Type II autoimmune mechanism
Autoantibody (antagonistic) for acetylcholine receptor at post-synaptic neuromuscular junction
Acetylcholine receptors are
Blocked
Altered
Destroyed
Muscle contraction is prevented

17. IMMUNOPATHOLOGY OF MYASTHENIA GRAVIS
Role of thymus gland is unclear
75% of patients have thymus abnormality
85% thymic hyperplasia
15% thyroma
Disease usually more severe with thyroma

18. TREATMENT OF MYASTHENIA GRAVIS
Anticholinesterase agents
Neostigmine (Prostigmin)
Pyridostigmine (Mestinon)
Corticosteroids / Immunosuppressive agents
Prednisone
Azathioprine
Intravenous Immunoglobulin (IVIG)
Thymectomy
Plasmapheresis (plasma exchange)