Myasthenia Gravis

Question 1

MG def and prevalence

Answer 1

disorder of neuromuscular junction
ragdoll weakness
1 in 200,000, rare
Men 50-60 yo
Women 20-30 yo
destroys AcH receptors so AcH can't att for ms contraction

Question 2

Pathogenesis

Answer 2

autoimmune disorder- assoc with thymic disorder, Lupus, RA
# AcH receptors decrease or flattened
decrease efficiency of nm transmission

Question 3

Presentation

Answer 3

fluctuating weakness and fatigue
spectrum of mild to severe
worse with exertion, improves with rest
no other- neuro signs

Question 4

Etiology

Answer 4

unclear
virus/bacteria trigger to autoimmune response
role of thymus gland- can remove for tx- 35% achieved drug free remission
not hereditary

Question 5

S/S

Answer 5

ocular- impaired eye mvts, double vision, ptosis

generalized weak- face>neck>UE>hands, may affect breathing, talking, eating, progress to proximal, weak hip girdle

Question 6

Presentation

Answer 6

fatigue fluctuates
over time, usually progressive
severity of weakness
remission- spontaneous or remove thymus

Question 7

Dx

Answer 7

eye ms weakness, physical exam, blood test to detect antibodies to AcH receptor, EMG, Tensilon test- drug given, msr STR before and after, no sensory component

Question 8

Medical Management

Answer 8

cholinesterase inhibitors (Mestinon)- take to boost ms function, before eating to help chew
immunosuppressant drug- not long-term
plasmapheresis an IVIG- not long-term
myasthenic crisis- emergency, weak resp ms-->resp arrest

Question 9

Exercise

Answer 9

can increase weakness during acute exacerbation/ or when poorly controlled, not during acute
energy conservation
exhaustion, lasting jt pain/ms pain, or SOB means exercise too strenuous