MG Flashcards
cause
autoimmune dz attack the acetylcholine receptor and the postsynaptic membrane of the neuromuscular junction results in acetylcholine dysfunction and jeopardize normal muscular tx
age and sex
20-40 women 20-30 and men 50-70
S&S
sensory and deep tendon reflex remain normal
wake up feeling good by end of day feels weak
affected by repetitive movements like: chewing
1st symptoms: diplopia and ptosis, weakness
dysphagia and dysarthria: bulbar muscle weakness: regurgitation of food, aspiration and increased risk
neck weak, resp weak, upper limbs affected before lower
diag
antibody test: AChR and Musk AChr + 85%, Musk 50%, Electrodiagnostic:
repetitive nerve stimulation: decremental resp occurs after maximal voluntary contraction, test (+) if motor resp declines more than 10%
single fiber electromyography: high sensitive but less specific, technically diff to perform and limited availability
Tensilon test: sudden brief improvement of muscle fibers. give 2 mg iv, after 2 min give 10 mg, SE: bradycardia, DANGEROUS: have atropine and intubation ready
management
monitor by neurologist
1st line: cholinesterase inhibitor (Mestinon)
stop breakdown and increase the concentration of acetylcholine
immunosuppressive drugs: prednisone decrease the production of autoantibodies
thymectomy: decrease muscle weakness
plasmapheresis and IVIG
Side effects of Mestinon
n/v/d/cramps increase secretions and muscle twitch
test
thyroid function test: will be high
lp normal
b12 low dt pernicious anemia
tensilon test
myasthenia crisis
medical emergency dt resp failure
s&s
oropharyngeal/laryngeal muscle weakness, results in airway obstruction
precipitating factors
inf, stress (trauma, sx), rapid intro or tapering of steroids, withdrawal of cholinesterase inhibitors, exposure to drugs, increase muscle weakness and diplopia see prior
Manage crisis
admit icu for airway/vent management
ivig and plasmapheresis
