myasthenia gravis

Question 1

myasthenia gravis

Answer 1

autoimmune, fluctuating weakness of certain muscle groups -> occular, bulbar (brain stem), limb, resp
antibody mediated -> post synaptic membrane of NM junction (ACH), communication breakdown btw nerves and muscles

Question 2

disease course

Answer 2

variable, difficult to educate pt
short term remission, stabilization, severe, progression

Question 3

rf

Answer 3

10 - 65 yr
F
genetic + env factor

Question 4

patho

Answer 4

anti ACH antibodies attack ACH receptors, decrease receptors at NM junction (ACH cant bind), prevent muscle contraction
body is producing enough ACH but there are not enough spots for it to bind

Question 5

cm

Answer 5

insidious
fluctuating weakness of skeletal muscle (eyes/eyelid - droop, facial - nutrition, asp; speaking, breathing)
strength comes back after resting
muscle fatigue common after exercise
often appear in preg, post partum, after anesthesia

Question 6

myasthenia crisis

Answer 6

acute exacerbation of muscle weakness
triggered by stressor: infection, sx, emotional distress, preg/menses, inadequate pharm or other drugs
major comp: breathing muscle weakness -> resp insuff

Question 7

pharm

Answer 7

immunosuppressants (steroids) -> autoimmune
cholinesterase inhibitor: give 30 - 45 min prior to eating to swallow better

Question 8

cholinesterase I

Answer 8

prevent inactivation of ACH, increase ACH effects, increase muscle strength
not cure but help S
multiple routes

Question 9

cholinergic

Answer 9

GI: increase motility, d
mouth: increase secretions
bladder: urinary urgency
heart: brady
lungs: bronchial constriction
eyes: miosis (contrict)

Question 10

antichol

Answer 10

GI: decrease motility, c
mouth: dry mouth
bladder: urinary retention
heart: tachy
lungs: bronchodilation
eyes: mydriasis (dilation)

Question 11

MG v cholinergic crisis

Answer 11

edrophonium: short acting cholinesterase I (increase ACH temporarily)
MG = improve
cholinergic crisis = worsen

Question 12

Neostigmine

Answer 12

Parasympathomimetic (reversible)
Cholinesterase I
Inhibits acetylcholinesterase which is responsible for degradation of acetylcholine, so more ACH is present
Affects both muscarinic (glands) and nicotinic (skeletal and adrenal, this is what MG affects) receptors
Myasthenia gravis

Question 13

Neostigmine: SE

Answer 13

Muscarinic: increased secretions, GI motility, urinary urgency, brady, bronchial constriction (careful with asthma), miosis, near sightedness
Nicotinic: increased muscle contraction with therapeutic, decreased with toxic, can l/t cholinergic crisis

Question 14

Neostigmine: nc

Answer 14

Give 30-45 min prior to eating to increase swallow strength
Cholinergic crisis: extreme muscle weakness or paralysis bc worn out, s/s of excessive muscarinic stim, tm = mechanical vent and atropine (antidote), med alert bracelet