Myathesia Gravis

Question 1

What is it?

Answer 1

Autoimmune Disorder
-Destruction or impairment of Acetylcholine receptors at the neuromuscular junction
Type II hypersensitivity

Question 2

Symptoms

Answer 2

• muscle weakness, droopy eyelids, double vision, can’t swallow, fatigue, pain muscle cramps
• worsen with heat, stress, infection, pregnancy, menstrual cycle

Question 3

Acetylcholinesterase inhibitors

MOA

Answer 3

Reversible - symptom relief)

• Inhibits acetylcholinesterase
• Stops destruction of Acetylcholine
• Increases cholinergic transmission:

1. Autonomic cholinergic synapse
   - Same as muscarinic agonist
   - ↑ fluid, urinary urgency, ↑motility of GI
2. NMJ
   - nicotinic receptors
   - ↑force of contraction
   - twitching
3. CNS synapses (for Organophosphates ONLY)
   - stimulation – convulsions
   - toxic doses = respiratory depression

Question 4

Edrophonium
(Tensilon)

About

Answer 4

Reversible short acting

• Ammonium compound
• binds to anionic site of enzyme only
• not used clinically
• mainly used for diagnosis

Question 5

Pyridostigmine (1st)

Neostigmine

Answer 5

Reversible Long acting

• binds to anionic AND catalytic sites
• transfer of carbamyl group to serine hydroxyl group
• 30mg tid every 4-7 days when patient is most tired during the day

Question 6

What immuosuppressants can you use if Patient doesnt respond to pryidostigmine?

Answer 6

azathirprine
mycophenolate
cyclosporin
tacrolimus

Question 7

DUMBBELLS

cholinergic crisis

Answer 7

Too much stimulation - rest and digest overload 
Diarrhoea
urination 
miosis 
bradycardia 
bronchospasms
excitation
larrcimation (tear production)
lethargy
salvation

Question 8

How to treat DUMBELL / cholinergic crisis

Answer 8

IV atropine