Myasthenia Gravis Flashcards
Myasthenia gravis (MG) is a disorder of muscular weakness from the production of ____ against _______ at the _______.
antibodies
acetylcholine receptors
neuromuscular junction
Presentation/“What Is the Most Likely Diagnosis?”
“double vision and difficulty chewing,”
“dysphonia,” or
“weakness of limb muscles worse at the end of the day.”
why would you see combined “double vision and difficulty chewing,” ?
This is because the extraocular muscles and mastication (masseter) are often the only 2 muscular activities universally done by people (i.e., watching TV and eating).
Severe myasthenia affects
respiratory muscles.
Physical examination reveals
ptosis
weakness with sustained activity, and
normal pupillary responses.
Best initial test,
sensitivity
acetylcholine receptor antibodies
This is a better first answer than edrophonium testing
For patients without acetylcholine receptor
antibodies, get ______ antibodies. It means_____
anti-MUSK.
muscle-specific kinase
Most accurate test:
Electromyography shows decreased strength with repetitive stimulation.
Edrophonium is a __________________.
short-acting inhibitor of acetylcholinesterase.
How does Edrophonium test work?
The temporary
bump up in acetylcholine levels is associated with a clear improvement in motor
function that lasts for a few minutes.
Why isn’t Edrophonium test so recommended?
High false positive rate
If asked, “What imaging test should be done?” Answer:_______ because _____
chest something. Chest x-ray, CT, or MRI is done to look for thymoma or thymic hyperplasia. CT with contrast is best.
Best initial treatment:
Neostigmine or pyridostigmine.
These are longer acting versions of edrophonium.
If these medications do not control the disease, the “most appropriate next step
in management” is
thymectomy if the patient is under age 60.
if first line Tx failed, and the patient is over age 60, what to do?
prednisone
