MYASTHENIA GRAVIS Flashcards
What is myasthenia gravis?
an acquired, autoimmune, progressive disease characterized by muscle weakness
When does the disease peak?
typically within two years
What does it result from?
a reduction of acetylcholine receptors
What are the two types?
ocular and generalized
Where does it typically originate?
face, neck and jaw. the arm and leg muscles are affected later
What do 50% of people present with?
ocular symptoms: ptosis, diplopia
What do 15% of people present with?
bulbar symptoms: dysarthria (speech), dysphagia, fatigable chewing
What do <5% of people present with?
proximal limb weakness alone
diagnosis of MG: Tension (Edrophonium) test
tensilon = acetylcholinesterase inhibitor; onset 30-45 sec; duration of action 5-10 min
given IV - watch eyelids; ptosis will improve if MG
diagnosis of MG: ice pack test
based on principle of improving neuromuscular transmission at lower muscle temperatures
surgical glove of ice on lid x 2min; remove ice; immediately asses ptosis/will improve if MG
diagnosis of MG: serologic tests
acetylcholine receptor (AChR-Ab) antibodies
muscle-specific tyramine kinase (MuSK0 antibodies
diagnosis of MG: electrophysiological studies
repetitive nerve stimulation (RNS) study (most used)
single fiber EMG (most sensitive)
drug therapy
acetylcholinesterase inhibitors
immunotherapeutics
intravenous immunoglobulin (IVIG)
plasmapheresis (plasma exchange)
surgical management
thymectomy (removal of thymus)
done early
