Myasthenia Gravis Flashcards
1
Q
What kind of disorder is myasthenia gravis?
A
autoimmune
2
Q
Who is most often affected by myasthenia gravis?
A
- young women, 20-30 years old
- older men 60-70 years old
3
Q
What happens in myasthenia gravis? What is the pathophysiology?
A
- antibodies target and destroy/damage Ach receptors on muscle
- causes fewer Ach receptors to be available, can also reduce the surface area
- causes impaired transmission across the neuromuscular junction = weakness
- 75-80% also have thymus abnormality (hyperplasia or tumour)
4
Q
What are the signs and symptoms of myasthenia gravis?
A
- general weakness of voluntary muscles
- ptosis, diplopia (drooping eyelids, double vision)
- weak facial muscles = flat expression
- dysphonia (soft voice)
- breathing difficulty
5
Q
Are there problems with coordination or sensation in myasthenia gravis?
A
no
6
Q
How is myasthenia gravis diagnosed?
A
- acetylcholinesterase inhibitor test (give Ach-esterase inhibitor by IV, immediate improvement is a positive test)
- antibody titres
- single fiber electromyography
- enlarged thymus can be seen on an MRI
7
Q
How is myasthenia gravis treated?
A
- anti-acetylcholinesterase medications (have lots of SE)
- immunosuppression (to decrease antibody production)
- —- corticosteroids
- —- azathioprine inhibits T-lymphocytes to decrease antibody production
- IV immune globulin (not sure how this works)
- plasmapheresis (plasma exchange removes antibodies temporarily)
- remove thymus via surgery
8
Q
What is a myasthenic crisis? Why do we worry about it?
A
It is an exacerbation of myasthenia gravis, can be precipitated by a respiratory infection, medication, surgery etc.
It causes severe muscle weakness, particularly respiratory and bulbar (cough and gag reflex) weakness that can lead to respiratory failure.
