Neurology: Weakness and Muscle Disease Flashcards
What feature on CT scan of the thorax may indicate MG?
Enlarged thymus or thymoma due to increased Ab production.
Describe the pathogenesis of Myasthenia Gravis.
A trigger causes antibodies to be directed against ACh receptors which block and prevent activation. Complement may also activate and cause damage to muscle membranes.
What two muscular regions are the biggest worry if they are affected by MG?
Pharyngeal muscles and respiratory muscles.
Describe the test that can be used for MG diagnosis.
Tensilon Test
-use edrophonium (AChase inhhibitor) and if symptoms improve it is a (+) test
Other tests include:
-Ab testing for anti-AChR, anti-MUSK, anti-striated muscle antibodies
How can MG be differentiated from:
- ALS
- Muscular Dystorphies
- Lambert-Eaton
- Botulism
- No diplopia or eye symptoms
- No diplopia or eye symptoms
- Symptoms gets worse with exercise (LE it gets better)
- Botulism can be diagnosed with micro tests and generalized descending paralysis
Name two medications that can treat MG.
- Pyridostigmine
2. Neostigmine
Name 3 procedures that can treat MG.
- Plasmapheresis
- IV IgG
- both clear immune attack on host - Surgical removal of thymoma
Name some immunosuppressive drugs that can be used to treat MG.
Steroids, azathioprine, cyclophosphamide, cyclosporin, mycophenolate mofetil
What is Myasthenic Crisis?
Progression of myasthenia gravis that is defined as a need for ventilator support.
Can occur after major surgery, infection, or steroids.
How is MG different from Cholinergic crisis?
CC won’t get better with a tensilon test because no ACh is being made.
What causes neonatal mysathenia?
Maternal antibodies cross the placenta and affect the fetus.
What is the cause of congenital myasthenia?
Autosomal recessive inheritance leading to a synaptic dysfunction from faulty protein production. Patients usually present with ophthalmoplegia.
What are some drugs that can cause Drug-Induced Myasthenia?
Neuromuscular blockers and “-mycin” antibiotics.
D-penicillamine, phenytoin, trimethodone, colistin
What is the pathogenesis of Lambert Eaton syndrome?
Ab attack of presynaptic calcium channels to prevent NT release.
What condition is associated with LE syndrome?
Small cell lung carcinoma (also breast and lymphomas)
-considered a paraneoplastic syndrome
What are 5 clinical features of LE syndrome?
- Areflexia
- Weakness
- Dry mouth
- Metallic Taste
- Autonomic Signs