Musculoskeletal Diseases

Question 1

What is the pathophys of myasthenia gravis?

Answer 1

• acetylcholine receptors are blocked by antibodies
• there is normal ACh production
• skeletal muscle weakness becomes worse later in the day or develops with exercise
• thymectomy brings symptom relief
• pregnancy makes it worse - crosses the placenta and may cause weakness in neonates for up to 4-6 wks

Question 2

What is the treatment for myasthenia gravis?

Answer 2

• oral pyridostigmine = first line tx
• corticosteroids, cyclosporine, azathioprine, mycophenolate
• thymectomy - via median sternotomy or transcervical approach
• plasmapheresis

Question 3

Does myasthenia graves cause an increased sensitivity or resistance to depolarizing and non-depolarizing NMB?

Answer 3

• Non-depolarizing NMB: inc. sensitivity

- Depolarizing NMB: dec. sensitivity

Question 4

How is Myasthenia Gravis diagnosed?

Answer 4

• Tension test (with edrophoium)

Question 5

What are the characteristics of Eaton-Lambert Syndrome?

Answer 5

• destruction of presynaptic voltage-gated calcium channel at the presynaptic nerve terminal
• post synaptic nicotinic receptor is present in normal quantity and functions normally
• proximal muscles are most affected
• is worse in the morning and gets better throughout the day
• associated w/small cell carcinoma of the lung
• pts are sensitive to succs and nondepolarizers

Question 6

What is the pathophysiology of Guillian-Barre?

Answer 6

• an acute idiopathic polyneuritis characterized by an immunologic assault on myelin in the peripheral nerves
• action potential can’t be conducted, so the motor endplate never receives the signal
• usually persists for 2 wks with full recovery in 4 wks

Question 7

What is the clinical presentation of Guillian-Barre?

Answer 7

• flu-like symptoms followed by ascending paralysis
• common culprits = campylobacter jejune bacteria, epstein-barr virus, cytomegalovirus,
• other causes = vaccinations, surgery, lymphomatous disease

Question 8

What are anesthetic considerations for Guillian-Barre?

Answer 8

• avoid succs d/t risk of hyperkalemia
• inc. sensitivity to nondepolarizers
• facial and pharyngeal weakness causes difficulty swallowing
• pts w/autonomic dysfunction are at risk for hemodynamic instability
• exaggerated response to indirect acting sympathomimetics
• steroids do NOT help

Question 9

What is safe to give in both hyper- and hypokalemic periodic paralysis?

Answer 9

• Acetazolamide

Question 10

What co-existing diseases is MH linked to?

Answer 10

• King-Denborough Syndrome
• Central Core Disease
• Multiminicore Disease

Question 11

What are the most common causes of drug-induced SLE?

Answer 11

• isoniasid

- hydralazine

Question 12

What is a medication given for SLE that increases the duration of Succs?

Answer 12

• cyclophosphamide (inhibits plasma cholinesterase)