39. Myasthenia Gravis

Question 1

What is Myasthenia Gravis

Answer 1

autoimmune neuromuscular disease that causes weakness in the skeletal muscles
- worsens after periods of activity and improves after periods of rest

Question 2

What antibodies does Myasthenia Gravis affect

Answer 2

Antibodies against nicotinic acetylcholine receptors between the nerve and muscles

Question 3

MG is sometimes caused by _____

Answer 3

MuSK (Muscle-Specific Kinase)

- prevents nerve impulses from triggering muscle contractions

Question 4

MG:

_____ gland causes autoimmune disease

Answer 4

thymus

Question 5

s/s MG

Answer 5

• ocular myasthenia: eye muscle weakness
• Ptosis
• Diplopia
• dysphagia
• inability to cough or gag
• SOB
• slurred speech
• weakness in arms/hands/finger/legs/neck

Question 6

Does HR increase or decrease with MG

Answer 6

increase

Question 7

Does BP increase or decrease with MG

Answer 7

increase

Question 8

What is myasthenia crisis

Answer 8

severe muscle weakness and resp failure

Question 9

4 ways to test MG

Answer 9

• tensilon test
• blood tests
• electrodiagnostics
• CT or MRI

Question 10

Describe purpose of tensilon test

Answer 10

• Will differentiate between myasthenic vs cholinergic crisis
• Edrophonium briefly relieves weakness by blocking the break down acetylcholine and increasing levels at the neuromuscular junction
• ↑ acetylcholine at the neuromuscular junction

Question 11

What to prepare for tensilon test

Answer 11

• 10mg tensilon prepared lasting 10 min

- have 2mg atropine in case of cholinergic crisis

Question 12

Two types blood tests for MG

Answer 12

• acetylcholine

- Anti-MuSK antibody

Question 13

type of electrodiagnostic for MG

Answer 13

single fiber electromyography (EMG)

Question 14

purpose of CT or MRI for MG

Answer 14

detect presence of a thymoma

Question 15

2 meds used for MG and examples of each

Answer 15

• cholinesterase inhibitors (neostigmine & pyridostigmine)

- autoimmune treatments (prednisone, use 4-6 wks then taper)

Question 16

side effects of MG

Answer 16

• ↑ mucus salivation, urination, sweating, abdominal cramps, muscle twitching, nausea, vomiting, diarrhea, decreased pupil size, slowed or slurred speech, convulsion, dizziness, headache, low blood pressure, shortness of breath

Question 17

Therapeutic levels of Cholinesterase Inhibitors _____. Toxic levels _____.

Answer 17

• Produce mild stimulation

- depress the CNS

Question 18

How to treat toxic levels of cholinesterase inhibitors

Answer 18

Treat with respiratory support and atropine

Question 19

Non-pharmacologic treatments of MG

Answer 19

• plasmapheresis
• IV immunoglobulin
• thymectomy
• hydrotherapy

Question 20

s/s Cholinergic Crisis

Answer 20

1. Increased salivation, lacrimation, sweating, urination, abdominal cramping, emesis.
2. Bronchospasm, tachycardia
3. Muscular weakness, fatigue, fasciculation leading to paralysis
4. Respiratory muscle weakness, respiratory failure