Myasthenia Gravis

Question 1

What is the clinical name for a droopy eyelid

Answer 1

Ptosis

Question 2

What is the clinical term for double vision

Answer 2

Diplopia

Question 3

What is the cause of diplopia in MG?

Answer 3

One eye doesn’t move properly

Question 4

Face and throat muscles are affected in what % of people?

Answer 4

15%

Question 5

What are the initial signs and symptoms of MG?

Answer 5

Ptosis
Diplopia
Altered speech (may be soft or nasally)
Limited facial expression
Problems chewing and swallowing

Question 6

What are some symptoms of MG which affect the limbs?

Answer 6

-Difficulty holding head up
-Climbing stairs
-Activities involving holding arm up for some time
-Waddling gait

Question 7

What is a very serious symptom of MG?

Answer 7

Diaphragm muscle is affected and you can’t breathe properly - artificial ventilation is needed

Question 8

What is the basic PATHOPHYSIOLOGY of MG?

Answer 8

Antibodies bind to nicotinic receptors in the NMJ so ACh can’t bind - EPP can’t be generated and muscle can’t contract

Question 9

MG is an autoimmune disease t/f

Answer 9

True

Question 10

List some tests used to diagnose MG

Answer 10

-test for muscle weakness with repeated action
-anticholinesterase test
-neurophysiological testing
-test for anticholinergic receptor antibodies

Question 11

How do you test for muscle weakness which worsens with repeated action?

Answer 11

Ask patient to look at ceiling/hold arms at side for an extended time
Eventually head/arms will droop

Question 12

What is another name for the anticholinesterase test?

Answer 12

Tensilon Challenge Test

Question 13

How do you Carry out an anticholinesterase test

Answer 13

Give the patient anticholinesterase
Muscle strength will improve immediately

Question 14

What drugs are used in Tensilon Challenge test ?

Answer 14

Neostigmine/edrophonium

Question 15

How do you carry out neurophysiological testing?

Answer 15

Repeatedly stimulate the nerve
A fall in compound muscle actions will occur

Question 16

Anticholinergic receptor antibodies are present in what % of patients?

Answer 16

80%

Question 17

Why does MG get worse with repeated action?

Answer 17

-when action is initiated lots of ACh is released
- only a limited store on ACh in the presynapticc terminal so less ACh released with each AP
- less ACh released + less nicotinic receptors available means weakness is more pronounced.

Question 18

What is the incidence rate of MG

Answer 18

15/100,000

Question 19

Many autoimmune diseases get progressively worse t/f?

Answer 19

False. Many have relapses and remissions

Question 20

Women of what age are most likely to get MG?

Answer 20

3rd decade/20’s

Question 21

Men of what age are most likely to get MG?

Answer 21

In 6th/7th decade
50’s and 60’s

Question 22

List ways to treat MG

Answer 22

-Anticholinesterases
- Thymectomy
- immunosupression
-plasmaphoresis
-intravenous immunoglobulin

Question 23

What do anticholinesterases do?

Answer 23

Prevent breakdown of ACh

Question 24

List some anticholinesterases

Answer 24

Neostigmine
Pyridostigmine Bromide
Edrophonium

Question 25

Name an Anticholinesterase which works immediately

Answer 25

Edrophonium

Question 26

What is a thymectomy

Answer 26

Removal of thymus gland

Question 27

How many patients benefit from a thymectomy

Answer 27

85% of patients under 55 benefit

Question 28

How many patients who have a thymectomy no longer require drug treatment?

Answer 28

35%

Question 29

What drug can be used to dampen the immune system when using imunosupression as a treatment?

Answer 29

Azathioprine

Question 30

What class of drugs are used when treating a patient with immunosupression and what do they do?

Answer 30

Steroids
They dampen the immune system

Question 31

What is plasmaphoresis

Answer 31

Wash out the antibodies from the plasms

Question 32

What happens to the patient when you administer intravenous immunoglobulin?

Answer 32

It dampens the production of antibodies in the patients body.