Myasthenia Gravis

Question 1

what type of disease is myasthenia gravis?

Answer 1

autoimmune

Question 2

Cause?

Answer 2

autoantibodies block Acetylcholine (Ach)

Question 3

what is the main overall symptom?

Answer 3

muscle weakness

Question 4

which receptor does Ach bind to at the muscle?

Answer 4

nicotinic acetylcholine receptor

Question 5

small proportion of patients also have antibodies against a post-synaptic protein.

what is this protein called?

Answer 5

muscle-specific kinase, MuSK

Question 6

60% of MG cases get reactive hyperplasia of what cell and in what organ?

Answer 6

intrathymic B cell

thyroid

Question 7

how many myasthenia gravis pts get thymoma?

-% wise

Answer 7

12%

Question 8

ptosis is due to weakness of what muscle?

Answer 8

levator palpebrae superioris muscle

Question 9

weak swallowing muscles causes what symptom?

Answer 9

dysphagia

Question 10

weak facial muscles leads to what symptoms?

-2

Answer 10

slurred speech + snarl smile

Question 11

why is there head drop?

Answer 11

Neck extensor muscles weak

Question 12

why is there SOB?

Answer 12

Resp muscles weak

Question 13

what is worldwide prevalence?

-%wise

Answer 13

0.02%

Question 14

which gender is a risk factor?

Answer 14

females

Question 15

do younger or older people get onset of this disease?

Answer 15

younger onset

Question 16

which complication has increased risk due to the dysphagia?

Answer 16

↑aspiration pneumonia

Question 17

Weak respiratory muscles can cause what complication?

how do you treat this?
-2

Answer 17

myasthenic crisis

plasmapheresis + intubation

Question 18

how does the muscle weakness vary during the day?

Answer 18

worse at end of day

Question 19

Risk Factors for MG?

-6

Answer 19

Female 
young
FHx 
Autoimmune disorder 
Thymoma 
Thymic hyperplasia

Question 20

which imaging do you use to exclude thymoma?

Answer 20

exclude thymoma

Question 21

what test is appropriate for checking nerve behaviour in MG?

result on this test?

Answer 21

Electromyography

nerves show a decremental response to repetitive stimulation

Question 22

what is 1st line blood test ?
2nd line blood test?

how many pts will be postiive for the above two test?

if not positive in above test but they have a strong history what is the 2nd line Ix you do?

Answer 22

check blood for anti-AChR antibodies - 85%
anti-muSK antibodies - 40%

Electromyography

Question 23

how does exercise affect symptoms?

Answer 23

makes it worse

Question 24

pt has positive Hx but nothing abnormal in blood tests.

what Ix should you do now?

positive result on said Ix?

how sensitive is said test?

Answer 24

Electromyography

nerves show a decremental response to repetitive stimulation

95%

Question 25

1st line drug? group of this drug?

Answer 25

PYRIDOSTIGMINE acetylcholinesterase inhibitor

Question 26

if thymoma is seen on imaging. what Mx do you do?

Answer 26

Thymectomy

Question 27

1st line drug fails. what is 2nd line drug? ``` class of this drug? group of this drug? ```

Answer 27

Prednisolone corticosteroids immunosuppression

Question 28

what is 2nd line drug? 2nd line drug fails. what is 3rd line drug? ``` class of this drug? group of this drug? ```

Answer 28

Prednisolone azathioprine purine synthesis inhibitor immunosuppression

Question 29

what is nutshell Mx? | -2 things

Answer 29

boost ACh (&downregulate immune system)

Question 30

on examination how can you exacerbate ptosis?

Answer 30

ask pt to look up

Question 31

symptoms? | -7

Answer 31

``` Lethargy Muscle weakness, worse at end of day Double vision Slurred speech Dysphagia SOB Head drop ```

Question 32

does rest make symptoms better or worse?

Answer 32

better

Question 33

signs on examination? | -4

Answer 33

muscle weakness muscles fatigue on use Ptosis Myasthenic snarl

Question 34

what is 1st line blood test ? 2nd line blood test? how many pts will be postiive for the above two test? if not positive in above test but they have a strong history what is the 2nd line Ix you do?

Answer 34

check blood for anti-AChR antibodies - 85% anti-muSK antibodies - 40% Electromyography