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Flashcards in MSK immunology Deck (21)
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1

what is myasthenia gravis?

Autoimmune neuromuscular disorder
Severe muscle weakness and severe fatigue

2

what is the pathology behind MG?

Auto-reactive antibodies (auto-IgG) bind with acetylcholine receptors on muscle cells

3

diseases assoc with MG

SLE, rheumatoid and thyrotoxicosis

4

cause of MG in 10%

thymus tumour

5

cause of MG in 90%

unknown

6

genetic assoc of MG

HLA associations

7

appearance of MG

pregnancy
post partum
certain anaesthetic agents

8

which body parts are usually affected first

eyes
face
mouth
throat
neck

9

when is it life threatening

when all muscle are weak -> impairment of respiration

10

most important factor in recovery

rest

11

pathophysiology 1

CD4+ T cells are activated by unfolded AChR subunits expressed by thymic epithelial cells

12

pathophysiology 2

Effector T cells stimulate auto-reactive B cells resulting in the production of anti-AChR IgG antibodies

13

pathophysiology 3

Thymic myoid cells are attacked by these antibodies and release AChR-IgG immune complexes

14

pathophysiology 4

These immune complexes activate other antigen presenting cells increasing the response

15

result of pathophysiology

AChR antibodies block binding of endogenous ACh ligands to these receptors, leading to defects in nerve impulse transmission at the skeletal muscle NMJ

16

final result of MG

Antibody-bound receptors are internalised and degraded
AChR antibodies bind complement, leading to destruction of the muscle endplate (type II hypersensitivity)

17

lab test to diagnose MG

presence of anti-AChR IgG in serum

18

repetitive nerve stimulation to diagnose MG

gradually reducing responses indicates NMJ dysfunction

19

treatment to increase neurotransmission

Anti-cholinesterase agents eg pyridostigmine

20

surgery for MG that may be indicated in the case of a tumour

Thymectomy

21

treatment to reduce autoimmune reactions

Immunosuppressive drugs
Corticosteroids