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CIMS > Myasthenia Gravis > Flashcards

Myasthenia Gravis Flashcards

1
Q

Neuromuscular disorder caused by a decrease in the number of available acetylcholine receptors

A

Myasthenia Gravis

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2
Q

Acetylcholine is synthesized in the _______ nerve terminal and stored in________

A

motor, vesicles (quanta)

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3
Q

Acetylcholine combines with the binding sites on the _____ subunits of the acetylcholine receptors

A

alpha

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4
Q

Acetylcholine receptor opens and permits the entry of _______ cations which produces depolarization

A

sodium

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5
Q

(TRUE or FALSE) Depolarization happens on the end-plate region of the muscle fiber

A

TRUE

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6
Q

Acetylcholine is hydrolyzed by ________ which terminates muscle contraction

A

acetylcholinesterase

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7
Q

In myasthenia gravis, the postsynaptic folds are __________

A

flattened or simplified

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8
Q

______________ is the amount of ACh released per impulse that normally decreases on repeated activity

A

Presynaptic rundown

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9
Q

MG is an autoimmune disorder most commonly caused by ___________

A

anti-AChR antibodies

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10
Q

Muscles commonly chosen in muscle biopsy are ______, _______, and ________

A

deltoid, biceps, and quadriceps

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11
Q

(men, women) are frequently affected in myasthenia gravis

A

women

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12
Q

Protein in NMJ which is involved in AChR clustering with reduction of AChRs

A

muscle-specific kinase (MuSK)

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13
Q

Low-density protein that is important in clustering of AChRs which is present in 1-3% of MG patients

A

lipoprotein receptor-related protein 4 (LRP4)

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14
Q

Class of MG which manifests as any ocular muscle weakness while all other muscles groups are normal

A

Class I

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15
Q

Class of MG which is characterized by moderate weakness of muscles other than ocular muscles that involves mostly oropharyngeal, respiratory muscles or both

A

Class IIIb

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16
Q

Class IVa MG is characterized by severe muscles weakness other than ocular muscles that involves mostly _____, _______, or both

A

limb, axial muscles

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17
Q

Bulbar weakness is seen mainly in _____________ positive MG

A

MuSK-antibody

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18
Q

The pathogenic antibodies in MG are _________ and __________ dependent

A

IgG, T cell

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19
Q

Cardinal features of myasthenia gravis are ________ and ___________ of muscles

A

weakness, fatigability

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20
Q

Common initial complaints of MG patients (2)

A

diplopia and ptosis

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21
Q

(TRUE or FALSE) Limb weakness in MG is often proximal and may be symmetric

A

FALSE

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22
Q

_____________ occurs when ventilatory weakness requires respiratory assistance

A

Myasthenia crisis

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23
Q

Thymus is abnormal in ~75% of (AChR antibody positive, MuSK antibody positive, LRP4 antibody positive) myasthenia gravis

A

AChR antibody positive

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24
Q

(TRUE or FALSE) Ocular MG is when the weakness is restricted to EOMs for 3 years is more likely to become generalized

A

FALSE

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25
Q

A quick and easy diagnostic test for MG that can be done in the clinic or at the bedside of a hospitalized patient, which is due to less depletion of quanta of AChR in the cold and reduced activity of AChE at the NMJ

A

Ice-pack test

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26
Q

_________ occurs when there is a combination of presynaptic rundown and decreased efficiency of neuromuscular transmission

A

Myasthenic fatigue

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27
Q

___________ is an autoimmune disorder caused by antibodies that block ACh release by inhibiting a presynaptic calcium channel

A

Lambert-Eatan Myasthenic Syndrome

28
Q

_______ is a protein derived from motor nerves that normally binds to LRP4 and important for normal clustering of AChRs at NMJ

A

Agrin

29
Q

Antibodies directed against _______ receptors and ________ are associated in patients with thymoma and MG and neuromyotonia or Morvan syndrome

A

Netrin-1, Caspr2

30
Q

(TRUE or FALSE) In electrodiagnostic testing, myasthenic patients have a rapid reduction of >10% in amplitude of the evoked responses

A

TRUE

31
Q

Edrophonium is used to (treat/diagnose) MG because of its rapid onset (30s) and short duration (~5min) of its effect

A

diagnose

32
Q

Positive result in Tensilon test is diagnostic for MG who have negative ______, ________________ , or ________.

A

antibody, electrodiagnostic test, ice-pack test

33
Q

People with certain genetic markers called __________ are at risk of MG

A

HLA-B8, D3

34
Q

__________ patients typically do not experience myasthenic crisis, but are generally difficult to treat than _________ MG

A

Anti-MuSk, Anti-AChR

35
Q

__________ or _________ can cause exacerbation of weakness in myasthenic patients

A

Aminoglycoside antibiotics, procainamide

36
Q

Initial dose of ____ of Edrophonium is given, and thye result is said to be positive if definitive improvement occurs

A

2mg IV

37
Q

Common side effects of Edrophonium are nausea, diarrhea, salivation, fasciculation, syncope and bradycardia, so _______ is given when the symptoms of the side effects worsen

A

Atropine

38
Q

A synthetic quaternary amine that binds reversibly to the active center of AChE to prevent the hydrolysis of ACh

A

Edrophonium

39
Q

A synthetic quaternary amine that is a reversible AChE inhibitor that has greater effect on skeletal muscle and contraindications to patients with intestinal or urinary bladder obstruction

A

Neostigmine

40
Q

An intermediate-acting cholinesterase inhibitor that has a duration of 3-6hrs and is used in the management of chronic myasthenia gravis

A

Pyridostigmine

41
Q

Physostigmine is also called ________, a naturally occurring tertiary amine that acts as substrate for AChE

A

Eserine

42
Q

Intermediate-acting cholinesterase inhibitors such as neostigmine, pyridostigmine and physostigmine are called _________

A

Carbamates

43
Q

Muscle-like cells within the thymus

A

Myoid cells

44
Q

Treatment with _________ and ____ may be used before thymectomy to maximize strength in weak patients

A

plasmapheresis, IVIg

45
Q

It is the mechanical separation of plasma with blood cells that produces short-term reduction in AChR

A

plasmapheresis

46
Q

Prednisone is converted to _________ and alters the gene expression by binding to glucocorticoid receptors in the body

A

Prednisolone

47
Q

A csDMARD drug that inhibits the de novo synthesis of purine and inhibits the proliferation of lymphocytes

A

Mycophenolate Motefil

48
Q

It suppresses inosinic acid synthesis, B-cell and T-cell function, Ig production and IL-2 secretion, through its major metabolite 6-thioguanine

A

Azathioprine

49
Q

Calcineurin inhibitor that regulates gene transcription, inhibits IL-1 and IL-2 receptor productions, and macrophage-T cell interaction and T cell responsiveness

A

Cyclosporine

50
Q

Rituximab binds to the ____ molecule on B lymphocytes

A

CD20

51
Q

Chimeric monoclonal antibody that is more effective in MuSK antibody-positive MG

A

Rituximab

52
Q

csDMARD that is converted to Phosphoramide mustard (active form) which cross-links DNA to prevent cell replication

A

Cyclophosphamide

53
Q

Exacerbation of weakness sufficient to endanger life

A

Myasthenic crisis

54
Q

Treatment for myasthenic crisis include (give at least 2, there are 5 answers)

A

Antibiotics, ventilatory assistance, pulmonary physiotherapy, plasmapheresis, IVIg

55
Q

Weakness and fatigability of proximal or distal etemity muscles, EOMs and eyelids caused by genetic mutations

A

Non-autoimmune congenital myasthenia

56
Q

Symptoms include ptosis of the eyelids, diplopia, depressed or absent reflexes, dry mouth and impotence

A

Lambert-Eaton Myasthenic Syndrome (LEMS)

57
Q

LEMS is caused by autoantibodies directed against __________ calcium channels at the motor nerve terminals

A

P/Q-type

58
Q

In older adults, LEMS is associated with malignancy, most commonly ______________________

A

small-cell lung cancer (SCLC)

59
Q

Symptoms of Botulism (Give the 4 Ds)

A

Diplopia, Dysarthria, Dysphonia, Dysphagia

60
Q

Most common cause of botulism

A

ingestion of improperly prepared food containing toxin

61
Q

Historic name for myasthenia-like fatigue syndrome without organic basis

A

Neurasthenia

62
Q

Muscle testing in neurasthenia reveals that it is a ___________ which is a characteristic of nonorganic disorder or tiredness or apathy

A

“give-away weakness”

63
Q

Diplopia resembling in MG is due to an intracranial mass lesion that compresses nerves to the EOMs

A

Hyperthyroidism

64
Q

Weakness of the EOMs which may be accompanied by weakness of the proximal muscles of the limb and is associated with mitochondrial conditions

A

Progressive external opthalmoplegia

65
Q

Penicillamine induces the production of AChR antibodies

A

Drug-induced myasthenia

66
Q

Neoplastic change also called ______ may produce enlargement of the thymus

A

thymoma

CIMS (5 decks)

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