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(2) MS: Neurological Conditions 🩺 > S3_L1: Myasthenia Gravis > Flashcards

S3_L1: Myasthenia Gravis Flashcards

1
Q

Who wrote the first written description of myasthenia gravis about a woman who temporarily lost her power of speech and became mute as a fish?

A

Thomas Willis

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2
Q

What is the most common primary disorder of neuromuscular transmission that is chronic and autoimmune in nature?

A

Myasthenia gravis

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3
Q

What is the usual cause of myasthenia gravis?

A

acquired immunological abnormality

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4
Q

What does the Latin & Greek term “Myasthenia Gravis” mean?

A

grave muscle weakness

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5
Q

The hallmark of Myasthenia Gravis is muscle weakness that increases during (1)___ & improves after (2)___.

A
  1. periods of activity
  2. periods of rest
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6
Q

What is the most notorious drug known to adversely affect MG or trigger the recurrence of MG?

A

Antibiotics

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7
Q

What is the important immunological organ related to myasthenia gravis?

A

Thymus gland

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8
Q

Which cells found in the thymus express the AChR antigen?

A

Myoid cells

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9
Q

What is the age of onset of MG for males and females?

A

Male: middle aged (60-69)
Female: younger aged (20-30)

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10
Q

TRUE OR FALSE: MG is equally present in men and women older than the age of 40 years; however, it is three times more common in women than men under 40 years of age.

A

True

Source: Merritt

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11
Q

Which stage of MG classification by Osserman is described as mild generalized, slow progression, no crises, drug responsive?

A

2A

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12
Q

Which stage of MG classification by Osserman is described as acute fulminating, rapid progression with respiratory crises, poor response, some are with thymoma; Hook to mechanical tube and ventilated?

A

3

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13
Q

Which stage of MG classification by Osserman is described as late severe, severe myasthenia, progression of symptoms over 2 years from class 1 to 2?

A

4

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14
Q

Which stage of MG classification by Osserman is described as moderately severe, generalized severe skeletal and bulbar involvement, no crises, drug response is less satisfactory?

A

2B

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15
Q

Which stage of MG classification by Osserman is described as ocular myasthenia?

A

1

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16
Q

Which stage of MG classification by Osserman is described as MG with poor response to medication as well as muscle atrophy?

A

5

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17
Q

What is the most sensitive clinical test of neuromuscular transmission and shows increased jitter?

A

Single Fiber EMG

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18
Q

It is found to be greatest in weak muscles but may be abnormal even in muscles with normal strength

A

Jitter

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19
Q

TRUE OR FALSE: Patients with mild or purely ocular muscle weakness may have increased jitter only in facial muscles

A

True

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20
Q

In acquired myasthenia gravis, the ___ muscle membrane is distorted and simplified, having lost its normal folded shape.

A

Postsynaptic

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21
Q

It is the gold standard and mainstay of treatment for MG

A

Cholinesterase Inhibitors (pyridostigmine-Mestinon)

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22
Q

The most dramatic response to MG will be from taking what medication?

A

Pyridostigmine-Mestinon

23
Q

TRUE OR FALSE: In MG, muscles that control eye and eyelid movement, facial expression, chewing, talking, and swallowing are more affected than muscles that control breathing and neck and limb movements.

A

True

24
Q

It is the most commonly used diagnostic procedure for MG

A

Electromyography (Repetitive Nerve Stimulation)

25
Q

In RNS and RNSS, the decrementing response of > or ≥ 10% from the initial value is usually seen in the ___ muscles

A

Proximal

26
Q

SFEMG is indicated and helpful in pts c ____ RNS

A

Normal

27
Q

In generalized MG, the RNS is (1)___, while in ocular MG, the RNS is (2)___.

A
  1. sensitive
  2. not as sensitive (depends on muscle tested)
28
Q

It is a diagnostic test that determines the amount of antibodies against AChR

A

Antibodies Against Acetylcholine Receptor Test

29
Q

3 types of cells present in the thymus that are necessary for the pathogenesis of MG

A
  1. Myoid cells
  2. Antigen presenting cells
  3. Immunocompetent T-cells
30
Q

What is affected in MG

A

Neuromuscular junction

31
Q

The presence of antibodies reaching the receptors before the released ACh do is an event termed as?

A

Competitive Inhibition

32
Q

What are the most common initial symptoms in MG patients?

A

Ocular motor disturbances (ptosis or diplopia)

33
Q

TRUE OR FALSE: Bilateral ptosis is a very common manifestation in patients with MG

A

True

34
Q

This type of thymectomy approach assures a more complete removal of thymic tissue.

A

Transsternal

35
Q

Match the cardinal features of MG with its description/details

  1. Extraocular muscle weakness
  2. Nasal speech, LMN
  3. It is often asymmetric
  4. Dyspnea, hypoxia (a late finding)
  5. Affects proximal arms or legs. Affects neck flexors more than extensors

A. Dysarthria
B. Fluctuating weakness
C. Diplopia
D. Ptosis
E. Respiratory insufficiency

A
  1. C
  2. A
  3. D
  4. E
  5. B
36
Q

What are the two types of cells that interact with each other to produce antibodies within the lymphoid tissue of the thymus?

A

B-cells and helper T-cells

37
Q

TRUE OR FALSE: Patients with thymoma usually have more severe disease, higher levels of AChR antibodies, and more severe EMG abnormalities than patients without thymoma

A

True

38
Q

TRUE OR FALSE: A pattern is seen in patients whose sx began when they were young (30-60 y/o), a thymoma is detected; however, it is not detected in those whose sx began after age 60

A

True

39
Q

Determine whether plasma exchange or IVIG is described

  1. Used as a short-term treatment for pts c acute/sudden worsening myasthenia
  2. Pts have a favorable response to high-dose: 2g/kg infused over 2-5 days
  3. A chronic intermittent treatment for pts who are refractory to all other treatments
  4. Mechanisms of action: Down-regulation of antibodies directed against AChR and introduction of anti-idiotypic antibodies
  5. Used to rapidly improve strength before surgery

A. Plasma exchange
B. Intravenous Immune Globulin (IVIG)
C. Both

A
  1. C
  2. B
  3. A
  4. B
  5. A
40
Q

When during the day does the severity of weakness worsen?

A

As the day progresses after prolonged use of affected muscles

41
Q

What stage is described as weakness often becomes fixed and the most severely involved muscles are frequently atrophic after 15-20 years?

A

Burnt-out stage

42
Q

Differentiate Bell’s Palsy from Myasthenia gravis

A

Bell’s palsy - nerve problem
MG - neuromuscular junction problem

43
Q

Determine which immunosuppressant drug is described

  1. It is reserved for refractory cases d/t toxicity
  2. Main adverse effect of the drug is diarrhea
  3. Acts as a calcineurin inhibitor and reduces the function of effector T cells
  4. Not as popular due to renal toxicity
  5. Useful adjunct to steroids in patients who cannot tolerate or fail to respond to prednisone. Most studied immunosuppressant

A. Azathioprine
B. Cyclosporine
C. Cyclophosphamide
D. Mycophenolate
E. Methotrexate

A
  1. C
  2. D
  3. B
  4. B
  5. A
44
Q

Immunosuppressive drugs are also known as?

A

Steroid-sparing agents

Source: Merritt

45
Q

Enumerate the 7 factors that worsen MG Sx

A
  1. Emotional upset
  2. Systemic illness
  3. Hypothyroidism or hyperthyroidism
  4. Pregnancy
  5. Menstrual cycle
  6. Drugs affecting neuromuscular transmission
  7. Increase in body temperature
46
Q

What is the corticosteroid that patients with thymoma have an excellent response to before or after the removal of their tumor?

A

Prednisone

47
Q

The maximal favorable response after a thymectomy generally occurs how long after the surgery?

A

2-5 years

48
Q

TRUE OR FALSE: Patients with thymomas do not respond as well to thymectomy as do patients without thymoma

A

True

49
Q

TRUE OR FALSE: Hyperplastic changes in the thymus indicate an ongoing active immune response

A

True

50
Q

TRUE OR FALSE: In MG, ACh is released normally, but its effect on the postsynaptic membrane is reduced and the probability that any nerve impulse will cause a muscle action potential is reduced

A

True

51
Q

TRUE OR FALSE: In the era before corticosteroids were used for treatment, approximately one-third of patients c MG improved spontaneously, one-third become worse, and one-third died of the disease. This is the same epidemiologic presentation with stroke

A

True

52
Q

What stage is described where symptoms fluctuate over a relatively short period of time and then become progressively severe for several years?

A

Active stage

53
Q

What stage is described where fluctuations in strength still occurred but are attributable to fatigue, intercurrent illness, or other identifiable factors?

A

Inactive stage

54
Q

TRUE OR FALSE: In 2/3 of patients, maximum weakness occurs during the first year

A

True

(2) MS: Neurological Conditions 🩺 (12 decks)

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