[MCQ] Myasthenia Gravis and Diseases of the Neuromuscular Junction- Part 2

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Myasthenia Gravis and Diseases of the Neuromuscular Junction- Part 2

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Question 1

MG muscle weakness will not become generalized if it remains restricted to extraocular muscles for ?

A	6 months
B	1 year
C	2 years
D	3 years

Question 1 Explanation:

In MG, if muscle weakness remains restricted to extraocular muscles for 3 years (ocular MG), it is unlikely to become generalized.

Question 2

Which of the following is false about MG ?

A	No loss of reflexes
B	No impairment of sensation
C	No HMF neurologic defect
D	None of the above

Question 2 Explanation:

MG is characterized by typical distribution of skeletal muscle weakness & fatigability, without loss of reflexes or impairment of sensation or other neurologic function

Question 3

In seronegative MG, antibodies can be found against ?

A	Muscle-specific tyrosine kinase
B	Myasthenia-specific tyrosine kinase
C	Membrane-specific tyrosine kinase
D	None of the above

Question 3 Explanation:

Presence of anti-AChR antibodies is diagnostic of MG, but a negative test does not exclude MG. Antibodies to muscle-specific tyrosine kinase (MuSK) are present in ~40% of AChR antibodynegative patients with generalized MG.

Question 4

Anti-AChR antibodies are detectable in what percentage of all myasthenic patients ?

A	~ 45 %
B	~ 65 %
C	~ 85 %
D	~ 99 %

Question 5

Anti-AChR antibodies are detectable in what percentage of ocular MG patients ?

A	~ 25 %
B	~ 50 %
C	~ 75 %
D	~ 99 %

Question 6

Anti-MuSK antibodies are found in what percentage of AChR antibody-negative patients with generalized MG ?

A	~ 10 %
B	~ 40 %
C	~ 80 %
D	~ 100 %

Question 6 Explanation:

~40% of AChR antibody-negative patients with generalized MG have anti-MuSK antibodies.

Question 7

Anti MuSK antibodies are present in what percentage of AChR antibody-positive MG patients ?

A	Rare
B	25 %
C	50 %
D	80 %

Question 8

Anti MuSK antibodies are present in what percentage of patients with MG limited to ocular muscles ?

A	Rare
B	25 %
C	50 %
D	80 %

Question 8 Explanation:

MuSK antibodies are rarely present in AChR antibody-positive MG patients or in patients with MG limited to ocular muscles.

Question 9

Which of the following statements about antibodies to musclespecific kinase (MuSK) is false ?

A	Found in ~40% of AChR antibody-negative generalized MG
B	Not present in AChR antibody-positive patients
C	Not present in MG limited to ocular muscles
D	None of the above

Question 10

It is best to test which of the following muscles in repetitive nerve stimulation for evidence of MG ?

A	Proximal muscle groups
B	Distal muscle groups
C	Interosseous muscles
D	Any of the above

Question 10 Explanation:

It is best to test weak muscles or proximal muscle groups in repetitive nerve stimulation for evidence of MG. Anti-AChE medication must be stopped 6 - 24 hours before testing.

Question 11

In myasthenic patients, rapid reduction of what proportion in amplitude of evoked responses is noted ?

A	> 10 - 15 %
B	> 20 - 30 %
C	> 30 - 45 %
D	> 50 - 75 %

Question 11 Explanation:

in repetitive nerve stimulation for evidence of MG, electric shocks are delivered at a rate of two or three per second to the appropriate nerves, and action potentials are recorded from muscles. In myasthenic patients there is a rapid reduction of > 10 - 15% in the amplitude of the evoked responses.

Question 12

Which of the following drug must be kept at hand while conducting Edrophonium anticholinesterase test ?

A	Atropine
B	Neostigmine
C	Adrenaline
D	All of the above

Question 12 Explanation:

Atropine (0.6 mg) should be drawn up in a syringe, ready for IV use if nausea, diarrhea, salivation, fasciculations, syncope or bradycardia develop following IV edrophonium.

Question 13

Apart from Edrophonium which drug can be used for Anticholinesterase Test ?

A	Atropine
B	Neostigmine
C	Adrenaline
D	All of the above

Question 13 Explanation:

A longer acting drug like neostigmine (orally) may be used for anticholinesterase test, as it permits more time for detailed evaluation of strength.

Question 14

Which of the following diseases can cause false-positive Edrophonium anticholinesterase test ?

A	Amyotrophic lateral sclerosis
B	Hodgkin lymphoma
C	Charcot-Marie-Tooth disease
D	Creutzfeldt-Jakob disease (CJD)

Question 14 Explanation:

False-positive Edrophonium anticholinesterase test occur in occasional patients with amyotrophic lateral sclerosis, and in placebo-reactors.

Question 15

Which of the following component of the neuromuscular junction may be affected in congenital myasthenic syndromes (CMS) ?

A	Presynaptic nerve terminal
B	Various subunits of AChR
C	Various subunits of AChE
D	All of the following

Question 15 Explanation:

Congenital myasthenic syndromes (CMS) are disorders of neuromuscular junction that are not autoimmune but are due to genetic mutations in which virtually any component of the neuromuscular junction may be affected. Alterations in function of presynaptic nerve terminal or in various subunits of the AChR or AChE have been identified in different forms of CMS.

Question 16

Which of the following statements about congenital myasthenic syndromes (CMS) is false ?

A	Due to genetic mutations
B	Symptoms begin in infancy or childhood
C	AChR antibody tests are consistently negative
D	α subunit of AChR is affected in ~75% of cases

Question 16 Explanation:

CMS should be suspected when symptoms of myasthenia begin in infancy or childhood & AChR antibody tests are consistently negative. CMS that involve AChR,  subunit is affected in ~75%.

Question 17

Drugs that can exacerbate weakness in myasthenic patients are all except ?

A	Penicillamine
B	Aminoglycoside antibiotics
C	Procainamide
D	Diazepam

Question 17 Explanation:

Drugs that may exacerbate MG include aminoglycosides (streptomycin, tobramycin, kanamycin), Quinolones (ciprofloxacin, levofloxacin, ofloxacin, gatifloxacin), macrolides (erythromycin, azithromycin), Nondepolarizing muscle relaxants (D-Tubocurarine, pancuronium, vecuronium, atracurium), Beta-blockers (Propranolol, atenolol, metoprolol), Local anesthetics (Procaine, Xylocaine), Procainamide, Botulinum toxin, Quinine derivatives (Quinine, quinidine, chloroquine, mefloquine), Magnesium, Penicillamine.

Question 18

Myasthenia gravis may be “induced” by ?

A	Penicillamine
B	Aminoglycoside antibiotics
C	Procainamide
D	Diazepam

Question 19

Disorders associated with myasthenia gravis include ?

A	Hashimoto’s thyroiditis
B	Graves’ disease
C	Systemic lupus erythematosus
D	All of the above

Question 19 Explanation:

Disorders associated with Myasthenia Gravis are thymoma, thymus hyperplasia, Hashimoto’s thyroiditis, Graves’ disease, rheumatoid arthritis, lupus erythematosus, skin disorders, family history of autoimmune disorder. Hyperthyroidism or hypothyroidism, occult infection, medical treatment for other conditions may exacerbate myasthenia gravis. Tuberculosis, diabetes, peptic ulcer, gastrointestinal bleeding, renal disease, hypertension, asthma, osteoporosis, obesity are disorders that may interfere with therapy.

Question 20

Which of the following is false about Lambert-Eaton myasthenic syndrome (LEMS) ?

A	Presynaptic disorder of neuromuscular junction
B	Proximal muscles of lower limbs most commonly affected
C	Normal deep tendon reflexes
D	Incremental responses on repetitive nerve stimulation

Question 20 Explanation:

LEMS is a presynaptic disorder of NM junction. Proximal muscles of lower limbs are most commonly affected. Ptosis & diplopia occur in ~70% of patients. Patients with LEMS have depressed or absent reflexes, experience autonomic changes such as dry mouth and impotence, and have incremental responses on repetitive nerve stimulation.

Question 21

Which of the following is false about Lambert-Eaton myasthenic syndrome (LEMS) ?

A	Autoantibodies against P/Q type calcium channels
B	Associated small-cell carcinoma of lung
C	Plasmapheresis ineffective
D	3,4 Diaminopyridine (3,4-DAP) helpful

Question 21 Explanation:

LEMS is caused by autoantibodies directed against P/Q type calcium channels at the motor nerve terminals impairing release of ACh & are detected in ~85% of LEMS patients. Small cell lung carcinoma is common in LEMS. Treatment of LEMS involves plasmapheresis & immunosuppression, 3,4-Diaminopyridine (3,4-DAP) & pyridostigmine

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See all quizzes of Myasthenia Gravis and Diseases of the Neuromuscular Junction here:

1 MG muscle weakness will not become generalized if it remains
restricted to extraocular muscles for ?
A. 6 months
B. 1 year
C. 2 years
D. 3 years

2 Which of the following is false about MG ?
A. No loss of reflexes
B. No impairment of sensation
C. No HMF neurologic defect
D. None of the above

3 In seronegative MG, antibodies can be found against ?
A. Muscle-specific tyrosine kinase
B. Myasthenia-specific tyrosine kinase
C. Membrane-specific tyrosine kinase
D. None of the above

4 Anti-AChR antibodies are detectable in what percentage of all
myasthenic patients ?
A. ~ 45 %
B. ~ 65 %
C. ~ 85 %
D. ~ 99 %
5 Anti-AChR antibodies are detectable in what percentage of ocular
MG patients ?
A. ~ 25 %
B. ~ 50 %
C. ~ 75 %
D. ~ 99 %

6 Anti-MuSK antibodies are found in what percentage of AChR
antibody-negative patients with generalized MG ?
A. ~ 10 %
B. ~ 40 %
C. ~ 80 %
D. ~ 100 %

7 Anti MuSK antibodies are present in what percentage of AChR
antibody-positive MG patients ?
A. Rare
B. 25 %
C. 50 %
D. 80 %
8 Anti MuSK antibodies are present in what percentage of patients
with MG limited to ocular muscles ?
A. Rare
B. 25 %
C. 50 %
D. 80 %

9 Which of the following statements about antibodies to musclespecific
kinase (MuSK) is false ?
A. Found in ~40% of AChR antibody-negative generalized MG
B. Not present in AChR antibody-positive patients
C. Not present in MG limited to ocular muscles
D. None of the above
10 It is best to test which of the following muscles in repetitive nerve
stimulation for evidence of MG ?
A. Proximal muscle groups
B. Distal muscle groups
C. Interosseous muscles
D. Any of the above

11 In myasthenic patients, rapid reduction of what proportion in
amplitude of evoked responses is noted ?
A. > 10 – 15 %
B. > 20 – 30 %
C. > 30 – 45 %
D. > 50 – 75 %

12 Which of the following drug must be kept at hand while conducting
Edrophonium anticholinesterase test ?
A. Atropine
B. Neostigmine
C. Adrenaline
D. All of the above

13 Apart from Edrophonium which drug can be used for
Anticholinesterase Test ?
A. Atropine
B. Neostigmine
C. Adrenaline
D. All of the above

14 Which of the following diseases can cause false-positive
Edrophonium anticholinesterase test ?
A. Amyotrophic lateral sclerosis
B. Hodgkin lymphoma
C. Charcot-Marie-Tooth disease
D. Creutzfeldt-Jakob disease (CJD)

15 Which of the following component of the neuromuscular junction
may be affected in congenital myasthenic syndromes (CMS) ?
A. Presynaptic nerve terminal
B. Various subunits of AChR
C. Various subunits of AChE
D. All of the following

16 Which of the following statements about congenital myasthenic
syndromes (CMS) is false ?
A. Due to genetic mutations
B. Symptoms begin in infancy or childhood
C. AChR antibody tests are consistently negative
D.  subunit of AChR is affected in ~75% of cases
CMS should be suspected when symptoms of myasthenia begin in infancy or childhood & AChR
antibody tests are consistently negative. CMS that involve AChR,  subunit is affected in ~75%.
17 Drugs that can exacerbate weakness in myasthenic patients are all
except ?
A. Penicillamine
B. Aminoglycoside antibiotics
C. Procainamide
D. Diazepam

18 Myasthenia gravis may be “induced” by ?
A. Penicillamine
B. Aminoglycoside antibiotics
C. Procainamide
D. Diazepam
19 Disorders associated with myasthenia gravis include ?
A. Hashimoto’s thyroiditis
B. Graves’ disease
C. Systemic lupus erythematosus
D. All of the above

20 Which of the following is false about Lambert-Eaton myasthenic
syndrome (LEMS) ?
A. Presynaptic disorder of neuromuscular junction
B. Proximal muscles of lower limbs most commonly affected
C. Normal deep tendon reflexes
D. Incremental responses on repetitive nerve stimulation

21 Which of the following is false about Lambert-Eaton myasthenic
syndrome (LEMS) ?
A. Autoantibodies against P/Q type calcium channels
B. Associated small-cell carcinoma of lung
C. Plasmapheresis ineffective
D. 3,4 Diaminopyridine (3,4-DAP) helpful

Myasthenia Gravis and Diseases of the Neuromuscular Junction

[MCQ] Myasthenia Gravis and Diseases of the Neuromuscular Junction- Part 2

I. Start the exam by click the “Start” button

Myasthenia Gravis and Diseases of the Neuromuscular Junction- Part 2

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