L80 - NMJ Dysfunction

Question 1

acetylcholinesterase inhibitor for myasthenia gravis

Answer 1

pyridostigmine (Mestinon®)

Question 2

immunosuppression of ab production (slower) for myasthenia gravis

Answer 2

corticosteroids

Question 3

pooled antibodies from blood donors: removes the problem abs for myasthenia gravis

Answer 3

intravenous immune globulin (IVIG)

Question 4

Prolongs nerve terminal depolarization  increased calcium influx (for LEMS)

Answer 4

3,4-diaminopyridine (3,4-DAP)

Question 5

List 3 post synaptic NMJ dysfunctions

Answer 5

1. Myasthenia gravis
2. Congenital myasthenia gravis
3. Congenital myasthenic syndromes - Rapsyn, DOK7

Question 6

List 2 Pre-synaptic NMJ dysfunctions

Answer 6

1. Lambert-eaton myasthenic syndrome (LEMS)

2. Botulism

Question 7

List 2 NMJ synaptic dysfunctions

Answer 7

Organophosphate toxicity & drug toxicity

Congenital myasthenic syndrome

Question 8

IgG antibodies (Ab’s) targeting acetylcholine receptor (AChR) –> loss of safety factor –> fatigable nature of ________? what condition?

Answer 8

Mechanism of Myasthenia gravis

Question 9

Characteristics of pre-synaptic NMJ

Answer 9

symptoms of flaccid proximal weakness by impairing release of Ach from the axon terminal. temporarily improved by rapid motor nerve firing/AP’s, either voluntarily (during brief exercise) or with electrical stimulation, resulting in calcium accumulation in the axon terminal and increased ACh release.

Question 10

Mechanism of Synaptic NMJ dysfunction

Answer 10

Cholinesterase deficiency –> Ach excess in NMJ –> mm twitch/cramp bc hyperexcitable

Question 11

Long-term (typically hereditary) cholinesterase deficiency causes muscle weakness (end plate myopathy)

Answer 11

Congenital myasthenic syndrome