RNS

Question 1

Define

Quantum

Answer 1

Number of ACh modules per vesicule.
1 quantum generates 1 mEPP.
20-25 quanta needed to generate an EPP

Question 2

Safety factor

Answer 2

Amount of ACh release above the amount needed to generate an EPP

*’ refers tothe ability of neuromuscular transmission to remain effective under various physiological conditions and stresses. This is a result of the amount of transmitter released per nerve impulse being greater than that required to trigger an action potential in the muscle fibre

Question 3

The safety factor is ____ in proximal muscles. Therefore, recordings for disease detection is more reliable in ____ muscles.

Answer 3

Greater
Distal
(distal fibers are more susceptible to transmission failure)

Question 4

Nerves should be stimulated with a ____ stimulus.

Answer 4

Supramaximal

Question 5

Repetitive nerve stimuation: what’s the principle?

Answer 5

Recording of CMAPs through repeated supramaximal (distal) nerve stimulation (1,2,3,5,10,20 Hz)

Note: stimulations > 5 Hz not recommened

me: > 5Hz there are physiologic changes in CMAP amplitudes

Question 6

In healthy nerves, what happens to CMAP amplitudes with RNS…
a) < 5Hz ( >200 ms intervals)
b) 5-66 Hz (200-15 ms intervals)
c) > 66 Hz (< 15 ms intervals)

Answer 6

a) stays the same over time (Ca2+ dffuses out and ACh replenishes) (< 5% decrement accceptable)
b) mild or no decrement due to ACh store depletion
c) decrement due to ACh stire depletion –> FATIGUE

Question 7

Define

Fatigue

Answer 7

Decrement in CMAP amplitude with fast stimulations due to ACh store depletion (> 66-100Hz)

Question 8

with PRESYNAPTIC diseases (e.g. botulism, tick paralysis, myasthenic syndrome), what happens to CMAP amplitude at:

a) < 5 Hz
b) 5-66 Hz
c) > 66 Hz

Answer 8

a) no change
b) Increment (due to Ca+ accumulation)
c) Increment (‘’ ‘’)

Question 9

with POST-SYNAPTIC diseases (e.g. MG), what happens to CMAP amplitude at:

a) < 5 Hz
b) 5-66 Hz
c) > 66 Hz

Answer 9

a) decrement
b) decrement
c) decrement

Question 10

Summary

Answer 10

HEALTHY = Decrement in CMAP starting at > 5 Hz (refractoriness)

PRESYNAPTIC Dz = Increment in CMAP amplitude > 5 Hz

POSTSYNAPTIC = Decrement in CMAP amplitude at all frequencies, even < 5Hz

Question 11

Is there an age difference in RNS CMAPs between adults vs puppies?

Answer 11

no

Question 12

What is the effect of:
a) heat
b) cold

Answer 12

a) HEAT = amplifies decremental responses (e.g. can immerse in warm water) (ca fond)
b) COLD = less decremental responses (ca gele)

Question 13

Name and exaplain the 2 phenomenon that can happen after RNS or voluntary muscle contraction

Answer 13

• Post-tetanic potentiation: first 1-2 min = Ca2+ accumuation = enhanced ACh release and EPP
• Post-tetanic exhaustion: > 2 min, ACh store depletion

diapo 42-43… pas sure de comprendre