- To detect neurogenic blocking on SFEMG, you need to record 3 spikes simultaneously. - To detect neurogenic jitter on SFEMG, you need to record 4 spikes simultaneously. If only 3 spikes are recorded, the jitter may be due to triggering issues rather than a neurogenic cause. - To ascertain that distal and proximal stimulation is of the exact same axon during conduction velocity testing, stimulate distally and proximally simultaneously. If the proximal response disappears with dual stimulation, it indicates collision and the same axon was stimulated.

1. QUIZ SFEMG
Most of the questions are found
on SFEMG homepage
sfemg.info/FAQ

2. SFEMG: how many spikes do you need to record
simultaneously to detect neurogenic blocking
3 (ref.8)
concomittant blocking
concomittant blocking

3. SFEMG: how many spikes do you need to record
simultaneously to detect neurogenic blocking
3 (ref.8)
concomitant blocking
concomitant blocking

4. normal jitter increased jitter
Increased jitter
SFEMG: how many spikes do you need to record
simultaneously to detect neurogenic jitter?
4
If you have only 3,
the jitter may be in the
nm-j of the triggering
Here, the jitter between spike 1 and 2
Is normal, so the large jitter to spikes
3 and 4 is not due to large trigger jitter

5. normal jitter increased jitter
Increased jitter
SFEMG: how many spikes do you need to record
simultaneously to detect neurogenic jitter?
4
If you have only 3,
the jitter may be in the
nm-j of the triggering
Here, the jitter between spike 1 and 2
Is normal, so the large jitter to spikes
3 and 4 is not due to large trigger jitter

6. You may stimulate one or very few axons at two different sites (prox and dist) and record an
EMG (or SFEMG) response from corresponding muscle and so measure the conduction
velocity in a single axon. How do you ascertain that you have stimulated exactly the same
axon?
Stimulate distally and proximally simultaneously. If you stimulate the same axon, no
response will be seen from the proximal stimulation site at dual (dist+prox) stimulation.
Distal and proximal stimulation activates DIFFERENT axons
since dual stimulation does not block the proximal response
Proximal response disappears on dual stimulation, collision

7. You may stimulate one or very few axons at two different sites (prox and dist) and record an
EMG (or SFEMG) response from corresponding muscle and so measure the conduction
velocity in a single axon. How do you ascertain that you have stimulated exactly the same
axon?
Stimulate distally and proximally simultaneously. If you stimulate the same axon, no
response will be seen from the proximal stimulation.
Distal and proximal stimulation activates DIFFERENT axons
since dual stimulation does not block the proximal response
Proximal response disappears on dual stimulation, collision