These are some questions both for mainly for electromyographers.
If you get 50% correct in your answers, you have a good knowledge.
Naturally the answers can always be discussed, but the most reasonable alternative is enough.


1. In routine EMG we usually ask the patient to perform a strong contraction, and the EMG pattern is analyzed.
    Give a few words of argument why each of these descriptions are less than optimal:
  • Interference pattern ?
  • Summation pattern ?
  • Pattern at strong contraction ?
  • Recruitment pattern ?
  Show/Hide Answer

2. Can a MUP have a longer total duration than the interval between discharges of this MUP ?   Show/Hide Answer

3. Is it possible to decide whether a recorded EMG signal originates in the nerve or in the muscle ?   Show/Hide Answer

4. Is there any difference in MUP parameters if the recording is obtained 2 cm or 10 cm from the end-plate?   Show/Hide Answer

5. We sometimes record double discharges (extra discharges) in voluntary EMG. Do we require that the two discharges are identical in shape (amplitude, duration, phases), as a mean to separate them from occasional occurrence of discharges from 2 different MUPs?   Show/Hide Answer

6. Critical illness: are fibrillations usually a sign of neuropathy (CIP)?   Show/Hide Answer

7. Critical illness: is the myosin content lower in CIM than in CIP?   Show/Hide Answer

8. Critical illness: is sural amplitude different in CIM and CIP?   Show/Hide Answer

9. Can an A-wave appear after the F-waves?   Show/Hide Answer

10. Can an A-wave and a F-response be generated in the same axon by a given stimulus (SFEMG necessary to identify the we record from the same axon)?   Show/Hide Answer

11. Is there any difference in amplitudes between A-waves and individual F-responses?   Show/Hide Answer

12. Monopolar recording. Is there any difference in the pattern at strong voluntary contraction if the distance between the two recording monopolar electrodes (“active” and “reference”) is 1 cm or 10 cm?   Show/Hide Answer

13. Can you detect the “size principle” with conventional needle electrodes?   Show/Hide Answer

14. Concentric electrode has an oval recording surface: are the MUP parameters different for transversal or longitudinal insertion of the electrode (in relation to the fiber direction)?   Show/Hide Answer

15. Which is the concentric needle electrode recording uptake radius (180 or 360 degree) for the duration parameter in a MUP?
Which is the concentric needle electrode recording uptake radius (180 or 360 degree) for the spiky part of the MUP?   Show/Hide Answer

16. Is it possible to make sure that you are stimulating muscle fibers directly and not intramuscular nerves in intramuscular muscle stimulation (critical illness tests)?   Show/Hide Answer

17. You may stimulate one or very few axons at two different sites (prox and dist) and record a SFEMG response from corresponding muscle and so measure the conduction in a single axon.
How do you ascertain that you have stimulated exactly the same axon?   Show/Hide Answer

18. SFEMG: how many spikes do you need to record simultaneously to detect neurogenic blocking?   Show/Hide Answer

19. SFEMG: how many spikes do you need to record simultaneously to detect neurogenic jitter?   Show/Hide Answer

20. Reinnervation. In the early stage of reinnervation (20-30 days) after a partial nerve lesion, you start to see MUPs with some jittering spikes. In general is the MUP “small” or “large”?   Show/Hide Answer

21. In monopolar EMG recording you often see a small positive going signal on the slow slope of the signal, before it ends. What is this, and why do you not see that in concentric needle EMG?   Show/Hide Answer

22. With increasing force, the EMG amplitude (envelope amplitude) increases. Why?   Show/Hide Answer

23. In concentric needle electrode recordings, one can sometimes obtain low amplitude MUP that looks “upside down”. Explanation?   Show/Hide Answer

24. Directly after a short pause in voluntary activaction of a normal muscle, you may see a double discharge (interval 10 msec). Mechanism?   Show/Hide Answer


[1] Stålberg E and L Karlsson. Simulation of the normal concentric needle electromyogram by using a muscle model. Clin.Neurophysiol.:2001;112(3): 464-71.
[2] Stålberg E, et al. Single Fiber EMG (ed. 3rd). Uppsala, Edshagen Publishing House. 2010
[3] Ertas M, et al. Can the size principle be detected in conventional EMG recordings? Muscle Nerve:1995;18: 435-9.
[4] Nandedkar S D, et al. Selectivity of electromyographic recording techniques; a simulation study. Med Biol Eng Comput:1985;23: 536-40.
[5] Nandedkar S D and D B Sanders. Recording characteristics of monopolar EMG electrodes. Muscle Nerve:1991;14: 108-12.
[6] Stålberg E, et al. Electrical microstimulation with single-fiber electromyography: a useful method to study the physiology of the motor unit. Journal of Clinical Neurophysiology:1992;9: 105-19.
[7] Gydikov A and D Kosarov. Extraterritorial potential field of impulses from separate motor units in human muscles. Electromyography Clinical Neurophysiology:1972;12: 283-305.