Dear Dr Freilich, thank you very much for your videos! I am working in a near-EMG field and I would like to ask a dilettante question related to the SFEMG. Short version: what makes the needle record from the same fiber during muscle contraction? Expanded version: The needle may slightly change its position relative to the observed muscle fiber due to the deformation of the surrounding tissues during muscle contraction. Considering the fact that the mean diameter of a fiber is around 55um, a slighest shift should be sufficient for the needle to "switch" to a neighbouring fiber. However, this does not happen during SFEMG procedures. What makes the needle so stable? Thank you, best regards!
Hi Smetana, sometimes when a question is better than the answer, it's best to keep with the question which is excellent! I think the answer is that what's really being detected are the electrical fields rather than the muscle fibers themselves and they are sufficiently large to maintain stability within the detection field of the needle. If someone has a better answer though - please feel free to add it below!
@@DrSimonFreilich Thank you, I'm glad to receive your answer! Yes, I agree that the needle detects the electrical fields generated by the muscle fibers. What I meant is that when the needle moves from the vicinity of one fiber to the vicinity of another, the electrical field generated by that another fiber will be "seen" by the needle as much stronger than that of the first. On the screen, that would look as an attenuation of the first SFAP and an apparition of the second one. I guess this is when the electrical stimulation helps. Since it doesn't cause a continuous muscle contraction, the needle returns to a certain position during the muscle relaxation between the stimulation pulses. Also, muscle fibers of the same motor unit are rarely positioned right next to each other (self-avoidance). Neighboring motor units may be not recruited by the stimulation and therefore their fibers are "quiet". And that gives a little bit more slack to the whole process. But this is a speculation and I may be wrong about the way the stimulation works. Yes, having more opinions would be helpful here. We can also raise the question on researchgate once we run out of versions.
Dear Dr Freilich, thank you very much for your videos! I am working in a near-EMG field and I would like to ask a dilettante question related to the SFEMG.
Short version: what makes the needle record from the same fiber during muscle contraction?
Expanded version: The needle may slightly change its position relative to the observed muscle fiber due to the deformation of the surrounding tissues during muscle contraction. Considering the fact that the mean diameter of a fiber is around 55um, a slighest shift should be sufficient for the needle to "switch" to a neighbouring fiber. However, this does not happen during SFEMG procedures. What makes the needle so stable?
Thank you, best regards!
Hi Smetana, sometimes when a question is better than the answer, it's best to keep with the question which is excellent! I think the answer is that what's really being detected are the electrical fields rather than the muscle fibers themselves and they are sufficiently large to maintain stability within the detection field of the needle. If someone has a better answer though - please feel free to add it below!
@@DrSimonFreilich Thank you, I'm glad to receive your answer!
Yes, I agree that the needle detects the electrical fields generated by the muscle fibers. What I meant is that when the needle moves from the vicinity of one fiber to the vicinity of another, the electrical field generated by that another fiber will be "seen" by the needle as much stronger than that of the first. On the screen, that would look as an attenuation of the first SFAP and an apparition of the second one. I guess this is when the electrical stimulation helps. Since it doesn't cause a continuous muscle contraction, the needle returns to a certain position during the muscle relaxation between the stimulation pulses.
Also, muscle fibers of the same motor unit are rarely positioned right next to each other (self-avoidance). Neighboring motor units may be not recruited by the stimulation and therefore their fibers are "quiet". And that gives a little bit more slack to the whole process. But this is a speculation and I may be wrong about the way the stimulation works.
Yes, having more opinions would be helpful here. We can also raise the question on researchgate once we run out of versions.
Great work
Hi I know this doesn't relate this video but u gave some questions about my son's body jerks, am at my wits end with answers about it .please reply
Sz typo ment I have some questions.
Hi, I'm sorry but I can't answer personal questions. Bw Simon
Ok thanks fr reply anyway
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