We are conducting a study with intramuscular EMG electrode inserted in the neck, but the targeted muscle is a bit difficult to locate. To be sure that the electrode is actually inserted in the right muscle, we would like to use electrical nerve stimulation to see bursts in the signals when the electrode actual inters the muscle.
The physician that performs insertion of the electrodes is not very familiar with electrical nerve stimulation, and i am quit lost on the proper procedure and devices to perform it. Is there ready to use devices to do that ? what pulse level and duration should i use ? what are the precautions ?
Any resources is welcomed.
First: How did you get the ethical approval for that (I assume your subjects are humans)?
I would not advise doing intramuscular EMG in the neck. If you are not familiar with the anatomy of the neck ("targeted muscle difficult to locate") you can easily hurt the rich arterial plexus located there (not to mention other organs).
Second: Are you afraid that the electrode is not in the muscle tissue or not in the right muscle (what is the name of that muscle)? The former you can easily check with the insertion burst or by simply ask the subject to move his/her neck. The later issue I don't really understand why important. Usually, neck muscles are working in a synergic way and not antagonists, so you will most likely see the same activity in the targeted muscle as in the muscle next to it.
Third: I would not advise doing electric stimulation. There is a high chance that you will stimulate more muscles than you want and the patient will choke.
I am familiar with the anatomy of the neck ! there is a surgeon dedicated to the electrode insertion! There will be an ethical comitte that will review our protocol ! Our stimulation approach is only transcutaneous, which is routinely applied in various domain (as long as dedicated device is used) and no contre-indication were mentioned by a physician regarding the location.
Now: The main problem is that the surgeon is used to locate the muscle during surgery, but not with intramuscular electrodes. So, what i wonder is about the proper protocol to electrical stimulation, and the frequency/amplitude/duration I should use to stimulate the stylohyoid muscle which is inervated by the facial nerve. And if there is any addition information to know. The stimulation site will probably be at the level of the ear lobe, around the posterior border of the mandibule.
again: if you stimulate the facial nerve you will most likely not just stimulate the stylohyoid muscle but other muscles for example the digastric m. Don't do that!
I'm also a physician and I would certainly not advise putting transcutaneous EMG electrodes in the neck, especially targeting the stylohyoid muscle, which is located just next to the a. carotis. Use surface electrodes instead.
I agree with András Puszta, there is a high level of risk associated with the proposed study. Without knowing the research question, it is not possible to comment on the risk:benefit ratio. IF the benefits of answering the research question outweigh the risks, I still would not recommend electrical stimulation. A better approach would be to use ultrasound imagaing to guide the insertion of the electrode. Use of imaging can help you avoid damage during placement and confirm the correct loaction at the same time.
Our goal is only to obtain a clear cut when introducing the intramuscular EMG eletrodes. Which means the electrical stimulation is about short pulses, every 1 second. Way under any treatement based on electrical stimulation. Also, indeed other muscles will fire, like already existing treatement such as Bell's palsy that stimulates muscles on the face. In any case, whatever the pros and cons, we are not willing to do it without knowledge and a surgeon will do the stimulation and EMG electrodes insertion (who would have told me if this was not possible. Also, it has already been done in a well recognized literrature). Sorry, I don't get your point as it goes against all i read and talked with the surgeon and the physician. And again, an ethical committe will review all this. If your actually right, it will likely not pass that step.
transcutaneous electrical stimulation is actually about using surface electrodes. With regard to EMG recording, by no means the signal will be representative of the stylohyoid with surface electrode. Even though intramuscular EMG is also prone to cross-talk, it is largely reduced with intramuscular electrodes. My point here was just to have a discussion about the proper manner/parameters to do the stimulation.
EDIT: ultrasound imaging is planned. Also, be sure I will talk again with the surgeon about your concerns though.
I note the edit that US imagaing is planned, which is encouraging, though I am still not clear what the research question is or why there is a need for an invasive approach.
If it helps, here is a link to a similar neck muscle that was assessed via surface electrodes:
Article Discharge Rate of Sternohyoid Motor Units Activated With Sur...
OK, can you expend about your concerns on that ? I am really surprised about your disagreement. Regarding the sternohyoid, it is more easily measurable with surface electrode than the stylohyoid.
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