Thank you both for the replies. I will ask my physician about seeing an otolaryngologist and trying biofeedback.
Regarding purpose of treatment: I had minor tingling in both forearms and my right jaw that came and went. No painful. MS runs in the family, but an MRI of the brain ruled it out. The neurologist mentioned my symptoms might be explained by anxiety, which would make sense due to DNA test results I learned about at the time. He said it might also be poor blood circulation, but didn't think it was anything serious. He mentioned electrical treatment of the neck as a "low-risk" approach to try that may increase blood circulation.
Regarding the device and settings: I am not certain whether it was an EMS, NMES, or TENS. I read that TENS doesn't necessarily induce muscle contractions while EMS does, and inferred it was more similar to an EMS. The electrodes were small, circular, and appeared rubber. The same facility also placed two larger circular rubber electrodes between my shoulder blades that caused my shoulders to bounce, but this was not simultaneous with the neck electrodes and did not appear to have any negative effect.
Regarding pulse: neck muscles contracted between 2-3 times per second.
Regarding current: electrodes on the lower back of my neck were strong enough to pull the skin from the top of my head down towards my neck. Presumably the front was similar.
There was only one English speaking technician and he appeared undertrained. When I pointed out my right-front neck wasn't responding to electricity on my 2nd visit I asked for the name of the muscles he placed the electrodes on so I could inform the neurologist. He could not name any muscles in the neck. On my 2nd visit, I asked him to monitor treatment longer to see what we could learn and he dialed up the current on the right higher than the left. When the current was turned "high", my right/front neck finally showed a small reaction, but nothing like the left.
When I told the neurologist about the experience and how my head was now turning right, he mentioned nothing could have possibly hurt me and that the device focused on "muscles only." He said any imbalance in reaction was due purely to the placement of the electrodes. (note: this neurologist also explained that Alzheimer's disease is caused by "too much water in the brain", which brought his expertise into question in my mind)
I mentioned the electrode placement to the technician on my 3rd visit for electrical stimulation and he tried placing the electrodes in a few different areas on my lower right/front neck, none of which had much reaction. At one point he invited me to try testing different positions myself, which is when I decided to end the treatment early and left.
I've asked my girlfriend to call and ask whether the device was EMS, TENS, or NMES, and will follow up when I learn more.
Appreciate any more suggestions regarding what may have been affected and what tests or treatment you suggest.