EMG is a test where they stick electrodes into your muscle and record how they react to stimulation. Most of the times they do EMG along with NCV (nerve conduction velocity) and those combined can help differentiate causes. Although I find it slightly interesting that they want this study. Usually EMG/NCV are used for patients with some sort of weakness and usually for some time as it can tell you if it's a peripheral nerve problem versus central (spinal cord) problem because a pinch nerve will give a different pattern vs a pinched spinal cord.
Just curious what are your neuro sx as I can't seem to read what you have
good luck