Well it depends on when the NCS was ordered and what the requesting doctor was looking for. What I mean is that if the NCS/EMG was ordered looking for a Brachial plexus injury the testing more likely was looking at the motor nerves or nerves the supply the muscles. Since CRPS is a disease process that originates from peripheral nerves then different testing such as the SNAP (sensory nerve action potential) during what is a complete PNE (peripheral neurophysiological examination) unfortunately unless the doctor requesting these more in depth studies or the diagnosis in question doesn't point to this then they aren't always done. Then to make matters even more confusing the timing of the EMG/NCS also plays a role in whether or not it will show the damage. After nerve injury or damage it the nerve goes through several changes over the course of hours - weeks and even months depending on the type of injury or damage. So even if your nerve was partially severed and the study was done.. say 3 days later the testing most likely will come back normal. If however the same test was performed 3 weeks later those same results would be markedly different.

Sensory nerves are challenging to test through NCS/EMG but, MRI's (certain ones) or even ultrasound can make the nerve injury much more visible. My nerve tumors and entrapment were visualized through both.. I was even given an ultrasound picture of the large nerve tumor (neuroma) to take to my PT so they would know exactly where it was.. lol.. my CRPS II souvenir Ugh And the first EMG/NCS was considered a normal study but the one done just 2 weeks later came back as an abnormal study.

You can ask your doctor specifically which nerve was injured/entrapped since in order to make a CRPS type II diagnosis they are required to have a "verifiable" nerve injury. This is not to question your doctor but, it should clear up any confusion which is your right as a patient to ask. If nothing else it might result in further testing or a second opinion to confirm.