I would call Dr. Scott Frieds office, DeKalb Pike near the Plymouth Meeting Mall. He uses Rick Reed and Tom Tolson. Tolson of the two has published on EMG for TOS.
I found the test not a real pain, the needle part of the emg near the wrist to check for carpal tunnel was the most pain and it was over swiftly.
THe NVC is a probe in the palm, and the probls is at the brachial plexus area of the collar bone pressed down hard to send a signal to the palm receiver. Anythingpressing hard on the inside of the collar bone is sensitive with TOS.

You can trust Scott, and his staff!

They are top in the field of EMG/NVC for TOS. Dr Fried is dedicated to his patients and does a great detailed exam and evaluation.
We have been there several times in our family.

He is online at www.nervepain.com
Dianne