A nerve study is the only way to find out if it truly is carpal tunnel, and also to find out the extent of it.
They start testing the nerve in the upper arm, down to the wrist area.
Your doc wants these tests done to see how extensively you have it and whether surgery is needed/warranted or not.
I had the surgery done on my right hand in 1987, and have not had any further problems with it since.
I did also learn more "ergonomic" ways of doing things to prevent it from coming back, too :D:D:D