As far as the C6 nerve and TOS, I think a lot of the symptoms can be similar; however, as I have had both problems, I am learning to tell the difference. I just had a two-level fusion from C5-7 this summer, and once the pressure was off those nerves some of my symptoms started to improve, including neck spasms and headaches. However, some of them didn't, including facial numbness, eye twitching, hand and arm weakness/numbness/pain, shoulder blade pain, and pain and swelling on the side of my neck and over my collarbone. When I do have pain in my hand (it's usually more numb than painful there), if it's coming from the TOS or brachial plexus area, it's usually on the outer side of my hand, but if it's coming from my neck, it's usually the first finger and thumb.

Before my fusion, both my neurosurgeon and Dr. Sanders had hoped that relieving the pressure on the C6 nerve would ease up a lot of the arm symptoms...but while the surgery did help some things, it didn't make the TOS go away...so even two good surgeons can't always tell the difference between C-spine issues and TOS.

FWIW, Dr. Sanders said he'd never base a surgical decision on the result of an EMG/NCV test, as it can change from day to day. I agree that a diagnosis can be difficult to come by with testing. And I also agree with Jo...make sure your PT doesn't do strengthening exercises; according to Dr. Sanders, my own experience, and that of many others here, they only make the TOS flare.

Just thought I'd share my experience. I hope you can get some answers! Have they done a cervical MRI?