I went to PT places first actually but it was a work comp injury & my doc Rx'd the PT.

Long story but due to claim & denial and a few other changes I went to about 5 diff places, each was better than the one before.
But if I was referred to a good DC early on I might have avoided some of the ongoing issues or just plain got beyond the almost healed stage sooner.
Chiropractors -I know there are good ones and poor ones , luckily I happened upon a good one. Been going since mid 04 & no problems to report only feeling better stuff.

The adv PT were the ones that actually did the in depth positional /pulse testing for me - to rule out if sx were from c spine or TOS, none of my MDs did the full group of those tests - DC did.
this page has good info on those positions - http://www.nismat.org/ptcor/thoracic_outlet/

due to sports, falls & roughhousing tomboy stunts as a kid and a minor car accident in my 20s I had some long time minor misalignments - they played a part - plus age - my mid 40's then, and being hyper mobile.
All these things add up along with rep work or static upper body postures.
IMO - the longer misalignments go without being addressed the longer it will take to resolve them.

Trigger point sticky thread- I'm slowly adding to it - there are more posts scattered thru the forum.
http://neurotalk.psychcentral.com/thread125577.html

for a firm diagnosis many other things need to be ruled out - there isn't a test that will prove you have TOS.

basically x rays/ MRI of C & T spine to be sure nothing as a cause there.

EMG & NCV will show if there is a actual compression on the ulnar or radial nerve but it doesn't test the sensory nerves