Yes I think quite a few have been that route- a dr says they know TOS but what they know is old or just incomplete - not to mention sometimes wrong!
Good for you to make a second opinion appt.

sometimes it will help to make a simple but complete list of symptoms and your history of those.
To take along for the doctor - if you can type it out and keep it brief they may absorb the info better.

I wish I would have done this - I always let the doc be the leader and they didn't get all my symptoms written down or they ignored the ones they didn't care to deal with.

A single vein showing up like that might even be a clot or something else - does it hurt and swell in the area?
my sis in law had a clot in her arm and my niece had one in her calf -

Did you find or useful sites and links thread in the stickys too?

Welcome and it's nice to meet you.

Have you had any xray or MRI of the Neck or spine to check those for a cause?
I'm assuming you are having neck, upper back , arm and hand pains?

How is your basic posture?
head aligned -not forward of the body, tilted or crooked shoulders, hips etc, forward rolled, hunched or slumped shoulders

If you want to post your specific symptoms we might be able to suggest some helpful things.