That makes no sense. I used to be a very muscular person. I threw discus and shotput, ran cross country and track, swam, and just was overall- pretty active. Then my shoulders gave out on me and I did practically nothing to baby them. Now, I naturally hold more muscle than most people, but NO ONE would look at me and say "wow, you look athletic." I've had a bit of atrophy due to the TOS especially on my left hand side. There was also no indication that I was made aware of that I had any boney abnormality. That being said, I did, indeed, have AVNTOS. Scar tissue, poor posture, and prior injury can all cause TOS so your vascular surgeons are full of crap if they say that you aren't muscular enough to have it. Am I positive you have TOS? Of course not, I'm no doctor, however your doctors can't be positive that you don't because they haven't run the necessary tests to rule it out.