Thoracic outlet syndrome - TOS for short..
http://neurotalk.psychcentral.com/forum24.html

It is our more active forum ,related to and can be caused by chronic RSIs. and these other things can be a factor- forward head/forward shoulders, weight lifting, musicians, athletes..previous whiplash... on an on.. bone or ligament anomalies..

You might want to post there for more input & info.