more info on it some of these sites have been recently updated.

http://emedicine.medscape.com/article/418203-overview
http://en.wikipedia.org/wiki/Subclavian_steal_syndrome

[Subclavian steal syndrome is a relatively uncommon form of peripheral artery disease (PAD) in which a blockage is present in a critical location within one of the subclavian arteries, causing symptoms that involve both the arm and the brain. ]
http://heartdisease.about.com/od/les...l-Syndrome.htm

* Looks like it depends on what is causing the blockage or blood slowdown.