I am writing hoping that someone can give me some insight. I've been recently diagnosed with Thoracic Outlet Syndrome (by several drs), although I found out yesterday that the cause is more relative to Thoracic Outlet Compression symptoms.

I've had several problems since June 1st -- numbing of left side of face, shoulder, arm, and hand...and lots of pain! I had a brachial MRI done recently. My primary is great, but he only told me that the radiologist reported compression on my subclavian artery and brachial nerve. He sent me to the surgeon and the surgeon said that I had a rare case of TOS and couldn't figure out the next step. I discovered through this site that he is one of the most reputable vascular surgeons. Unfortunately, he didn't have the MRI results and I wasn't informed enough to explain it to him.

I had an MRA performed yesterday and am waiting for the results. While I was there, I requested my MRI results. To my surprise, the radiologist reported that "there does appear to be mass effect upon the left subclavian artery at the costoclavicular space" and later in the report, "suspected mass effect upon the neurovasicular bundle including the subclavian artery and the brachial plexus".

I'm confused, and feel like "mass effect" should be somewhat self explanatory, but I'm still having a hard time piecing it together. I'm not quite sure what a "mass effect" is, or what it possibly means. I am aware of what an actual mass is, but even googling a "mass effect" in relation to the subclavian artery doesn't turn up much information.

Does anyone have any knowledge of this, or any further explanation of what a "mass effect" entails?

I'd appreciate any insight.

Thanks!