I'm sorry you're feeling so awful and not getting the answers you need.

I'm 39 and have been dealing with this for 15 years. Finally this year...it all started to come together in my head. I had an MRI/MRA/MRV in January that identified an anterior scalene muscle insertion point 3x larger than it should be...a congenital issue. The scalenes have been described to me as accessory breathing muscles.

From this new info, I've made the following wild but plausible waterfall, which I'll try to type out for the first time (AKA my descent into hell!) :

1. Normal activation of the scalene muscles is hindered by the insertion point abnormality.
2. Activation of the scalenes during normal breathing constricts the subclavian vein, causing arm symptoms and brachial nerve irritation. Some altered breathing patterns develop to compensate.
3. chronic compression results in scar tissue developing around nerves and scalenes, complicating the original condition.
4. Shallow breathing becomes the default, affecting posture, which further complicates all issues.
5. Chronic bad posture due to physiological restrictions and type of work performed daily wreaks havoc with spinal integrity, develop cervical spinal issues and worsening of original symptoms and complications.
6. Cervical spinal fusion performed to stabilize cervical spinal integrity, but spinal pressure is now manifesting in lower spine, which is also weakened by bad posture & breathing habits.

I'm sure I can refine the above much better, it's occurred over at least the past 15 years, and I'm not sure what the trigger for number 2 above was...maybe all my life and it just developed enough scar tissue to trigger other symptoms?

Marabunta in N.California.