Moderator note: Thread moved from 'General ME/CFS News' sub-forum. This article was posted on PR, and it really speaks to my symptoms and diagnosis of Thoracic Outlet Syndrome. It ties together POTS with TOS and MCAS and other symptoms often seen in ME folks. https://mermaidcentralresearch.com....ion-Syndromes-in-POTS-A-Preliminary-Study.pdf In a study of 33 consecutive patients with established POTS, all were shown to have one or more venous compression syndromes. 28 were shown to have popliteal vein compression syndrome (17 with complete obstruction and 11 with partial obstruction,) while 25 (of 27 tested) had thoracic outlet vein (axillary or subclavian) compression. Twenty had both popliteal (either partial or complete) and thoracic outlet vein compression. And I thought this was also interesting: ...studied 85 Multiple Sclerosis patients demonstrating all had undiagnosed thoracic outlet syndrome, unilateral or bilateral, and usually predominantly of a venous type.