Thank you for that excellent question! Typically, Raynaud’s phenomenon impacts multiple digits of both hands (and often feet; sometimes tip of the nose, ears, nipples) and is often symmetric in the case of primary and can be asymmetric in Secondary Raynaud’s (often sparing the thumb). I...

Agree with Dr. @Makol's excellent response. I will also add that some patients with compressive neuropathy (like carpal tunnel syndrome) can have an associated Raynaud's phenomenon in that territory.

It is very important to ascertain that there is no correctable vascular cause.