Hi Joby,
I have no idea about the cyst situation or how that may complicate things.
I've had 22 Stellate ganglion blocks now. I was scared to death at first.
I have other suggestions on that if you want more info. right now I'm short on time & it takes me forever to type.

In my case I had ALL RSD symptoms full blown in hand & wrist. The first
three SGB's had a dramatic effect by reducing the swelling & some of the pain.
This in turn made immediate Physical therapy visits more successful.
I was able to regain about 30-40 % of movement (over time) when I had 0.
At first I could not stand to have them hardly touch me in P.T.
From what I've read this means the pain was "sympathetically managed" as
in sympathetic nervous system.