I had scintillating scotoma (SS) over ten years ago which was around time I got my first TOS symptoms in my arm, although I did not know what either was.

I have not had SS in a long, long time, but I have eye muscle twitches on the symptomatic side.

I don't know if these are individually "common" as you say, but I think it's common for TOS people to have *something* in addition to classic signs. That's my inference just from reading these forums. But maybe it's only common in problem cases.