I had an epidural steroid injection for a pinched l5 nerve, since then i have been having symptoms very similar to restless leg syndrome (leg twitching, internal buzzing, and tingling). my radicular pain is now gone, but can an esi cause rls?

While some people can feel restless & anxious after a steroid injection, I'm not aware of their causing restless leg syndrome which generally occurs after age 45 but can occur earlier. A neurologist is best to evaluate and advise you.

There is absolutely NO cause and effect from a TFESI resulting in RLS. "Symptoms very similar" is not confirmatory, and your issues need a consultation from an expert neurologist. If you do have RLS, it can be treated easily and effectively.