Well, it was revealed that Twitchers are just Slashers that fused with Stasis Modules (Which made them faster for some strange reason...), and the Oracles rings were revealed to have stasis-like capabilities sooo... yeah. Theres your answer.
On another note, it could be possible that the fusion of the Stasis module doesn't speed the Twitcher up, but rather slow everything around it down. This would make more sense, since Stasis is intended to slow things down rather than speed them. Just a thought.
Pretty sure it was said that a reaction with [SOMETHING] reversed the effects of the Stasis generator, causing it to speed up things instead of slow them down. The Stasis was then fused with the Necromorph to create the Twitcher.