A friend just told me about a relatively new bike helmet technology that reduces torsion (rotational) stress in a bike accident. My wife is a speech therapist (and I write speech therapy software) so I'm well aware that tearing is more damaging than concussive forces.
It's called MIPS: Multi-directional Impact Protection System.
But, I'm not convinced the MIPS system actually improves on that. The only independent research I've seen a citation to is in swedish. And the next best research was on motorcycle helmets