If he crushed the front of his helmet, he had a concussion, and its usually termed MTBI (mild traumatic brain injury) these days. Look at definition in Wikipedia to start. Note "Most concussions cannot be detected with MRI or CT scans." The CT helps to find a bleed, like the seemingly mild head injury that killed Natasha Richardson. If his head was decelerated fast enough to deform helmet, his brain rotated and impacted the inside front of his skull. I had two cracked LAS Squalos and two "concussions" a couple of years ago. Super glad he's OK. He should continue to be watched and evaluated for post crash symptoms. And any additional head trauma in the near future would not be a good thing. I know. Again - extremely glad he's OK.