at this stage (three-four years after his original concussions), the acute effects of a concussion such as headaches, inability to focus, vertigo, etc have stopped. the inflammation in his brain has largely subsided. but now is when he the long term effects of chronic traumatic encephlopathy might be setting in. in many, perhaps most cases of concussions/tbi/cte the true effects arent felt for several years sometimes even decades. at this stage sid, there is scarring in the brain that leads to impairment in visuospatial functioning (a recent paper found that visual working memory in athletes is impaired following tbi), executive functioning (decision-making), mood, personality, and behavior, etc. these effects are very subtle at first but can become more pronounced with time.
this stuff about his soft tissue injury/vertebral fracture injury causing all his symptoms is hogwash. thats was reported by one guy who ran with it, and pens fans have clung to it because it sounds better than sid having a concussion. his symptoms werent even consistent with the reported injury. no one on the previous or present medical staff ever said that and i have spoken to the docs on the previous medical staff and they agreed unequivocally that sid had one maybe two standard concussions.