Not likely. Post concussive syndrome should not be fatal. Although this is one of the disorders under traumatic brain injury, concussion should not show abnormalities on ct scan or the diagnosis changes to something more severe such as diffuse axonal injury.
Increased risk later. Post concussive syndrome describes the constellation of chronic headaches, confusion, emotional lability, sleep disorder for 6 months to a year after head injury. History of previous brain surgery may prolong the recovery period from concussion. If there is additional head injury while recovering from concussion, that may have lethal consequences. Follow established guidelines to prevent injury.