what is concussion syndrome
By Mayo Clinic Staff. Post-concussion syndrome is a complex disorder in which various symptoms â such as headaches and dizziness â last for weeks and sometimes months after the injury that caused the concussion. Concussion is a mild traumatic brain injury, usually occurring after a blow to the head. Loss of consciousness isn't required for a diagnosis of concussion or post-concussion syndrome. In fact, the risk of post-concussion syndrome doesn't appear to be associated with the severity of the initial injury.