Post-concussion syndrome
Post-concussion syndrome, also known as postconcussive syndrome or PCS, is a set of symptoms that may continue for weeks, months, or a year or more after a concussion – a mild form of traumatic brain injury (TBI). The rates of PCS vary, but most studies report that about 15% of individuals with a history of a single concussion develop persistent symptoms associated with the injury. A diagnosis may be made when symptoms resulting from concussion last for more than three months after the injury. Loss of consciousness is not required for a diagnosis of concussion or post-concussion syndrome.
Second-impact syndrome
The condition was first described in 1973 by R.C. Schneider, and the term second-impact syndrome was coined in 1984. In 1984, R.L. Saunders described the death of a football player who had died after a second, unremarkable concussion and hypothesized that the second blow caused a catastrophic rise in ICP, possibly through loss of vasomotor tone, because the brain was in a vulnerable state. Between 1984 and 1991, only four cases were documented. Between 1992 and 1998, reports of the condition began to be made more frequently than they had before, a fact is thought to be due to wider recognition of the syndrome by clinicians. In 1991, J.P. Kelly and others reported another football death after repeated concussions and coined the term "vascular congestion syndrome".