Post-concussion syndrome
Though no universally accepted definition of postconcussive syndrome exists, most of the literature defines the syndrome as the development of at least 3 of the following symptoms: headache, dizziness, fatigue, irritability, impaired memory and concentration, insomnia, and lowered tolerance for noise and light. One complication in diagnosis is that symptoms of PCS also occur in people who have no history of head injury, but who have other medical and psychological complaints. In one study 64% of people with TBI, 11% of those with brain injuries, and 7% of those with other injuries met the DSM-IV criteria for post-concussion syndrome. Many of these PCS sufferers were misdiagnosed as having other unrelated conditions due to commonality of symptoms. (see diagnosis, below).
Concussion grading systems
The Colorado Medical Society guidelines were published in 1991 in response to the death of a high school athlete due to what was thought to be second-impact syndrome. According to the guidelines, a grade I concussion consists of confusion only, grade II includes confusion and post-traumatic amnesia, and grade III and IV involve a loss of consciousness.