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).
Post-concussion syndrome
While the causes of symptoms occurring immediately after a concussion are likely to be physiological, it is less evident that persistent post-concussive symptoms have an entirely organic basis, and nonorganic factors are likely to be involved in symptoms that last longer than three months. PCS may also be exacerbated by psychosocial factors, chronic pain, or an interaction of some or all of these. The majority of experts believe that PCS results from a mix of factors, including preexisting psychological factors and those directly relating to the physical injury.