British authorities banned the term shell shock during World War II to avoid an epidemic of cases, and the term posttrauma concussion state was coined in 1939 to describe "disturbance of consciousness with no immediate or obvious pathologic change in the brain". The term postconcussion syndrome was in use by 1941.In 1961, H. Miller first used the term "accident neurosis" to refer to the syndrome which is now called PCS and asserted that the condition only occurs in situations where people stand to be compensated for the injury. The real causes of the condition remain unclear. Controversy
Though no universally accepted definition of postconcussive syndrome exists, most of the literature defines the syndrome as the development of at least three 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 individuals with PCS were misdiagnosed as having other unrelated conditions due to commonality of symptoms. (see diagnosis above).Headache is one of the criteria for PCS, but it is notably undetermined where the headache comes from.
With their focus on psychological factors, the ICD-10 criteria support the idea that the cause of PCS is functional. Like the ICD-10, the ICD-9-CM defines PCS in terms of subjective symptoms and discusses the greater frequency of PCS in people with histories of mental disorders or a financial incentive for a diagnosis.The DSM-IV lists criteria for diagnosis of PCD in people who have had a head trauma with persistent post-traumatic amnesia, loss of consciousness, or post-traumatic seizures. In addition, for a diagnosis of PCD, patients must have neuropsychological impairment as well as at least three of the symptoms marked with a check mark in the table at right under "DSM-IV". These symptoms must be present for three months after the injury and must have been absent or less severe before the injury. In addition, the patient must experience social problems as a result, and must not meet criteria for another disorder that explains the symptoms better.Neuropsychological tests exist to measure deficits in cognitive functioning that can result from PCS. The Stroop Color Test and the 2&7 Processing Speed Test (which both detect deficits in speed of mental processing) can predict the development of cognitive problems from PCS. A test called the Rivermead Postconcussion Symptoms Questionnaire, a set of questions that measure the severity of 16 different post-concussion symptoms, can be self-administered or administered by an interviewer. Other tests that can predict the development of PCS include the Hopkins Verbal Learning A test (HVLA) and the Digit Span Forward examination.