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
The symptoms that occur after a concussion have been described in various reports and writings for hundreds of years. The idea that this set of symptoms forms a distinct entity began to attain greater recognition in the latter part of the 19th century. John Erichsen, a surgeon from London, played an important role in developing the study of PCS. The controversy surrounding the cause of PCS began in 1866 when Erichsen published a paper about persisting symptoms after sustaining mild head trauma. He suggested that the condition was due to "molecular disarrangement" to the spine. The condition was originally called "railroad spine" because most of the injuries studied had happened to railroad workers. While some of his contemporaries agreed that the syndrome had an organic basis, others attributed the symptoms to psychological factors or to outright feigning. In 1879, the idea that a physical problem was responsible for the symptoms was challenged by Rigler, who suggested that the cause of the persisting symptoms was actually "compensation neurosis": the railroad's practice of compensating workers who had been injured was bringing about the complaints. Later, the idea that hysteria was responsible for the symptoms after a mild head injury was suggested by Charcot. Controversy about the syndrome continued through the 20th century. During World War I many soldiers suffered from puzzling symptoms after being close to a detonation but without any evidence of a head wound. The illness was called "shell shock," and a psychological explanation was eventually favoured. By 1934 the current concept of PCS had replaced ideas of hysteria as the cause of post-concussion symptoms. 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.