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-traumatic seizure
Early PTS occur at least once in about 4 or 5% of people hospitalized with TBI, and late PTS occur at some point in 5% of them. Of the seizures that occur within the first week of trauma, about half occur within the first 24 hours. In children, early seizures are more likely to occur within an hour and a day of injury than in adults. Of the seizures that occur within the first four weeks of head trauma, about 10% occur after the first week. Late seizures occur at the highest rate in the first few weeks after injury. About 40% of late seizures start within six months of injury, and 50% start within a year.