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
The most important factor in whether a person will develop early and late seizures is the extent of the damage to the brain. More severe brain injury also confers a risk for developing PTS for a longer time after the event. One study found that the probability that seizures will occur within 5 years of injury is in 0.5% of mild traumatic brain injuries (defined as no skull fracture and less than 30 minutes of post-traumatic amnesia, abbreviated PTA, or loss of consciousness, abbreviated LOC); 1.2% of moderate injuries (skull fracture or PTA or LOC lasting between 30 minutes and 24 hours); and 10.0% of severe injuries (cerebral contusion, intracranial hematoma, or LOC or PTA for over 24 hours). Another study found that the risk of seizures 5 years after TBI is 1.5% in mild (defined as PTA or LOC for less than 30 minutes), 2.9% in moderate (LOC lasting between 30 minutes and 1 day), and 17.2% in severe TBI (cerebral contusion, subdural hematoma, or LOC for over a day; image at right).