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).
Sports-related traumatic brain injury
Short-term effects deal mostly with Post-concussion Syndrome, which has no clearly defined definition. A person suffering from a single concussive incident typically has a strong recovery rate. The most common Post-concussion symptom is a persistent headache which usually disappears within 1–2 weeks. Other common short-term effects include dizziness, vomiting, nausea, sensitivity to light and sound, irritability, cognitive lapses and memory impairment. 20-90% of the persons affected develop one symptom within a month of the incident, after 3 months 40% of the affected persons show at least 3 symptoms.