It is frequently stated in the literature and considered to be common knowledge that 15–30% of people with PCS have not recovered by a year after the injury, but this estimate is imprecise because it is based on studies of people admitted to a hospital, the methodologies of which have been criticized. In approximately 15% of people, symptoms may persist for years or be permanent. If symptoms are not resolved by one year, they are likely to be permanent, though improvements may occur after even two or three years, or may suddenly occur after a long time without much improvement. Older people and those who have previously had another head injury are likely to take longer to recover.The way in which children cope with the injury after it occurs may have more of an impact than factors that existed prior to the injury. Childrens mechanisms for dealing with their injuries may have an effect on the duration of symptoms, and parents who do not deal effectively with anxiety about childrens post-injury functioning may be less able to help their children recover.If another blow to the head occurs after a concussion but before its symptoms have gone away, there is a slight risk of developing the serious second-impact syndrome (SIS). In SIS, the brain rapidly swells, greatly increasing intracranial pressure.
PCS may cause insomnia, fatigue, or other problems with sleep. Psychological and behavioral
Psychological conditions, which are present in about half of people with PCS, may include irritability, anxiety, depression, and a change in personality. Other emotional and behavioral symptoms include restlessness, aggression, and mood swings. Some common symptoms, such as apathy, insomnia, irritability, or lack of motivation, may result from other co-occurring conditions, such as depression. Higher mental functions
Common symptoms associated with a diagnosis of PCS are related to cognition, attention, and memory, especially short-term memory, which can also worsen other problems such as forgetting appointments or difficulties at work. In one study, one in four people diagnosed with PCS continued to report memory problems a year after the injury, but most experts agree that cognitive symptoms clear within six months to a year after injury in the vast majority of individuals. Causes
The question of the cause or causes of PCS has been heavily debated for many years and remain controversial. It is not known to exactly what degree the symptoms are due to physiological changes or to other factors, such as pre-existing psychiatric disorders or factors related to secondary gain or disability compensation. The subjectivity of the complaints complicates assessment and makes it difficult to determine whether symptoms are being exaggerated or feigned.PCS may also be exacerbated by psychosocial factors, chronic pain, or an interaction of some or all of these.