post-concussion syndrome post-concussion syndrome post-concussion syndrome (pcs) is a set of symptoms that may continue for weeks, months, years after a concussion. pcs is medically classified as a mild traumatic brain injury (tbi). about 35% of people with concussion experience persistent or prolonged symptoms 3 to 6 months after injury. prolonged concussion is defined as having concussion symptoms for over four weeks following the first accident in youth and for weeks or months in adults. post-concussion syndromeother namespostconcussive syndromespecialtypsychiatry, neurology, physical medicine and rehabilitation a diagnosis may be made when symptoms resulting from concussion last for more than three months after the injury. loss of consciousness is not required for a diagnosis of concussion or post-concussion syndrome. however, it is important that patients find help as soon as they notice lingering symptoms within one month, and especially when they notice their mental health deteriorating, since they are at risk of post-concussion syndrome depression. though there is no specific treatment for pcs, symptoms can be improved with medications and physical and behavioral therapy. education about symptoms and details about expectation of recovery are important. the majority of pcs cases resolve after a period of time. signs and symptoms in the past, the term pcs was also used to refer to immediate physical symptoms or post-concussive symptoms following a minor tbi or concussion. the severity of these symptoms typically decreases rapidly. in addition, the nature of the symptoms may change over time: acute symptoms are most commonly of a physical nature, while persisting symptoms tend to be predominantly psychological. symptoms such as noise sensitivity, problems with concentration and memory, irritability, depression, and anxiety may be called 'late symptoms' because they generally do not occur immediately after the injury, but rather in the days or weeks after the injury. nausea and drowsiness commonly occur acutely following concussion. headache and dizziness occur immediately after the injury, but also can be long lasting. the condition is associated with a wide range of non-specific symptoms: physical, such as headache; cognitive, such as difficulty concentrating; and emotional and behavioral, such as irritability. many of the symptoms associated with pcs are common or may be exacerbated by other disorders, so there is considerable risk of misdiagnosis. headaches that occur after a concussion may feel like migraine headaches or tension-type headaches. most headaches are tension-type headaches, which may be associated with a neck injury that occurred at the same time of the head injury. physical a common condition associated with pcs is headache. while most people have headaches of the same type they experienced before the injury, people diagnosed with pcs often report more frequent or longer-lasting headaches. between 30% and 90% of people treated for pcs report having more frequent headaches and between 8% and 32% still report them a year after the injury. dizziness is another common symptom reported in about half of people diagnosed with pcs and is still present in up to a quarter of them a year after the injury. older people are at especially high risk for dizziness, which can contribute to subsequent injuries and higher rates of mortality due to falls. about 10% of people with pcs develop sensitivity to light or noise, about 5% experience a decreased sense of taste or smell, and about 14% report blurred vision. people may also have double vision or ringing in the ears, also called tinnitus. 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 it is not known what causes pcs to occur and persist, or why some people who have a mild traumatic brain injury later develop pcs while others do not. the nature of the syndrome and the diagnosis itself have been the subject of intense debate since the 19th century. however, certain risk factors have been identified; for example, preexisting medical or psychological conditions, expectations of disability, being female, and older age all increase the chances that someone will have pcs. physiological and psychological factors present before, during, and after the injury are all thought to be involved in the development of pcs. some experts believe post-concussion symptoms are caused by structural damage to the brain or disruption of neurotransmitter systems, resulting from the impact that caused the concussion. others believe that post-concussion symptoms are related to common psychological factors. most common symptoms like headache, dizziness, and sleep problems are similar to those often experienced by individuals diagnosed with depression, anxiety, or post traumatic stress disorder. in many cases, both physiological effects of brain trauma and emotional reactions to these events play a role in the development of symptoms. pcs may be exacerbated by chronic pain. the majority of experts believe that pcs results from a mix of factors, including preexisting psychological factors and those directly relating to the physical injury. physiological conventional neuroimaging studies of the brain following a concussion are typically normal. however, studies have found some subtle physiological changes associated with pcs using more novel imaging modalities. studies using positron emission tomography have linked pcs to a reduction in glucose use by the brain. changes in cerebral blood flow have also been observed as long as three years after a concussion in studies using single photon emission computed tomography (spect). at least one study with functional magnetic resonance imaging (fmri) has shown differences in brain function during tasks involving memory after mild traumatic brain injury (mtbi) although they were not examining pcs specifically. not all people with pcs have abnormalities on imaging, however, and abnormalities found in studies such as fmri, pet, and spect could result from other comorbid conditions such as depression, chronic pain, or posttraumatic stress disorder (ptsd). proponents of the view that pcs has a physiological basis point to findings that children demonstrate deficits on standardized tests of cognitive function following a mild tbi. a few studies have shown that people with pcs score lower than controls on neuropsychological tests that measure attention, verbal learning, reasoning, and information processing, but issues related to effort and secondary gain can not be ruled out as contributing to these differences. recovery as measured by scores on cognitive tests frequently do not correlate with resolution of symptoms; individuals diagnosed with pcs may still report subjective symptoms after their performance on tests of cognitive functioning have returned to normal. another study found that although children with pcs had poorer scores on tests of cognitive functioning after the injury, they also had poorer behavioral adjustment before the injury than children with no persistent symptoms; these findings support the idea that pcs may result from a combination of factors such as brain dysfunction resulting from head injury and preexisting psychological or social problems. different symptoms may be predicted by different factors; for example, one study found that cognitive and physical symptoms were not predicted by the manner in which parents and family members coped with the injury and adjusted to its effects, but psychological and behavioral symptoms were. brain inflammation is suggested to play a role in post-concussive syndrome. psychological it has been argued that psychological factors play an important role in the presence of post-concussion symptoms. the development of pcs may be due to a combination of factors such as adjustment to effects of the injury, preexisting vulnerabilities, and brain dysfunction. setbacks related to the injury, for example problems at work or with physical or social functioning, may act as stressors that interact with preexisting factors such as personality and mental conditions to cause and perpetuate pcs. in one study, levels of daily stress were found to be correlated to pcs symptoms in both concussed subjects and controls, but in another, stress was not significantly related to symptoms. iatrogenic effects (those caused by the medical intervention) may also occur when individuals are provided with misleading or incorrect information related to recovery of symptoms. this information may cause people to focus and dwell on the idea that their brains are permanently damaged. it appears that even the expectation of symptoms may contribute to the development of pcs by causing individuals with mtbi to focus on symptoms and therefore perceive them to be more intense, to attribute symptoms that occur for other reasons to the injury, and to underestimate the rate of symptoms before the injury. diagnosis symptomicd-10dsm-iv headache yy dizziness yy fatigue yy irritability yy sleep problems yy concentration problems y- memory problems y- problems tolerating stress/emotion/alcohol y- affect changes, anxiety, or depression -y changes in personality -y apathy -y the international statistical classification of diseases and related health problems (icd-10) and the american psychiatric association's diagnostic and statistical manual of mental disorders have set out criteria for post-concussion syndrome (pcs) and post-concussional disorder (pcd), respectively. the icd-10 established a set of diagnostic criteria for pcs in 1992. in order to meet these criteria, a patient has had a head injury "usually sufficiently severe to result in loss of consciousness" and then develop at least three of the eight symptoms marked with a check mark in the table at right under "icd-10" within four weeks. about 38% of people who have a head injury with symptoms of concussion and no radiological evidence of brain lesions meet these criteria. in addition to these symptoms, people that meet the icd-10 criteria for pcs may fear that they will have permanent brain damage, which may worsen the original symptoms. preoccupation with the injury may be accompanied by the assumption of a "sick role" and hypochondriasis. the criteria focus on subjective symptoms and mention that neuropsychological evidence of significant impairment is not present. with their focus on psychological factors, the icd-10 criteria support the idea that the cause of pcs is functional. like the icd-10, the icd-9-cm defines pcs in terms of subjective symptoms and discusses the greater frequency of pcs in people with histories of mental disorders or a financial incentive for a diagnosis. the dsm-iv lists criteria for diagnosis of pcd in people who have had a head trauma with persistent post-traumatic amnesia, loss of consciousness, or post-traumatic seizures. in addition, for a diagnosis of pcd, patients must have neuropsychological impairment as well as at least three of the symptoms marked with a check mark in the table at right under "dsm-iv". these symptoms must be present for three months after the injury and must have been absent or less severe before the injury. in addition, the patient must experience social problems as a result, and must not meet criteria for another disorder that explains the symptoms better. neuropsychological tests exist to measure deficits in cognitive functioning that can result from pcs. the stroop color test and the 2&7 processing speed test (which both detect deficits in speed of mental processing) can predict the development of cognitive problems from pcs. a test called the rivermead postconcussion symptoms questionnaire, a set of questions that measure the severity of 16 different post-concussion symptoms, can be self-administered or administered by an interviewer. other tests that can predict the development of pcs include the hopkins verbal learning a test (hvla) and the digit span forward examination. the hvla tests verbal learning and memory by presenting a series of words and assigning points based on the number recalled, and digit span measures attention efficiency by asking the examinee to repeat back digits spoken by the tester in the same order as they are presented. in addition, neuropsychological tests may be performed to detect malingering (exaggerating or making up symptoms) . differential diagnosis pcs, which shares symptoms with a variety of other conditions, is highly likely to be misdiagnosed in people with