Post-concussion syndrome

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Post-concussion syndrome (PCS), also known as persisting symptoms after concussion, is a set of

A diagnosis may be made when symptoms resulting from concussion last for more than three months after the injury.[8]^[9][6] Loss of consciousness is not required for a diagnosis of concussion or post-concussion syndrome.^[10] 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.^[11][12]

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.

A common condition associated with PCS is headache.^{[18][needs update]} 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.^[18] 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.^{[18][needs update]}

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.^[18] Older people are at especially high risk for dizziness, which can contribute to subsequent injuries and higher rates of mortality due to falls.^[19]

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.^[18] People may also have double vision or ringing in the ears, also called tinnitus.^[20] PCS may cause insomnia, fatigue,^[21] or other problems with sleep.^[14]

Psychological and behavioral

Psychological conditions, which are present in about half of people with PCS, may include

Common symptoms associated with a diagnosis of PCS are related to cognition,^[25] attention,^[26] and memory, especially short-term memory, which can also worsen other problems such as forgetting appointments or difficulties at work.^[18] In one study, one in four people diagnosed with PCS continued to report memory problems a year after the injury,^[18][27] but most experts agree that cognitive symptoms clear within six months to a year after injury in the vast majority of individuals.^{[18][needs update]}

Causes

It is not known what causes PCS to occur and persist,^[28] or why some people who have a mild traumatic brain injury later develop PCS while others do not.^{[29][needs update]} 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.^{[13][needs update]}

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.^{[medical citation needed]} 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.^{[medical citation needed]} In many cases, both physiological effects of brain trauma and emotional reactions to these events play a role in the development of symptoms.^[30]

PCS may be exacerbated by chronic pain.^[31] 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.^[13]

Physiological

Conventional

Brain inflammation is suggested to play a role in post-concussive syndrome.^[35]

Psychological

It has been argued that psychological factors play an important role in the presence of post-concussion symptoms.^[36] 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.^[37] 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.^[31] 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.^[13]

Diagnosis

Symptom	ICD-10[38]	DSM-IV[33]
Headache	Y	Y
Dizziness	Y	Y
Fatigue	Y	Y
Irritability	Y	Y
Sleep problems	Y	Y
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.^[38] In order to meet these criteria, a patient has had a head injury "usually sufficiently severe to result in loss of consciousness"^[33][39] 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.^[38][40] About 38% of people who have a head injury with symptoms of concussion and no radiological evidence of brain lesions meet these criteria.^[41] 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.^[3] Preoccupation with the injury may be accompanied by the assumption of a "sick role" and hypochondriasis.^[37] The criteria focus on subjective symptoms and mention that neuropsychological evidence of significant impairment is not present.^[42] With their focus on psychological factors, the ICD-10 criteria support the idea that the cause of PCS is functional.^[33] 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.^[42]

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.^[33] 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".^[33] These symptoms must be present for three months after the injury and must have been absent or less severe before the injury.^[43] In addition, the patient must experience social problems as a result, and must not meet criteria for another disorder that explains the symptoms better.^[43]

Concussion protocols are continuously changing, with the common recommendation remaining both physical and cognitive rest. Exercise should be implemented as soon as possible after the initial rest period as this lowers the risk of post concussion syndrome (PCS) and overall symptoms. Moderate intensity aerobic exercise will provide therapeutic benefits and reintroduce the body to movement. Patients should begin with 20 minutes of brisk walking or an exercise bike set with mild resistance. If this exacerbates any symptoms, like headache or dizziness, the individual should stop exercising and try again the following day.[55]

Education

Education about symptoms and their usual time course is a part of psychological therapy, and is most effective when provided soon after the injury.

Neurotherapy is an operant conditioning test where patients are given conditional audio/visual rewards after producing particular types of brainwave activity. Recent neurotherapy improvements in quantitative electroencephalography can identify the specific brainwave patterns that need to be corrected. Studies have shown that neurotherapy is effective in the treatment of post-concussion syndrome and other disorders with similar symptoms.^[57] Transcranial low-frequency pulsating electromagnetic fields (T-PEMF) has shown some positive results in treating PCS patients. The tolerability was assessed in a  2020 study, which resulted in 61% of patients reporting decreased symptoms based on the Rivermead Post-Concussion Symptoms Questionnaire.^[58]

Multimodal

Multimodal physical therapy has been shown to improve PCS symptoms. The therapy is most effective when it is symptom-specific. Dizziness and unsteady gait were treated with exercises such as gaze stabilization and static and dynamic balance exercises. Decreased range of motion and cervical instability (known specifically as cervicogenic PCS) are best treated with cervical soft tissue and joint mobilization, deep cervical flexor strengthening exercises and stretching. Symptoms indicative of physiologic PCS (symptoms exacerbated by cardiovascular exercise) seem to improve with light cardio exercises like walking and using a stationary bike while the PT carefully monitors HR. Overall, a patient-specific PT plan of care has proven significantly effective in reducing PCS symptoms.^[56]

Prognosis

The prognosis for PCS is generally considered positive, with total resolution of symptoms in many, but not all, cases. For 50% of people, post-concussion symptoms go away within a few days to several weeks after the original injury occurs.^[59] In others, symptoms may remain for three to six months,^[25] but evidence indicates that many cases are completely resolved within six months.^[18] The majority of symptoms are largely gone in about half of people with concussion one month after the injury, and about two thirds of people with minor head trauma are nearly symptom-free within three months. Persistent, often severe headaches are the longest lingering symptom in most cases and are the most likely symptom to never fully resolve.^[51] 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.^[31][46][60] 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,^[43] or may suddenly occur after a long time without much improvement.^[61] Older people and those who have previously had another head injury are likely to take longer to recover.^[61]

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.^[33] Children's 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 children's post-injury functioning may be less able to help their children recover.^[33]

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

It is not known exactly how common PCS is. Estimates of the prevalence at three  months post-injury are between 24 and 84%, a variation possibly caused by different populations or study methodologies.^{[13][needs update]} The estimated incidence of PPCS (persistent postconcussive syndrome) is around 10% of mTBI cases.^[42] Since PCS by definition only exists in people who have had a head injury, demographics and risk factors are similar to those for head injury; for example, young adults are at higher risk than others for receiving head injury, and, consequently, of developing PCS.^[43]

The existence of PCS in children is controversial. It is possible that children's brains have enough plasticity that they are not affected by long-term consequences of concussion (though such consequences are known to result from moderate and severe head trauma).^[65] On the other hand, children's brains may be more vulnerable to the injury, since they are still developing and have fewer skills that can compensate for deficits.^[66] Clinical research has found higher rates of post-concussion symptoms in children with TBI than in those with injuries to other parts of the body, and that the symptoms are more common in anxious children.^[37] Symptoms in children are similar to those in adults, but children exhibit fewer of them.^[37] Evidence from clinical studies found that high school-aged athletes had slower recoveries from concussion as measured by neuropsychological tests than college-aged ones and adults.^[66] PCS is rare in young children.^[52]

Risk factors

A wide range of factors have been identified as being predictive of PCS, including low

In 1961, H. Miller first used the term "accident neurosis" to refer to the syndrome which is now called PCS and asserted that the condition only occurs in situations where people stand to be compensated for the injury.[34] The real causes of the condition remain unclear.^[18]

Controversy

Though no universally accepted definition of postconcussive syndrome exists, most of the literature defines the syndrome as the development of at least three of the following symptoms: headache, dizziness, fatigue, irritability, impaired memory and concentration, insomnia, and lowered tolerance for noise and light.^[43] 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.^[31] 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 individuals with PCS were misdiagnosed as having other unrelated conditions due to commonality of symptoms. (see diagnosis above).^[74]

Headache is one of the criteria for PCS, but it is notably undetermined where the headache comes from. Couch, Lipton, Stewart and Scher (2007)

In a syndrome, a set of symptoms is consistently present, and symptoms are linked such that the presence of one symptom suggests that of others. Because PCS symptoms are so varied and many can be associated with a large number of other conditions, doubt exists about whether the term "syndrome" is appropriate for the constellation of symptoms found after concussion.^[82] The fact that the persistence of one symptom is not necessarily linked to that of another has similarly led to doubt about whether "syndrome" is the appropriate term.^[51]

A longstanding controversy surrounding PCS concerns the nature of its etiology – that is, the cause behind it^[33] – and the degree to which psychological factors and organic factors involving brain dysfunction are responsible. The debate has been referred to as 'psychogenesis versus physiogenesis' (psychogenesis referring to a psychological origin for the condition, physiogenesis to a physical one).^[33]

See also

• Daniel Amen, post-concussion expert for the National Football League

References