Practice Essentials
Postconcussion (postconcussive) syndrome (PCS), a sequela of minor head injury (MHI), has been a much-debated topic. Understanding of this condition has been hindered by conflicting findings regarding symptom duration, an absence of objective neurologic findings, inconsistencies in presentation, poorly defined etiology, and significant methodologic problems in the literature. Depending on the definition employed and the population examined, 29-90% of patients experience postconcussion symptoms shortly after the traumatic insult. [1, 2, 3, 4]
The terms MHI and concussion are generally used interchangeably in the medical literature; however, it should be noted that the traditional definition of concussion precludes findings of intracranial hemorrhage (ICH) on computed tomography (CT), whereas the definition of MHI does not (though it does preclude the presence of a skull fracture). The term mild traumatic brain injury (TBI) is sometimes used as well.
An MHI typically indicates a blow to the head with a brief period of loss of consciousness (LOC) or posttraumatic amnesia or disorientation. At presentation, the Glasgow Coma Scale (GCS) score ranges from 13 to 15. However, the literature has suggested (and many clinicians concur) that there is a significantly lesser chance of intracranial injury on CT with a GCS score of 14 or 15 than with a GCS score of 13.
Although no universally accepted definition of PCS exists, most of the literature defines the syndrome as the development of at least three of the following symptoms:
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Headache
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Dizziness
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Fatigue
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Irritability
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Impaired memory and concentration
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Insomnia
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Lowered tolerance for noise and light
There has been some disagreement in the literature with regard to the timing and duration of symptoms in PCS. Some authors define the syndrome as involving symptoms of at least 3 months' duration, whereas others define it as involving symptoms appearing within the first week. In this article, PCS is loosely defined as the occurrence and persistence of symptoms within several weeks after the initial insult. To define persistent PCS (PPCS), most authors cite a symptom duration of more than 1 month, whereas others cite 6 months or 1 year. Generally, however, the term PPCS applies to ongoing chronic symptoms that continue past their expected resolution.
In a study of patients aged 5 years to younger than 18 years who presented with acute head injury in pediatric emergency departments (EDs), 801 of the 2584 patients (31%) experienced PPCS or acute concussion followed by ongoing somatic, cognitive, and psychological or behavioral symptoms. [5]
The ICD-10 criteria for PCS include a history of TBI and the presence of three or more of the following eight symptoms:
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Headache
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Dizziness
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Fatigue
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Irritability
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Insomnia
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Concentration difficulty
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Memory difficulty
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Intolerance of stress, emotion, or alcohol
In the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), published by the American Psychiatric Association (APA), PCS is given a diagnosis of either major or mild neurocognitive disorder (NCD) due to TBI. [4] The DSM-5 criteria for neurocognitive disorder due to TBI include the following:
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Evidence of TBI is present - Impact to the head or other mechanisms of rapid movement or displacement of the brain within the skull with any of the following: loss of consciousness, posttraumatic amnesia, disorientation and confusion, neurologic signs such as new onset of seizures, anosmia, or hemiparesis
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The neurocognitive disorder presents immediately after the occurrence of the TBI or immediately after recovery of consciousness and persists past the acute postinjury period
Findings may include headache, cranial nerve signs and symptoms (eg, dizziness, vertigo, and nausea), psychological and neurovegetative problems (eg, anxiety, depression, or sleep disturbance), and cognitive impairment (eg, memory loss and decreased ability to concentrate). [6]
Imaging modalities such as magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), and magnetoencephalography (MEG) have been shown to be more sensitive than CT at detecting brain injuries associated with PCS.
Patients who have a symptom constellation consistent with PCS require thorough physical and neurologic examinations. A CT scan should be obtained if significant concern about ICH exists.
Pathophysiology
There has been some debate as to which symptoms of PCS are due to organic causes and which have a psychological basis. It has been hypothesized that early PCS symptoms are more likely to be organic, whereas PCS symptoms that persist beyond 3 months have a nonorganic, psychological basis. Although it is known that psychological factors may be present early, studies using imaging techniques such as MRI, SPECT, and MEG have demonstrated the presence of organic brain injury in patients with persistent PCS at more than 1 year after injury.
Neuropsychological assessments have pointed toward an organic basis for some of the symptoms of PCS. Patients with PCS have been found to have cognitive deficits in memory, attention, and learning when compared with controls. A prospective study found that patients with PCS, compared with control subjects, had impaired eye movements that were both persistent and independent of factors such as depression or intellectual ability. [7]
Findings from neuropsychological evaluations have demonstrate that symptom severity is not necessarily dependent on neurologic status immediately following injury. In other series, however, the duration of LOC or posttraumatic amnesia may be correlated with the probability of developing PCS.
Some studies have found the certain patient characteristics (eg, female sex, noise sensitivity, and anxiety) can predict development of symptoms. [8] One study found that a simple test in the ED of immediate and delayed memory for five words, along with a Visual Analogue Scale (VAS) for acute headache, provided an 80% sensitivity and 76% specificity for the development of PCS. [9] Another study found that higher educational levels, along with mild symptoms and the absence of any extracranial symptoms, predicted a low likelihood of significant dysfunction from PCS.
Etiology
Risk factors for the development of PCS include nonsporting mechanisms, LOC, amnesia for the event, female sex, and abnormal neurobehavioral testing results after the incident.
A common perception is that patients who develop PCS from head injury are those who perceive a source of blame for the injury and desire to pursue litigation. However, a single study evaluating this did not demonstrate any correlation between blame and litigation. In fact, PCS symptoms persisted after settlement.
Some authors have suggested that persons with a history of depressive and anxiety disorders, [10] certain premorbid personality types, or poor coping skills may be predisposed to PCS, but the data are conflicting.
Neck pain after a head injury has not been correlated with the development of PCS.
Although the numbers of patients tend to be relatively small, there is some evidence to suggest that PCS is more likely to develop in patients presenting with nausea, headache, and dizziness.
One study found an inverse association between the number of years of education and development of PCS in adult patients. [11]
Patients with premorbid physical problems have also been found to have a higher incidence of PCS after MHI.
One study found that perception of the illness itself may have an effect on the development of PCS. [12] Patients who believed that their symptoms had serious negative consequences on their lives were at increased risk for developing PCS.
Epidemiology
More than 2 million instances of TBI occur in the United States each year. In a descriptive study that examined ED visits for mild TBI (mTBI) in the United States between 2006 and 2012, Cancelliere et al found that the annual frequency of such visits rose from 569.4 per 100,000 to 807.9 over this period. [13] Depending on the definitions employed and the population examined, approximately 50% of patients with MHI have PCS symptoms at 1 month, and 15% have symptoms at 1 year. The number of patients who sustain MHI but do not present for medical care is unknown; therefore, it is likely that PCS is significantly underdiagnosed.
Morbidity is mainly due to the persistence of symptoms, which make it difficult for patients to resume premorbid functions. Between 14% and 29% of children with mTBI will continue to have postconcussion symptoms at 3 months. [14, 15]
Approximately 50% of those who sustain MHIs are in the age range of 15-34 years; however, PCS has not been shown to have a predilection for any specific age group. [1, 16]
More than 800,000 children a year visit an ED for head injuries each year in the United States; the vast majority of these are MHIs. [17] TBIs are largest cause of ED visits for adolescents. Although 80-90% of these are mTBIs, or concussions, and are not life-threatening, even an mTBI can have ongoing effects. Young children are more susceptible to concussion than adults not only because they are more likely to be active and involved in sports but also because their brains are not yet fully developed and therefore are more vulnerable to injury.
It has been estimated that more than 300,000 sports-related concussions occur annually in the United States and that the likelihood of sustaining a concussion while playing a contact sport may be as high as 19% per year of play. [18] Participants in high school contact sports sustain more than 62,000 concussions annually; in college football, 34% of players have had one concussion and 20% have had more than one. Over the course of a single season, 4-20% of college and high school football players will sustain a brain injury. The risk of concussion in football players is three to six times higher in players who have had a previous concussion.
In a study from McGill University, concussion rates in soccer players were found to be comparable to those in football players. [19] Approximately 60% of college soccer players experienced concussion symptoms at least once during the playing season. Once an athlete sustained a concussion, he or she was four to six times more likely to sustain a second one.
Prognosis
An accurate prognosis has been difficult to achieve, given that many patients with minor symptoms may not enter the healthcare system and that those who participate in research appear to have more significant symptoms at baseline. In addition, a wide heterogeneity exists in patients enrolled in studies.
Most patients recover fully in less than 3 months, though some small studies have suggested persistence of minor cognitive defects can persist in asymptomatic mTBI patients. [20]
Approximately 15% of patients report still having problems more than 12 months after injury. This group is likely to experience persistent and intrusive symptoms that may be refractory to treatment and may impose a lifelong disability.
At least one study found that the persistence of dizziness as a symptom seemed to portend a longer and more significant symptom complex. [21] Other studies found that depression, pain, and symptom invalidity were correlated with longer and worse symptoms. [22] Some evidence suggests that patients with early clinical symptoms (eg, headache, dizziness, and intracranial lesions) are more likely to have PPCS.
PCS is commonly associated with multiple concussions, but in one series (N = 221; average number of concussions, 3.3, median symptom duration, 7 mo), 23.1% of patients experienced PCS after only one concussion. [23]
Hiploylee et al found that the time to recovery often depended on the number of initial symptoms reported, with each symptom reducing the recovery rate by about 20%. [24] They also found that PCS may be permanent if recovery does not occur within 3 years. Those who did not recover were more likely to be noncompliant regarding the recommendation to refrain from returning to play.
A meta-analysis (six studies) by Wyrwa et al evaluated 13 prognostic prediction models (PPMs) for predicting postconcussion recovery in pediatric patients. [25] All of the studies defined outcomes differently, and none of them specifically addressed the clinical utility of the models. The risk of bias was high for all six studies. The PPM with the best evidentiary support was the Predicting and Preventing Postconcussive Problems in Pediatrics (5P) score, which the authors suggested could be considered for clinical application; the other PPMs would require external validation.
