Traumatic brain injury (TBI) occurs in patients of all age groups and is a significant public health issue. In the United States, 1.5 million TBIs occur annually, 75% of TBIs are classified as mild, and costs are generated of $17 billion each year. Most patients that suffer from TBI will have spontaneous resolution of symptoms, but for some patients, symptoms may linger and negatively affect daily cognitive function. Post-concussive syndrome (PCS) demarcates the constellation of symptoms seen most often in prolonged mild TBI. Clinical criteria for PCS is outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).
PCS is a constellation of physical, cognitive, behavioral, and emotional symptoms occurring after TBI. These symptoms include a headache, fatigue, vision changes, disturbances in balance, confusion, dizziness, insomnia, and difficulty with concentration. Approximately 90% of concussion symptoms are transient, with symptoms resolving within 10 to 14 days but may linger for weeks. Persistent PCS occurs when symptoms persist past 3 months. Fifteen percent of mild TBI patients will suffer from PCS, and a small minority of those patients will experience persistent PCS requiring further evaluation and treatment.
Research has shown that mild TBI resulting in persistent PCS has lasting effects on cognition, memory, learning, and executive function. Patients who suffer more than one brain injury are at increased risk for PCS. Due to limited diagnostic tools, those permanent changes in executive function can go undocumented. Thus, the 15% incidence of PCS is an underestimation of the true incidence.
Most cases of PCS occur in patients with mild TBI but can occur with TBI of any severity. TBI results from trauma, assault or sports-related injuries. Mild TBI is defined as a Glasgow coma score (GCS) of 13 to 15 and is further sub-grouped as complicated versus uncomplicated. Complicated mild TBI comprises symptoms of a concussion with associated head CT abnormalities, including hematoma, subarachnoid or subdural bleed, midline shifts, or fractures. Uncomplicated mild TBI presents with a normal head CT. Patients with uncomplicated mild TBI are more likely to have a resolution of symptoms in less than 3 months. Patients with complicated TBI or more than one TBI are more likely to suffer from PCS or persistent PCS. Other risk factors include female gender, age, psychiatric history, or a history of chronic pain syndromes.
Current studies and analysis show that women are at greater risk for persistent PCS. Women are more likely to endorse a headache, irritability, fatigue, and concentration problems. Increases in age are also associated with a higher risk of PCS. Among minors, no comparisons have been made with the symptoms endorsed. Female minors are more likely to endorse symptoms while male minors are more likely to experience loss of consciousness at the time of injury and seek medical attention in an emergency department. It is also thought minors are less likely to experience PCS due to increased neuroplasticity when compared to adults. These studies were conducted in sports-related cases, but experts believe that similar trends occur in any mechanism of TBI.
The pathophysiology of concussion includes a combination of metabolic, physiology and microstructural injuries to the brain. Symptoms consistent with PCS result from autonomic nervous system damage. This damage occurs to the white matter tracks between cortical control centers and vagal nerve control via the spinal cord. This affects both the sympathetic and parasympathetic nervous systems. As a result, patients will often experience symptoms consistent with depression. Autonomic nervous system damage also causes difficulties with control of cerebral blood flood, blood pressure and heart rate leading to dizziness, headache, confusion, difficulty with concentration, and orthostatic intolerance. Decreases in cerebral blood flow at rest in the immediate post-injury period can account for PCS symptoms outlined above. Also, increased cerebral blood flow post-injury can cause headache, vision changes, and dizziness leading to exercise intolerance. Heart rate variability due to damage in the vagal nerve tracts results in disproportionate increases in blood pressure and heart rate during exercise causing early fatigue.
A thorough history and physical exam are crucial in the evaluation of PCS patients. Mechanism of injury, date of injury, loss of consciousness at the time of injury, the number of times injured, and reported symptoms are all critical in the initial and subsequent evaluation. Past medical history is especially helpful for identifying patients are at increased risk of PCS. Important past medical history to document includes headache history, history of depression, anxiety or mood disorders, and chronic pain history. The physical exam should include a full neurological exam including evaluation of cranial nerves, visual acuity, reflexes, strength, proprioception, and sensation, and should be completed with each encounter.
Evaluation of PCS requires recognition of residual symptoms following TBI. Due to the ambiguity of symptoms, recognition takes time, and thus, treatment is often delayed. Concussion refers to the condition that resolved within 30 days of injury and symptoms identified during this time attributed to the concussion or mild TBI before the diagnosis of PCS is made. As outlined in the DSM-IV, PCS is diagnosed with the presence of cognitive deficits in attention or memory and at least 3 of the following:
The International Classification of Disease-10 defines PCS as the symptoms outlined above persisting for longer than 3 weeks, is more general and encompasses more patients. Most patients recover in the first 7 to 10 days following injury and will require no further evaluation.
The initial evaluation will include a thorough history and physical exam. Initial evaluation can occur on the scene in sports-related cases, in the emergency department (ED) during trauma or emergency, or by a primary care physician on an outpatient basis in patients who do not seek medical care at the time of injury. Highlighted areas include clearance of the cervical spine (if emergency), mental status, cranial nerves (including visual acuity), balance, strength, proprioception, sensation, and reflexes. Patients should be screened with vestibular-ocular motor screening exam to be repeated once the patient becomes asymptomatic.
Any neurological or mental status deficits should be documented regarding time lapsed from the time of injury. The evaluation may also include imaging if completed in the emergent setting via head CT. Get an MRI in patients who continue to endorse symptoms at greater than 1-month post-injury. Imaging allows for the evaluating physician to rule out other etiologies that may be responsible for symptoms before referral for symptom-specific therapies.
In 85% to 90% of cases, mild TBI is self-limited and does not progress to PCS. In the minority of cases that do not recover to baseline at 4 weeks post-injury, management, and physiological treatment is important in patients returning to baseline mental and physical activity. Physical and cognitive rest is recommended for at least the first 24 to 48 hours post-injury as outlined by Zurich guidelines. Patients are only to return to play or usual activity once symptom-free at rest. It has been shown in studies reviewed that patients who rested for 2 days versus 5 days returned to baseline more quickly.
For patients continuing to endorse visual and balance symptoms the vestibular-ocular motor screening tool may be completed in the outpatient setting. By using the screening tool to identify the root cause of a patient’s residual post-concussive symptoms, the provider can prescribe active forms of therapy, which include cervical physical therapy, vision therapy or vestibular rehabilitation.
Lastly, Zurich guidelines acknowledge that patients with PCS who engage in low-level exercise recover faster. The Buffalo concussion treadmill test assesses when patients may resume full activity by measuring the patient’s ability to achieve target heart rate without experiencing symptoms or early exhaustion. Once patients can achieve age-related maximal heart rate and exercise without symptoms for at least 20 minutes for 2 to 3 consecutive days, the patient is deemed physiologically recovered. For athletes, this may not correlate to return to play but allows the athlete to train aerobically until other post-concussive symptoms resolve.
Traumatic brain injury is a hallmark injury of veterans and athletes. Most studies reviewed centered on these specific patient populations presenting difficulties in using results for the general patient population. Overall, mild TBI can have lasting effects on neurocognition despite the mild nature of the disease process. If symptoms of mild TBI persist for greater than 4 weeks, patients are diagnosed with PCS and require further intervention. The difficulty of identifying PCS is that symptoms of PCS are ubiquitous in the population and can be due to other causes such as psychiatric disorders, headache syndromes and chronic pain syndromes as outlined in previous sections of this article. An interprofessional approach to the care of mild TBI patients and those that develop PCS is necessary for the care of these patients.
In a randomized control trial which looked at veterans returning to the workforce, studied the benefits of an online evaluation tool CogSMART when used with enhanced, supported employment to place veterans with varying degrees of mild TBI and comorbid psychiatric disorders in jobs of varying cognitive demand. The study showed benefit with a rapid return to baseline and decreased prevalence of PCS in patients that used CogSMART with enhanced, supported employment when compared to groups that did not use CogSMART with enhanced, supported employment.
In veterans with comorbid psychiatric disorders, psychiatric care is necessary for a more rapid recovery of PCS symptoms. Specifically, treatment of PTSD is often required in patients with mild TBI to facilitate recovery. Patients that also suffer from chronic headaches and pain syndromes will require additional treatment from specializing physicians to facilitate the recovery. In athletes, reviews completed by sports trainers presented data that early exercise aided in the recovery of mild TBI and prevention of PCS. The benefit comes from decreased incidence of depression, anxiety, and sleep-related symptoms by allowing the athlete safe return to exercise and conditioning.
In the prevention and treatment of PCS in patients that have suffered mild TBI, patient education is key to successful recovery. Physicians should educate patients on returning to work or school with a resolution of symptoms at rest. Patient education should include that extended bed rest and delayed cognitive rest can lead to worse outcomes. Addressing patient comorbidities with treatment also helps patients return to baseline in most cases. (Level II)
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