1. Answer E. (MN-46) The patient described has the typical sequelae of a concussion, defined as transient neurological signs and symptoms with or without loss of consciousness. There are no warning signs to suggest an intracranial mass lesion. The likelihood of detecting evidence of TBI on standard neuroimaging (particularly MRI) is thought to be <1/1,000. A CT head is relatively contraindicated given the clinical picture, and it is also discouraged in youth populations unless there is an urgent or emergent indication for imaging. An EEG is not warranted but could reveal diffuse slowing if done. Formal neuropsychological testing may be a part of the work at a future time, such as if the patient is having some difficulty at school several weeks from now despite having advised on an appropriate treatment plan targeting recovery. Thus, no further workup will clarify the diagnosis.

2. Answer E. (MN-46) Following a concussion, it may be advisable to suggest brief period of relative rest for 1 to 2 days as necessary, although some persons may feel well enough to begin re-engaging with many of their activities on a more rapid timeline. After a concussion, patients should be advised to engage in a stepwise manner in social, academic, and athletic activity. It is now recognized that sensory withdrawal therapy or “cocoon therapy” may not only be ineffective but harmful in recovery timelines and psychologically disabling both during and after its use. Along with a return to sport program focusing on return to athletics, a return to learn (return to academics) strategy must be identified. Athletes should not return to full contact sports until they have fully re-engaged in academic work. Psychological support and counseling may be advisable for some students, particularly those who express anxiety for feeling out of step with their academic and social expectations and obligations. Working with school staff immediately after the injury is very helpful to assure that academic accommodations are in place. Many schools are developing a team-based approach with a central person (including a school administrator, nurse, or athletic trainer) serving as a liaison between teachers, families, students, and treating physicians. Athletes require formal clearance by a clinician prior to return to sport. Targeted treatment of posttraumatic migraines or related headaches is advisable in some patients, but all such medications will need to be stopped before a complete assessment of recovery (off medications) can be determined. The general principles in managing the youth athlete with concussion apply to adults with concussion, independent of context. Many adults face challenges in returning to professional, social, or family obligations and require a personalized approach.

3. Answer D. (MN-46) Most studies of youth, adolescent, and collegiate athletes suggest 80% or more will have full recovery within 1 to 2 weeks. At the collegiate level, full return to sports has gradually increased such that most athletes return to sport by 3 to 4 weeks after injury, suggesting appropriately conservative approach to care. Risk factors for those experiencing delayed recovery include multiple prior concussions, severe symptoms or signs at the time of injury, long-term exposure to injury (typically years), female gender, hiding or prior symptoms, and comorbid mood and headache disorders. The risk of long-term cognitive impairment in youth athletes with an isolated, uncomplicated concussion is thought to be very low, and acceptably so relative to the health and social benefits of participating in team sports. Cognitive impairment typically only follows those with more serious TBI or longitudinal exposures, but the frequency of this remains uncertain and has only been explored in highest-risk sports (tackle football) or those with long-term careers.

4. Answer E. (MN-46) Some pathological studies suggest coexpression of CTE with other pathologies including Alzheimer disease, Lewy body diseases, and cerebral amyloid angiopathy is common and TBI exposure may make these other copathologies more severe. CTE as a sole pathology may be more likely discovered among younger persons with a history of recurrent TBI exposure. Microscopically, patients with CTE exhibit marked accumulation of abnormal aggregates containing hyperphosphorylated forms of the microtubule-associated protein tau. Tau pathology is present in neurons and glia, leading to some diagnostic confusion at autopsy, especially in older patients who may have comorbid primary age-related tauopathy or aging-related tau astrogliopathy. Importantly, the regional distribution pattern of tau pathology in CTE is distinct, with accentuation in mechanically vulnerable brain regions, including the neocortical sulcal depths and perivascular regions. At present, there are no FDA-approved diagnostic tools to distinguish CTE from other tau-related pathologies. Findings on an MRI that have been associated with CTE include cavum septum pellucidum, regional atrophy, and white matter changes, but these are nonspecific. Relatedly, many of his cognitive features overlap with other cognitive and behavioral syndromes associated with aging, including depression and dementia due to other pathologies (including AD and FTD among others). Research criteria for traumatic encephalopathy syndrome are in development in an effort to establish a clinical correlate to CTE but are not yet established. Thus, CTE remains diagnosable only through neuropathological study. Overall, it is estimated that at least 8% of former professional American football players have pathological evidence of CTE and an inflection point of risk may occur at 11 years or more of exposure.

5. Answer D. (MN-47) The most likely diagnosis is DAI. The most common cause of depressed consciousness in the patient with TBI without elevated ICP or large structural brain injury is DAI. DAI is also known as axonal shear injury and occurs most frequently when the brain accelerates or decelerates at a high speed. This leads to axonal disruption and neuronal dysfunction and often results in severe neurologic impairment with minimal evidence of injury on head CT. A CT has minimal sensitivity for DAI and demonstrates only a very small percentage of injured axons and can be considered as the most likely etiology for the patient’s neurological deficits when there is a large discrepancy between the patient’s CTH and neurological examination. MRI has better sensitivity for DAI and will show restricted diffusion and microbleeds most often in white matter. Thus, clinicians should consider DAI when there is a large discrepancy between the patient’s imaging and clinical examination. Recovery from DAI is variable, and there is no prediction algorithm that can accurately discriminate arousal recovery and outcomes.

6. Answer D. (MN-47) Prophylactic anticonvulsants are recommended in all patients with moderate to severe TBI, as they have been demonstrated to decrease the risk of early posttraumatic seizures. At first, it appeared as though this patient only had an immediate posttraumatic seizure in the setting of a mild traumatic brain injury. However, he experienced an early neurologic deterioration with radiographic evidence of injury progression qualifying as moderate TBI. Posttraumatic seizures are a significant problem in the patient with TBI, occurring in between 4% and 25% of adults with TBI. Posttraumatic seizures may be divided into three groups: immediate seizures (occurring less than 24 hours after injury), early seizures (occurring less than a week after injury), and late seizures (occurring more than 7 days after injury). Phenytoin was demonstrated in a randomized double-blind study to decrease the risk of early posttraumatic seizures from 14.2% to 3.6%. Of note, studies have shown that immediate posttraumatic seizures increase risk of further early posttraumatic seizures but not late posttraumatic seizures.

7. Answer E. (MN-47) This patient falls into a minimal risk category and does not require neuroimaging or any other diagnostic testing and can be discharged home from the ED with follow-up in the outpatient clinic. This patient was neurologically normal and did not experience loss of consciousness, amnesia, or mental status changes. In adult patients with GCS 13 to 15 (aged less than 65 years) presenting to the ED after blunt head trauma with at least one of the following—witnessed loss of consciousness, amnesia, or mental status changes—the Canadian CT Head Rule is a well-validated clinical support tool. This decision aide safely rules out the presence of clinically significant intracranial injuries that would require hospital admission for observation and/or neurosurgical intervention, without the need for CT imaging. Furthermore, in (neurologically normal) adult patients with trauma with GCS 15 (aged 18-60 years) with witnessed loss of consciousness, the New Orleans Head CT Rule can help determine which patients with blunt head trauma can be discharged home from the ED without undergoing a CT head or admission for further clinical observation.

8. Answer E. (MN-47) Although GCS (see Table 5.8.1) is still the most widely used scoring system to assess severity of TBI and prognosis, it has limitations as in an intubated patient where verbal response cannot be detected and it does not provide information on brainstem function. The Full Outline of UnResponsiveness (FOUR) score that assesses four components of neurologic function—eye, motor, brainstem, and respiratory functions—has been developed to overcome some of these limitations. It also identifies a locked-in state and detects the presence of a vegetative state. Hypotension <90 mm Hg, hypoxemia PaO2 <60 mm Hg, fever, seizures, and hypo/hyperglycemia are all avoidable and treatable factors. Clinically increased ICP and decreased CPP should be urgently detected and treated to prevent secondary brain injury. Hence the patient should be monitored continuously. Neuronal and glial damage that occurs at the time of primary injury is exacerbated by a cascade of pathophysiological and neurochemical events during the course of the initial days. Progressive encephalomalacia continues for many years post injury secondary to diffuse axonal injury and/or neurodegeneration. According to the Brain Trauma Foundation guidelines an intracranial monitor should be placed in a salvageable patient with severe TBI with an abnormal head CT (intracranial hemorrhage, contusions, edema, herniation, or compressed basal cisterns). The first component of the systematic approach to any patient with trauma is called the primary survey—A, Airway maintenance with cervical spine protection; B, Breathing and Ventilation; C, Circulation with hemorrhage control; D, Disability (neurologic evaluation to exclude cervical spine injury and/or serious brain injury); and E, Exposure and Environmental control. A simple pneumonic, ABCDE, is used to guide these quick and methodical steps, the purpose of which is to identify life-threatening injuries and initiate appropriate resuscitation (Table 5.8.2).