In 2014, adults accounted for almost 70% of approximately 2.5 million emergency department (ED) visits for traumatic brain injury (TBI) in the United States. The most common causes were unintentional falls (48%), being unintentionally struck by an object (17%), and motor vehicle crashes (13%). TBI-related ED visits were highest in 3 age groups: adults aged =75 years, children aged < 5 years, and teens/young adults aged 15 to 24 years.

In a nationwide study, nearly 95% of patients presenting with TBI were classified with mild TBI; approximately 2% had moderate TBI; and approximately 4% had severe TBI. About 1 in every 10 who underwent head CT scan had evidence of traumatic abnormalities. Additionally, as many as 15% of patients with head trauma evaluated in the ED with a Glasgow Coma Scale (GCS) score of 15 will have an acute lesion on head CT, of which 1% will require neurosurgical intervention.

Given that most ED visits for traumatic head injuries are for mild TBI, it is crucial to differentiate between the few patients who need further evaluation or intervention and the many that can be safely sent home. In 2008, the American College of Emergency Physicians (ACEP) collaborated with the Centers for Disease Control and Prevention (CDC) on a clinical policy about diagnosis and decision-making in mild TBI. It applies to patients aged =16 years with nonpenetrating trauma to the head who present to the ED within 24 hours of injury and a GCS score of 14 to 15 on initial ED evaluation. It does not apply to patients with penetrating or multisystem trauma, a GCS score < 14 on initial ED evaluation, or those aged < 16 years. Given that the ACEP policy was drafted more than a decade ago, Manquen et al reviewed clinical research about the diagnosis of mild TBI in adults completed since the policy was drafted. They found little new high-quality data about key issues identified in the policy.

Recommendation

A non-contrast head CT is indicated for head trauma patients with loss of consciousness or posttraumatic amnesia if =1 of the factors in the table below is present. [Level A] CT should also be considered for patients without loss of consciousness or posttraumatic amnesia if 1 of the factors in the table below is present. [Level B]

Non-contrast head CT is…
Indicated for patients with a loss of consciousness or posttraumatic amnesia and ≥1 of the following: headache vomiting age >60 years drug or alcohol intoxication short-term memory deficits physical evidence of trauma above the clavicle posttraumatic seizure GCS score <15 focal neurologic deficit coagulopathy	Considered for patients with no loss of consciousness or posttraumatic amnesia and 1 of the following focal neurologic deficit vomiting severe headache age ≥65 years physical signs of a basilar skull fracture GCS score <15 coagulopathy dangerous mechanism of injury (eg, motor vehicle ejection, struck pedestrian, or fall from a height of >3 feet or 5 stairs

GCS=Glasgow Coma Scale

Details

The primary outcome the panel selected for whether to perform noncontrast head CT in patients with mild TBI was an acute traumatic intracranial lesion on the scan. Panel recommendations are based on 2 Class I studies, 8 Class II studies, and 10 Class III studies.

Comments

Overuse of CT scans to diagnose mild TBI consumes time and resources, increases health care costs, and exposes patients to unnecessary radiation that may increase the risk of cancer. A CT scan accounts for about half the time a patient spends in the ED (mean length of stay, 6.6 hours) for evaluation of mild TBI. In a nationwide ED study, >90% of head CTs obtained to evaluate TBI were negative. A study conducted at an urban Level 1 ED found that a quarter of CTs obtained in adults with mild TBI did not meet ACEP policy criteria. These statistics explain why an ACEP Choosing Wisely statement is: “Avoid CT scans of the head in ED patients with minor head injury who are at low risk based on validated decision rules.”

An additional study of >27,000 adult trauma head CTs obtained across several community ED’s in Southern California found that about one-third of those head CTs performed could have been avoided by applying validated clinical decision rules.

A follow-up study evaluated the implementation of the Canadian CT Head Rule (CCHR) in almost 45,000 encounters in these same EDs over a 2-year period. Implementation components included clinical leadership endorsement, physician education, and integrated clinical decision support. After CCHR implementation, the proportion of patients receiving a head CT (the primary study outcome) had an absolute reduction of 5.3% (95% CI: 2.5, 8.1) and a relative reduction of 15.8%. Post-implementation, the diagnostic yield of CT-identified intracranial injuries increased by 2.3% (95% CI: 1.5, 3.1).

Other clinical decision rules exist to screen patients presenting with TBI. A recent cohort study compared and externally validated 4 head CT decision rules in patients aged =16 years with a GCS score of 13 to 15:

• CT in head injury patients (CHIP) Prediction Rule
• New Orleans criteria (NOC)
• Canadian CT Head Injury/Trauma Rule (CCHR)
• National Institute for Health and Care Excellence (NICE) guideline for head injury.

The primary outcome was any intracranial traumatic finding on CT; the secondary outcome was a potential neurosurgical lesion on CT. In >4500 consecutive patients, 82% received a CT scan, of which 10% were positive, including 8% with an intracranial traumatic finding and 2% with a potential neurosurgical lesion. The authors found that application of the CHIP, NOC, CCHR, or NICE decision rules led to wide variation in CT scanning among patients with minor head injury. The NOC and CHIP criteria had the highest sensitivity (98.8% and 94.1%, respectively) but low specificity (4.4% and 21.6%, respectively), while the NICE guideline was the most specific (60.9%) but had a sensitivity of only 72.5%. For CCHR, sensitivity was 80.3% and specificity was 44.2%. The authors estimated that 96% of patients in the validation study would need CT with NOC, 80% with CHIP criteria, 58% with CCHR, and 42% with NICE guidelines. They concluded the CHIP criteria best balanced the benefit of identifying findings on CT with the harms of both false negatives and false positives. Limitations of this study, however, prevent it from being widely generalizable.

As all 4 decision rules had negative predictive values >99%, all could be used with reasonable confidence to screen patients presenting with TBI, but the NOC and CCHR remain the best validated and most often used decision rules.

Recommendation

A recommendation could not be made due to a lack of well-designed studies evaluating the use of MRI within 24 hours of injury in adults with mild TBI.

Comments

OPotentially limiting factors for using MRI to diagnose mild TBI include cost constraints, availability, and accessibility issues. Challenges to patient care include safety issues, such as patients with pacemakers and certain ferromagnetic foreign bodies. Compatibility with life-support and traction/stabilization devices is also somewhat problematic. Further, patient motion artifacts are less of an issue with CT than with MRI, and acute “neurosurgically relevant” hemorrhage is still reliably diagnosed with CT.

As MRI technology continues to evolve and becomes more uniformly available, there could be a role for its use in the ED. Studies examining the role of MRI at early time points (<24 hours) and the relationship of pathologic changes to outcome (postconcussive symptoms and postconcussive syndrome) are needed.

IV. Brain-Specific Serum Biomarkers to Predict Acute Traumatic Intracranial Injury

Recommendation

Consider not performing a CT in mild TBI patients without significant extracranial injuries and a serum S-100B level < 0.1 g/L measured within 4 hours of injury. [Level C] Panel recommendations are based on 6 Class II studies and 2 Class III studies.

Details

Of the markers studied to date, S100-B appears to have the most promise as a pre–head CT screening test. Lack of wide availability of these markers, however, limit their utility in clinical practice. Furthermore, serum markers, such as S100-B, have not been studied in larger populations nor have they been externally validated. Therefore, these markers should not yet be recommended as screening tools in patients presenting with TBI.

Comment

Several brain-specific serum proteins have been examined for their ability to predict traumatic abnormalities on head CT scan after mild TBI. Serum biomarkers for TBI are brain-specific neuronal proteins that can be released by injured neurons and astrocytes and diffuse into the peripheral circulation where they can be detected in serum. Potential biomarkers receiving the most attention include S-100B (a calcium-binding protein released by damaged glial cells), creatine kinase BB isoenzyme, and glial fibrillary acidic protein (GFAP). Glucose, norepinephrine, epinephrine, and dopamine have also been studied as markers for injury. Of these serum markers, S-100B is perhaps the best studied. Serum markers have the potential to limit the need for head CT scans in mild TBI patients. Unlike the clinical variables used in head CT decision rules, serum marker measurements are more objective and less prone to interrater variability.

Clinical algorithms that incorporate serum biomarkers have been developed to reduce the burden of CT imaging. In a validation study, the Scandinavian Guidelines that incorporate serum S-100B into managing adults with head trauma had sensitivity of 0.94 (95% CI: 0.77, 0.99) and specificity of 0.19 (95% CI, 0.13, 0.26) for predicting traumatic intracranial CT abnormalities. Positive and negative predictive values for a positive head CT were 0.18 (95% CI, 0.12, 0.25) and 0.94 (95% CI, 0.78, 0.99). The role of S-100B in the Scandinavian Guidelines is shown in the figure below.

Figure. Role of S-100B in the Scandinavian Guidelines for managing adult head injuries

Recommendation

Consider not performing a CT in mild TBI patients without significant extracranial injuries and a serum S-100B level < 0.1 g/L measured within 4 hours of injury. [Level C] Panel recommendations are based on 6 Class II studies and 2 Class III studies.

Details

Of the markers studied to date, S100-B appears to have the most promise as a pre–head CT screening test. Lack of wide availability of these markers, however, limit their utility in clinical practice. Furthermore, serum markers, such as S100-B, have not been studied in larger populations nor have they been externally validated. Therefore, these markers should not yet be recommended as screening tools in patients presenting with TBI.

Comment

Several brain-specific serum proteins have been examined for their ability to predict traumatic abnormalities on head CT scan after mild TBI. Serum biomarkers for TBI are brain-specific neuronal proteins that can be released by injured neurons and astrocytes and diffuse into the peripheral circulation where they can be detected in serum. Potential biomarkers receiving the most attention include S-100B (a calcium-binding protein released by damaged glial cells), creatine kinase BB isoenzyme, and glial fibrillary acidic protein (GFAP). Glucose, norepinephrine, epinephrine, and dopamine have also been studied as markers for injury. Of these serum markers, S-100B is perhaps the best studied. Serum markers have the potential to limit the need for head CT scans in mild TBI patients. Unlike the clinical variables used in head CT decision rules, serum marker measurements are more objective and less prone to interrater variability.

Clinical algorithms that incorporate serum biomarkers have been developed to reduce the burden of CT imaging. In a validation study, the Scandinavian Guidelines that incorporate serum S-100B into managing adults with head trauma had sensitivity of 0.94 (95% CI: 0.77, 0.99) and specificity of 0.19 (95% CI, 0.13, 0.26) for predicting traumatic intracranial CT abnormalities. Positive and negative predictive values for a positive head CT were 0.18 (95% CI, 0.12, 0.25) and 0.94 (95% CI, 0.78, 0.99). The role of S-100B in the Scandinavian Guidelines is shown in the figure below.

Figure. Role of S-100B in the Scandinavian Guidelines for managing adult head injuries

Recommendation

A patient with an isolated mild TBI and a negative head CT scan may be safely discharged from the ED because the risk of developing an intracranial lesion is minimal. [Level B] Patients with mild TBI should be educated about post-concussive symptoms before ED discharge. [Level C]

Details

The primary outcome chosen by the panel for whether patients with a normal neurological evaluation and negative head CT can be discharged was neurological deterioration. Panel recommendations are based on 1 Class I study, 1 Class II study, and 12 Class III studies. The data are inadequate to address whether ED discharge is safe in patients with isolated mild TBI and a negative head CT scan who have specific risk factors for complications. This includes:

• A bleeding disorder
• Treatment with an anticoagulant or antiplatelet agent
• A previous neurosurgical procedure

Comments

Gaps in follow-up care were recently documented by the Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) cohort study. The study looked at patterns of follow-up care after head CT for mild TBI in >800 adults. Only 42% of patients reported receiving written information at discharge, and this ranged from 19% to 72% at different facilities. Written information is crucial because patients with mild TBI may have difficulty recalling verbal instructions. A follow-up visit within 3 months of the injury was reported by only 61% of patients with a positive head CT scan and 52% of patients with severe post-concussive symptoms. The need for improved follow-up in mild TBI is underscored by other recent TRACK-TBI data indicating the potential for substantial and long-lasting morbidity in mild TBI. A year after their injury, less than half of patients with mild TBI reported a full return to their previous level of functioning. Providing education and coping strategies can reduce anxiety and the burden of post-concussive symptoms. The CDC has developed patient take-home instructions and a brief wallet card that provide patients with basic information about post-concussive symptoms, including those that require ED re-evaluation.

Patients on oral anticoagulants may have an increased risk of delayed intracranial hemorrhage (ICH). One study found an approximate 2.5% risk of delayed ICH after an initial normal head CT. More prolonged observation, subsequent diagnostic studies, or additional treatment may be required for patients with TBI who are anticoagulated, receive antiplatelet co-medication or have a medical or neurosurgical history which can increase their risk for ICH.

Evidence Levels

• Level A: Generally accepted principles for patient care that reflect a high degree of clinical certainty (eg, based on evidence from 1 or more Class of Evidence I or multiple Class of Evidence II studies).
• Level B: Recommendations for patient care that may identify a particular strategy or range of strategies that reflect moderate clinical certainty (eg, based on evidence from 1 or more Class of Evidence II studies or strong consensus of Class of Evidence III studies).
• Level C: Recommendations for patient care that are based on evidence from Class of Evidence III studies or, in the absence of any adequate published literature, based on expert consensus. In instances where consensus recommendations are made, “consensus” is placed in parentheses at the end of the recommendation.

Class of Evidence	Criteria for Studies Evaluating Diagnostic Strategies
I	Prospective cohort using a criterion standard or meta-analysis of prospective studies
II	Retrospective observational
III	Case series, case report, or other (eg, consensus or review)

Scope, Inclusion Criteria, Exclusion Criteria

• Scope of Application. This guideline is intended for physicians working in hospital-based EDs.
• Inclusion Criteria. This guideline is intended for patients with blunt trauma to the head who present to the ED within 24 hours of injury, who have a GCS score of 14 or 15 on initial evaluation in the ED, and are 16 years of age or older.
• Exclusion Criteria. This guideline is not intended for patients with penetrating trauma or multisystem trauma, who are younger than 16 years, or who have a GCS score of < 14 on initial evaluation in the ED.

Dr Allen is a drug information consultant and medical writer at Pin Oak Associates, which she founded in 1995. Dr Silver is an emergency physician with the Southern California Permanente Medical Group (SCPMG) in San Diego, and a clinical editor of CMEinfo Emergency Medicine Insider.

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