Traumatic brain injury remains a common complaint in emergency departments, accounting for more that 1 million visits annually.¹ Even though most of these are classified as “mild,” an estimated 10% will have an acute traumatic lesion on head CT, less than 1% will have a lesion requiring a neurosurgical intervention, and up to 15% of these patients may have some degree of functional compromise at 1 year after their injury.

Thus, two challenges confront the clinician: 1) determining which patients can be safely discharged home and which ones have an acute intracranial injury requiring further monitoring, imaging, or possibly neurosurgical intervention; and 2) which patients are at risk for developing postconcussive symptoms.

In 2002, the American College of Emergency Physicians published a clinical policy on the management of mild traumatic brain injury (TBI).² In the 2002 document, an evidence-based approach was used to answer clinically relevant questions on the acute management of mild TBI. New evidence has become available that prompted an update of the 2002 clinical policy.

The most integral challenge in this topic is actually defining ‘mild traumatic brain injury.’

The revised clinical policy was developed by a multidisciplinary panel and funded by the Centers for Disease Control and Prevention. Presented below is an abstraction of the revised clinical policy which was published in the Annals of Emergency Medicine in December 2008.³ This clinical policy can also be found on ACEP’s Web site at www.acep.org under “Practice Resources.”

The most integral challenge in this topic is actually defining “mild traumatic brain injury.” Delineated inclusion criteria for a diagnosis of mild TBI from the American Congress of Rehabilitation Medicine⁴ and the Centers for Disease Control and Prevention⁵ were taken into consideration. Both of these classification schemes include one or more of the following criteria: alteration in mentation, amnesia, and a period of loss of consciousness.

Traditionally, mild TBI has included a Glasgow Coma Scale score (GCS) of 13-15; however, a growing body of literature supports moving a GCS of 13 into the “moderate” category. The document acknowledges that the GCS was originally developed before the availability of head computed tomography (CT) as a standardized clinical scale to facilitate reliable interobserver neurologic assessments of comatose patients with head injury. The GCS was neither developed nor suited to classify mild traumatic brain injury based upon one initial measurement.

On the other hand, serial GCS scores are quite valuable in patients with mild TBI. A low GCS score that remains low, or a high GCS that decreases, predicts a poorer outcome than a high GCS score that remains high or a low GCS score that progressively improves.⁶ From an emergency medical services and ED perspective, the key to using the GCS in patients with mild TBI is in serial determinations.

The inclusion criteria for application of the recommendations of this clinical policy are:

• Nonpenetrating trauma to the head;
• Presentation to the ED within 24 hours of injury;
• A GCS score of 14 or 15 on initial evaluation in the ED; and
• Age 16 years or older.

The exclusion criteria are:

• Penetrating trauma;
• Patients with multisystem trauma;
• GCS score less than 14 on initial evaluation in the ED; and
• Age younger than 16 years.

Neither loss of consciousness nor posttraumatic amnesia was used as an inclusion or exclusion criterion. Since the publication of the first edition of this clinical policy in 2002, two well-designed studies have demonstrated that neither loss of consciousness nor posttraumatic amnesia is sufficiently sensitive to identify patients at risk for intracranial injury.^7,8 After a review of these studies, the panel decided to eliminate these factors as criteria for the 2008 clinical policy.

The questions addressed in this clinical policy update are:

• Which patients with mild TBI should have a noncontrast head CT scan in the ED?
• Is there a role for head magnetic resonance imaging (MRI) over noncontrast CT in the ED evaluation of a patient with acute mild TBI?
• In patients with mild TBI, are brain-specific serum biomarkers predictive of an acute traumatic intracranial injury?
• Can a patient with an isolated mild TBI and a normal neurologic evaluation result be safely discharged from the ED if a noncontrast head CT scan shows no evidence of intracranial injury?

The 2002 document included a question regarding the role of plain film radiography in assessing mild TBI patients. This question was not included in this update, because there has been no new evidence regarding this subject.

Thus the original recommendation remains unchanged:

“Level B recommendation: Skull film radiographs are not recommended in the evaluation of mild TBI. Although the presence of a skull fracture increases the likelihood of an intracranial lesion, its sensitivity is not sufficient to be a useful screening test. Indeed, negative findings on skull films may mislead the clinician.”

Outcome measures were adjusted to the question being addressed. Presence of an acute intracranial injury on noncontrast head CT scan was chosen as the primary outcome measure for the questions regarding CT scanning, the use of MRI, and the utility of biomarkers. Neurologic deterioration was the primary outcome measure for the final question regarding discharge.

The ACEP clinical policy development process was used. Articles were first classified according to the strength of evidence based on the design of the study, then graded based on six dimensions thought to be most relevant to the development of clinical guidelines. Articles were given a final question-specific level of evidence grade on the basis of a predetermined formula, taking into account design and quality of the study. The recommendations made in the policy were given a level of A, B, or C (with A being the strongest level of evidence and C being the least) according to the strength of the evidence supporting them.

Critical Questions

1. Which patients with mild TBI should have a noncontrast head CT scan in the ED?

• Level A recommendation. A noncontrast head CT is indicated in head trauma patients with loss of consciousness or posttraumatic amnesia only if one or more of the following is present: headache, vomiting, age older than 60 years, drug or alcohol intoxication, deficits in short-term memory, physical evidence of trauma above the clavicle, posttraumatic seizure, GCS score less than 15, focal neurologic deficit, or coagulopathy.
• Level B recommendation. A noncontrast head CT should be considered in head trauma patients with no loss of consciousness or posttraumatic amnesia if there is a focal neurologic deficit, vomiting, severe headache, age 65 years or older, physical signs of a basilar skull fracture, GCS score less than 15, coagulopathy, or a dangerous mechanism of injury such as ejection from a motor vehicle, a pedestrian struck, or fall from a height of greater than 3 feet or five stairs.
• Level C recommendation. None specified.

Two seminal studies have laid the foundation for prediction rules guiding neuroimaging in mild TBI: the Canadian CT Head Rule (CCHR) developed by Stiell et al.,⁹ and the New Orleans Criteria developed by Haydel et al.¹⁰ Subsequent studies have prospectively compared these two criteria sets.

In a Class I study, Smits et al. found that the New Orleans Criteria and the Canadian CT Head Rule had an equal sensitivity of essentially 100% regarding the identification of lesions requiring neurosurgical interventions.¹¹ A difference was seen in identifying acute intracranial injuries, where the New Orleans Criteria had a sensitivity of 98.3% (95% CI, 94% to 99.5%) and the Canadian CT Head Rule a sensitivity of 83.4% (95% CI, 77.7% to 87.9%). This higher sensitivity seen with the New Orleans Criteria came at the expense of specificity, with 5.6% (95% CI, 2.7% to 8.8%) for identifying intracranial injury, versus a specificity of 39.4% (95% CI, 36.0% to 42.8%) seen with the Canadian CT Head Rule. Other studies have had similar findings.^12,13

Two recent studies have refuted a commonly held belief that loss of consciousness or posttraumatic amnesia is a prerequisite for significant intracranial injury.

In a Class II study, Ibanez et al. prospectively studied 1,101 mild TBI patients older than 14 years who had a GCS score of 14 or 15.⁷ A comprehensive clinical variable data collection sheet was used, and all patients had a head CT regardless of loss of consciousness or amnesia. Of the 491 patients in this study who did not have loss of consciousness, 1.8% had an intracranial injury and 0.6% required neurosurgery.

In a Class II study, Smits et al. analyzed a prospectively collected database of mild TBI patients older than 15 years with a GCS score of 15.⁸ Of 2,462 patients, 754 had neither loss of consciousness nor posttraumatic amnesia. There was an 8.7% occurrence of an intracranial injury in those patients with loss of consciousness or posttraumatic amnesia, versus 4.9% in those without; the need for neurosurgical intervention was 0.4%, versus 0.5% in patients with no loss of consciousness or posttraumatic amnesia.

These studies have thus challenged the previously held tenet that loss of consciousness can reliably be used to decide which mild TBI patients require neuroimaging.

These studies serve to reinforce the instruction that although both the New Orleans Criteria and the Canadian CT Head Rule have been validated, they must be applied within the limits of their inclusion criteria, and the clinician should understand their sensitivity and specificity both for neurosurgical lesions and for intracranial injury. Specifically, these rules are valid when applied to patients who have had loss of consciousness or amnesia and who are not on anticoagulants.

2. Is there a role for head MRI over noncontrast CT in the ED evaluation of a patient with acute mild TBI?

• Level A recommendation. None specified.
• Level B recommendation. None specified.
• Level C recommendation. None specified.

There are no well-designed studies that specifically examine the use of MRI within 24 hours of injury in mild TBI patients. Therefore, at this time no evidence-based recommendations can be made regarding the use of MRI compared with CT in the ED setting. Most studies comparing CT results with MRI results in patients with TBI do not distinguish between mild TBI and more severe TBI.

Four studies were identified in which concussion patients with mild TBI can be isolated; the prevalence of abnormal MRI in these four studies ranged from 10% to 57%.^14-17 None of these studies demonstrated clear clinical relevance of these abnormal MRI scan results in patients with mild TBI, and none was conducted within a time frame relevant for ED disposition of patients.

3. In patients with mild TBI, are brain-specific serum biomarkers predictive of an acute traumatic intracranial injury?

• Level A recommendation. None specified.
• Level B recommendation. None specified.
• Level C recommendation. In mild TBI patients without significant extracranial injuries and a serum S-100B level less than 0.1 mcg/L measured within 4 hours of injury, consideration can be given to not performing a CT. (Of note: This test, however, has not yet received FDA approval for clinical use in the United States).

There are a number of brain-specific proteins that are released from neurons and from supporting cells as a result of traumatic brain injury. Enolase and tau are two examples of neuronal proteins, while S-100B, creatine kinase BB isoenzyme, and glial fibrillary acidic protein are released from astrocytes. From the above list, S-100B has been the most studied in TBI and seems to show the most promise as a biomarker for injury.

Several Class II studies have compared S-100B with head CT finding in an attempt to gauge sensitivity and specificity in conjunction with finding the proper cutoff level for the assay. Biberthaler et al. measured serum S100-B levels within 3 hours of injury in 1,309 patients with isolated mild TBI and correlated these to CT scan.¹⁸ The sensitivity of S-100B was found to be 0.99 (95% CI, 0.96 to 1.0) and the specificity 0.30 (95% CI, 0.29 to 0.31).

In a Class II study, Poli-de-Figueiredo et al. studied S-100B in 50 consecutive patients with mild TBI (2 had a GCS of 13).¹⁹ They reported a sensitivity of serum S-100B measured within 3 hours of injury to be 1.0 (95% CI, 0.8 to 1.0) and the specificity 0.²⁰ (95% CI, 0.11 to 0.35). With a higher cut-off of 0.2 mcg/L, S100-B performed similarly well.20

The studies reviewed suggest that brain specific biomarkers may have a role in determining which patients with head injury need neuroimaging. This might be of great value in resource utilization, especially in small facilities where CT is not readily available.

4. Can a patient with an isolated mild TBI and a normal neurologic evaluation result be safely discharged from the ED if a noncontrast head CT scan shows no evidence of intracranial injury?

• Level A recommendation. None specified.
• Level B recommendation. Patients with an isolated mild TBI who have a negative head CT result are at minimal risk for developing an intracranial lesion and therefore may be safely discharged from the ED. (There are inadequate data to include patients with a bleeding disorder, who are receiving anticoagulation therapy or antiplatelet therapy, or who have had a previous neurosurgical procedure in this population.)
• Level C recommendation. Mild TBI patients discharged from the ED should be informed about postconcussive symptoms.

Risk of neurologic deterioration after discharge remains of prime clinical importance. A well-designed prospective, multicenter study involving 39 hospitals and 1,292 mild TBI patients reported that, at 3-month follow-up, no patient with a negative CT developed a complication requiring hospitalization.²¹ A comprehensive literature review by af Geijerstam and Britton included more than 62,000 cases of mild TBI with a GCS of 15; only 3 patients who had a normal CT deteriorated after discharge thus supporting the safety of home discharge after normal head CT scan results.²²

The studies to date have unfortunately lacked power enough to address specific subpopulations of patients with mild TBI who may be at greater risk for delayed complications despite the initial negative head CT. These subpopulations include patients with bleeding disorders, patients on anticoagulant therapy, patients who have had previous neurosurgical procedures (e.g., ventriculoperitoneal shunt), and those with significant previous neurologic disease.

Central to ED management of all patients is delivery of good follow-up and aftercare instructions at discharge. These instructions should include both verbal and written information that is framed in an appropriate grade reading level. Up to 58% of patients with mild TBI will have some sequelae at 1 month post injury.²³ These symptoms, referred to as postconcussive symptoms, can be cognitive, affective, or somatic. Patient education regarding these symptoms provides important reassurance and may decrease symptom duration.

The research that has prompted this updated version of the clinical policy has helped to expand our knowledge and understanding of patients with mild TBI. There is a need for future collaboration within the neuroscience community on how best to define mild TBI, the role of diagnostic testing, and outcomes. Outcome studies must focus not only on identifying neuroimaging abnormalities but also on identifying risk for the development of postconcussive symptoms.

The clinical policy establishes the best evidence available for the specific critical questions addressed; however, of the five recommendations, there is only one level A recommendation. Regardless of the strength of evidence, a recommendation must always be placed in the context of a patient’s presentation and the setting where the patient is being treated.

Dr. Constantine and Dr. Jagoda are both members of ACEP’s Clinical Policies Committee, and both are practicing emergency physicians at Mount Sinai School of Medicine, New York, N.Y.

References

1. Rutland-Brown W, Langlois JA, Thomas KE, et al. Incidence of traumatic brain injury in the United States, 2003. J Head Trauma Rehabil. 2006;21:544-8.
2. Jagoda AS, Cantrill SV, Wears RL, et al. Clinical Policy: Neuroimaging and decisionmaking in adult mild traumatic brain injury in the acute setting. Ann Emerg Med. 2002;40:231-49.
3. Jagoda AS, Bazarian JJ, Bruns JJ Jr, et al. American College of Emergency Physicians and Centers for Disease Control and Prevention. Clinical policy: neuroimaging and decisionmaking in adult mild traumatic brain injury in the acute setting. Ann Emerg Med. 2008;52:714-48.
4. Kay T, Harrington D, Adams R, et al. Definition of mild traumatic brain injury. J Head Trauma Rehabil. 1993;8:86-7.
5. Centers for Disease Control and Prevention, National Center for Injury Prevention and Control. Report to Congress on Mild Traumatic Brain Injury in the United States: Steps to Prevent a Serious Public Health Problem. Atlanta, GA: Centers for Disease Control and Prevention; 2003:1-47.
6. Jennett B, Teasdale G, Galbraith S, et al. Severe head injuries in three countries. J Neurol Neurosurg Psychiatry. 1977;40:291-8.
7. Ibanez J, Arikan F, Pedraza S, et al. Reliability of clinical guidelines in the detection of patients at risk following mild head injury: results of a prospective study. J Neurosurg. 2004;100:825-34.
8. Smits M, Hunink MG, Nederkoorn PJ, et al. A history of loss of consciousness or post-traumatic amnesia in minor head injury: “condition sine qua non” or one of the risk factors? J Neurol Neurosurg Psychiatry. 2007;78:1359-64.
9. Stiell IG, Wells GA, Vandemheen K, et al. The Canadian CT Head Rule for patients with minor head injury. Lancet. 2001;357:1391-6.
10. Haydel MJ, Preston CA, Mills TJ, et al. Indications for computed tomography in patients with minor head injury. N Engl J Med. 2000;343:100-5.
11. Smits M, Dippel DW, de Haan GG, et al. External validation of the Canadian CT Head Rule and the New Orleans Criteria for CT scanning in patients with minor head injury. JAMA. 2005;294:1519-25.
12. Yates D, Chater N, Cooper P, et al, for the National Collaborative Centre for Acute Care. National Institute for Health and Clinical Excellence. Head Injury. Triage, assessment, investigation, and early management of head injury in infants, children, and adults; 2007. Available at: http://www.nice.org.uk/nicemedia/pdf/CG56NICEGuideline.pdf. Accessed Jan. 16, 2008.
13. Servadei F, Teasdale G, Merry G, for the Neurotraumatology Committee of the World Federation of Neurosurgical Societies. Defining acute mild head injury in adults: a proposal based on prognostic factors, diagnosis, and management. J Neurotrauma. 2001;18:657-64.
14. Doezema D, King J, Tandberg D, et al. Magnetic resonance imaging in mild head injury. Ann Emerg Med. 1991;20:1281-5.
15. Hofman PAM, Stapert SZ, van Kroonenburgh MJPG, et al. MR imaging, single-photon emission CT, and neurocognitive performance after mild traumatic brain injury. Am J Neuroradiol. 2001;22:441-9.
16. Hughes D, Jackson A, Mason D, et al. Abnormalities on magnetic resonance imaging seen acutely following mild traumatic brain injury: correlation with neuropsychological tests and delayed recovery. Neuroradiology. 2004;46:550-8.
17. Voller B, Benke T, Benedetto K, et al. Neuropsychological, MRI and EEG findings after very mild traumatic brain injury. Brain Injury. 1999;13:821-7.
18. Biberthaler P, Linsenmeier U, Pfeifer K-J, et al. Serum S-100B concentration provides additional information for the indication of computed tomography in patients after minor head injury. A prospective multicenter study. Shock. 2006;25:446-53.
19. Poli-de-Figueiredo LF, Biberthaler P, Filho CS, et al. Measurement of S-100B for risk classification of victims sustaining minor head injury—first pilot study in Brazil. Clinics. 2006;61:41-6.
20. Ingebrigtsen T, Romner B, Marup-Jensen S, et al. The clinical value of serum S-100 protein measurements in minor head injury: a Scandinavian multicentre study. Brain Injury. 2000;14:1047-55.
21. af Geijerstam JL, Oredsson S, Britton M. OCTOPUS Study Investigators. Medical outcome after immediate computed tomography or admission for observation in patients with mild head injury: randomised controlled trial. BMJ. 2006;333:465-571.
22. af Geijerstam JL, Britton M. Mild head injury: reliability of early head computed tomographic findings in triage for admission. Emerg Med J. 2005;22:103-7.
23. Bazarian JJ, Atabaki S. Predicting postconcussion syndrome after minor traumatic brain injury. Acad Emerg Med. 2001;8:788-95.