Of the estimated 1.7 million people suffering head trauma per year in the United States, approximately 90% will suffer from mild (or minor) traumatic brain injury (TBI) (Harnan). Mild TBI is defined as head injury with a history of loss of consciousness, amnesia, or disorientation with a Glasgow Coma Scale score of 12-15 (Stiell). A majority of these patients will not require neurosurgical intervention, and several decision rules exist to determine when initial diagnostic imaging is appropriate in this population.
A 2011 meta-analysis of leading decision rules by Harnan et al evaluated 19 studies assessing the validity of 25 decision rules (1). Some of the most prominent and heavily tested rules include the Canadian CT Head Rule (CCHR), the New Orleans Criteria (NOC), the National Emergency X-Radiography Utilization Study II (NEXUS II), and the National Institute for Health and Clinical Excellence guidelines (NICE). The CCHR consistently demonstrated the highest sensitivity for mild TBI requiring neurosurgical intervention, with specificity superior to the others evaluated (sensitivity 0.99-1.00, specificity 0.37-0.77 over five studies).
A 2011 meta-analysis of leading decision rules by Harnan et al evaluated 19 studies assessing the validity of 25 decision rules (1). Some of the most prominent and heavily tested rules include the Canadian CT Head Rule (CCHR), the New Orleans Criteria (NOC), the National Emergency X-Radiography Utilization Study II (NEXUS II), and the National Institute for Health and Clinical Excellence guidelines (NICE). The CCHR consistently demonstrated the highest sensitivity for mild TBI requiring neurosurgical intervention, with specificity superior to the others evaluated (sensitivity 0.99-1.00, specificity 0.37-0.77 over five studies).
from Stiell et al. The Canadian CT Head Rule for patients with minor head injury. The Lancet. May 5;357(9266):1391-6.
Evidence based guidelines for the use of follow up CT imaging beyond the initial work up of mild TBI have not been developed, and standardized criteria have not been adopted on a nationwide level. The historical standard of care has been to obtain a routine follow up scan, usually about 24 hours after the first (AbdelFattah). Recent retrospective studies have been performed to determine the utility of these follow up scans, and to evaluate if their results altered the clinical course or determination to pursue neurosurgical intervention. Several have suggested the repeat scans alone, in the setting of unchanged neurological status, rarely alter care (Stippler, Almenawer).
A 2012 prospective cohort study divided 145 patients presenting to a Level I trauma center with mild TBI, GCS 13-15, and intracranial hemorrhage not requiring immediate intervention into two study groups (Abdelfattah). One group (n=92) received routine, scheduled repeat head CT within 24 hours regardless of their neurological status (ROUTINE group). The second group (n=53) was to selectively receive repeat CT only if warranted by changes in neurologic status (SELECTIVE group). The study found that the routine CT group received more imaging per patient, had longer ICU and total hospital stays, and did not have a statistically significant difference in mortality and GCS. The authors note that performing one routine follow up CT often led to a need for additional follow up scans to monitor injury that continue to progress radiographically but without clinical progression requiring intervention.
Evidence based guidelines for the use of follow up CT imaging beyond the initial work up of mild TBI have not been developed, and standardized criteria have not been adopted on a nationwide level. The historical standard of care has been to obtain a routine follow up scan, usually about 24 hours after the first (AbdelFattah). Recent retrospective studies have been performed to determine the utility of these follow up scans, and to evaluate if their results altered the clinical course or determination to pursue neurosurgical intervention. Several have suggested the repeat scans alone, in the setting of unchanged neurological status, rarely alter care (Stippler, Almenawer).
A 2012 prospective cohort study divided 145 patients presenting to a Level I trauma center with mild TBI, GCS 13-15, and intracranial hemorrhage not requiring immediate intervention into two study groups (Abdelfattah). One group (n=92) received routine, scheduled repeat head CT within 24 hours regardless of their neurological status (ROUTINE group). The second group (n=53) was to selectively receive repeat CT only if warranted by changes in neurologic status (SELECTIVE group). The study found that the routine CT group received more imaging per patient, had longer ICU and total hospital stays, and did not have a statistically significant difference in mortality and GCS. The authors note that performing one routine follow up CT often led to a need for additional follow up scans to monitor injury that continue to progress radiographically but without clinical progression requiring intervention.
Given concerns about excessive cost and radiation exposure associated with routine head CT reimaging in mild TBI, the results of the Abdelfattah et al study, and other research yielding similar conclusions, may help to direct physicians away from scheduling repeat CTs in the setting of unchanged neurological status. Perhaps consensus guidelines will follow.
Sources:
1. Harnan SE, Pickering A, Pandor A, and Goodacre SW. Clinical decision rules for adults with minor head injury: a systematic review. J Trauma. July 2011;71(1):245-51.
2. Stiell IG, Wells GA, Vendemheen K et al. The Canadian CT Head Rule for patients with minor head injury. The Lancet. May 5 2001;357(9266):1391-6.
3. AbdelFattah KR, Eastman AL, Aldy KN et al. A prospective evaluation of the use of routine repeat cranial CT scans in patients with intracranial hemorrhage and GCS score of 13 to 15. Journal of Trauma and Acute Care Surgery. Sept 2012;73(3):685-8.
4. Stippler M, Smith C, McLean AR et al. Utility of routine follow-up head CT scanning after mild traumatic brain injury: a systematic review of the literature. Emerg Med J. 2012 Jul;29(7):528-32.
5. Almenawer SA, Bogza I, Yarascavitch B et al. The value of scheduled repeat cranial computed tomography after mild head injury; single-center series and meta-analysis. Neurosurgery. 2013 Jan;72(1):56-62.
Submitted by Ben Savage, MS4
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