ABSTRACT
Isolated traumatic subarachnoid hemorrhage (tSAH) after traumatic brain injury (TBI) on head computed tomography (CT) scan is often regarded as a "mild" injury, with reduced need for additional workup. However, tSAH is also a predictor of incomplete recovery and unfavorable outcome. This study aimed to evaluate the characteristics of CT-occult intracranial injuries on brain magnetic resonance imaging (MRI) scan in TBI patients with emergency department (ED) arrival Glasgow Coma Scale (GCS) score 13-15 and isolated tSAH on CT. The prospective, 18-center Transforming Research and Clinical Knowledge in Traumatic Brain Injury Study (TRACK-TBI; enrollment years 2014-2019) enrolled participants who presented to the ED and received a clinically-indicated head CT within 24 hours (h) of TBI. A subset of TRACK-TBI participants underwent venipuncture within 24h for plasma glial fibrillary acidic protein (GFAP) analysis, and research MRI at 2-weeks post-injury. In the current study, TRACK-TBI participants aged ≥17 years with ED arrival GCS 13-15, isolated tSAH on initial head CT, plasma GFAP level, and 2-week MRI data were analyzed. In 57 participants, median age was 46.0 years [quartile 1 to 3 (Q1-Q3): 34-57] and 52.6% were male. At ED disposition, 12.3% were discharged home, 61.4% were admitted to hospital ward, and 26.3% to intensive care unit. MRI identified CT-occult traumatic intracranial lesions in 45.6% (26 of 57 participants; 1 additional lesion type: 31.6%; 2 additional lesion types: 14.0%); of these 26 participants with CT-occult intracranial lesions, 65.4% had axonal injury, 42.3% had subdural hematoma, and 23.1% had intracerebral contusion. GFAP levels were higher in participants with CT-occult MRI lesions compared to without (median: 630.6 pg/ml, Q1-Q3: [172.4-941.2] vs. 226.4 [105.8-436.1], p=0.049), and were associated with axonal injury (no: median 226.7 pg/ml [109.6-435.1], yes: 828.6 pg/ml [204.0-1194.3], p=0.009). Our results indicate that isolated tSAH on head CT is often not the sole intracranial traumatic injury in GCS 13-15 TBI. Forty-six percent of patients in our cohort (26 of 57 participants) had additional CT-occult traumatic lesions on MRI. Plasma GFAP may be an important biomarker for the identification of additional CT-occult injuries, including axonal injury. These findings should be interpreted cautiously given our modest sample size and await validation from larger studies.
ABSTRACT
CONTEXT: Excessive use of medical imaging increases health care costs and exposure to ionizing radiation (a potential carcinogen) without yielding significant benefits to all patients. OBJECTIVE: To determine whether there has been a change in the prevalence of emergency department visits for injury-related conditions for which computed tomography (CT) or magnetic resonance imaging (MRI) was obtained and whether there has been a change in the diagnosis of life-threatening conditions and patient disposition. DESIGN, SETTING, AND PARTICIPANTS: Retrospective cross-sectional analysis of emergency department visits using data from the National Hospital Ambulatory Medical Care Survey (1998-2007). Sampled visits were weighted to produce estimates for the United States. MAIN OUTCOMES MEASURES: Proportion of visits for injury-related conditions during which a CT or MRI was obtained, a life-threatening condition was diagnosed (eg, cervical spine fracture, skull fracture, intracranial bleeding, liver and spleen laceration), and which resulted in hospital and intensive care unit admission. RESULTS: The prevalence of CT or MRI use during emergency department visits for injury-related conditions increased from 6% (95% confidence interval [CI], 5%-7%) (257 of 5237 visits) in 1998 to 15% (95% CI, 14%-17%) (981 of 6567 visits) in 2007 (P < .001 for trend). There was a small increase in the prevalence of life-threatening conditions (1.7% [95% CI, 1.2%-2.2%; 89 of 5237 visits] in 1998 and 2.0% [95% CI, 1.6%-2.5%; 142 of 6567 visits] in 2007; P=.04 for trend) [corrected].There was no change in prevalence of visits during which patients were either admitted to the hospital (5.9% [95% CI, 4.9%-6.9%] in 1998 and 5.5% [95% CI, 4.7%-6.5%] in 2007; P = .50 for trend) or to an intensive care unit (0.62% [95% CI, 0.40%-1.00%] in 1998 and 0.80% [95% CI, 0.53%-1.21%] in 2007; P = .14 for trend). Visits during which CT or MRI was obtained lasted 126 minutes (95% CI, 123-131 minutes) longer than those for which CT or MRI was not obtained. CONCLUSION: From 1998 to 2007, the prevalence of CT or MRI use during emergency department visits for injury-related conditions increased significantly, without an equal increase in the prevalence of life-threatening conditions.
