248 Isolated Traumatic Subarachnoid Hemorrhage on Head Computed Tomography Scan May Not Be Isolated

INTRODUCTION: Isolated traumatic subarachnoid hemorrhage (tSAH) after traumatic brain injury (TBI) on head computed tomography (CT) is often regarded as a “mild” injury, with reduced need for additional workup. However, tSAH is also a predictor of unfavorable outcomes. Magnetic resonance imaging (MRI) and blood-based biomarkers may improve the diagnosis of concurrent intracranial injury. METHODS: The prospective, 18-center Transforming Research and Clinical Knowledge in Traumatic Brain Injury study enrolled patients presenting to ED within 24 hours (h) of TBI who received a clinically-indicated head CT. A subset underwent venipuncture within 24h for plasma glial fibrillary acidic protein (GFAP) analysis, and 2-week research MRI. Participants aged = 17-years with GCS 13-15, isolated tSAH on initial CT, GFAP, and MRI data were analyzed. RESULTS: In 57 patients, median age was 46.0-years [quartile 1 to 3 (Q1-Q3): 34-57] and 53% were male. At ED disposition, 12.3% were discharged home, 61.4% admitted to hospital ward, and 26.3% to intensive care.MRI identified additional traumatic intracranial lesions in 45.6% of patients (1 type: 31.6%; 2 types: 14.0%); of these, 65.4% had axonal injury, 42.3% subdural hematoma, and 23.1% contusion. GFAP levels were higher in patients with additional MRI lesions (median: 630.6-pg/ml, Q1-Q3: [172.4-941.2] vs. 226.4 [105.8-436.1], p = 0.049), and correlated with axonal injury severity (none: median 226.7 [109.6-435.1], traumatic axonal injury: 716.3 [304.0-892.3], diffuse axonal injury: 873.2 [407.2-1321.4], p = 0.034). CONCLUSIONS: Isolated tSAH on head CT is insufficient to rule out additional traumatic injuries in GCS 13-15 TBI. Forty-six percent of patients had additional traumatic lesions on MRI. Plasma GFAP may be an important biomarker for the identification of additional injuries, including axonal injury. Patients with isolated tSAH on CT may require close clinical surveillance and follow-up.