Study Objective: US emergency departments treat 1.5 million cases of traumatic brain injury (TBI) annually. There is currently no method of determining which patients will recover from TBI and which will have persistent symptoms. A noninvasive marker of injury severity would be invaluable in addressing this ongoing public health issue. Microparticles (MP), 0.1-1um anucleoid vesicles derived from the membrane of different cell types, have the potential to fill this need. Methods: Prospective cohort study of patients evaluated at an urban level-I trauma center and referral center. Inclusion criteria: Age > 18, Age < 80, within 8 hours of new TBI, as demonstrated by a out-of-hospital Glasgow Coma Score (GCS) of 3-8 (severe TBI [sevTBI]) or 9-13 (moderate TBI [modTBI]) and only minor associated injuries (Abbreviated Injury Score [AIS] ≤2). Patients outside of the age range, those with severe multi-trauma (any area with AIS > 2), GCS ≥ 14, or pre-existing comorbidities and diagnoses that affect MP expression (eg, shock, ARDS, renal failure) were excluded. Each sample was refined from whole venous blood taken on arrival to the hospital and then 24 and 48 hours later. The resulting serum was centrifuged and MP concentration measured using flow cytometry. A repeated measure ANOVA was used to determine differences between cases and controls. Pearson coefficient was used to show the time-dependent release of MP. Subjects (or their legal representative) provided consent per our institutional review board approved protocol. Results: Thirteen patients (64% male, mean=47.7±18.1 years) with TBI (out-of hospital GCS =9.4±4.6) and 10 controls were enrolled. Injury mechanisms included falls (54%), motor vehicle crashes (38%), and pedestrian-struck (8%). Most patients had multiple injuries on computed tomography (CT) head: subarachnoid (77%) and/or subdural hemorrhage (38%), intraparenchymal contusion (23%), epidural hematoma (8%), and diffuse axonal injury (8%). The average log10 MP concentration on admission of patients with TBI was significantly higher than healthy controls (mean=3.36±0.51 vs 2.81±0.27, P = .027, Figure), including subgroups with modTBI (mean=3.40±0.52, P = .018) and sevTBI (mean=3.33±0.54, P = .029). The MP concentrations of the patients at 24 (mean=3.68±1.42, P = .13) and 48 hours (mean=3.08±1.32, P = .72) after admission were not significantly different from controls. There was a moderately strong correlation between the time to the first blood draw after injury and MP concentration (r=0.621, P = .055). Conclusions: MP concentration is increased in patients with new TBI compared to uninjured controls. MP concentration also increased with time after the injury, suggesting a time-dependent release of MP after TBI. (Figure Presented).
Dezman, Z. D. W., Browne, D. R., Yang, M., Stein, D. M., Thom, S. S., & Tran, Q. K. (2015). 344 Serum Microparticle Concentration: A Novel Marker of Moderate and Severe Traumatic Brain Injury. Annals of Emergency Medicine, 66(4), S124. https://doi.org/10.1016/j.annemergmed.2015.07.380