Head trauma adds little to early neutrophil surge in polytrauma patients, study finds

Severely injured patients who also suffer a traumatic brain injury show no greater activation of circulating neutrophils in the first moments after trauma than equally badly injured patients whose brains are spared, according to a prospective observational study published in Acta Neurochirurgica. The finding challenges the assumption that brain injury acts as an additional, immediate trigger for the systemic inflammatory response that follows major trauma.

They enrolled adult polytrauma patients with an Injury Severity Score of at least 16, a threshold defining severe injury across multiple body regions.

The cohort comprised 46 patients with a median Injury Severity Score of 34 and a mean age of 53.9 years, indicating injuries of substantial severity. Patients were compared according to the presence of traumatic brain injury. Admission leukocyte counts did not differ between the groups, nor did absolute neutrophil counts or the neutrophil-to-lymphocyte ratio, a widely used index of inflammatory stress. The statistical comparisons showed no significant differences for any of these measures.

The surface receptor results were equally unambiguous. Expression of CD11b, an adhesion and complement receptor whose upregulation marks neutrophil priming, showed no significant difference between patients with and without brain injury. The same held for CD16, part of the receptor for the Fc portion of IgG antibodies; CD62L, a selectin adhesion molecule that is shed when neutrophils are activated; CD10, an ectoenzyme associated with mature neutrophils; and CD64, the high-affinity IgG receptor that appears on neutrophils during inflammatory activation. None of the five markers separated the two patient groups.

The investigators then probed whether the burden of brain injury itself, rather than its mere presence, shaped the neutrophil response. Surface marker expression did not differ across categories of the Glasgow Coma Scale, the standard clinical grading of consciousness after head trauma, and none of the investigated markers showed a significant association with the severity of cranial injury. The team also examined whether early neutrophil characteristics predicted later complications, but found no association between the measured markers and the subsequent development of delirium in these patients.

The authors draw two possible interpretations from these results. One is that the immediate peripheral neutrophil response predominantly reflects the overall trauma burden, the total destructive force of the accident on the body, rather than the presence of a brain injury. The other is that traumatic brain injury does contribute to neutrophil activation, but only at a later timepoint, because the blood-brain barrier, the tightly sealed endothelial layer that normally keeps brain tissue and blood apart, is still intact at the moment of admission.

The study’s design carries clear strengths and boundaries. Yet the cohort of 46 patients is modest, all comparisons are cross-sectional at a single early timepoint, and the reported differences were tested for statistical significance rather than proven to be absent with certainty. The authors state explicitly that longitudinal studies are required to determine whether TBI-specific immune alterations emerge during later phases after injury.

Subject of Research: Early systemic neutrophil activation in polytrauma patients with and without traumatic brain injury

Article Title: Traumatic brain injury is not a major driver of early systemic neutrophil activation in polytrauma patients

Article References: Hübner, C. T., Benkendorff, G., Wohlgemuth, J., Klingebiel, F. K.-L., de Fraiture, E., Isenmann, K., Staartjes, V. E., Herzog, A., Shehu, A., Hietbrink, F., Brands, S., Pfeifer, R., Pape, H.-C., & Teuben, M. P. J. (2026). Traumatic brain injury is not a major driver of early systemic neutrophil activation in polytrauma patients. Acta Neurochirurgica. https://doi.org/10.1007/s00701-026-07077-x

Image Credits: AI Generated

DOI: 10.1007/s00701-026-07077-x

Keywords: traumatic brain injury, polytrauma, neutrophils, flow cytometry, systemic inflammation, Injury Severity Score, blood-brain barrier, post-traumatic delirium, CD11b, CD64, prospective observational study, emergency medicine