Frontal sinus volume predicts incidence of brain contusion in patients with head trauma.

Background: The function of the paranasal sinuses is a topic of debate. One hypothesis suggested has been that sinuses act as a "crumple zone," serving to protect the contents of the head from impact. In this study, we examine the interactions of the frontal sinus and the brain in the setting of head trauma. Our formal hypothesis is that frontal sinus volume is less in head trauma patients with contusion than in head trauma patients without contusion.

Methods: Computed tomographic (CT) scans of patients who sustained blunt head trauma performed at the University of Pittsburgh Medical Center from 2007 to 2012 were reviewed retrospectively. Inclusion criteria were presence of blunt trauma and complete brain and maxillofacial CT scan. Exclusion criteria included patients with incomplete imaging, imaging unrelated to trauma, previous cranial injury, and penetrating trauma.With the use of maxillofacial CT scans, height, depth, and width were measured, and a cubical approximation of volume was determined for each frontal sinus. Presence of frontal sinus fracture was considered an indicator of high-impact trauma. Grading of brain contusion severity was performed using head CT scans. A scale of 0 to 5 was used based on the Marshall Criteria.Categorical data were analyzed using the χ(2) or Fisher's exact test. Continuous data were analyzed using Student's t test or analysis of variance. p < 0.05 was considered statistically significant.

Results: Among patients with frontal sinus fracture, the average sinus volume of those without contusion was 32.72 mL, while the average sinus volume of those with brain contusion was 21.85 mL (p = 0.023). Thus, the volume of the frontal sinuses was 33% less in patients with contusion than in patients without contusion.

Conclusion: Our study supports the theory that the frontal sinuses impart a protective advantage against frontal brain contusion. The dynamics of head injury and force distribution during trauma may be the basis for more advanced protective devices.

Level Of Evidence: Prognostic study, level III.