Computed tomography exclusion of osseous paranasal sinus injury in blunt trauma patients: The “clear sinus” sign

Purpose: This prospective study was designed to assess the association of clear paranasal sinuses (no free fluid) as shown by facial computed tomography (CT) with the absence of fractures involving the paranasal sinus walls. Patients and Methods: All facial CT scans performed during a 12-month period to rule out maxillofacial injury in blunt trauma patients were reviewed. The scans were made using 5-mm slice thickness and 4-mm table incrementation. They were assessed for the presence or absence of free paranasal sinus fluid (hemorrhage) and the presence and location of facial fractures. Results: A total of 366 CT scans of the face were performed during the study. Among them, 180 scans (49%) were identified that showed no evidence of free paranasal fluid. Twenty-two (12%) of these 180 CT studies showed isolated nasal fractures (n = 13) orzygomatic arch fractures (n = 9). No patient without free paranasal sinus fluid had any midfacial fracture involving a paranasal sinus wall ( P < .001 by Fischer exact test). Conclusion: The absence of free paranasal sinus fluid after facial trauma is a highly reliable criterion to exclude fractures involving the paranasal sinus walls. Other fractures involving osseous structures not contiguous with the paranasal sinus walls, such as nasal or zygomatic arch fractures, are not excluded. The CT “clear sinus” sign is a simple, rapid method to exclude paranasal sinus fractures.