Abstract Objectives Silent sinus syndrome (SSS) arises from negative pressure in the maxillary sinus through occlusion of the ethmoidal infundibulum. Convexity of the surrounding bone towards the lumen and a hypoglobus can occur. It may endanger surrounding structures during endoscopic sinus surgery. This research identifies and quantifies radiological changes in inferoposterior anatomical structures associated with SSS. Study design Retrospective case series study. Setting Computed tomography and magnetic resonance imaging scans of 23 patients with SSS who were treated at the University Hospital of Zurich between 2013 and 2023 were evaluated. Methods The volume of the maxillary sinus, the orbital floor and sinus rear wall convexity, the height of the tuber maxillae, and the pterygopalatine fossa dimension were measured. The affected side was quantitatively compared with the healthy side. Results The extension of the pterygopalatine fossa and the height of the tuber maxillae were significantly larger on the affected side (mean difference = 2.354 mm, 4.99 mm; P < .01 for both). A stronger indentation of the back wall (mean difference = 3.763 mm; P < .01) and the orbital floor (mean difference = 2.268 mm; P < .01) was measured in SSS. In addition, the syndrome reduces the volume of the affected maxillary sinus (mean difference = 8.885 mL; P < .01). Conclusion SSS causes a marked enlargement of the neighbouring inferoposterior anatomical spaces. Shrinking of the sinus' volume could explain this effect. These findings have direct clinical implications, as the surgeon might inadvertently enter these structures more easily in SSS.