RESUMO
BACKGROUND: Maxillary sinus hypoplasia (MSH), associated with enophthalmos and hypoglobus in the silent sinus syndrome (SSS), is a poorly studied condition. The real incidence of MSH and SSS in the adult population is not known. Our study aims at estimating the radiological prevalence of MSH and identifying undiagnosed cases of SSS in a retrospective cohort. METHODS: A cross-sectional retrospective cohort study was performed in adults, without a history of maxillofacial surgery or trauma, undergoing head CT scans. A radiological database of 1012 consecutive scans was reviewed independently by two authors to identify patients with signs of MSH and SSS and associated findings (septal deviation, uncinate deviation, concha bullosa, sinus opacification, bony rarefaction, and pterygopalatine fossa enlargement). The findings of MSH and SSS were compared with radiological reports. RESULTS: 891 eligible CT scans were analyzed. MSH and SSS prevalences were 6.17% (n = 55) and 0,56% (n = 5), respectively. The maxillary sinus was normally or partially ventilated in 96.36% of MSH patients. Lateralization of the uncinate process was detected in about 50% of MSH patients, while a septal deviation towards the affected sinus was detected in 21.82%. In 20% of MSH scans, a concha bullosa was identified. Radiological reports identified a single MSH case. CONCLUSIONS: Our study confirmed the literature data on MSH prevalence, while it determined a precedently unknown prevalence for SSS, underestimated in the radiology reports. This prevalence needs further confirmation but suggests a routine accurate comparison of both maxillary sinuses in CT scans.