Chronic maxillary atelectasis is an infrequent entity and data on its prevalence are lacking. This study investigated the prevalence of chronic maxillary atelectasis and aimed to determine the bilaterality of this entity.

The data for 5835 patients who underwent paranasal sinus computed tomography from 2016 to 2020 were retrospectively analysed.

Fifty-four patients were diagnosed with chronic maxillary atelectasis; its prevalence was 0.92 per cent. The mean age of these 54 patients was 42.98 ± 18.89 years (range, 18–85 years); 17 of the patients were female and 37 were male. Chronic maxillary atelectasis was unilateral in 42 patients and bilateral in 12 patients (22.2 per cent). Eight patients were found to have enophthalmos with apparent facial asymmetry.

The prevalence of bilateral chronic maxillary atelectasis may be higher than previously reported and bilaterality may increase as the number of diagnosed cases increases. A unified classification is also proposed, which describes the silent sinus syndrome as chronic maxillary atelectasis IIIS.

We describe a previously unreported case of ethmoid silent sinus syndrome.

Case report and review of the world literature regarding silent sinus syndrome.

A 33-year-old woman developed medial displacement of the left orbital contents in the absence of trauma, surgery or other significant pathology. Imaging showed opacification of the left ethmoid sinus and implosion of the medial orbital wall. Previously reported cases of silent sinus syndrome have all involved the maxillary sinus, with subsequent implosion of the orbital floor. Computed tomography scans of our patient showed wide, flat ethmoidal bulla and surrounding cells, with few horizontal bony septae reinforcing the area of collapse.

This case represents the first report of ethmoid silent sinus syndrome. We argue that, in anatomically susceptible individuals, the silent sinus syndrome can present due to chronic ethmoidal sinusitis.