Objective To describe the radiographic findings in chronic maxillary atelectasis and analyse the volume changes of the affected maxillary sinus, orbit, nasal vault and infratemporal fossa.

Methods Case series of all patients with diagnosis of chronic maxillary atelectasis presenting between January 2000 and August 2012 who underwent full oculoplastic and orbital evaluation including standardised photography and CT or MRI. Two-dimensional imaging features and volumetric changes were assessed. Affected and unaffected sides were compared. Demographic data, clinical presentation, Hertel measurements, photographic and radiological findings were analysed.

Results 22 patients (64% men) met the inclusion criteria. Mean relative enophthalmos was 2.1 mm and mean hypoglobus was 1.8 mm. The most common radiographic findings were sinus opacification (91%), uncinate process retraction/middle meatus increase (91%), orbit enlargement (100%), ipsilateral septum deviation (64%) and infratemporal fossa fat enlargement (100%). Infratemporal fossa fat area and volume were significantly larger in the affected side (p<0.01). Additionally, ipsilateral orbit (p<0.01) and nasal vault volume (p<0.01) were similarly increased. Maxillary sinus volume correlated significantly only with infratemporal fossa fat enlargement (p<0.05).

Conclusions There is a significant increase in the infratemporal fossa fat, nasal and orbital volume corresponding to a decrease in maxillary sinus size in chronic maxillary atelectasis. Chronic maxillary atelectasis is associated with redistribution of volume between the maxillary sinus and the surrounding infratemporal fossa, orbit and nasal cavity.