Head and Neck ImagingAtelectasis, of the maxillary sinus
(also called silent
sinus syndrome), volume loss of the maxillary
sinus, leading to enophthalmos and sometimes facial asymmetry.
Obstruction of the
ostiomeatal unit and more specifically the
ethmoid infundibulum is the common factor in these cases; impaired
sinus ventilation with a build-up of negative pressure and inward collapse of the thin orbital floor (and sometimes also the other maxillary walls) is thought to be the mechanism (
Fig.1). Treatment of the underlying sinonasal disease is needed to prevent enophthalmos recurring; in a number of cases reconstruction of the orbital floor is also required. Radiographically this condition has to be differentiated from hypoplasia of the
maxillary sinus, showing on the affected side a smaller maxillary
sinus with a somewhat lower position of the orbital floor; however, in such cases maxillary pneumatization is incomplete (no penetration of
sinus pneumatization into the maxillary ridge and malar eminence).
Partial collapse of the maxillary sinus is commonly seen after a Caldwell Luc procedure, but this does not usually lead to cosmetic deformity.
RH
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Patient presenting with progressive facial deformity. Axial T2-weighted MR image (a) shows inflammatory changes in the left maxillary sinus, with retraction of its anterior and posterolateral walls. The coronal T1-weighted image (b) also shows inferior displacement of the orbital floor; enophthalmia was not present in this patient.
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Atelectasis, of the maxillary sinus, Fig.1 (a) | | Atelectasis, of the maxillary sinus, Fig.1 (b) | |