The imploding antrum: An unusual case of nontraumatic painless enophthalmos.

The imploding antrum or silent sinus syndrome is a rare phenomenon that presents with spontaneous painless enophthalmos and hypoglobus. It occurs due to ipsilateral maxillary antral atelectasis secondary to asymptomatic obstructive chronic sinus mucosal disease. Ophthalmologists, otorhinolaryngologists, and radiologists must be aware of this entity. This article illustrates the typical presentation in a 17-year-old male with unilateral ptosis and a deep superior sulcus, and characteristic imaging findings of ipsilateral increased orbital volume and depression of the orbital floor, maxillary sinus opacification and atelectasis with retraction of the posterolateral and medial walls, lateralization of the uncinate process, and obstruction of the ostiomeatal unit. This is probably the first time that the syndrome is being reported in such a young person. The pathogenesis, differential diagnosis, and treatment modalities of this entity are also reviewed.