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Silent Sinus Syndrome

Summary

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  • Chronic maxillary sinus atelectasis causing enophthalmos and facial asymmetry
  • Characterised by painless, spontaneous collapse of the maxillary sinus
  • Diagnosis based on clinical presentation and distinctive imaging findings1

Pathophysiology

  • Chronic hypoventilation of the maxillary sinus due to ostial obstruction
  • Negative pressure within the sinus leads to:
    • Resorption of sinus contents
    • Inward bowing of sinus walls
    • Downward displacement of the orbital floor
  • Exact etiology remains unclear, but may involve:
    • Congenital anatomical variations
    • Chronic sinusitis
    • Previous sinus surgery

Demographics

  • Typically affects adults in their 3rd to 5th decades of life
  • No gender predilection
  • Rare condition, with limited epidemiological data available

Diagnosis

  • Clinical presentation:
    • Painless, gradual enophthalmos
    • Facial asymmetry
    • Deepening of the superior sulcus
    • Hypoglobus
  • Often asymptomatic or minimally symptomatic
  • Absence of significant sinonasal symptoms

Imaging

  • CT scan is the gold standard for diagnosis
    • Unilateral opacification and volume loss of the maxillary sinus
    • Inward bowing of sinus walls (lateral, superior, and medial)
    • Downward displacement of the orbital floor
    • Widening of the middle meatus
    • Lateralization of the uncinate process
  • MRI:
    • May show T2 hypointensity within the affected sinus
    • Useful for evaluating orbital soft tissues

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  • An incidental finding was a small volume fluid filled maxillary sinus.
  • The walls of the maxillary sinus were normally formed with no evidence of prior trauma.
  • The floor of the orbit was depressed, with compensatory enlargement of the orbit.
  • There was a hypoglobus of 2 mm.

Treatment

  • Endoscopic maxillary antrostomy to re-ventilate the sinus, ± orbital floor reconstruction. The triad of an opacified, contracted maxillary sinus with a depressed orbital floor and enophthalmos is diagnostic

Differential diagnosis

Differential Diagnosis Differentiating Feature
Chronic sinusitis Thickened sinus mucosa with air-fluid level; sinus volume normal; no progressive reduction in sinus volume or enophthalmos
Orbital floor fracture Visible fracture line on CT; associated soft tissue herniation or entrapment; no reduction in sinus volume
Granulomatosis with polyangiitis (GPA) Destructive sinonasal lesions with bone destruction; soft tissue masses in sinuses; septal perforation
Orbital tumour Solid mass within the orbit causing proptosis rather than enophthalmos; no sinus collapse
Osteomyelitis Bone destruction with periosteal reaction and soft tissue swelling; no inward retraction of sinus walls
Mucocele Expansile lesion with outward bowing of sinus walls; often associated with proptosis rather than enophthalmos
Fibrous dysplasia Ground-glass appearance of bone on CT; expanded rather than contracted sinus; typically involves multiple bones
Metastatic disease Multiple lytic lesions throughout skull base and facial bones; no pattern of sinus contraction

  1. Pula et al. Silent sinus syndrome. 2014. Current opinion in ophthalmology - Open in new tab. ↩