1

Introduction

Silent sinus syndrome is a clinical syndrome defined as progressive enophthalmos and hypoglobus secondary to maxillary sinus collapse with chronic hypoventilation. It is believed that the syndrome’s pathophysiology involves chronic negative pressure resulting from obstruction of the maxillary sinus ostium. In turn, atelectasis of the maxillary sinus pulls the orbital floor inferiorly and can affect ocular motor function and aesthetics. Patients often present with symptoms of facial asymmetry and diplopia . Physical examination often reveals orbital asymmetry, deepening of the superior sulcus, sinking or pulling sensation of the eye, lid lag or nasal shift toward the affected sinus.

Diagnosis is confirmed with imaging that demonstrates a loss of maxillary sinus volume, typically best seen with computed tomography (CT) . The critical finding is inward retraction of the sinus walls with downward retraction of the orbital floor. Sinus wall bone resorption is also frequently noted. The differential diagnosis includes chronic sinusitis, which does not produce the same contraction of the sinus . It has previously been asserted that the diagnosis of silent sinus syndrome requires exclusion of chronic sinusitis, otherwise the term chronic maxillary atelectasis should be used . However, this distinction has not clearly persisted. An increase in infratemporal fossa fat has also been noted in silent sinus syndrome, likely secondary to remodeling of the posterior maxillary sinus wall. An increase in the nasal and orbital volumes is another common finding.

Given the uncommon nature of silent sinus syndrome, optimal surgical management has not been clearly established. Specifically, the necessity for and timing of orbital reconstruction remain an open clinical question. Overall enophthalmos resolution rates are also unclear and may depend on disease variation not yet measured.

2

Case reports

A 27-year-old attorney presented to the otolaryngology clinic describing symptoms of chronic sinusitis with recurrent acute exacerbations. Previously she had reported chronic congestion and exacerbations with bilateral facial pressure and increased postnasal drainage and congestion. During these episodes, she also experienced anosmia and sore throat. Her exacerbations frequently followed upper respiratory infections. She had been previously treated with guaifenesin, fexofenadine, as well as fluticasone and mometasone nasal sprays. She also received azithromycin and sulfamethoxazole/trimethoprim for exacerbations of her symptoms. Her past medical history was significant for anemia, migraines and hypothyroidism, and she was a non-smoker. On physical examination, she had deepening of the superior sulcus of the orbit on the right-side and corresponding enophthalmos.

A CT scan ( Figs. 1 A and 2 A ) demonstrated partial opacification of the left maxillary sinus with mucosal thickening ethmoid sinuses bilaterally. The right maxillary sinus was completely opacified and there was inferior displacement of the right orbital floor and subsequent expansion of the bony orbit. The uncinate process was also lateralized. Remodeling of the posterolateral aspect of the maxillary sinus as well as low-density soft tissue enlargement of the inferotemporal fossa in this region were noted. On the basis of her clinical and radiographic findings, the patient was diagnosed with atelectatic maxillary sinus.

(A) Initial axial CT demonstrating loss of right maxillary sinus volume with complete opacification and partial opacification of the left maxillary sinus. Arrow indicates anterior bowing of the posterior wall of the right maxillary sinus. Pterygopalatine fat fills volume created by the anterior displacement of the bone. (B) Repeat axial CT scan 5 months after operation showing resolution of the anterior bowing of the posterior lateral wall of the right maxillary sinus.

(A) Initial coronal CT demonstrating loss of right maxillary sinus volume and mucosal thickening of the ethmoid sinuses bilaterally. Arrow indicating orbital wall bone resorption. (B) Repeat coronal CT scan 5 months after surgery. Arrowhead demonstrates new bone formation along the inferomedial orbit.

On 2/8/08, she underwent bilateral endoscopic sinus surgery including bilateral maxillary antrostomies. The uncinate process on the right side was noted to be atelectatic, and the right orbital floor was inferiorly displaced with rarefaction of the bone. A backbiter was used to remove the inferior aspect of the atelectatic uncinate process. This allowed visualization of thick mucus extruding through the natural ostium of the maxillary sinus. The antrostomy was enlarged posteriorly and inferiorly with care not to injure the inferiorly displaced orbital floor. Palpation of the globe confirmed absence of bone along the inferomedial aspect of the orbit. Although the maxillary sinus was full of thick cloudy mucus; no pathologic bacteria were identified on culture.

Following surgery, the patient noted persistent, mild right-sided enophthalmos. Because of these cosmetic concerns, she decided to undergo evaluation with an oculoplastic surgeon for consideration of placement of an orbital implant to improve her enophthalmos. Although her appearance improved while awaiting her appointment, she did follow through with a CT scan ordered as part of her evaluation. Her CT scan ( Figs. 1 B and 2 B) 5 months after her operation (7/8/2009) showed remarkable resolution of the anterior bowing of the posterior wall of the right maxillary sinus. Her right maxillary sinus appeared normal in contour and without significant mucosal disease. The previously noted rarefied bone along the inferomedial orbit demonstrated significant remodeling with layering of new bone in this region. The patient decided not to pursue orbital surgery.