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 Table of Contents  
Year : 2016  |  Volume : 28  |  Issue : 1  |  Page : 30-33

Silent sinus syndrome: An imploding antrum syndrome

1 Department of Oral Medicine and Radiology, Chhatrapati Shahu Maharaj Shikshan Sanstha Dental College and Hospital, Aurangabad, India
2 Department of Anesthesiology, Padmashree Dr. Vitthalrao Vikhe Patil Foundation's Medical College and Hospital, Ahmednagar, Maharashtra, India

Date of Web Publication8-Sep-2016

Correspondence Address:
Sneha H Choudhary
B/9, Annapurna Girls Hostel, Near Chhatrapati Shahu Maharaj Shikshan Sanstha Dental College and Hospital, Kanchanwadi, Aurangabad - 431 002, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0972-1363.189994

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Silent sinus syndrome (SSS) is a rare entity that is associated with spontaneous, painless, unilateral enophthalmos and hypoglobus resulting from downward bowing of the orbital floor in the absence of any symptomatic sinonasal disease. The diagnosis is suspected clinically, but it is confirmed radiologically by its characteristic imaging features that include maxillary sinus outlet obstruction, sinus opacification and sinus volume loss caused by inward retraction of the sinus walls. The purpose of this article is to acquaint the reader with the clinical and imaging features of the SSS, along with a brief discussion about its pathogenesis and treatment, which is relatively unknown among oral and maxillofacial radiologists.

Keywords: Chronic maxillary atelectasia, enophthalmos, hypoglobus, imploding antrum syndrome, silent sinus syndrome

How to cite this article:
Choudhary SH, Kale L, Mishra SS, Choudhary AK. Silent sinus syndrome: An imploding antrum syndrome. J Indian Acad Oral Med Radiol 2016;28:30-3

How to cite this URL:
Choudhary SH, Kale L, Mishra SS, Choudhary AK. Silent sinus syndrome: An imploding antrum syndrome. J Indian Acad Oral Med Radiol [serial online] 2016 [cited 2022 Dec 6];28:30-3. Available from: http://www.jiaomr.in/text.asp?2016/28/1/30/189994

   Introduction Top

In 1964, the first case of maxillary sinus opacification and collapse was reported by Montgomery.[1] However, the term “silent sinus syndrome” (SSS) for this phenomenon was coined by Soparkar et al. in 1994.[2] SSS is an interesting and rare clinical entity that is associated with characteristic clinical and radiological signs.[3] The term chronic maxillary atelectasia (CMA) is often used interchangeably with SSS, but CMA is classically distinguished from SSS by the presence of symptoms similar to those of chronic sinusitis.[4],[5] To the best of our knowledge, this condition has not yet been described in the oral and maxillofacial radiology literature. In this article, we have reviewed the SSS in terms of its clinical and radiographic features, pathogenesis, and treatment.

   Epidemiology Top

SSS has been reported to occur in third to fifth decades of life with no clear predilection for gender. Cases of SSS reported in the literature are limited mostly to single case reports, with only a small number of larger case series that have been described till date. Of these reported cases, only a few describe true SSS. In 2005, Numa et al. reported a comprehensive review of 84 previously published cases of SSS. Whereas, in 2008, Brandt and Wright published their own systematic review of all reported cases and found that only 55 reports contained complete data sets that were suitable for review, of which only 27 cases met their diagnostic criteria for SSS.[3] In 2009, Adly et al. published a case series of 11 patients of SSS.[4]

   Etiology and Pathogenesis Top

Soparkar et al. suggested maxillary hypoplasia to be the predisposing factor in some individuals that results in development of SSS. They assumed that SSS is the result of infection in the congenitally hypoplastic maxillary sinus. However, recently, it has been found that the collapse or implosion of the antral walls may occur in a previous normal-sized and normally developed maxillary sinus.[3] Thus, this may represent a less severe form of the SSS, with a relatively smaller sinus volume and shorter thicker walls of the sinus, affording the sinus protection against osteolysis and negative pressure effects.

The recent theory about the pathogenesis of SSS is based on chronic maxillary sinus obstruction related to occlusion of the maxillary infundibulum, which results in a hypoventilated sinus and negative pressures within the sinus.[3] This is similar to middle ear atelectasis that occurs secondary to Eustachian tube dysfunction.[5] The low-grade inflammatory response that occurs due to stagnant mucus within the sinus leads to osteolysis of the sinus walls. Therefore, the weakened sinus walls are pulled inward into the sinus lumen by the negative sinus pressure. Damage to the osteomeatal complex after endoscopic sinus surgery is also postulated as one of the causative factors.[4],[6]

   Clinical Features Top

The patient with true SSS usually presents with the complaints of spontaneous, painless and occasionally progressive enophthalmos and hypoglobus mostly to an ophthalmologist.[5] Although there have been no clear associations with smoking, it is interesting to note that some authors have postulated that there may be a negative association between smoking and the incidence of SSS.[3]

The primary symptom can be described as “sinking down of the eye” or “drooping of the upper eyelid” [Figure 1]a, which results from an unilateral enophthalmos and hypoglobus caused by expansion of the orbital space due to a downward bowing of the orbital floor, in the absence of any history of ocular disease or orbital trauma. Such symptoms usually progress over a period of months. Also, there is typically no significant history of a sinonasal disease. These characteristic clinical signs and symptoms are highly suggestive of SSS, which can be confirmed radiologically by its unique radiographic features.[3] Some other signs that may be associated including upper eyelid retraction, superior orbital sulcus deepening [Figure 1]b, fat loss in lower eyelid, malar depression, widening of middle meatus and ipsilateral retraction of the middle turbinate toward the affected side.[7] Exophthalmos of the uninvolved contralateral eye may be reported occasionally. Usually, the visual function is unaffected, but a few patients have been reported with alterations in ocular motility or muscle imbalance resulting in diplopia.[8] Also, there are instances of relatively acute onset of symptoms occurring after orbital decompression. In such cases, it has been appropriately described as “imploding antrum syndrome.”[3]
Figure 1: (a) Artist's rendition of silent sinus syndrome. Drawing shows enophthalmos and hypoglobus of right eye (black arrow). (b) Artist's rendition of silent sinus syndrome. Drawing shows deepening of left superior orbital sulcus (black arrow)

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   Radiological Features Top

The classical radiographic features are unique to SSS which can be clearly appreciated on computed tomographic (CT) scan. The primary finding is volume loss of maxillary sinus due to inward retraction of the sinus walls, which results in increased orbital volume and enlargement of the middle meatus. Usually, all four walls of the sinus are retracted, but sometimes one of the walls (medial, anterior or posterolateral) may be spared. Thinning or complete bony resorption of the orbital floor was reported by Soparkar et al. in all patients that they have reviewed. The orbital floor (maxillary roof) is commonly thinned and always retracted, whereas the other walls may be thinned, normal or slightly thickened. The maxillary infundibulum is occluded and the sinus is opacified. The uncinate process is retracted against the inferomedial aspect of the orbital wall.[4],[5] Other features that may be seen on radiograph include enlarged middle meatus and deviated nasal septum [Figure 2]a and [Figure 2]b.[7] Although this condition is primarily a disease of the maxillary sinus, it has also been found to be associated with inward bowing of the ipsilateral ethmoidal complex in patients with classical radiographic features of SSS.[3],[5]
Figure 2: (a) Artist's rendition of silent sinus syndrome. Drawing shows CT image in coronal plane revealing fully developed opacified right maxillary sinus. Uncinate process is retracted against the inferomedial orbital floor, occluding maxillary sinus infundibulum (arrow), associated with lateral retraction of medial sinus wall and middle turbinate with enlargement of middle meatus (asterisk). Orbital floor is retracted into sinus lumen. (b) Artist's rendition of silent sinus syndrome. Drawing shows axial section of CT paranasal sinuses revealing consolidation and contraction of left maxillary sinus and reduced antral volume

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   Differential Diagnosis Top

The differential diagnosis of enophthalmos should be ruled out along with trauma-related orbital fractures in patients with signs of SSS. These include orbital fracture, CSF shunting after childhood hydrocephalus, orbital varix, Parry–Romberg syndrome, linear scleroderma, chronic sinusitis, osteomyelitis, atrophy of orbital fat/contents (especially after surgery or trauma), malignant infiltration, contraction of orbital fat (metastatic carcinomas, most commonly breast), anophthalmic enophthalmos and pseudoenophthalmos (contralateral exophthalmos, Horner's syndrome).[7] Most frequently, the underlying causes for similar clinical presentation were unrecognized orbital fractures, contralateral exophthalmos, congenital facial asymmetry and Parry–Romberg syndrome; however, it was noted that in cases of misdiagnosis, patients complained of facial pain and mucopurulent discharges that preceded the orbital manifestations. Also, other diseased conditions causing spontaneous enophthalmos were observed to have lesser hypoglobus and pseudoretraction of the upper eye lid than SSS. SSS can be differentiated from all the above-mentioned entities by its unique clinical and radiological features which include facial asymmetry due to asymptomatic unilateral enophthalmos and hypoglobus that usually progresses over a period of months with the absence of any history of ocular disease, orbital trauma or sinonasal disease. Radiographic features include inward retraction of the sinus walls resulting in volume loss, downward bowing of the orbital wall causing increased orbital volume, without any signs of fracture and enlarged middle meatus in some cases.

   Management Top

The treatment for SSS is mostly surgical with otolaryngological intervention.[9] The main aim of treatment is to correct the problems which lead to development of SSS. Hence, the treatment should address obstruction of the sinus as well as the resultant ocular deformities, which consists of re-aeration of the atelectatic sinus by endoscopic sinus surgery. A wide antrostomy prevents future re-obstructions, and good re-aeration of the sinus helps to avoid recurrent enophthalmos.

Earlier, surgical treatment was done by performing a Caldwell–Luc procedure and transconjunctival repair of the orbital floor. Due to advances in endoscopic surgery, endoscopic treatment has become possible today. In 1993, Blackwell et al. described their success of treatment of SSS using endoscopic maxillary antrostomy in conjunction with a transconjunctival orbital floor repair in three patients. Currently, endoscopic sinus surgery for creating a wide maxillary antrostomy is considered the surgical gold standard treatment for SSS. After surgery, the sinus configuration may remain unchanged, improve slightly, or be restored to a nearly normal configuration over a period of time. The disease progression is arrested without development of further deformity once the surgery is done. The orbital floor can be repaired either after functional endoscopic sinus surgery or in conjunction with the procedure. This repair is required in patients with diplopia or severe cosmetic deformity, as well as in patients with little improvement after functional endoscopic sinus surgery.[3],[4],[7]

   Conclusion Top

SSS is a rare acquired diseased condition with striking clinical and radiological features. Significant feature is the absence of sinusitis symptoms and the history is usually not contributory. Since it is not documented in detail in the oral and maxillofacial radiology literature, many radiologists remain unfamiliar with the syndrome and its characteristic radiographic findings. Apart from being a rare disorder, it is also underdiagnosed because of the lack of recognition. As the well-known saying goes, “Eyes can't see what the mind doesn't know,” it is indeed important for the oral and maxillofacial radiologist to have knowledge about this rare disease entity for early diagnosis and appropriate treatment.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Montgomery WW. Mucocele of the maxillary sinus causing enophthalmos. Eye Ear Nose Throat Mon 1964;43:41-4.  Back to cited text no. 1
Soparkar CN, Patrinely JR, Cuaycong MJ, Dailey RA, Kersten RC, Rubin PA, et al. The silent sinus syndrome. A cause of spontaneous enophthalmos. Ophthalmology 1994;101:772-8.  Back to cited text no. 2
Choudhury N, Marais J. The silent sinus syndrome: A clinical review. An Int J Clin RhinolClinical Rhinology: An International Journal 2010;3:69-72.  Back to cited text no. 3
Adly A, Abdel-Fattah G, Shehata M, Amin S, Badran H. Spontaneous silent sinus syndrome (imploding sinus syndrome): Case series of 11 patients. EJENTAS Egyptian Journal of Ear, Nose, Throat and Allied Sciences 2009;10:42-6.  Back to cited text no. 4
Hourany R, Aygun N, Della Santina CC, Zinreich SJ. Silent sinus syndrome: An acquired condition. AJNR Am J Neuroradiol 2005;26:2390-2.  Back to cited text no. 5
Illner A, Davidson HC, Harnsberger HR, Hoffman J. The silent sinus syndrome: Clinical and radiographic findings. AJR Am J Roentgenol 2002;178:503-6.  Back to cited text no. 6
Hong ES, Allen RC. Silent Sinus Syndrome: 36 year old man with sunken left orbit (Enophthalmos). EyeRounds.org 2010; Available from: http://www.eyerounds.org/cases/102-enophthalmos-silent-sinus-syn.pdf.  Back to cited text no. 7
Guillen DE, Pinargote PM, Guarderas JC. The silent sinus syndrome: Protean manifestations of a rare upper respiratory disorder revisited. Clin Mol Allergy 2013;11:5.  Back to cited text no. 8
Gill HS, Silkiss RZ, Scott IU, Fekrat S. Diagnosis and management of silent sinus syndrome. Eye Net; Ophthalmic Pearls 2011;37-8.  Back to cited text no. 9


  [Figure 1], [Figure 2]


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