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The Silent Sinus Syndrome

Clinical and Radiographic Findings

¹ Department of Radiology, University of Utah, 1A71 Medical Ctr., 50 N. Medical Dr., Salt Lake City, UT 84132.
² Department of Otolaryngology, University of Utah, School of Medicine, Salt Lake City, UT 84132.

Received February 21, 2001; accepted after revision August 9, 2001.

 
Address correspondence to A. Illner.

Abstract

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OBJECTIVE. The purpose of this article is to acquaint the reader with the clinical and imaging features of the silent sinus syndrome, which is relatively unknown. Discussion of the presentation, treatment, and theory regarding pathogenesis of the syndrome follows.

CONCLUSION. The silent sinus syndrome consists of painless facial asymmetry and enophthalmos caused by chronic maxillary sinus atelectasis. Although the diagnosis is usually suspected clinically, it is confirmed radiologically by characteristic imaging features that include maxillary sinus outlet obstruction, sinus opacification, and sinus volume loss caused by inward retraction of the sinus walls.

Introduction

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The term "silent sinus syndrome" was coined by Soparkar et al. [1] in 1994 to denote painless enophthalmos associated with chronic maxillary sinus atelectasis, a phenomenon originally described in 1964 by Montgomery [2] (Fig. 1A,1B). Since that time, numerous cases have been documented and presented, primarily in the otolaryngology and ophthalmology literature [1,2,3,4,5,6,7,8,9], with the largest series, of 22 cases, reported by Kass et al. [3] in 1997. To our knowledge, this condition has not been described in the radiologic literature, and many radiologists remain unfamiliar with the syndrome and its characteristic radiologic findings. Although the diagnosis of silent sinus syndrome is initially made clinically, it is confirmed radiologically. In this article, we introduce the silent sinus syndrome through five case examples and discuss the presentation, treatment, and theory regarding its pathogenesis.

View larger version (66K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1A. —Artist's rendition of silent sinus syndrome. Drawing shows typical facial asymmetry seen in silent sinus syndrome. Right globe is displaced downward (hypoglobus) with associated upper-lid retraction and deepening of upper-lid sulcus.

View larger version (36K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1B. —Artist's rendition of silent sinus syndrome. Drawing shows appearance of sinus in silent sinus syndrome. Uncinate process and medial sinus wall are retracted laterally with associated enlargement of medial meatus (asterisk). Orbital floor is retracted into sinus lumen (arrows), which increases orbital volume.

Materials and Methods

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During a 10-year period, four patients were clinically diagnosed with silent sinus syndrome by physicians in the ear, nose, and throat service at our institution. One patient who had radiologic findings suggestive of silent sinus syndrome was also included; these findings were confirmed by otolaryngologic examination. The clinical charts and radiology files of all five patients were retrospectively reviewed. The charts were reviewed for patient demographic data and clinical findings, including clinical presentation, physical examination findings, treatment, findings at pathology, and follow-up. The images were reviewed for the overall appearance of the maxillary sinus, including evaluation of sinus development, sinus volume, degree of aeration, wall configuration, and the appearance of the sinus infundibulum and uncinate process. Evaluation of adjacent structures, including the orbit, middle meatus, and middle turbinate, was also performed. All images were reviewed by a staff neuroradiologist and a neuroradiology fellow.

Four of the five patients were imaged with unenhanced CT in bone algorithm on a scanner (General Electric Medical Systems, Waukesha, WI). Three of these four patients were imaged with 3-mm-thick slices in both the coronal and axial planes. The fourth patient was imaged in the coronal plane only. The CT scans of all four patients were reviewed in bone and soft-tissue windows. The fifth patient was imaged using 4-mm multiplanar gadolinium-enhanced MR imaging on a 1.5-T magnet (Signa; General Electric Medical Systems).

The clinical and imaging findings were organized into chart format.

Four of the five patients were men. Patients ranged in age from 39 to 65 years (mean age, 47 years). Of the four patients initially diagnosed by the ear, nose, and throat service, two presented with histories of eye asymmetry, reported as "eye sagging," of several months to 2 years. One of these two patients also presented with mild diplopia. The other two patients diagnosed by the ear, nose, and throat service presented with histories of diplopia of several months to 1 year in duration. Two of these four patients also presented with histories of vague dental and facial pain for several months. None of the five patients had a medical history of sinus disease or of facial trauma to the affected side.

Physical examination performed by the ear, nose, and throat surgeons disclosed enophthalmos in all patients. Enophthalmos ranging from 2 to 4 mm was confirmed by Hertel ophthalmometer in three of these patients, who were referred to ophthalmology for further workup. Hypoglobus (downward position of the globe within the orbit), malar depression, upper-lid retraction, and deep upper sulcus were variably present in the five patients. Endoscopic findings, documented in three patients, included widening of the middle meatus on the affected side and lateral retraction of the middle turbinate.

Three patients were treated with functional endoscopic sinus surgery with maxillary antrostomy, one patient was treated with antibiotics, and one received no treatment. In all three surgical cases, chronic inflammatory changes were documented within the sinus. In none of the five patients were follow-up imaging studies available.

Results

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The right maxillary sinus was involved in three of the five patients. In all five patients, the maxillary sinus was fully developed, with the sinus extending laterally into the malar eminence and inferiorly into the maxillary alveolar ridge. In four of the five patients the maxillary sinus was completely opacified; in the fifth, it was almost completely opacified. The maxillary sinus infundibulum was obstructed in all patients.

In four patients, obstruction was caused by lateral retraction of the uncinate process, with apposition of the uncinate process against the inferomedial aspect of the orbital wall. In the fifth patient, the uncinate process was in near-normal position, but it was substantially thinned, with infundibular occlusion caused by mucous plugging. In all patients, the middle meatus adjacent to the affected sinus was expanded relative to the unaffected side, with varying degrees of lateral retraction of the middle turbinate.

In three of the four patients evaluated using both axial and coronal images, inward retraction of all four sinus walls (roof, anterior, medial, and posterolateral) into the sinus was seen. Another patient had inward retraction of three sinus walls (roof, medial, and posterolateral). The fifth patient, who underwent coronal imaging only, had inward retraction of all three walls evaluated (roof, medial, posterolateral). In all patients, orbital volume was increased on the affected side as a result of downward retraction of the sinus roof (orbital floor) into the maxillary sinus.

Discussion

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The silent sinus syndrome is characterized by painless enophthalmos associated with involution of the maxillary sinus after infundibular occlusion [1,2,3,4,5,6,7,8,9,10]. It is a well-recognized entity in the field of otolaryngology, but the syndrome remains relatively unknown among radiologists despite its characteristic radiologic features. As highlighted by the five patients discussed and the cases documented in the literature, the typical patient with the silent sinus syndrome is an adult who presents to an ophthalmologist or an ear, nose, and throat specialist with a prolonged history of painless eye or facial asymmetry, diplopia, or both [1,2,3,4,5,6,7] (Fig. 1A). Symptoms related to sinusitis may or may not be present [1,2,3,4, 6, 7]. Enophthalmos is usually seen on physical examination [1,2,3,4,5,6,7]. Hypoglobus, upper-lid retraction, deepened upper-lid sulcus, and malar depression are variably present [1,2,3,4,5,6,7]. Radiologic consultation usually ensues to exclude underlying orbital tumor or evidence of trauma.

The imaging findings of the silent sinus syndrome are characteristic. The sinus is usually fully developed and opacified [3,4,5]. The maxillary infundibulum is occluded. Occlusion is usually caused by lateral retraction of the uncinate process with apposition of the uncinate process against the inferomedial aspect of the orbital wall [3, 4, 6]. The adjacent middle meatus is correspondingly enlarged with varying degrees of lateral retraction of the middle turbinate (Figs. 2A and 3A). The most characteristic imaging feature of the silent sinus syndrome is the inward retraction of the sinus walls into the sinus lumen with associated decrease in sinus volume [1,2,3,4,5,6,7] (Figs. 2B, 2C, 3B). In our study, the medial wall, posterolateral wall, and orbital floor were involved in all patients. Typically, it is the downward retraction of the orbital floor into the maxillary sinus that creates the eye or facial asymmetry identified by the patient.

View larger version (116K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2A. —44-year-old man with 18-month history of painless, sagging right eye. Unenhanced CT image in coronal plane reveals fully developed opacified right maxillary sinus. Uncinate process is apposed to inferomedial orbital floor, occluding maxillary sinus infundibulum (arrow). Associated lateral retraction of medial sinus wall and middle turbinate with enlargement of middle meatus (asterisk) can be seen. Orbital floor is retracted into sinus lumen (arrowhead).

View larger version (125K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3A. —39-year-old man with 2-month history of diplopia. T2-weighted MR image obtained in coronal plane using fat-saturation technique shows opacified fully developed right maxillary sinus with retraction of orbital floor (arrowhead) into sinus lumen. Position of left uncinate process (U) is normal. Right uncinate process is apposed to inferomedial orbital floor, occluding maxillary sinus infundibulum (arrow). Medial sinus wall and middle turbinate are laterally retracted, causing enlargement of middle meatus (asterisk).

View larger version (159K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2B. —44-year-old man with 18-month history of painless, sagging right eye. CT image obtained in coronal plane posterior to A shows posterior wall of affected right maxillary sinus retracted into sinus lumen (arrow).

View larger version (99K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2C. —44-year-old man with 18-month history of painless, sagging right eye. CT image obtained in axial plane shows retraction of anterior wall (arrowhead), posterior wall (black arrow), and medial wall (white arrow) into sinus lumen.

View larger version (147K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3B. —39-year-old man with 2-month history of diplopia. T2-weighted fat-saturated MR image obtained in coronal plane at a position posterior to A graphically displays inward retraction of posterior (arrow) and medial (arrowhead) walls of right maxillary sinus.

The silent sinus syndrome can be definitively treated by creating an outlet for mucous drainage from the obstructed sinus. The treatment is performed endoscopically by creating a nasal antral window or a maxillary antrostomy [1,2,3,4,5,6,7]. After surgery, the configuration of the sinus may remain unchanged, improve slightly, or be restored to a near-normal configuration over time [5,6,7]. Regardless of the final appearance of the sinus after functional endoscopic sinus surgery, disease progression is arrested without development of further deformity [1,2,3,4,5,6]. The orbital floor may be repaired after functional endoscopic sinus surgery or in conjunction with this procedure. This repair is usually performed in patients with diplopia or severe cosmetic deformity and in patients with little improvement after functional endoscopic sinus surgery [1,2,3,4,5,6,7].

Two of the five patients in this study were not treated surgically. One patient presented with dental pain in addition to diplopia and was treated with antibiotics for presumed superimposed sinusitis. This patient never returned for follow-up. The second patient had an initial CT scan obtained for other reasons with additional findings suggestive of the silent sinus syndrome. Enophthalmos, malar depression, and middle meatus expansion were identified by the ear, nose, and throat surgeon, and the diagnosis was confirmed. At the time of this writing, the patient had not agreed to surgery. These two patients probably reflect the indolent nature of the disease and the mild physical manifestations associated with it.

The leading theory regarding the pathogenesis of the silent sinus syndrome is based on chronic maxillary sinus obstruction with hypoventilation, a state that eventually causes negative pressure to develop within the sinus [1,2,3,4,5,6,7,8,9]. After occlusion of the maxillary infundibulum, mucous begins to accumulate and eventually fills the sinus. The stagnant mucous incites a low-grade inflammatory response within the sinus and causes osteolysis of the sinus walls. The sinus walls, thinned by inflammation, are pulled into the sinus by the negative sinus pressure.

Although most patients with the silent sinus syndrome are idiopathic [1,2,3,4,5,6,7], Levine and Mitra [11] report the case of a child who had undergone endoscopic sinus surgery. In this patient, damage to the osteomeatal complex was postulated as the causative factor.

It is probable that, regardless of the inciting event, the final common pathway leading to the silent sinus syndrome is obstruction of mucous drainage from the sinus, which leads to a chronic, hypoventilated state. Although the exact sequence of events and causal relationship have not been definitively established, negative sinus pressure, osteolysis of the orbital floor, and chronic inflammatory changes have been documented in the literature, both in experimental models and in patients with the silent sinus syndrome [3, 4, 8,9,10]. Some authors have likened the process of sinus wall retraction to the tympanic membrane retraction seen with chronic Eustachian tube obstruction [5].

A similar process may be responsible for the appearance of the opacified hypoplastic maxillary sinus, an entity with imaging findings similar to that of the silent sinus syndrome and often used interchangeably with the silent sinus syndrome in the literature [1, 3, 12]. The opacified hypoplastic maxillary sinus may represent a less severe form of the silent sinus syndrome, with the smaller sinus volume and shorter, thicker sinus walls affording the sinus protection against osteolysis and negative pressure effects.

In summary, the silent sinus syndrome is a rare entity that is well-known to the ophthalmologist and the ear, nose, and throat surgeon. This condition is characterized by painless enophthalmos and facial asymmetry caused by chronic maxillary sinus atelectasis [1,2,3,4,5,6,7]. Radiologic findings involving the maxillary sinus and orbit confirm the diagnosis of the silent sinus syndrome.

References

Top Abstract Introduction Materials and Methods Results Discussion References

 

1. Soparkar CNS, Patrinely JR, Cuaycong MJ, et al. The silent sinus syndrome: a cause of spontaneous enophthalmos. Ophthalmology 1994;101:772 -778[Medline]
2. Montgomery WW. Mucocele of the maxillary sinus causing enophthalmos. Eye Ear Nose Throat Monthly, May 1964;43:41 -44
3. Kass ES, Salman S, Rubin PAD, Weber AL, Montgomery WW. Chronic maxillary atelectasis. Ann Otol Rhinol Laryngol 1997;106:109 -116[Medline]
4. Boyd JH, Yaffee K, Holds J. Maxillary sinus atelectasis with enophthalmos. Ann Otol Rhinol Laryngol 1998;107:34 -39[Medline]
5. Gillman GS, Schaitkin BM, May M. Asymptomatic enophthalmos: the silent sinus syndrome. Am J Rhinol 1999;13:459 -462[Medline]
6. Hunt SM, Tami TA. Sinusitis-induced enophthalmos: the silent sinus syndrome. Ear Nose Throat J 2000;79:576 , 579-581, 584[Medline]
7. Wan MK, Francis IC, Carter PR, Griffits R, van Rooljen ML, Coroneo MT. The spectrum of presentation of silent sinus syndrome. J Neuroophthalmol 2000;20:207 -212[Medline]
8. Kass ES, Salman S, Montgomery WW. Manometric study of complete ostial occlusion in chronic maxillary atelectasis. Laryngoscope 1996;106:1255 -1258[Medline]
9. Davidson JK, Soparkar CNS, Williams JB, Patrinely JR. Negative sinus pressure and normal predisease imaging in the silent sinus syndrome. Arch Ophthalmol 1999;117:1653 -1654[Free Full Text]
10. Scharf KE, Lawson W, Shapiro JM, Gannon PJ. Pressure measurements in the normal and occluded rabbit maxillary sinus. Laryngoscope 1995;105:570 -574[Medline]
11. Levine SB, Mitra S. Maxillary sinus involution after endoscopic sinus surgery in a child: a case report. Am J Rhinol 2000;14:7 -11[Medline]
12. Furin MJ, Zinreich JS, Kennedy DW. The atelectatic maxillary sinus. Am J Rhinol 1991;5:79 -83

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