What Is Silent Sinus Syndrome (SSS)?
Silent sinus syndrome is also known as imploding antrum syndrome or chronic maxillary sinus atelectasis. It is a disorder of the maxillary sinus (air-filled cavity present around the nose), mainly affecting one side. It is prevalent in the age group of 30 to 60 years without any gender preference. It is characterized by various clinical features such as sinus obstruction, opacification, and loss of volume due to retraction of the walls of the maxillary sinus.
What Are the Clinical Features of Silent Sinus Syndrome (SSS)?
Silent sinus syndrome is an uncommon yet severe condition that involves the following clinical features such as -
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The most common feature is painless enophthalmos (posterior eyeball displacement into the orbit).
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Imaging studies can determine inward retraction of the maxillary sinus.
In addition, some of the following characteristic clinical features can also be observed -
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Upper lid retraction.
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Deepening of the sulcus of the upper eyelid.
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Malar depressions.
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Double vision (diplopia).
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Facial asymmetry.
What Is the Etiology and Pathogenesis of Silent Sinus Syndrome?
The etiologic factors of this condition are not linked with any predisposing factors such as smoking, alcohol, or hereditary factors, and the symptoms differ from other sinonasal-origin (diseases starting from the sinus or the nasal cavity) diseases. Various theories have been proposed to establish the actual cause of silent sinus syndrome. The most accepted hypothesis is that it occurs due to the complete or partial obstruction of the ostium of the maxillary sinus (drainage opening present on the highest part of the medial wall of the sinus). This creates a negative pressure within the maxillary sinus, causing problems like hypoventilation or accumulation of sinus secretions.
Moreover, in the case of gas resorption in the sinus, it can create more negative pressure that can lead to conditions like osteopenia, bone remodeling defects, and inward retraction of one or more walls of the maxillary sinus. The immediate sequel would be a certain chain of events leading to the thinning of the orbital floor. When the orbital floor thins down, this fails to support the orbital content expanding more into the sinus and results in enophthalmos (sinking of eyes). Therefore this condition can only be treated by considering all the symptoms and making a timely diagnosis.
How to Diagnose Silent Sinus Syndrome?
Patients with silent sinus syndrome can be asymptomatic without showing features like diplopia or extraocular eye movement. The physician can only suspect this condition when the patient experiences the symptoms like recurrent infections of the sinus (sinusitis). Therefore radiographic interpretation has to be done to confirm the diagnosis, such as -
Computed Tomography (CT) - This is a three-dimensional scan in which the opacified maxillary sinus wall can be seen, and the orbital floor can also be visualized. The sinus is fully opacified and reduced in volume, with the walls of the sinus bowing inwards.
Radiography - Radiographs are not considered a good choice for diagnosing this condition. A CT scan (computed tomography) is the most commonly recommended for paranasal sinus conditions. The findings in radiographs are usually the same as those in the CT scan. The findings can also be seen, like inferior displacement of the orbital floor and concavity of the maxilla walls. The thinning of the bony orbital floor and decreased bone density can also be found.
Therefore the physician has to compare the clinical features with the imaging findings to confirm the diagnosis.
What Is the Differential Diagnosis of Silent Sinus Syndrome?
The differential diagnosis of silent sinus syndrome includes -
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Orofacial tumors.
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Facial asymmetry.
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Facial lipodystrophy. (loss of adipose tissue and leading to flattening or indentation of convex contours of the face).
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Parry-Romberg syndrome. (progressive deterioration of the skin and soft tissues of half the face).
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Scleroderma (conditions causing hardening and tightening of the skin).
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Sinonasal diseases.
What Is the Management of Silent Sinus Syndrome?
The treatment mainly involves the restoration of normal ventilation of the maxillary sinus in patients with respiratory difficulties. In addition, the restoration of the normal position of the ocular globe is also crucial in the management. The common facial surgical procedure known as Caldwell Luc procedure was more often implemented over the last few decades because it used to be the gold standard. However, nowadays, the goal of the treatment is to use conservative treatment modalities and to restore sinus function. Hence, endoscopic sinus surgery (ESS) is currently most preferred by surgeons, and additional procedures like uncinectomy (removal of unicate process of the nose, the first step in endoscopic surgery) and antrostomy (procedure to clear the sinus opening) would also be performed.
The reconstruction of the orbital floor is a clinically challenging and controversial procedure owing to the invasiveness of the surgery and the clinical difficulties encountered. Some clinicians also practice second-stage operations, which may be much safer and are usually implemented two months after the sinus surgery. This second stage operation aims at least partial or complete resolution of the enophthalmos. Immediate orbital floor reconstruction may be needed in severely affected patients to resolve the issues of respiratory hypoventilation and restore the normalcy of intra-sinus pressure.
Conclusion:
Silent sinus syndrome is a serious condition leading to various complications such as retracted upper eyelids, asymmetry of the face, double vision, and commonly encountered enophthalmos. Therefore to prevent all these complications, a confirmatory diagnosis should be made as soon as possible, and a multidisciplinary treatment strategy would be needed for a good prognosis.
