The sinking eyeball: Silent sinus syndrome—A rare cause of enophthalmos

A 54-year-old lady, presented with a history of the left eye appearing smaller for 8 months. It was painless and gradually progressive. She was unaware of preexisting sinus disease or orbitofacial trauma. On examination, there was pseudoptosis, deep superior sulcus, and 3-mm inferior dystopia in the left eye [Fig. 1]. Hertel exophthalmometry showed 17 mm in the right eye and 13 mm in the left eye suggestive of left eye enophthalmos. Extraocular motility, diplopia charting, and the rest of the eye examinations were normal. Computed tomography showed complete opacification and decreased volume of the left maxillary sinus with small ostium, downward displacement of the orbital floor, and increased left orbital volume [Fig. 2]. Based on clinic-radiological findings, a diagnosis of silent sinus syndrome (SSS) was made. The patient was referred for otolaryngological consultation. She was advised of functional endoscopic sinus surgery with uncinectomy and opening of the maxillary sinus ostium.Figure 1: Photograph showing enophthalmos, hypoglobus, and pseudoptosis in the left eye and left malar flatteningFigure 2: Computed tomography coronal view showing decreased volume and opacification of the left maxillary sinus with increased left orbital volumeDiscussion SSS is a condition characterized by spontaneous unilateral enophthalmos and hypoglobus. This condition was first reported by Montgomery[1] in 1964. Thirty years later, Soparkar coined the term “Silent Sinus Syndrome.”[2] Patients tend to present during the third to fifth decade of life. This occurs as a sequel of the obstruction of the maxillary sinus osteomeatal complex. Occlusion and hypoventilation of the sinus lead to negative pressure development. Consequently, the sinus cavity is filled with a combination of mucus and acellular transudate, resulting in chronic low-grade mucosal inflammation. Due to secondary demineralization of the bony orbital floor, the maxillary sinus implodes and collapses.[3] If left untreated, it may result in complete obliteration of the sinus with worsening enophthalmos and hypoglobus. Clinical features are enophthalmos (1–6 mm), hypoglobus (0–6 mm), lagophthalmos, deepening of the superior sulcus, malar depression, and diplopia. Eye movements may be affected in severe hypoglobus.[4,5] Visual function will be normal. Radiological features are volume loss and opacification of the maxillary sinus with or without air-fluid levels and thickened mucosa, lowering of inferior orbital wall, osteopenia, lateral retraction of the uncinate process, inward retraction of other sinus walls, nasal septum deviation, and lateralization of the ipsilateral middle nasal concha.[4-6] SSS has been considered a subgroup of chronic maxillary atelectasis by many authors. Atelectasis of the maxillary sinus is the persistent decrease in the volume of the maxillary sinus due to a centripetal retraction of its wall. Most of these patients will present with sinonasal symptoms.[6] The maxillary sinus, present at birth, increases in size until the end of the 18th year.[7] The growth pattern includes changes in vertical, horizontal, and anteroposterior directions. The silent sinus should be differentiated from congenital sinus hypoplasia, which is the term reserved for congenital unilateral or bilateral underdevelopment of the maxillary sinus. CT scan in sinus hypoplasia is stable, whereas, in SSS, changes in CT scans are progressing.[6] Other causes of spontaneous enophthalmos such as Parry–Romberg syndrome (progressive hemifacial atrophy) and linear scleroderma should be ruled out clinically and radiologically.[8] Osseous metastasis and osteomyelitis of the orbital floor may also cause enophthalmos and hypoglobus. The treatment of SSS aims to reestablish maxillary antral ventilation by endoscopically creating a nasoantral window with uncinectomy and antrostomy and restoring orbital architecture.[9] Orbital reconstruction has to be planned 2–6 months later, depending on the degree of cosmetic deficit. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship: Nil. Conflicts of interest: There are no conflicts of interest.