Sinusitis-induced enophthalmos: The silent sinus syndrome.
Enophthalmos caused by inadequate maxillary sinus function was first reported in 1964. Since this initial report, scattered case reports and, more recently, reviews have appeared in the literature detailing the pathophysiology, clinical findings, and management of this process. We present a classic case of the asymptomatic development of enophthalmos caused by maxillary sinus hypoventilation: the silent sinus syndrome. In addition, this case included findings in the ethmoid sinuses that suggested their contribution to this disorder, which by our review of the literature has not been well described.
Prolonged hypoventilation of the maxillary sinus can result in atelectasis. The silent sinus syndrome is an example of this phenomenon, characterized by an absence of symptoms and the development of enophthalmos. Because the signs of this syndrome relate primarily to the eye, the diagnosis is typically made by our ophthalmology colleagues. Nevertheless, the otolaryngologist should be aware of this condition and be prepared to assist in its management. In this article, we describe a case of silent sinus syndrome, and we discuss its management and review the literature.
An otherwise healthy 49-year-old man sought the consultation of an ophthalmologist for an asymptomatic "sinking in" of his left eye over a 2-month period. Ophthalmologic examination revealed a prominent left superior palpebral sulcus, 2 mm of inferior globe displacement (hypoglobus), and 3 mm of enophthalmos as compared with his contralateral eye. Extraocular motility was intact. Evaluation included computed tomography (CT) of the orbits, which demonstrated an increased left orbital volume and left maxillary, ethmoid, and frontal sinusitis. Referral was made to the otolaryngologist for management of chronic sinusitis prior to the placement of an orbital floor implant.
Upon review, the patient specifically denied any history of facial trauma, sinonasal or visual symptoms, or sinus surgery. Review of the CT scans revealed a partially opacified, atelectatic left maxillary sinus with centripetal retraction of the medial, posterolateral, and superior (orbital floor) walls of the sinus (figure 1). The medial orbital floor and uncinate process were demineralized. The uncinate process was laterally bowed and indistinguishable from the lateral nasal wall. The osteomeatal complex was obstructed. On axial view, there was focal inward bowing of the posterolateral wall of the sinus, with widening of the pterygopalatine fossa and infratemporal fat plane (figure 2). The ipsilateral middle turbinate was vestigial in nature and retracted onto the lamina papyracea, and it occluded the frontal recess. Hypoplasia of the anterior ethmoid air cells was noted.
The patient underwent a left endoscopic uncinectomy, maxillary antrostomy, and partial ethmoidectomy. Although he experienced a prompt resolution of the enophthalmos, the postoperative course was complicated by the development of symptomatic left frontal sinusitis, which was unresponsive to medical therapy. CT at this point revealed a patent left maxillary antrostomy, aeration of the previously affected sinus, and a return of the posterior and superior sinus wall periosteum to their normal positions (figure 3). A subsequent procedure was performed, which included an endoscopic partial middle turbinectomy and a frontal sinusotomy with stent placement. The stent was removed 4 weeks later. The patient returned to cosmetic baseline 6 months postoperatively, and he remains symptom free.
Proper paranasal sinus function requires ventilation, appropriate mucus production, and mucociliary clearance. Obstruction of maxillary sinus ventilation at the osteomeatal complex is accepted as a pathologic precursor for the development of acute and chronic sinusitis. Additionally, alterations in ventilation can result in bone remodeling or destruction as a result of pressure effects. For instance, an aerocele causes sinus expansion because of one-way air-trapping,  whereas atelectasis reduces sinus volume because of a complete ostial obstruction, with a subsequent gas resorption and formation of a vacuum.
Drawing an analogy to eustachian tube dysfunction in the development of negative middle ear pressure, Scharf et al used rabbits to experimentally prove a causal relationship between ostial occlusion and the development of subatmospheric pressure in the maxillary sinus.  Kass et al manometrically verified this finding in humans who had reduced maxillary sinus volume as noted by CT. 
Enophthalmos resulting from maxillary sinus pathology was first reported by Montgomery in 1964.  In the two cases he reported, asymptomatic mucoceles were the cause of orbital floor destruction, which resulted in a prolapse of the orbital contents, with associated ocular findings only. Over the ensuing 35 years, numerous case studies and reviews have shed further light on the pathogenesis and management of this and similar conditions. Chronic maxillary atelectasis is a descriptive term to describe a long-standing diminution of maxillary sinus volume and radiographic findings of an inward bowing of the walls of the antrum.  As one man's ceiling is the next man's floor, an increase in orbital volume would be expected as the antral roof sags. Although chronic maxillary atelectasis does not necessarily result in enophthalmos, changes in orbital volume are common, as the thin superior and posterolateral walls of the maxillary sinus are most frequently involved in the remodeling process.  When chronic obs truction of ventilation to the maxillary sinus afflicts the developing facial structure of a child, a hypoplastic sinus asymmetry [6,7] and possibly vertical dystopia of the eye can result.  Differentiation from a Parry-Romberg syndrome can be difficult in this setting.  Radiologic studies have shown that maxillary sinus hypoplasia is found in 1 to 17.5% of radiographs taken for the evaluation of chronic sinusitis. [6,10,11]
The characteristic CT findings in patients with hypoplastic or atelectatic maxillary sinus include osteomeatal complex obstruction, a C-shaped lateral bowing of the uncinate process, sinus opacification, and internal bowing of the posterolateral, superior, and medial walls of the sinus. Additionally, anterior wall bowing, a widening of the pterygopalatine fossa and infratemporal fossa fat plane, an elevation of the canine fossa, or a relatively lateral position of the infraorbital canal might be seen. [12,13] Whether the maxillary sinus walls simply remodel or attenuate seems to relate to the duration of the pathologic process. A trend that we noted upon reviewing the literature was that patient recognition of progressive enophthalmos over a period of 3 months or less corresponded with an attenuation or absence of the involved bony sinus walls, whereas a more insidious development of this change corresponded with bony remodeling.
Symptoms resulting from prolonged hypoventilation of the maxillary sinus are sometimes absent. When they do manifest, they can include a constellation of pressure, pain, and obstruction similar to that seen in chronic sinusitis. The presence or absence of symptoms can be determined by the degree and duration of negative pressure, the presence of inflammation, or the degree of previous pneumatization. Patients who have few or no symptoms have been observed to demonstrate more significant bony changes than their more symptomatic counterparts. 
Our patient's condition fits the description of chronic maxillary atelectasis as proposed by Kass et al.  The asymptomatic nature of his maxillary sinus pathology allowed for the development of cosmetically significant enophthalmos prior to diagnosis. More specifically, because he had no known history of trauma or inflammatory disease of the paranasal sinuses, our patient's condition more closely fits the features of the silent sinus syndrome proposed by Soparkar et al in 1994 (table 1).  In the only other reference to this syndrome to date, Rose described a case that was nearly identical to ours.  In reviewing the reported cases of acquired maxillary sinus hypoplasia and chronic maxillary atelectasis (of adequate detail), we found 18 patients who met these more selective criteria (table 2). [4,5,9,16-23] Including our case and that of Rose, the mean age at diagnosis was 42 years, and the male-to-female ratio was 14-to-6. When noted, the mean duration of cosmetic change prior to diagnosis was 8.9 months.
Management of patients with maxillary sinus atelectasis is primarily by endoscopic uncinectomy and maxillary antrostomy to remove the obstructing soft tissue and to reestablish an isobaric sinus. We reiterate the counsel of caution given by several authors regarding endoscopic surgery on the lateral nasal wall in this setting of altered uncinate process anatomy. [5,8,11,23] Penetration of the lamina papyracea might occur if a vigilant search for the free margin of the lateralized uncinate is not undertaken. Exploration with reconstruction of the orbital floor might be necessary to re-establish ocular symmetry, and it can be performed in a variety of ways.[16,19,21-23] We did not find orbital implantation necessary in this case because the enophthalmos resolved by simply alleviating the inciting vacuum process.
From the Department of Otolaryngology--Head and Neck Surgery, the University of Cincinnati Medical Center.
(1.) Zizmor J, Noyek AM. An Atlas of Otolaryngologic Radiology. Philadelphia: W.B. Saunders, 1978.
(2.) Scharf KE, Lawson W, Shapiro JM, Gannon PJ. Pressure measurements in the normal and occluded rabbit maxillary sinus. Laryngoscope 1995;105:570-4.
(3.) Kass ES, Salman S, Montgomery WW. Manometric study of complete ostial occlusion in chronic maxillary atelectasis. Laryngoscope 1996;106:1255-8.
(4.) Montgomery WW. Mucocele of the maxillary sinus causing enophthalmos. The Ear, Eye, Nose and Throat Monthly 1964;43:41-4.
(5.) Kass ES, Salman S, Rubin PA, et al. Chronic maxillary atelectasis. Ann Otol Rhinol Laryngol 1997;106:109-16.
(6.) Proctor T, Naclerio R. Development of a hypoplastic maxillary sinus. Ann Otol Rhinol Laryngol 1996;105:327-8.
(7.) Kass ES, Salman S, Montgomery WW. Chronic maxillary atelectasis in a child. Ann Otol Rhinol Laryngol 1998;107:623-5.
(8.) Weed DT, Cole RR. Maxillary sinus hypoplasia and vertical dystopia of the orbit. Laryngoscope 1994;104:758-62.
(9.) Kumar BU, Naisby G, Flood LM. Acquired involution of the maxillary antrum. J Laryngol Otol 1994;108:74-5.
(10.) Bolger WE, Woodruff WW Jr., Morehead J, Parsons DS. Maxillary sinus hypoplasia: Classification and description of associated uncinate process hypoplasia. Otolaryngol Head Neck Surg 1990; 103 :759-65.
(11.) Milczuk HA, Dalley RW, Wessbacher FW, Richardson MA. Nasal and paranasal sinus anomalies in children with chronic sinusitis. Laryngoscope 1993;103:247-52.
(12.) Hayes EJ, Weber AL. Chronic sinus disease: A rare cause of enophthalmos. Ann Otol Rhinol Laryngol 1987;96:35 1-3.
(13.) Geraghty JJ, Dolan KD. Computed tomography of the hypoplastic maxillary sinus. Ann Otol Rhinol Laryngol 1989;98:916-8.
(14.) Soparkar CN, Patrinely JR, Cuaycong MJ, et al. The silent sinus syndrome: A cause of spontaneous enophthalmos. Ophthalmology 1994;101:772-8.
(15.) Rose TP. Spontaneous enophthalmos associated with asymptomatic maxillary sinus disease (silent sinus syndrome): Case report. J Am Optom Assoc 1998;69:236-40.
(16.) Wilkins RB, Kulwin DR. Spontaneous enophthalmos associated with chronic maxillary sinusitis. Ophthalmology 1981 ;88:981-5.
(17.) Traustason 01, Feldon SE. Cause of enophthalmos secondary to maxillary sinus mucocele. Am J Ophthalmol 1983;95:835-40.
(18.) Martelli A, Hoyt WF, Newton TH. Enophthalmos and orbital expansion from chronic sinusitis. CT evaluation with reformatted images. J Clin Neuroophthalmol 1984;4: 167-72.
(19.) Kaltreider SA, Dortzbach RK. Destructive cysts of the maxillary sinus affecting the orbit. Arch Ophthalmol 1988;106:1398-402.
(20.) Blackwell KE, Goldberg RA, Calcaterra TC. Atelectasis of the maxillary sinus with enophthalmos and midface depression. Ann Otol Rhinol Laryngol 1993;102:429-32.
(21.) Eto RT, House JM. Enophthalmos, a sequela of maxillary sinusitis. AJNR Am J Neuroradiol 1995;16(4 Suppl):939-41.
(22.) Garber PF, Abramson AL, Stallman PT, Wasserman PG. Globe ptosis secondary to maxillary sinus mucocele. Ophthal Plast Reconstr Surg 1995;ll:254-60.
(23.) Boyd JH, Yaffee K, Holds J. Maxillary sinus atelectasis with enophthalmos. Ann Otol Rhinol Laryngol 1998;107:34-9.
Features of silent sinus syndrome
No previous trauma, surgery, or symptoms
Onset during the fifth decade (mean age: 42 yr)
Bone resorption and remodeling of the orbital floor
Ipsilateral maxillary sinus atelectasis
|Printer friendly Cite/link Email Feedback|
|Author:||Tami, Thomas A.|
|Publication:||Ear, Nose and Throat Journal|
|Date:||Aug 1, 2000|
|Previous Article:||Combined vestibular neurectomy and endolymphatic sac shunt via the retrosigmoid approach in the treatment of Meniere's disease.|
|Next Article:||The role of ultrasonography in the management of tumors of the neck.|