Patient Demographics, Clinical Presentation, and Preoperative Workup
Sinonasal mucoceles are benign lesions arising from progressive expansion of respiratory epithelium. Obstruction of the natural ostia of the corresponding sinus leads to noted expansion of the sinus epithelium with mucoid secretions. The mucocele can expand and exert mass effect on surrounding nasal, orbital, and intracranial structures. The inciting factor for mucocele development can range and include chronic infection, trauma, postoperative scarring, and systemic disease states.
Sinonasal mucoceles represent approximately 8% of all sinus masses. The most common site of occurrence is the frontal sinus followed by the ethmoid cavity. Approximately 70% to 90% of mucoceles occur in the frontoethmoidal region. The globe is therefore at risk owing to associated mass effects and potential infectious progression to a mucopyocele. In addition, there is a cytokine cascade with local upregulation of osteolytic cytokines such as interleukin 1 potentiating bony erosion of the orbit with mucocele propagation.
The onset of symptoms is typically insidious, and the spectrum of presentation of orbital mucoceles is variable. In a retrospective study of 102 patients with mucoceles who underwent operative intervention, the most common presenting symptoms were headache (42%), facial pressure (28%), and congestion (26%). Although patients traditionally present with accompanying symptoms of rhinosinusitis, a heightened index of suspicion should be included for patients with proptosis, diplopia, ophthalmoplegia, orbital cellulitis, or facial asymmetry. Retrospective studies of mucoceles with significant intraorbital extension have shown the most common presenting symptoms to include ptosis (33%) and periorbital swelling (29%).
Patients present to a wide spectrum of providers before diagnosis because of the interplay between the sinuses and the orbit. Diagnosing patients appropriately is dependent on clinical history, physical examination including endoscopic examination, and radiographic findings. Patients typically present with a long-standing history of rhinosinusitis symptoms, a history of sinus surgery, or facial trauma. Mucocele development is not an acute process, and the clinical history needs to include chronic conditions as there is a delay between sinonasal insult and mucocele development. One study noted patients presented on average 5.3 years after functional endoscopic sinus surgery (FESS), 17 years after maxillofacial trauma, and 18 years after open surgery.
In addition to the clinical history, a thorough physical examination can help identify sequelae of mucocele expansion. Providers should perform a comprehensive head and neck examination including a focus on the orbit. Visual acuity, visual field testing, and extraocular movements should all be included in the ophthalmologic test battery. Identifying vision loss is key, especially in the acute setting. A systematic review of patients with orbital mucoceles presenting with vision loss concluded that vision loss is potentially reversible in most cases. In a review of 207 patients, those who presented with vision equal to 20/650 or worse and had operative management within 6 days were those that were most likely to have a visual acuity improvement with an improvement comparable to progressing from 20/200 to 20/20. Therefore early identification and intervention are critical for any vision loss associated with orbital mucoceles.
Although a clinical index of suspicion can help identify patients with potential orbital mucoceles, maxillofacial/sinus imaging is critical to identify intracranial and intraorbital extension of mucoceles. Computed tomography helps delineate sinonasal structures and the extent of bony erosion. Magnetic resonance imaging is useful for the evaluation of the orbital, soft-tissue, and intracranial contents. Computed tomography and magnetic resonance imaging have a complementary role in identifying intracranial and intraorbital disease. At a tertiary referral center that surgically addressed 133 mucoceles, intracranial and intraorbital extension was identified preoperatively in 14% and 20% of cases, respectively. Intraorbital extension was most commonly associated with frontoethmoidal mucoceles.
Management of mucoceles requires surgical extirpation and long-term follow-up. Surgical approaches include open approaches, endoscopic approaches, or combined techniques. The varying techniques for surgically addressing sinonasal mucoceles with orbital involvement are discussed further in this chapter.
Transnasal Endoscopic Approaches
Historically, expansile mucoceles involving the orbit and anterior cranial fossa were managed with open techniques. Original thought processes revolved around complete mucocele resection with implementation of obliterative techniques to prevent further recurrence. Although descriptions and outcomes of these operations demonstrated some initial success, the associated morbidity of open procedures to achieve the desired goal remained. Howarth became the first to champion the idea of preservation of mucosal lining and simple marsupialization, which he described in 1921. This slowly gained acceptance during the early 20th century, but for extensive mucoceles, open surgical techniques remained the mainstay of definitive management.
Transnasal techniques progressively gained popularity and were used with increasing frequency, demonstrating acceptable outcomes with limited morbidity. Ultimately, with the technological advancement of endoscopes and the early descriptions of FESS, endoscopic endonasal techniques became the primary operation for management of mucoceles involving the paranasal sinuses. Morbidity was certainly decreased, and the frequency of recurrence was comparable to those of open procedures. It would be later demonstrated that the epithelial lining of mucoceles maintained the normal respiratory epithelium with its associated physiologic properties of mucociliary clearance. Postoperative imaging also showed bony remodeling and neo-osteogenesis of suspected areas of erosion after adequate marsupialization. As otolaryngologists gained experience with endoscopic sinus surgery, outcomes of endoscopic endonasal marsupialization were published. Woodworth et al. reported a 92% success rate (34 of 37 patients) over a mean follow-up interval of 32.6 months with endoscopic management of mucoceles involving erosion of the anterior table of the frontal sinus. Similarly, Sautter et al. described outcomes of 57 patients treated endoscopically for mucoceles with anterior skull base and/or orbital erosion. Fifty-six patients (98.2%) were found to have a patent cavity with no evidence of recurrence at a mean follow-up of 15 months, with no major complications reported. Other case series and meta-analyses have demonstrated similar efficacy and complication rates similar to those previously reported.
Endoscopic techniques for management of frontoethmoid mucoceles follow the same principles as those described for endoscopic sinus surgery. With the frontal and ethmoid sinuses being the most common location for mucoceles to develop, the pseudocyst is often present in the middle meatus ( Figs. 32.1 and 32.2 ). The floor of the mucocele is removed, and the contents can subsequently be expressed. Palpation of the orbit often allows for visualization of any site of bony dehiscence, while simultaneously assisting in evacuation of the mucocele contents. After this has been completed, the cavity is then widely marsupialized. Mucosal-sparing sphenoethmoidectomy is often completed with the approach given the expansile nature of the mucocele. This maneuver also improves visualization and postoperative clinical surveillance.