eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > Nasal & Sinus Diseases

Functional Endoscopic Sinus Surgery

Author: Ankit Patel, MD, Staff Physician, Department of Otolaryngology-Head and Neck Surgery, St Joseph Medical Center, Silver Cross Hospital
Contributor Information and Disclosures

Updated: Mar 6, 2008

Introduction

History of the Procedure

Rhinology and sinus surgery have undergone a tremendous expansion since the discourses of Messerklinger and Wigand in the late 1970s. Imaging advances, increased understanding of the anatomy and the pathophysiology of chronic sinusitis, and image-guided surgery have allowed surgeons to perform more complex procedures with increased safety.

Outstanding short- and long-term results have been reported in the literature. Senior et al reported that symptoms improved in 66 of 72 (91.6%) patients following endoscopic sinus surgery, with a mean follow-up time of 7.8 years.¹ In addition, endoscopic sinus surgery significantly influences quality of life; Damm et al reported an improvement in quality of life for 85% of their patient population, with a mean follow-up time of 31.7 months.²

Although functional endoscopic sinus surgery is the primary approach used today for the surgical treatment of chronic sinusitis, the time-honored external approaches still play a role. Therefore, familiarity with both approaches, in conjunction with a precise understanding of the anatomy, ensures optimal patient care and outcome.

Presentation

The cornerstone of accurate diagnosis and treatment of chronic sinusitis is a thorough history and a complete physical examination, including nasal endoscopy. Before considering surgery, the evaluation should clearly indicate that chronic sinusitis is responsible for the patient's constellation of symptoms.

The history should elucidate the frequency of infections, the type and the duration of symptoms, and the response to medical therapy. Patients with chronic or recurrent symptoms typically report nasal congestion, purulent drainage, postnasal drip, facial pressure and headache, hyposmia or anosmia, and nasal obstruction; however, other conditions can mimic chronic sinusitis, causing one or more of the above symptoms. Therefore, ruling out other etiologies for the patient's symptoms is imperative. For example, patients with allergic rhinitis may have similar problems, such as sneezing, watery eyes, itchy eyes, nasal congestion, and postnasal drip. If the patient's only problem is allergic rhinitis, then endoscopic sinus surgery is not the solution, and proper medical treatment should be prescribed.

The physical examination is an excellent adjunct to the history in diagnosing or excluding chronic sinusitis. A complete head and neck examination, along with anterior rhinoscopy, should be performed. If further nasal examination is required, a full nasal endoscopy should be performed. The patient should be assessed for the following conditions: septal deviation; turbinate hypertrophy; nasal polyps; nasal airway problems, including dynamic internal or external valve collapse; ostiomeatal complex, if visible; and adenoidal hypertrophy. Percussion of the sinuses to elicit tenderness may provide additional information; however, this is an imperfect technique in terms of both sensitivity and specificity.

The history and the physical examination can often be used to confirm a diagnosis of chronic sinusitis. Because ascertaining the contribution of confounding factors to the patient's symptoms is difficult, a reasonable approach is to provide maximal medical therapy (see Treatment) for chronic sinusitis and then to perform a paranasal sinus CT scan. In difficult cases, the findings on CT scans after appropriate medical treatment may assist in diagnosing or ruling out ostiomeatal disease or chronic sinusitis as the etiology for the patient's complaints. In patients with normal CT findings and no change in symptoms after undergoing medical treatment, a diagnosis of chronic sinusitis is suspect at best. These patients should not be offered functional endoscopic sinus surgery as a treatment for their symptoms.

Indications

Endoscopic sinus surgery is most commonly performed for inflammatory and infectious sinus disease. The most common indications for endoscopic sinus surgery are as follows:

• Chronic sinusitis refractory to medical treatment
• Recurrent sinusitis
• Nasal polyposis
• Antrochoanal polyps
• Sinus mucoceles
• Excision of selected tumors
• Cerebrospinal fluid (CSF) leak closure
• Orbital decompression (eg, Graves ophthalmopathy)
• Optic nerve decompression
• Dacryocystorhinostomy (DCR)
• Choanal atresia repair
• Foreign body removal
• Epistaxis control

Typically, endoscopic sinus surgery is reserved for patients with documented rhinosinusitis, based on a thorough history and a complete physical examination, including CT scans if appropriate, and in whom appropriate medical treatment has failed. Patients with nasal polyposis commonly have poor results with medical therapy alone; therefore, surgical intervention may be considered earlier in the course of treatment. Similarly, antrochoanal polyps require surgical removal.

Increasingly, selected nasal masses and tumors are being removed endoscopically. Endoscopic removal of inverted papilloma is controversial. Endoscopic surgery can be performed for limited lesions in which definitive control and margins can be obtained endoscopically; this circumstance can be predicted preoperatively via nasal endoscopy and imaging. More extensive lesions should be approached externally with use of either a lateral rhinotomy method or a midfacial degloving method in order to perform en bloc tumor removal. Further research with long-term monitoring in this area will better delineate the optimal treatment for these patients.

CSF leaks associated with CSF rhinorrhea can be managed endoscopically. Success rates of 80% have been reported in the literature with primary endoscopic attempts; success rates increase to 90% if revision endoscopic closures are included. With endoscopic repair of CSF leaks, the more extensive neurosurgical external approaches via craniotomy can be avoided. In certain clinical settings, endonasal encephaloceles are repaired via endoscopic approaches.

Endoscopic approaches may also be applied for ophthalmologic procedures, including orbital decompression, endoscopic DCR, and optic nerve decompression for traumatic indirect optic neuropathy. Traditionally, these procedures were performed through external approaches, but, with increasing experience in nasal endoscopic techniques, they are now performed endoscopically. Only surgeons with extensive training in and expertise with endoscopic techniques should perform these procedures.

Relevant Anatomy

Knowledge of the anatomy of the lateral nasal wall and the sinuses is critical for performing safe and complete endoscopic sinus surgery. This description of endonasal anatomy is roughly based on the order of dissection during nasal endoscopy and surgery.

Immediately upon entering the nasal cavity, the first structures encountered are the nasal septum and the inferior turbinate. The nasal septum consists of the quadrangular cartilage anteriorly, extending to the perpendicular plate of the ethmoid bone posterosuperiorly and the vomer posteroinferiorly. Recognizing deflections of the nasal septum preoperatively is important because they may significantly contribute to nasal obstruction and limit endoscopic visualization during surgery. As appropriate, patients with septum deflections may be counseled regarding the need for septoplasty in conjunction with functional endoscopic sinus surgery.

The inferior turbinate extends along the inferior lateral nasal wall posteriorly toward the nasopharynx. In patients with a significant allergic component to their problems, the inferior turbinates may be edematous. These patients may benefit from a turbinate reduction at the same time as the endoscopic sinus surgery. The inferior meatus, where the nasolacrimal duct opens, is located approximately 1 cm beyond the most anterior edge of the inferior turbinate.

As the endoscope is further advanced into the nose, the next structure encountered is the middle turbinate. The middle turbinate is a key landmark in endoscopic sinus surgery. It has both a vertical component (lying in the sagittal plane, running from posterior to anterior) and a horizontal component (lying in the coronal plane, running from medial to lateral). Superiorly, the middle turbinate attaches to the skull base at the cribriform plate. As such, care should always be taken when manipulating the middle turbinate. The horizontal component of the middle turbinate is referred to as the basal (or grand) lamella, and it represents the dividing point between anterior and posterior ethmoid air cells. Posteriorly and inferiorly, the middle turbinate attaches to the lateral nasal wall at the crista ethmoidalis, just anterior to the sphenopalatine foramen.

The uncinate process is the next key structure to be identified in endoscopic sinus surgery. This L-shaped bone of the lateral nasal wall forms the anterior border of the hiatus semilunaris, or the infundibulum. The infundibulum is the location of the ostiomeatal complex, where the natural ostium of the maxillary sinus opens. For patients with sinus disease, a patent ostiomeatal complex is critical for an improvement of symptoms. Anteriorly, the uncinate process attaches to the lacrimal bone, and, inferiorly, the uncinate process attaches to the ethmoidal process of the inferior turbinate. Once the uncinate process is removed, the natural maxillary ostium can be seen, typically just posterior to the uncinate process, roughly one third of the distance along the middle turbinate from its anterior edge. It lies at approximately the level of the inferior border of the middle turbinate, superior to the inferior turbinate.

The natural maxillary ostium is the destination for the mucociliary flow within the maxillary sinus. Therefore, for optimal results, the surgically enlarged maxillary antrostomy must include the natural ostium. In fact, failure to include the maxillary ostium in endoscopic surgical antrostomy is one of the key patterns of failure in functional endoscopic sinus surgery. The maxillary sinus, approximately 14-15 mL in volume, is bordered superiorly by the inferior orbital wall, medially by the lateral nasal wall, and inferiorly by the alveolar portion of the maxillary bone.

The next structure to be encountered is the ethmoid bulla, which is one of the most constant anterior ethmoidal air cells. It is just beyond the natural ostium of the maxillary sinus and forms the posterior border of the hiatus semilunaris. The lateral extent of the bulla is the lamina papyracea. Superiorly, the ethmoid bulla may extend all the way to the ethmoid roof (the skull base). Alternatively, a suprabullar recess may exist above the roof of the bulla. A careful preoperative review of the patient's CT scan clarifies this relationship.

The ethmoid sinus consists of a variable number (typically 7-15) of air cells. The most lateral border of these air cells is the lamina papyracea, and the most superior border of these cells is the skull base. Supraorbital ethmoid cells may be present. A review of the patient's CT scan alerts the surgeon to these variations. The basal lamella of the middle turbinate separates the anterior ethmoid cells from the posterior ethmoid cells. Anterior ethmoid cells drain to the middle meatus, and the posterior cells drain into the superior meatus.

Exenteration of the posterior ethmoid cells leads to the face of the sphenoid. The sphenoid sinus is the most posterior of the paranasal sinuses, sitting just superior to the nasopharynx and just anterior and inferior to the sella turcica. The anterior face of the sphenoid sits approximately 7 cm from the nasal sill on a 30° axis from the horizontal.

Several important structures are related to the sphenoid sinus. The internal carotid artery is typically the most posterior and medial impression seen within the sphenoid sinus. In approximately 7% of cases, the bone is dehiscent. The optic nerve and its bony encasement produce an anterosuperior indentation within the roof of the sphenoid sinus. In 4% of cases, the bone surrounding the optic nerve is dehiscent. Therefore, controlled opening of the sphenoid sinus, typically at its natural ostium, is critical for a safe outcome. The location of the natural ostium of the sphenoid sinus is variable; approximately 60% are located medial to the superior turbinate, and 40% are located lateral to the superior turbinate.

The frontal recess, or the frontal outflow tract, is the tract that leads from the frontal sinus into the nasal cavity. Often, the ethmoid bulla is the posterior border of the frontal sinus outflow tract. Anteriorly, the frontal sinus outflow tract is bordered by the uncinate process or the agger nasi cells (frontal anterior ethmoid air cells). If any of these cells are enlarged or if scarring is present from a previous surgery, resultant outflow tract obstruction, leading to frontal sinusitis, may occur. Typically, the medial wall of the frontal recess is formed by the lamina papyracea.

Intimate knowledge and understanding of the anatomy, in conjunction with a careful preoperative review of CT scans, are paramount in the safe and complete performance of endoscopic sinus surgery.

Contraindications

Certain conditions may require an external approach for complete treatment of disease; these include intraorbital complications of acute sinusitis, such as orbital abscess or frontal osteomyelitis with Potts puffy tumor. An open approach in these instances, with or without additional endoscopic assistance, may be preferable. A careful review of preoperative CT scans or MRI films helps to guide the surgeon.

After 2 failures to endoscopically manage CSF leaks associated with CSF rhinorrhea, patients should be referred to a neurosurgeon for closure using a neurosurgical approach. Likewise, after failure to endoscopically manage frontal sinus disease, open approaches should be considered.

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