Residency · Residency · Otolaryngology

Functional Endoscopic Sinus Surgery: Indications and Technique

Overview

Functional endoscopic sinus surgery (FESS) is the surgical standard for chronic rhinosinusitis refractory to maximal medical therapy. The guiding principle is to restore sinus ventilation and mucociliary clearance by removing obstructing tissue and widening natural sinus ostia while preserving normal mucosa. Preoperative CT interpretation and meticulous surgical technique minimize complications.

Indications

Chronic rhinosinusitis (with or without polyps) failing maximal medical therapy (typically 8-12 weeks). Recurrent acute rhinosinusitis (4+ episodes/year), Allergic fungal rhinosinusitis, Mucocele, Sinonasal tumors (biopsy or resection), CSF leak repair. Orbital decompression (Graves disease, subperiosteal abscess). Dacryocystorhinostomy (DCR), Access for skull base surgery.

Preoperative Assessment

CT Sinus (Non-Contrast)

Gold standard imaging; coronal, axial, and sagittal reconstructions. Lund-Mackay scoring: 0-24 points; score of 0-4 common in asymptomatic patients. Systematic review checklist: Keros classification (both sides) -- skull base height asymmetry. Onodi cells (posterior ethmoid cells lateral/superior to sphenoid). Haller cells (infraorbital ethmoid cells). Lamina papyracea integrity. Anterior ethmoidal artery position (within skull base vs. hanging mesentery). Frontal recess anatomy and frontal cells (KUHN classification). Sphenoid sinus pneumatization and ICA/optic nerve relationship. Maxillary sinus accessory ostium. Concha bullosa, paradoxical middle turbinate. Septal deviation (may require septoplasty for access).

Nasal Endoscopy

Document polyp grade, mucopurulent discharge, anatomic variants. Polyp grading: 0 = none; 1 = polyps in middle meatus only; 2 = polyps beyond middle meatus; 3 = polyps completely obstructing nose.

Medical Optimization

Ensure maximal medical therapy trial is documented. Preoperative oral steroids (5-7 days) for CRSwNP to reduce bleeding and polyp bulk. Discontinue anticoagulants/antiplatelets per protocol, Consider preoperative antibiotics for purulent sinusitis.

Surgical Technique

Setup

General anesthesia; total intravenous anesthesia (TIVA) preferred for reduced bleeding. Head of bed elevated 15-30 degrees (reverse Trendelenburg). Topical decongestion: oxymetazoline-soaked pledgets or 1:1000 epinephrine pledgets placed in middle meatus. Local injection: 1% lidocaine with 1:100,000 epinephrine at lateral nasal wall, uncinate process, middle turbinate axilla.

Step-by-Step FESS

1. Medialization of Middle Turbinate

Gentle medialization with Freer elevator for access to middle meatus. Assess for concha bullosa (crush or resect lateral lamella if obstructive).

2. Uncinectomy

Identify the uncinate process; incise with sickle knife or back-biter. Medial-to-lateral swing technique or retrograde removal. Exposes the ethmoid infundibulum and natural maxillary ostium. Avoid injury to the lamina papyracea laterally and nasolacrimal duct anteroinferiorly.

3. Maxillary Antrostomy

Identify the natural maxillary ostium (posterior fontanelle region). Enlarge posteriorly and inferiorly with back-biters or microdebrider. If accessory ostium present, connect it to the natural ostium to avoid mucociliary recirculation. Avoid extending too far anteriorly (nasolacrimal duct) or superiorly (orbital floor). Final opening typically 8-12 mm.

4. Anterior Ethmoidectomy

Enter the ethmoid bulla (most consistent anterior ethmoid cell) through its anterior face. Remove bulla partitions with through-cutting forceps or microdebrider. Work anterior to posterior, medial to lateral. Identify the basal lamella of the middle turbinate (divides anterior from posterior ethmoid). Stay medial to the lamina papyracea; use it as the lateral boundary.

5. Posterior Ethmoidectomy

Perforate the basal lamella (inferomedially to avoid skull base). Enter posterior ethmoid cells. Work with extreme caution: skull base is lower posteriorly, optic nerve is nearby. Identify Onodi cells if present, Clear posterior cells to the sphenoid face.

6. Sphenoidotomy

Identify the sphenoid ostium: medial to the superior turbinate, along the sphenoid face. Approximately 1.5 cm above the posterior choana. Enlarge inferiorly and medially (NEVER laterally -- ICA and optic nerve). Confirm entry into the sphenoid sinus; identify landmarks on posterior and lateral walls.

7. Frontal Sinusotomy (Draf Classification)

Most technically challenging sinus to address.

Draf I: uncinectomy alone; clears cells from frontal recess without entering frontal sinus. Draf IIa: remove cells between the middle turbinate and the lamina papyracea in the frontal recess. Draf IIb: extend dissection to include the frontal sinus floor from the lamina papyracea to the nasal septum. Draf III (modified Lothrop / endoscopic Lothrop): bilateral frontal sinusotomy with removal of the frontal sinus floor, intersinus septum, and superior nasal septum to create a single large neo-ostium. Landmarks: agger nasi cell (anterolateral), anterior ethmoidal artery (posterior limit of dissection), skull base, first olfactory fiber (medial limit). Angled endoscopes (45, 70 degrees) and curved instruments essential.

Image Guidance (Navigation)

Recommended for: revision surgery, distorted anatomy (extensive polyps), skull base/frontal sinus procedures, tumors. CT-based or CT/MRI fusion; registered intraoperatively, Accuracy ~1-2 mm; should NEVER replace anatomic knowledge. AAO-HNS position: appropriate for complex cases; not mandatory for primary FESS.

Postoperative Care

Nasal saline irrigation starting day 1 (high-volume, 240 mL). Topical intranasal corticosteroids after initial healing. Debridement in office at 1-2 weeks, then 3-4 weeks -- removal of crusts, blood clot, early synechiae. Oral steroids taper for CRSwNP patients. Oral antibiotics: culture-directed if purulent secretions encountered. Activity restrictions: no heavy lifting, straining, or nose-blowing for 1-2 weeks.

Complications

Minor

Synechiae (middle turbinate to lateral wall) -- most common; prevented by debridement and middle turbinate medialization or stenting. Hyposmia (usually temporary), Minor epistaxis, Periorbital ecchymosis.

Major

Orbital injury: lamina papyracea breach, orbital hematoma, diplopia (medial rectus injury), vision loss. Retrobulbar hematoma: emergent lateral canthotomy and cantholysis. CSF leak: skull base penetration; identified by clear fluid; repaired with mucosal graft or flap. Intracranial injury: rare; brain parenchyma injury, pneumocephalus, meningitis. Hemorrhage: anterior ethmoidal artery injury (most feared vascular complication); sphenopalatine artery. Nasolacrimal duct injury: epiphora. Loss of vision: most devastating complication; from direct optic nerve injury or orbital hematoma.

<image>Intraoperative endoscopic view sequence showing the key steps of right-sided functional endoscopic sinus surgery. Panel 1: Middle meatus after medialization of the middle turbinate, with the uncinate process visible. Panel 2: After uncinectomy, the natural maxillary sinus ostium and ethmoid infundibulum are exposed. Panel 3: Maxillary antrostomy enlarged posteroinferiorly, with the interior of the maxillary sinus visible. Panel 4: Anterior ethmoidectomy with the ethmoid bulla opened and the basal lamella visible posteriorly. Panel 5: Posterior ethmoid cavity opened with the sphenoid sinus face visible. Panel 6: Sphenoid sinus ostium identified medial to the superior turbinate. Each panel labeled with anatomic structures.</image>

<image>Draf classification of frontal sinus procedures illustrated in coronal and sagittal diagrams. Draf I: frontal recess cells cleared but frontal sinus floor preserved. Draf IIa: frontal recess opened between the middle turbinate and lamina papyracea. Draf IIb: extends medially to the nasal septum. Draf III (modified Lothrop): bilateral opening with removal of the frontal sinus floor, intersinus septum, and superior septum creating a single large drainage pathway. The agger nasi cell, anterior ethmoidal artery, and skull base are labeled as key landmarks in each panel.</image>

<image>Diagram illustrating the major complications of FESS and their anatomical basis. Coronal section showing: (1) skull base penetration with CSF leak at the lateral lamella of the cribriform plate, (2) lamina papyracea breach with orbital fat prolapse and potential medial rectus injury, (3) anterior ethmoidal artery injury with retrobulbar hematoma, (4) nasolacrimal duct injury at the anterior extent of maxillary antrostomy. Each complication zone is highlighted with the at-risk structure and the safe surgical direction indicated by arrows.</image>

Clinical Pearls

FESS is not curative for CRS -- it is an adjunct to ongoing medical therapy; patients must understand the need for continued postoperative medical management. The natural maxillary ostium is located high on the medial wall; always identify it and enlarge from the natural ostium (do not create a separate accessory antrostomy). "When in doubt, go medial" -- the septum is safe; the skull base and orbit are superolateral and lateral. The anterior ethmoidal artery is the key landmark for the posterior limit of safe frontal recess dissection. Image guidance provides a false sense of security if the surgeon does not independently verify anatomy; it is a supplement, not a substitute. Postoperative debridement is essential; synechiae form rapidly and can obstruct the neo-ostia. Revision FESS has higher complication rates due to distorted landmarks and scarring. The microdebrider is not safer than cold instruments -- it removes tissue rapidly and can injure any structure; always maintain visualization.

References

• Stammberger H. "Functional endoscopic sinus surgery: the Messerklinger technique." BC Decker. 1991.
• Draf W. "Endonasal micro-endoscopic frontal sinus surgery: the Fulda concept." Oper Tech Otolaryngol Head Neck Surg. 1991;2(4):234-240.
• Chandra RK, Palmer JN, Tangsujarittham T, Kennedy DW. "Factors associated with failure of frontal sinusotomy in the early follow-up period." Otolaryngol Head Neck Surg. 2004;131(4):514-518.
• Smith TL, Kern R, Palmer JN, et al. "Medical therapy vs surgery for chronic rhinosinusitis: a prospective, multi-institutional study with 1-year follow-up." Int Forum Allergy Rhinol. 2013;3(1):4-9.

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