Functional Endoscopic Sinus Surgery

Anesthesia for Endoscopic Sinus Surgery

Patients may undergo functional endoscopic sinus surgery under intravenous sedation and local anesthesia or under general anesthesia. The authors' institutional preference is general anesthesia.

Overview of Endoscopic Sinus Surgery

The procedure begins with decongestion of the nose and infiltration of lidocaine with epinephrine (1% lidocaine with 1:100,000 epinephrine is used for injection). The lateral nasal wall near the uncinate process is injected. Using a 3-mL syringe while placing a slight bend to the 27-gauge needle facilitates the injection.

Next, the superior inlet and the anterior face of the middle turbinate are injected submucosally. If the possibility of septoplasty exists, the septum should also be injected.

Next, 4 mL of 4% cocaine is placed onto pledgets, which are placed bilaterally in the nares. A throat pack may be placed, or alternatively, the stomach may be suctioned prior to extubation upon completion of the procedure.

The patient is then draped for surgery. If image-guided surgery is to be used, the appropriate headset apparatus should be applied at this time.

Endoscopic Uncinectomy

Functional endoscopic sinus surgery may begin with uncinectomy. If the uncinate process can be initially visualized without manipulating the middle turbinate, uncinectomy can be performed directly. Otherwise, the middle turbinate is gently medialized, carefully using the curved portion of the Freer elevator to avoid mucosal injury to the turbinate and to avoid forceful medialization and fracture of the turbinate.

Next, uncinectomy may be performed via an incision with either the sharp end of the Freer elevator or a sickle knife. The incision should be placed at the most anterior portion of the uncinate process, which is softer on palpation in comparison to the firmer lacrimal bone, where the nasolacrimal duct is located. Then, a Blakesley forceps is used to grasp the free uncinate edge and to remove it.

Complete uncinectomy is important for subsequent visualization. Incomplete uncinectomy is a common reason for failure with primary surgery. The backbiter may also be directly used to take down the uncinate process.

Maxillary Antrostomy/Ethmoidectomy

Once the uncinate process is taken down, the true natural ostium of the maxillary sinus should be identified. The protected eye may be palpated at this juncture to ensure that there is no dehiscence of the lamina papyracea and to confirm the location of the lamina. The natural ostium is typically at the level of the inferior edge of the middle turbinate about one third of the way back.

A true cutting instrument is used to circumferentially enlarge the natural ostium. The optimal diameter for the maxillary antrostomy is controversial; typically, a diameter of 1 cm allows for adequate outflow and for postoperative monitoring in the office. Care should always be taken to avoid penetrating the lamina papyracea.

Anterior Ethmoidectomy

Next, the ethmoid bulla should be identified and opened. A J-shaped curette may be used to open the bulla at its interior and medial aspect. Once the cell is entered, the bony portions may be carefully removed using a microdebrider or a true-cutting forceps. Complete resection of the lateral bulla facilitates proper visualization and dissection posteriorly. Again, care should be taken laterally to maintain an intact lamina papyracea.

The remainder of the anterior ethmoid cells may be uncapped initially with a J curette and further opened with a microdebrider or a true cutting forceps. Using a curette initially allows for tactile sensation and determination of the thickness of bone and verifies proper orientation prior to further opening of cells with powered instrumentation. Care should always be taken to avoid mucosal stripping, because mucosal preservation results in superior postoperative outcomes.

Anterior ethmoid cells should be cleared to the skull base, with the surgeon exercising caution when approaching the ethmoid roof and maintaining constant reference to the endoscopic view and to the preoperative CT scan. Image-guided surgery or computer-aided surgery also guides the surgeon as to the distance to the skull base, but it does not replace the need for an intimate knowledge of the anatomy.

While moving posteriorly to new air cells, the surgeon should always enter inferiorly and medially and then subsequently open laterally and superiorly once the more distal anatomy can be judged by visualization and palpation. Anterior ethmoidectomy is complete upon reaching the basal lamella of the middle turbinate.

If the sinus disease is limited to the anterior ethmoid cells and the maxillary sinus, the procedure may end with simple anterior ethmoidectomy and maxillary antrostomy. If, however, significant radiographic and clinical disease of the posterior ethmoid and sphenoid is present, then dissection should continue to exenterate the posterior ethmoid cells and to perform adequate sphenoidotomy as appropriate.

Posterior Ethmoidectomy

Posterior ethmoidectomy begins with perforating the basal lamella just superior and lateral to the junction of the vertical and horizontal segments of the middle turbinate. Care must be taken to preserve the posterior sagittal section of the middle turbinate and the inferior portion of the coronal segment of the basal lamella. Preserving this L-shaped strut ensures the stability of the middle turbinate. The lateral and superior portions of the basal lamella may then be removed using the microdebrider.

Further posterior ethmoid cells may be taken down in a similar fashion, keeping in mind the location of the skull base and the lamina. The surgeon must be cognizant that the skull base typically slopes inferiorly at an approximately 30° angle from anterior to posterior. Thus, the skull base lies lower posteriorly than anteriorly. This dissection is taken back to the face of the sphenoid.

Enlargement of the Natural Ostium of the Sphenoid Sinus

In the absence of Onodi cells, the sphenoid ostium lies medial and posterior to the final posterior ethmoid cell. A rough guide is that the face of the sphenoid is approximately 7 cm from the nasal sill at a 30° angle from the horizontal. Identifying the superior turbinate aids in the confirmation of position. The superior turbinate inserts on the anterior face of the sphenoid sinus.

The sphenoid sinus is entered just medial and inferior to its natural ostium with a J curette or an olive-tipped suction. Once the sinus is entered safely, the ostium can be enlarged using a mushroom punch forceps. Care must be taken not to aggressively enter the sinus because dehiscences may be present in the bony coverage of the carotid artery or the optic nerve.

Frontal Sinus Work

Frontal sinus work is typically reserved for the end of the surgical procedure because manipulation may create bleeding and obscure further posterior work. If frontal sinus work is indicated, a 45° or a 70° telescope proves useful.

Typically, an agger nasi or frontal cell is the cause of frontal outflow obstruction. Using an angled scope for visualization, a frontal sinus curette is passed above the cell and then pulled anteriorly, thus breaking posterior and superior cell walls.

Particular care must be exercised when working in the frontal recess, because the lamina and the skull base sit in immediate proximity to the outflow tract. Image-guided and navigational systems for computer-aided surgery and intimate knowledge of the anatomy are critical for safe frontal sinus work. Kuhn and Javer provide further discussion of endoscopic frontal sinus surgery. ^[8]

Nasal Packing and Spacer Placement

Once dissection is complete and hemostasis is achieved, a bacitracin-coated Telfa or Afrin soaked pledget is placed into the nostril. Some surgeons also place Gelfilm or a dissolvable spacer within the middle meatus to keep the space open and to prevent lateralization of the middle turbinate and synechiae formation.

Nasal packing is removed prior to discharge of the patient. The patient is discharged with saline nasal spray (eg, OCEAN Nasal Spray) and antibiotics, as well as instructions for a follow-up visit in 1 week. If a spacer was placed in the middle meatus, it should be removed or suctioned away on the first postoperative visit.

Outcome and Prognosis

Outstanding short- and long-term results have been reported for endoscopic sinus surgery. In one study, symptoms improved in 66 of 72 patients following this surgery, with a mean follow-up time of 7.8 years. ^[1] In another report, quality of life improved for 85% of the patient population, with a mean follow-up time of 31.7 months. ^[2]

Complications

All risks and benefits should be candidly discussed with patients as part of the informed consent process prior to surgery. A patient should never undergo surgery without a full discussion of all possible complications.

Risks associated with endoscopic sinus surgery are as follows:

• Bleeding

• Synechiae formation

• Orbital injury

• Diplopia

• Orbital hematoma

• Blindness

• CSF leak

• Direct brain injury

• Nasolacrimal duct injury/epiphora

A large retrospective study of the complications associated with functional endoscopic sinus surgery found an overall complication rate of 0.50%; the rates of CSF leakage, orbital injury, hemorrhage requiring surgery, blood transfusion, and TSS were 0.09%, 0.09%, 0.10%, 0.18%, and 0.02%, respectively. ^[9]