Endoscopic Ethmoidectomy

History of present illness

• a.

  Primary symptoms most bothersome to the patient

  • 1)

    Identification of these symptoms allows for effective counseling of what surgery can and cannot achieve, thus framing patient expectations.

• b.

  Duration of symptoms

• c.

  Specific symptoms

  • 1)

    Nasal obstruction

  • 2)

    Hyposmia

  • 3)

    Facial pressure/pain

  • 4)

    Nasal discharge/postnasal drip

• d.

  Previous attempts at treatment including systemic antibiotic and steroid therapies, topical therapies, and surgery

Past medical history

• a.

  Prior management: Medical and surgical

• b.

  Medical illness

  • 1)

    Comorbidities

  • 2)

    Allergies

  • 3)

    Asthma/reactive airway disease

    • a)

      Patients with reactive airway disease or asthma frequently have concomitant sinonasal disease. Surgery should be postponed until asthma is under good control and consultation with a pulmonologist is completed.

  • 4)

    Cystic fibrosis

    • a)

      Similarly, planning for ESS in cystic fibrosis patients should be completed in consultation with a qualified pulmonologist comfortable managing the pre- and postoperative care of these patients.

    • b)

      Perioperative antibiotics are usually necessary to prevent infectious complications in this patient group.

  • 5)

    Aspirin/nonsteroidal anti-inflammatory drug (NSAID) sensitivity

• c.

  Medications

  • 1)

    Anticoagulants/aspirin/NSAIDs

  • 2)

    Supplements that can increase the risk of bleeding

Nasal endoscopy is completed in an office setting using a topical anesthetic and decongestant. Documentation should be made of any polyps, mucopurulent exudate, anatomic abnormalities including septal deviation, and any sinonasal masses. Use of 0-degree and 30-degree endoscopes can help fully visualize the sinonasal cavity. The classic endoscopic evaluation involves three “passes” of the endoscope.

• a.

  The first pass is along the floor of the nose with special attention paid to the inferior turbinate, inferior meatus, nasolacrimal duct, and nasopharynx (fossa of Rosenmuller and eustachian tube orifice).

• b.

  The second pass is toward the middle turbinate (MT), examining the middle meatus, ethmoid bulla, uncinate, lateral nasal wall, sphenoethmoidal recess, superior turbinate, and sphenoid os.

• c.

  The third pass is made (often with a 30-degree endoscope) to visualize superiorly toward the olfactory cleft.

Maxillofacial CT scan

• a.

  A dedicated maxillofacial CT scan is a prerequisite for ESS. At our institution the scans are performed under a navigation protocol with at least 1-mm slice thickness and corresponding coronal and sagittal reformatting. These images can then be linked to conceptualize the sinus anatomy in three dimensions. Specific anatomic landmarks should be identified to prevent complications of cerebrospinal fluid (CSF) leak and orbital or vascular injury during endoscopic ethmoidectomy. Thus particular attention should be paid to these areas in preoperative CT evaluation and intraoperative dissection.

  • 1)

    The skull base should be assessed for its height, thickness, and slope ( Fig. 108.1 ). The roof of the ethmoid cavity tends to be thicker laterally and becomes thin medially near the lateral lamella of the cribriform plate. The Keros classification has divided the anatomic arrangement of the skull base based on the depth of the olfactory sulcus into type I (1 to 3 mm), type II (4 to 7 mm), and type III (8 to 16 mm), with increased depth representative of increased risk of skull base injury and subsequent CSF leak ( Fig. 108.2 ).

    
    

  • 2)

    The anterior and posterior ethmoid arteries should be carefully inspected on CT for relative position to the skull base. Those that course in a mesentery inferior to the skull base are at greater risk of injury than those contained within the bony skull base ( Fig. 108.3: anterior/posterior ethmoid arteries ). The anterior ethmoid artery can be reliably identified on CT scan on coronal images just posterior to the globe ( Fig. 108.4: CT anterior ethmoid artery ).

    
    

  • 3)

    The medial orbital wall should also be closely examined for erosion or previous trauma that may pose a risk to the orbital contents. Frequently, there is posterior/superior pneumatization of a posterior ethmoid cell over the sphenoid (an Onodi cell), bringing this ethmoid cell close to the optic nerve and cavernous sinus/carotid.

In cases of skull base tumors or sinonasal malignancies, a skull base magnetic resonance imaging (MRI) with and without contrast may be indicated.

• a.

  MRI with contrast can help differentiate tumors from surrounding inflamed mucosa and inspissated secretions.

• b.

  This imaging modality also helps determine perineural spread of disease toward the skull base in malignancies such as adenoid cystic carcinoma.

Patients selected for functional ethmoidectomy should demonstrate symptomatic and significant mucosal disease, causing anatomic obstruction. Other indications for endoscopic ethmoidectomy include mucocele formation or access to the other sinuses. Ethmoid mucoceles, which can cause erosion of the lamina papyracea and produce orbital symptoms such as proptosis and diplopia, are usually secondary to scarring from prior surgery or associated with hyperplastic mucosal diseases such as allergic fungal rhinosinusitis. Access to the sphenoid sinus may be gained via an anterior and posterior ethmoidectomy, but this is not always required. Approaching the sphenoid via the posterior ethmoid cavity preserves the vertical stability of the MT, which may be lost if the MT is lateralized to approach the natural ostium of the sphenoid, which usually lies medial to the middle and superior turbinate.

Ethmoidectomy is often performed for access to the frontal sinuses with removal of the agger nasi and associated suprabullar cells, which will be discussed further in Chapter 112 , “Endoscopic Approach to the Frontal Sinus.”

Medical comorbidities that would prevent the patient from safely undergoing general anesthesia. Patients should be appropriately screened for potential risks that outweigh the benefits of an elective surgery.

Uncontrolled asthma or reactive airway disease should be adequately controlled prior to ESS.

Dedicated maxillofacial CT scan should be obtained and carefully reviewed prior to surgery as discussed in the “Imaging” section.

Patients should stop taking aspirin, nonsteroidal anti-inflammatories, or other anticoagulants and supplements at least 7 days preoperatively. If there is a history of bleeding with prior surgery or trauma, then a coagulation profile is obtained. Profuse intraoperative bleeding precludes safe endoscopic visualization and is a contraindication to continuation of an endoscopic dissection.

Preoperatively, patients are counseled regarding the procedure, risks, and complications. This informed consent should be detailed and include the following risks: loss of smell, worsening of symptoms, bleeding, infection, CSF leak, and orbital injury, including diplopia and loss of vision.

Imaging studies and pathology slides from previous surgery done elsewhere should be obtained and reviewed by in-house experts.