3.9\ External Ethmoidectomy

3.9.1\ Discussion

In the past, before the advent of functional endoscopic surgery techniques, resection of the ethmoid labyrinth was commonly performed for the treatment of sinusitis via a transorbital approach. The lamina can also be removed endoscopically for tumors such as inverted papillomas. The surgery involves resection of the ipsilateral lamina papyracea through which the paranasal sinuses can be visualized and accessed. The resulting defect in the lamina papyracea can be substantial (Fig. 3.15). Although external ethmoidectomy has been largely supplanted by FESS for treating rhinosinusitis, the approach may still be implemented for resecting certain sinonasal tumors.

Fig. 3.15  External ethmoidectomy. Coronal CT image shows a defect in the right lamina papyracea (arrow), through which the right ethmoid air cells were resected. There is also right frontal blockage, which can be a complication of this approach

3.10\ Functional Endoscopic Sinus

Surgery

3.10.1\ Discussion

Functional endoscopic sinus surgery (FESS) is used to treat chronic sinusitis and is occasionally performed as part of tumor resection. The objective of FESS is to relieve obstruction of mucus drainage while preserving the mucociliary clearance mechanism. The procedure consists of resecting various portions of the paranasal sinuses using an intranasal endoscope depending on the extent of disease and whether the anterior or posterior drainage routes are predominantly affected. The resulting changes are not necessarily symmetric from right to left or reproducible from one patient to another. Nevertheless, certain fundamental strategies are generally implemented, which are based on the major mucosal drainage pathways. CT with multiplanar reformatted­ images is the first-line modality for evaluating the paranasal sinuses and surrounding structures following FESS.

Turbinoplasty or partial anterior middle turbinectomy is sometimes performed in order to increase the exposure of the paranasal sinuses. The middle turbinate can be completely resected if it is responsible for obstructing the middle meatus (Fig. 3.16).

Uncinectomy is essentially performed during all types of FESS when the ostiomeatal complex is affected by rhinosinusitis, along with resection of variable amounts of the anterior ethmoid air cells. Since the anterior ethmoid air cells normally comprise two-thirds to three-quarters of the ethmoid air cells, the resection cavity can extend rather far

posteriorly­ . Typically, anterior ethmoidectomies and uncinectomies are ­performed together in order to optimally decompress the ostiomeatal complex­ and access the maxillary sinuses (Fig. 3.17).

Disease of the posterior drainage system can be treated via ethmoidectomy alone or in combination with sphenoidotomy, which consists of enlarging the sphenoid sinus ostium (Figs. 3.18 and 3.19). This is often performed in conjunction with decompression of the ostiomeatal complex.

Disease that affects the frontoethmoid drainage pathway can be addressed via frontal recess sinusotomy. Frontal recess sinusotomy approaches have been traditionally classified as

Draf type I through III based on the extent of agger nasi and frontal air cells resected (Figs. 3.19, 3.20, 3.21, and 3.22). The Draf type III (modified Lothrop) procedure is the most radical form of frontal sinusotomy and involves resection of the upper internasal septum in addition to the frontal air cells.

Occasionally, a defect is created in the medial maxillary sinus wall (antrostomy or nasoantral window), although this is not considered a standard part of FESS (Fig. 3.23). Another twist that is sometimes performed during FESS is Bolgerization, which consists of stripping away part of the mucosa of the nasal septum in order to secure a loose middle turbinate and prevent lateralization.

Fig. 3.16  Middle turbinectomy. Coronal CT image shows resection of the left middle turbinate, leaving behind a portion of the left vertical lamella (arrow). There is a concha bullosa on right side

Fig. 3.17  Typical pattern of ostiomeatal unit FESS. Coronal CT image shows the absence of the bilateral anterior ethmoid air cells and uncinate processes, resulting in widely patent anterior drainage pathways and clear sinuses

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Fig. 3.18  Posterior drainage pathway FESS. Axial (a) and sagittal (b) CT images show bilateral enlarged sphenoid ostia (arrows). Bilateral total ethmoidectomies and middle turbinectomies were also performed

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Fig. 3.20  Draf type I frontal sinusotomy. Preoperative coronal CT image (a) shows a partially opacified right agger nasi cell (arrow). Postoperative coronal CT image

(b) shows a defect in the inferior aspect of the right agger nasi cell (arrow)