Endoscopic sinus surgery: role of the radiologist.

Endoscopic sinus surgery has become an increasingly popular procedure since Messerklinger [1) and Wigand et al. [2] described the advantages of the intranasal endoscope and its surgical application . The concept of "functional endoscopic sinus surgery" [3] evolved from the work of Hilding [4, 5), Proctor [6, 7], and Messerklinger [8-1 0] on mucociliary clearance and air flow in the paranasal sinuses and on the importance of establishing drainage and preserving the mucosa of the sinuses . Functional endoscopic sinus surgery is based on the hypothesis that the ostiomeatal complex (maxillary sinus ostium, anterior and middle ethmoid ostia, frontal recess, infundibulum, and middle meatal complex) is the key area in the pathogenesis of chronic sinus diseases [3, 8-17). Minor pathologic changes in the nasal mucosa in the vicinity of the ostiomeatal complex may interfere with mucociliary clearance or with the ventilation of the maxillary, ethmoidal, and frontal sinuses. The underlying principle of functional endoscopic sinus surgery is that the sinus mucosa will return to normal if adequate drainage can be established [13). No attempt is made to remove the sinus mucosa; rather, it is allowed to return to normal and to resume its normal function . In this issue of the AJNR, Babbel et al. [18) attempt to establish an optimal imaging protocol for preendoscopic screening CT of the sinuses, including preparation of the patient, CT technique, and data display (filming). I agree with the authors that pretreatment of patients with appropriate medical therapy and adequate preparation of patients enable the best CT assessment of mucosal disease of the nasal and paranasal sinuses. Coronal CT scanning with the patient in a prone position and the head hyperextended currently affords the best preoperative evaluation for endoscopic anterior ethmoidectomy, frontal sinusotomy [14, 17], and for posterior endoscopic total sphenoethmoidectomy [12). The anterior and posterior walls of the frontal sinuses and the anatomic relationship between the posterior ethmoidal and sphenoidal sinuses are best evaluated in the axial plane [16) . In terms of filming , Babbel et al. recommend an intermediate (2500 H/ 250 H) window width/level technique. I prefer CT images filmed with extended window width-bone technique (4000 H/ 700-800 H). I also require that the technicians provide a set obtained by using a soft-tissue technique. The soft-tissue technique allows better evaluation of inspissated mucosal debris, microcalcifications, and incidental findings in the orbit and eyeball , as well as in the parts of the face and cranium included in the study. I would like to discuss three issues related to the article by Babbel et al. : the concepts of functional endoscopic sinus surgery, the important role of the radiologist in preoperative assessment for endoscopic sinus surgery, and the increasing rate of significant and serious complications associated with endoscopic sinus surgery. The paranasal sinuses , like other parts of the upper respiratory system, are lined with a pseudostratified columnar ciliated epithelium under which is a tunica propria, which contains mucous and serous glands [13, 14]. The secretions of these glands form surface films of mucus and fluid (mucus blanket) that cover the epithelium. Cilia of the upper respiratory mucosa beat with a wavelike, synchronous rhythm that continuously propels a surface coat of mucus, containing entrapped particles, toward the pharynx [20) . In the paranasal sinuses and nasal cavity, the ciliated epithelium and the mucus blanket form the so-called mucociliary system that protects