3.11.5\ Discussion

Medial bowing of the lamina papyracea can occur following internal ethmoidectomy perhaps due to the loss of internal structural support and

a

c

forces of contracture during the postoperative healing period (Fig. 3.30). On average, the interorbital distance decreases by about 1 mm after surgery and mild enophthalmos results. These changes are usually subclinical.

b

d

Fig. 3.30  Medialized lamina papyracea. Preoperative axial (a) and coronal (b) CT images show normal alignment of the bilateral lamina papyracea. Postoperative axial (c) and coronal (d) CT images show bilateral internal

ethmoidectomies and middle turbinate with medial bowing of the laminae papyracea. There is also new opacification of the ethmoid sinuses

3.11.6\ Discussion

Mucosal inflammatory disease is common after FESS (Fig. 3.31). Mucosal thickening up to 3 mm is considered normal. However, the degree of mucosal thickening demonstrated on imaging does not necessarily correlate with

a

recurrent symptoms. Mucosal inflammation and synechiae are often indistinguishable on imaging and may certainly coexist. However, synechiae can appear as thin bands of soft tissue­ within or adjacent to the operative sinonasal cavity. These are most common after frontal sinusotomy.

b

Fig. 3.31  Mucosal inflammation. Preoperative coronal CT image (a) shows mild mucosal thickening. Postoperative CT image (b) shows diffusely increased

mucosal thickening, particularly in the right maxillary sinus after bilateral uncinectomy, as well as correction of septal deviation

Mucoceles can form in previously operated sinuses due to blockage by the bone and/or scar tissue. Mucoceles are characterized by expansion of the sinus (Fig. 3.32). Although the absence of air within the affected sinus is sine qua non for mucoceles in nonoperated patients, this is not necessarily the case for postoperative mucoceles. Postoperative scar tissue may isolate a portion of the sinus, forming a compartment where the mucocele can form. This is sometimes termed “surgical ciliated cyst.”

Recurrent polyposis after surgery may require revision surgery. The frequency varies with comorbidities like ASA sensitivity and asthma. This complication is particularly predisposed by a history of cystic fibrosis, aspirin-exaggerated respiratory disease (AERD), and allergic fungal sinusitis. These patients are also prone to developing inspissated secretions. Polyposis is recognized by the presence of soft tissue attenuation material with smooth, convex margins on CT (Fig. 3.33).

A laterally displaced remnant of the middle turbinate can obstruct the frontal recess after FESS. This can happen due to inadvertent loosening of the middle turbinate during surgery, whereby the turbinate can become adherent to the lamina papyracea. The altered anatomy and obstructed secretions are best depicted on coronal CT image (Fig. 3.34).

Osteoneogenesis is a form of osteitis or hyperostosis that can result from iatrogenic mucosal disruption. There may also be superimposed chronic inflammation or infection. On CT, osteoneogenesis appears as high-attenuation thickening of the sinus walls and septa (Fig. 3.35). The thickened bone may be patchy and irregular. There may also be accompanying mucosal thickening and scarring. The significance of osteoneogenesis is that it can predispose to restenosis of the involved sinus.

Fig. 3.34  Lateralized middle turbinate. Coronal CT image shows marked lateral deviation of the left middle turbinate (arrow) with resultant obstruction of the frontal and ethmoid sinuses, which are opacified (*)

Fig. 3.35  Osteoneogenesis. Coronal CT image demonstrates areas of new bone formation in the left frontoethmoid recess region