Fig. 3.22  Draf type III frontal sinusotomy (modified Lothrop). Coronal CT image shows contiguous bilateral enlargement of the frontal sinus floors and resection of the interfrontal sinus septum and superior nasal septum. Septoplasty was also performed with Silastic plates in position

3.11\ FESS Complications

3.11.1\ Discussion

Surgical packing material, such as gauze, may sometimes be left temporarily in the sinuses after functional endoscopic surgery for hemostasis. In the early postoperative period, the gauze can appear as heterogeneous material often containing foci of trapped air, but over time the retained gauze resembles a soft tissue mass with an attenuation of approximately 50 HU on CT (Fig. 3.24). Not all types of gauze packing contain radioattenuating markers. Furthermore, the retained packing may not show enhancement on CT or MRI. Occasionally, patients may not return for postsurgical follow-up, and the packing may remain for long periods of time, resulting in a gossypiboma. This may cause recurrence of sinus symptoms and may even predispose to infection. However, resorbable packing materials have also been developed that do not require removal.

Fig. 3.23  Nasoantral window. Coronal CT image shows surgical defects in the bilateral medial maxillary antrum walls (arrows) in addition to bilateral partial ethmoidectomies

Fig. 3.24  Retained surgical packing (gossypiboma). The patient presents with headache after functional endoscopic sinus surgery a couple of weeks before and neglected to attend the routine postoperative appointment to have the packing removed. Axial CT image shows changes related to FESS and non-enhancing material that contains foci of air filling the ethmoid sinuses (encircled)

3.11.2\ Discussion

Cephaloceles and cerebrospinal fluid leaks are serious complications of endoscopic sinus surgery that can result from inadvertently creating defects in the floor of the anterior cranial fossa. On CT, the presence of pneumocephalus is a helpful indicator that there is indeed intracranial penetration and cerebrospinal fluid leak (Fig. 3.25). High-resolution CT with multiplanar reconstructions is useful for evaluating the presence of bony dehiscence. However, the

presence of sinus opacification contiguous with the intracranial compartment is suggestive, but not specific for encephalocele or meningocele. Rather, MRI is better suited for diagnosing meningoceles, encephaloceles, and associated soft tissue­ injury (Fig. 3.26). Radionuclide cisternographic studies do not adequately localize and characterize skull base defects well enough to be the sole diagnostic examination. Rather, radionuclide cisternography is reserved for complex cases when the diagnosis is in uncertain.

Fig. 3.26  Encephalocele and intraparenchymal hemorrhage. Coronal CT image (a) shows internal ethmoidectomies and dehiscence of the right ethmoid roof (arrow). There is nonspecific opacification inferior to the dehiscence. Coronal (b) T1-weighted MRI shows herniation of

brain tissue through the defect in the ethmoid roof. In addition, there is high signal intensity in a linear distribution (arrows), which corresponds to hemorrhage along the path of the misdirected surgical instrument

3.11.3\ Discussion

Intraorbital complications related to FESS include herniation of intraorbital contents through iatrogenic defects in the lamina papyracea, orbital hemorrhage, optic nerve transection (Fig. 3.27), and orbital cellulitis. Intraorbital hemorrhage can

a

result from direct injury to orbital vessels, ethmoid arteries, or extension into the orbit through a medial wall defect and may cause an acute rise in orbital pressure with rapid onset of proptosis and loss of vision. Orbital CT and MRI are both suitable modalities for evaluating orbital trauma related to FESS.

b

Fig. 3.27  Orbital injury. The patient presented with left vision loss after FESS. Coronal CT images in the bone (a) and soft tissue (b) windows show a large defect in the left

lamina papyracea, abundant pneumo-orbit, retrobulbar hemorrhage, and deformity of the optic nerve on the left side

3.11.4\ Discussion

Both extracranial and intracranial vessels can be injured during FESS. The anterior ethmoidal arteries are particularly susceptible to laceration. Although this can be treated by clipping during the procedure (Fig. 3.28), the artery can ­potentially

retract into the orbit, resulting in intraorbital hemorrhage. High-resolution CT can accurately detect the site of entry, which is usually via the fovea ethmoidalis or roof of the ethmoid sinus. Cerebral angiography is recommended to locate an associated pseudoaneurysm, which can often be treated endovascularly (Fig. 3.29).

Fig. 3.29  Anterior cerebral artery pseudoaneurysm. The patient presented with sudden-onset mental status changes and headache a few days after undergoing polypectomy. Axial CT image (a) shows left gyrus rectus

intraparenchymal hemorrhage with a flame-shaped configuration (arrow). Digital subtraction cerebral angiogram (b) reveals a pseudoaneurysm (arrow)