**4. Acute rhinosinusitis and complications**

Acute rhinosinusitis (ARS), defined as symptoms less than 4 weeks, is the most common disease of the paranasal sinuses. Fluid is often an incidental finding at CT (**Figure 2**) and should not be misinterpreted as ARS. Mucosal thickening and air bubbles in the opacification can be interpreted as ARS, if clinical symptoms harmonize [7] (**Figure 5a** and **b**).

#### **Figure 5.**

*(a) Coronal CT shows right-sided maxillary opacification with air bubbles consistent with acute rhinosinusitis. (b) Coronal CT shows thick, sclerotic right maxillary sinus walls that indicate a long-standing infection. In addition, the sinus walls are retracted due to a vacuum effect, referred to as sinus silent syndrome. In the left maxillary sinus, the opacification contains air bubbles consistent with an active bacterial infection.*

#### **Figure 6.**

*(a) Coronal and (b) axial CT of a 6-year-old boy with complication to acute rhinosinusitis. The infection has spread through the thin lamina papyracea on the right side, and there is stranding of the fat preseptal and postseptal (intraorbital), consistent with phlegmon. Notice also the marked proptosis of the affected side and slightly lateral displacement of the medial rectus muscle.*

**15**

*Imaging in Sinonasal Disorders*

**Figure 7.**

*DOI: http://dx.doi.org/10.5772/intechopen.90773*

In acute rhinosinusitis, imaging is only indicated when complications are suspected. Extra-sinonasal spread of infection is rare but needs urgent treatment. Children are at most risk. Intraorbital spread from ethmoid and frontal ARS is the most common complication and may present as cellulitis, subperiosteal or intraorbital phlegmon and abscess, and lateral displacement of the medial rectus muscle (**Figure 6a** and **b**). The clinical presentation may be forward protrusion of the eyeball, proptosis [8–10]. Intracranial spread is most commonly seen in frontal and ethmoid ARS and presents as complications that include epidural and brain abscesses, subdural

*(a) Coronal CT in a patient with granulomatosis with polyangiitis shows a frontal sinus mucocele/pyocele due to obstruction of the frontal recess. By time remodelling of bone may cause erosion into the orbit. (b) Axial CT* 

Mucocele and pyocele if not treated may also erode into the orbit and cranial cavity by time (**Figure 7a** and **b**) or erode the anterior frontal bone resulting in a

A recent study has focused on the intake of ibuprofen in children as a risk factor

An underlying odontogenic infection is reported to be the cause in up to 40% of chronic rhinosinusitis (CRS). In addition, several other conditions may mimic

Five distinct radiological inflammatory patterns have been described, each with a different therapeutic course and surgical options [13], where the first three are caused by obstruction of the mucociliary flow. Obstruction of the maxillary sinus drainage is the most common. The level of obstruction is at the ostium and the thin ethmoid infundibulum and referred to as infundibular pattern. Obstruction of the middle meatus, the common drainage way for the frontal, anterior ethmoid, and maxillary sinuses, will cause obstruction of ipsilateral sinuses and is referred to as ostiomeatal (from ostium and meatus) complex (OMC) pattern. Less common is obstruction of the sphenoethmoidal recess that drains the posterior ethmoid and sphenoid sinuses.

Surgical intervention of mucociliary obstruction is referred to as functional endoscopic sinus surgery (FESS). Functional refers to the widening of the natural ostia. For the infundibular and OMC inflammatory pattern, FESS includes uncinectomy (removing the uncinate process), opening the ethmoid infundibulum, and making a larger opening to the antrum (maxillary sinus) referred to as media-antrostomy.

empyema, meningitis, and cavernous sinus thrombosis [11].

*demonstrates erosion of the posterior sinus wall and risk of intracranial involvement.*

for developing orbital and intracranial complications of ARS [12].

subcutaneous abscess, referred to as Pott's puffy tumor.

**5. Chronic rhinosinusitis and complications**

rhinosinusitis and challenge the radiological interpretation.

The two last patterns are sinonasal polyposis and incidental findings.

**Figure 7.**

*Sino-Nasal and Olfactory System Disorders*

**4. Acute rhinosinusitis and complications**

polyp [4] (**Figure 4a** and **b**).

nize [7] (**Figure 5a** and **b**).

rhinorrhea [6].

When more fluid is accumulated in the retention cysts, they may grow out of the maxillary sinus through the ethmoid infundibulum or the accessory maxillary ostium into the nasal cavity and choana and then be referred to as an antrochoanal

Pseudocysts are often referred to as a polyp in the radiological report. However, polyps contain more fibrous connective tissue than pseudocyst and tend to be more fibrotic. Hence polyps can surgically be removed intact, but not pseudocysts [4]. Pseudocysts may also rupture spontaneously or traumatically, causing unilateral

Acute rhinosinusitis (ARS), defined as symptoms less than 4 weeks, is the most common disease of the paranasal sinuses. Fluid is often an incidental finding at CT (**Figure 2**) and should not be misinterpreted as ARS. Mucosal thickening and air bubbles in the opacification can be interpreted as ARS, if clinical symptoms harmo-

*(a) Coronal and (b) axial CT of a 6-year-old boy with complication to acute rhinosinusitis. The infection has spread through the thin lamina papyracea on the right side, and there is stranding of the fat preseptal and postseptal (intraorbital), consistent with phlegmon. Notice also the marked proptosis of the affected side and* 

*(a) Coronal CT shows right-sided maxillary opacification with air bubbles consistent with acute rhinosinusitis. (b) Coronal CT shows thick, sclerotic right maxillary sinus walls that indicate a long-standing infection. In addition, the sinus walls are retracted due to a vacuum effect, referred to as sinus silent syndrome. In the left maxillary sinus, the opacification contains air bubbles consistent with an active bacterial infection.*

**14**

**Figure 6.**

**Figure 5.**

*slightly lateral displacement of the medial rectus muscle.*

*(a) Coronal CT in a patient with granulomatosis with polyangiitis shows a frontal sinus mucocele/pyocele due to obstruction of the frontal recess. By time remodelling of bone may cause erosion into the orbit. (b) Axial CT demonstrates erosion of the posterior sinus wall and risk of intracranial involvement.*

In acute rhinosinusitis, imaging is only indicated when complications are suspected. Extra-sinonasal spread of infection is rare but needs urgent treatment. Children are at most risk. Intraorbital spread from ethmoid and frontal ARS is the most common complication and may present as cellulitis, subperiosteal or intraorbital phlegmon and abscess, and lateral displacement of the medial rectus muscle (**Figure 6a** and **b**). The clinical presentation may be forward protrusion of the eyeball, proptosis [8–10].

Intracranial spread is most commonly seen in frontal and ethmoid ARS and presents as complications that include epidural and brain abscesses, subdural empyema, meningitis, and cavernous sinus thrombosis [11].

Mucocele and pyocele if not treated may also erode into the orbit and cranial cavity by time (**Figure 7a** and **b**) or erode the anterior frontal bone resulting in a subcutaneous abscess, referred to as Pott's puffy tumor.

A recent study has focused on the intake of ibuprofen in children as a risk factor for developing orbital and intracranial complications of ARS [12].
