• Persistent adenoids

*Rhinosinusitis*

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**Figure 17.**

**Figure 16.**

**Figure 15.**

*Endoscopy showing two accessory ostia.*

*CT showing hypoplasia of bilateral maxillary sinus.*

*CT (axial section) agenesis of right maxillary sinus.*

Adenoids are present at birth and usually regress by 12–14 years of age. With advent of CT PNS, it is now clear that adenoids may persist even after adolescence. In our case, adenoids persisted till 56 years of age; this patient too had presented with CRS (**Figures 19** and **20**).

There is evidence that the adenoid provides a reservoir of bacteria that may be a pathogenic factor in the development of CRS. Biofilms overlying the adenoid pad may prevent antibiotic therapy from clearing the infection. Adenoidectomy surgically removes this reservoir for chronic infection [17].

• KEROS classification (**Figures 21–24**)

Depending upon the depth of olfactory fossa Keros classification is as follows: KEROS type I—Depth of olfactory fossa is 1–3 mm.

KEROS type II—Depth of olfactory fossa is 4–7 mm.

KEROS type III—Depth of olfactory fossa is 8–14 mm.

Type I is the safest while type III has high chances of skull base injury during ethmoidectomy.

Asymmetry of ethmoid roof on both sides of the same patient is not uncommon. Hence, the surgeon should read CT thoroughly before any surgical intervention.

### • Low anterior ethmoidal artery

Anterior ethmoidal artery is an important landmark in sinus surgery. The anterior ethmoidal artery is seen as a classical breaking of the medial orbital wall. The artery may lie close to the skull base or may cross low within anterior ethmoid in which case the orbitocranial canal with its bony mesentery is clearly seen [4] (**Figure 25**). If the anterior ethmoidal notch is abutting the lateral lamella or the fovea ethmoidalis, the artery is considered protected during functional

**Figure 18.** *CT showing septal pneumatisation.*

**Figure 19.** *CT showing persistent adenoids in a 56-year-old patient.*

**Figure 20.** *Endoscopic showing persistent adenoids.*

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incidence.

**Figure 23.**

*CT showing KEROS type III.*

**Figure 22.**

*CT showing KEROS type II.*

*Rhinosinusitis: How Common Are Anatomical Variations Responsible?*

endoscopic sinus surgery as it is as the level of the skull base. If a supraorbital cell is seen above the anterior ethmoidal notch, or if the artery is located below the

Natural dehiscence in lamina papyracea will result in prolapse of orbital contents into the nasal cavity. The defects allow easy damage to the orbit during FESS and also increase the risk of orbital contents being drawn into the microdebrider. The incidence of anatomical variations responsible for CRS in decreasing order

Deviated nasal septum—the commonest anatomical variation with 69%

skull base, it is considered at risk [18, 19].

of their frequency is as follows:

• Dehiscent lamina papyracea (**Figure 26**)

*DOI: http://dx.doi.org/10.5772/intechopen.83689*

**Figure 21.** *CT showing KEROS type I.*

*Rhinosinusitis: How Common Are Anatomical Variations Responsible? DOI: http://dx.doi.org/10.5772/intechopen.83689*

**Figure 22.** *CT showing KEROS type II.*

*Rhinosinusitis*

**68**

**Figure 21.**

*CT showing KEROS type I.*

**Figure 20.**

**Figure 19.**

*Endoscopic showing persistent adenoids.*

*CT showing persistent adenoids in a 56-year-old patient.*

**Figure 23.** *CT showing KEROS type III.*

endoscopic sinus surgery as it is as the level of the skull base. If a supraorbital cell is seen above the anterior ethmoidal notch, or if the artery is located below the skull base, it is considered at risk [18, 19].

## • Dehiscent lamina papyracea (**Figure 26**)

Natural dehiscence in lamina papyracea will result in prolapse of orbital contents into the nasal cavity. The defects allow easy damage to the orbit during FESS and also increase the risk of orbital contents being drawn into the microdebrider.

The incidence of anatomical variations responsible for CRS in decreasing order of their frequency is as follows:

Deviated nasal septum—the commonest anatomical variation with 69% incidence.

**Figure 24.** *CT showing asymmetrical ethmoidal roof.*

**Figure 25.** *CT showing low bilateral low anterior ethmoidal artery.*

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provided the original work is properly cited.

*Rhinosinusitis: How Common Are Anatomical Variations Responsible?*

Pneumatised or medially bent uncinate—8%.

Unilateral concha was seen in 13%, while bilateral concha was seen in 11% cases.

Hypoplasia of maxillary sinus with dehiscent lamina was seen in less than 2% of

The presence of anatomical variations in nose and sinuses is frequently seen on imaging in patients with CRS. It is observed that the presence of more than one variation increases the probability of sinus infections. However, it is not the rule as

Dr. Sunil Chandiwal. Director Medical Services. Choithram Hospital & Research

there can be clear sinuses even with multiple anatomical variations.

Centre. Indore, India. Source of funding: None.

*DOI: http://dx.doi.org/10.5772/intechopen.83689*

Concha—24%.

Big agar—12%.

Onodi cell—4%. Haller cell—3%.

**Acknowledgements**

**Conflict of interest**

**Appendices and nomenclature**

OMC osteomeatal complex PNS paranasal sinuses

Shrikant Phatak\* and Richa Agrawal

DNE diagnostic nasal endoscopy CRS chronic rhinosinusitis

FESS functional endoscopic sinus surgery

\*Address all correspondence to: phatakshrikant2@gmail.com

None.

**Author details**

cases.

**3. Conclusion**

Accessory ostia—6%. Septal pneumatisation—5%.

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Department of ENT, Choithram Hospital and Research Centre, Indore, India

**Figure 26.** *CT PNS (coronal view) showing dehiscent lamina with fat prolapse on left side.*

*Rhinosinusitis: How Common Are Anatomical Variations Responsible? DOI: http://dx.doi.org/10.5772/intechopen.83689*

Concha—24%. Unilateral concha was seen in 13%, while bilateral concha was seen in 11% cases. Big agar—12%. Pneumatised or medially bent uncinate—8%. Accessory ostia—6%. Septal pneumatisation—5%. Onodi cell—4%. Haller cell—3%. Hypoplasia of maxillary sinus with dehiscent lamina was seen in less than 2% of

cases.

*Rhinosinusitis*

**Figure 24.**

**Figure 25.**

*CT showing asymmetrical ethmoidal roof.*

*CT showing low bilateral low anterior ethmoidal artery.*

*CT PNS (coronal view) showing dehiscent lamina with fat prolapse on left side.*

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**Figure 26.**
