The Anatomical Variations

Introduction

Anatomical variations in the nose and paranasal sinus region are common. local anatomic variations including deviated nasal septum, Concha bullosa, paradoxical middle turbinate,uncinate deviation,agger nasi and others may be the source of middle meatal obstruction and subsequent rhinosinusitis.

Related research

Deviated nasal septum

Deviated nasal septum or bony spur casus a decrease in the critical area of the OMC predisposing to obstruction and resulting in complications.it was found 65 of 100 patients,the maximum anatomical variation in our study 65%.it was more than 14.1% in study by Dutra and marchiore et al(2)and 36% reported by Asruddin et al (3) 55.7% by Maru (4)

Concha bullosa

Concha bullosa (pneumatised middle turbinate) has been implicated as a possible aetiological factor in the causation of recurrent chronic sinusitis. It is due to its negative influence on paranasal sinus ventilation and mucociliary clearance in the middle meatus region as quoted by Tonai (5) . The incidence of concha bullosa was 52 %,which is higher as compared to the reported incidence of 42.6% by Maru et al (4),28% by Asruddin et al (3)and 24% by Llyod (6)

Uncinte deviation

The uncinate process may be deviated or pneumatized. Uncinate deviation impede the sinus ventilation especially in the anterior ethmoid, frontal recess and infundibulum regions. The deviated uncinate was found in 30% of cases .It was more than that reported by Bolger et al., (7) 2.5%, Dua et al., (8) 6% and Asruddin et al.,(3)2% Llyod et al., (6) reported the prevalence of about 16% of deviation of the uncinate process in chronic rhino sinusitis cases and lesser than that reported Mamtha et al., 65%.(9)

Paradoxically Curved Middle Turbinate

The middle turbinate may be paradoxically curved(bent in the reverse direction).This may lead to impingement of the middle meatus and results in sinusitis. Stammberger and Wolf (10) accepted paradoxical curvature of the middle turbinate as an etiological factor for chronic sinusitis because it may cause obliteration or alteration in the nasal air flow dynamics. It was found in 15% of the patients; the prevalence is similar to that of 12% by Asruddin et al., (3) and 15% by Llyod (6) It is less than that reported by Bolger et al.,(7)

Onodi cell

Onodi cells are posterior ethmoid cells that extend posteriorly, laterally and sometimes superior to the sphenoid sinus, lying medial to the optic nerve. The chances of injury of optic nerve are increased when the bony canal of the nerve is dehiscent. The surgeon must pay close attention to the onodi cell in the preoperative evaluation to avoid potential complication of FESS. It was found in 7% of cases in our study.A similar incidence was found by Arslan in 12/200 patients and higher than the study by Jones (11).in 8/ 200 patients

Haller cells are ethmoid air cells that project beyond the limits of the ethmoid labyrinth into the maxillary sinus. They are considered as ethmoid cells that grow into the floor of orbit and may narrow the adjacent ostium of the maxillary sinus especially if they become infected The incidence of Haller cells in our study was 3 %. It was less than that reported by Bolger45.9%,(7) Llyod 15% (6), Maru 36% (4) and Asruddin 28% (3)

Agger NasiCell

Agger nasi cells lie just anterior to the antero superior attachment of the middle turbinate and frontal recess. These may invade the lacrimal bone or the ascending process of maxilla. The incidence of Agger nasi cells in our study was 3 %.similar results were observed by Liyod et al.(6)and less than 40% in study by due et al(8)

The osteomeatal unit was found to be involved in all the patients in our study. Maxillary sinus is the most common sinus involved in chronic sinusitis in our study. Zinreich et al (12) found middle meatus opacification in 72% of the patients with chronic sinusitis, and of these 65% had maxillary sinus mucoperiosteal sinus thickening. Yousem et al found that when the middle meatus was opacified, the maxillary and ethmoid sinuses showed inflammatory changes in 84% and 82% respectively. Another study found frontal or maxillary sinus disease in 84% patients who had OMC opacification.(13) Thus these findings support the contention that the anatomical variation in osteomeatal complex will lead to obstruction of the narrow drainage pathways, which in turn lead to subsequent sinus inflammation.

Conclusion

In our study it was found that the Anatomical variations are common in nose and paranasal sinuses. Prevalence of multiple anatomical variations was more common in comparison to single anatomical variation. Deviated nasal septum was the most common anatomical variation identified followed by concha bullosa and medialized uncinate process. Computerized tomography helps to delineate the anatomy of nose and paranasal sinuses.It is very essential to identify various anatomical variations preoperatively in order to prevent complications and better results.