STUDY OF OSTIOMEATAL COMPLEX, VARIATIONS IN THE LATERAL WALL OF NASAL CAVITY AND ITS APPLIED ANATOMY
Brief resume of the intended work:
6.1 Need for the study:
With the advent of functional endoscopic sinus surgery and coronal computed tomographic imaging, considerable attention has been directed towards ostiomeatal complex of the lateral wall of nasal cavity. Detailed knowledge of anatomical variations of ostiomeatal complex of the lateral wall of the nasal cavity is of great importance for surgeons performing endoscopic sinus surgery, as well as for the radiologists involved in the preoperative work up1.
The lateral wall of the nasal cavity is very complex, because of the presence of conchae, meati, openings of the paranasal air sinuses, and opening of nasolacrimal duct.2
The term ostiomeatal complex or ostiomeatal unit, refers to the maxillary sinus ostium, ethmoid infundibulum, hiatus semilunaris and frontal recess. It is the final common pathway for drainage of secretions from maxillary, frontal, anterior and middle ethmoidal sinuses into the middle meatus, and obstruction plays a pivotal role in the development and persistence of sinusitis.Computed tomography reveals these structures in detail, and is the imaging modality of choice. Any variation and any pathology in this area will disrupt physiology and leads to sinus dysfunction.2
Variations in the ostiomeatal complex have been observed.which includes frontal sinues opening into nasolacramial duct forming fronto nasal duct,maxillary sinus having accessory ostium opening in to anterior or posterior parts of the uncinate process,different situation of the maxillary sinus ostia also have been reported3,4,5.
Remarkable anatomic variations of ostiomeatal region and their possible pathologic consequences should be well defined in order to improve success of management strategies, and to avoid potential complications of endoscopic sinus surgery.1Hence in the present work, ostiomeatal complex will be studied by dissecting specimens.
6.2 Review of literature
Nasal cavity, in particular the lateral wall is complex. It is complicated because of the presence of conchae, meati and openings of the various paranasal air sinuses and nasolacrimal duct.2
The mucus membrane of the nasal cavity and sinuses are typically lined by a pseudostratified columnar ciliated epithelium. The direction of flow of mucosa is induced by ciliary beat which centers at the ostium4
In Kasper’s investigation of 100 frontal sinuses, he found ostium of frontal sinus opening into frontal recess anterior to the infundibulum in 55 percent cases,opening superior to the infundibulum in 30 percent,opening into the infundibulum in 14 percent of cases, opening above the bulla in 1 percent of cases.4
Ostium of the maxillary sinus is commonly said to open into the posterior half of the infundibulum; Van Alyea(‘36,) analyzing his 163 specimens, found only 9 ostia in the anterior third of the uncinate groove, 18 in the middle 1/3rd and 71percent in the posterior 1/3rd , the remaining 19 ostia opened at the extreme posterior tip of the groove.4
Accessibiity of the ostium depens upon the position and shape of the infundibulum, which would affect the accessibility of a maxillary ostium opening into it.4
Bony anatomic variations of the middle meatus, which includes pneumatisation or paradoxical curvature of the middle turbinate, Haller’s cells, and pneumatisation of the uncinate process, were detected in 64.9percent of patients. Variations in the aggernasi cells, middle turbinate, uncinate process, as well as the presence of Haller’s cell or a deviated nasal septum, are possible etiological factors in sinus disease and headache.6
Stenosis of the ostiomeatal complex, from either the anatomical configuration or hypertrophied mucosa, can cause obstruction and stagnation of secretions that may then become infected or perpetuate infection. A key issue is whether the anatomical variations that lead to
narrowing of the bony component of the ostiomeatal complex contribute to paranasal sinus disease.7
Many feel that the morphology and function of early paranasal sinuses evolved as an adaptation to respiratory and olfactory needs and modification to the cranial vault. As the need for olfaction diminished during later primate evolution and the molar enlarged, changing the shape of the dental arches and other cranial elements, the sinuses came to be more involved physiologically with respiration and thermoregulation.8
If the anatomical variant determining obliteration of the aerial space of the ostiomeatal complex drainage paths, the sinusal disease is more frequently detected at CT than when its anatomical variants does not obstruct these pathways.9
The prevalence of anatomical variants seems to increase with the age.9
CT provides the most useful surgical information both on bone and soft tissues as the preferred method of choice, for evaluation of the presence or extent of conditions of the in paranasal sinuses. Coronal 3-5 mm thick slices, perpendicular to the hard palate, allows an optimal visualization of ostiomeatal complex, besides simulating the plane seen by the endoscopist.10
6.3 Objectives of the study
To study the normal and variations of the ostiomeatal complex of the lateral wall of the nasal cavity.
Materials and methods
7.1 Source of data
Ostiomeatal complex will be studied in the cadavers dissected by J.S.S Medical / Dental College students.
7.2 Method of data collection Specimens obtained from the formalin fixed Cadavers, dissected by the1st year MBBS and BDS students, of the Department of Anatomy JSS Medical College / Dental College.
Statistical Analysis; Data will be analyzed in terms of the number, and percentage of the variations of the ostiomeatal complex. Cross tabulations will be done to study the variations according to side and sex. Chi-square test will be applied to assess the significance of association between the side and variations. The study will include the specimens dissected during JAN 2008 to JUN 2009.
Number of specimens 40.
7.3 Does the study require any investigations or interventions to be conducted on patients or other human or animals? If so, please describe briefly;
No, as this study is purely on the human cadavers only
7.4 Has ethical clearance been obtained from your institution in case 7.3?
YES (Certificate enclosed)
List of references Kantarci M, Karasen RM, Alper F, Onbas O, Okur A, Karaman A. Remarkable anatomic variations in paranasal sinus region and their clinical importance. Eur J Radiology 2004; 50(3): pp 296-302.
Williams PL, Gray’s anatomy, 39th ed, London. ELBS with Churchil Livingstone; 2005: pp 575-77.
Hamilton WJ, Harrison RJ. Anatomy of the Nose, Nasal cavity and parasanasal sinuses.In Ballntyne J, Groves J, editors.Scott-Brown`s Disease of ear, nose, and throat vol-I, basic sciences. 4th ed. London: Butterworth and co; 1979:pp141-56
Hollingshed WH,Rosse C,editors.Text book of Anatomy.4th ed.Philadelphia:Herper andRow,1985:pp.976-85.
Bolger WE, Butzin CA, Parson DS. Paranasal sinus bony anatomic variations and mucosal abnormalities: CT analysis for endoscopic sinus surgery. Largyngoscope 1991;101: pp 56-64.
Jones NS. CT of the paranasal sinuses: A review of the correlation with clinical, surgical and histopathological findings. Clin Otalaryngology 2002; 227(1): pp11-17.
Teul I, Czerwiski F, Cyryowski L, Sawiski G, Mikalszewska D. Morphologic evaluation of the paranasal sinuses of the skulls from different historic periods. DurhamnAnthropology J 2005:12:pp2-3 Available from ://www.nlm.nih.gov/pubmed/
De Araujo Neto SA et.al. The role of osteomeatal compelx anatomical variants in chronic rhinosinusitis. 2004; 14.Available from http://www.nlm.nih.gov/pubmed/
De Souza RP et.al. Sinonasal complex: Radiological anatomy. Radiol Bras: 2006; 39(5): pp 367-72.
The structure and variations of the ostiomeatal complex of the nose is an important parameter to understand it’s clinical applications. The present study should help in enlightening the above said implications