ANATOMY AND DEVELOPMENT OF PARANASAL SINUSES 2.pptx

About the anatomy and development

1. DEVELOPMENT AND ANATOMY OF PARANASAL SINUSES K. Neeraj Kumar 1 st year ENT PG KIMS, NARKETPALLY

2. Classification Anterior Group: which open anterior to the basal lamella of middle turbinate in the middle meatus. They are maxillary, frontal and the anterior ethmoidal sinuses. Posterior group: which open posterior and superior to basal lamella of middle turbinate. They are posterior ethmoid and sphenoid sinuses. The posterior ethmoidal sinuses open in the superior meatus and the sphenoid sinuses open in sphenoethmoidal recess.

3. Maxillary sinus( Antrum of Highmore) Development The maxillary is the first sinus to appear between the 7 Th and 10 th weeks of gestation. The maxillary sinus appears as a shallow groove expanding from the primitive ethmoidal infundibulum into the mass of maxilla. Expansion and absorption results in a small sinus cavity present at birth. Rapid growth of this cavity occurs during childhood until age seven followed by gradual enlargement , reaching its final size by age 17-18 years.

4. Any disruption or abnormality in the development of the maxillary sinus may result in maxillary sinus aplasia or hypoplasia. Maxillary sinus hypoplasia is present in up to 10% of CT scans. Radiographic diagnostic criteria for maxillary hypoplasia include Enlargement of vertical orbit Lateral position of the infraorbital neurovascular canal Elevated canine fossa Enlargement of superior orbital fissure Enlargement of pterygopalatine fissure.

5. Maxillary sinus- Anatomy It is the first to develop in human fetus . This is the largest paranasal sinus (15ml capacity in adult), it is 33mm high, 35mm deep and 25mm wide. It occupies the body of maxilla and is pyramidal in shape. The base faces the lateral wall of nose and the apex is directed laterally into the zygomatic process. The maxillary sinusitis is the most common cause of sinusitis in adults Arterial supply: Maxillary artery branch of external carotid artery and facial artery Nerve supply: Maxillary nerve.

6. Boundaries of maxillary sinuses Anterior wall : related to cheek. Posterior wall : infratemporal fossa and pterygopalatine fossa. Medial wall : It is thin and membranous at places and faces middle and inferior meatuses. Floor : It is situated about 1cm below the level of nose in adults. Until 3 years of age, sinus floor is 4-5mm above the nasal floor. It is formed by alveolar process of maxilla. The roots of all the molars, second premolar and first premolar sometimes are situated in the floor of maxillary sinuses.

7. These teeth roots are separated from the sinus mucosa by a thin lamina of bone, which may be dehiscent. The chances of oroantral fistulae are high after the extraction of these tooth, the infection of which can result in maxillary sinusitis. 5. Roof : The roof of the maxillary sinus is the floor of the orbit and is traversed by infraorbital nerve and vessels.

8. Ostium of Maxillary sinus : It is situated higher in medial wall and opens in the posterior part of ethmoidal infundibulum. Accessory ostium : In 30% of population, an accessory ostium, which may be quite large, is seen behind and in front of the natural main ostium. The maxillary sinus doesn’t drain through accessory ostium and is bypassed by the mucus blanket. APPLIED ASPECT During endoscopic sinus surgery, accessory maxillary ostium is joined with the natural maxillary ostium to prevent recirculation of the mucopus into the maxillary sinus.

9. Image showing mucocele in the left maxillary sinus

10. OROANTRAL FISTULA The roots of second premolar and first molar are in close relation to the floor of maxillary sinus separated from it by a thin lamina of bone or even no bone at all. Oroantral fistulae can result from extraction of any these teeth. Dental infection involving these teeth is also an important cause of maxillary sinusitis.

11. The relations of maxillary ostium are: Inferiorly is the inferior turbinate. 1 to 2 mm superiorly is the lamina papyracea and the orbit. Posteriorly is the posterior fontanelle. 0.5 cm anteriorly lies the nasolacrimal duct.

12. NATURAL OSTIUM 3 dimensional tunnel like, ovoid ACCESSORY OSTIUM 2 dimensional slit like, circular anterior and posterior fontanelle

13. CALDWELL-LUC APPROACH/ANTERIOR ANTROSTOMY It is a process of opening the maxillary antrum through canine fossa by sublabial approach. BOUNDARIES OF CANINE FOSSA: Superiorly – Infraorbital foramen Inferiorly- Alveolar ridge Laterally – Canine eminence Medially- Pyriform aperture

14. 1. Chronic maxillary sinusitis with irreversible changes in the sinus mucosa. 2. Removal of foreign bodies or root of a tooth. 3. Dental cyst. 4. Oroantral fistula. 5. Suspected neoplasm in the antrum and its biopsy. 6. Fracture of maxilla or blow-out fractures of the orbit. 7. As an approach to ethmoids (Horgan’s transantral ethmoidectomy). 8. Approach to pterygopalatine fossa for ligation of maxillary artery. INDICATIONS:

15. DENKER’S SURGERY Continuing Caldwell-Luc incision medially to gain access to nasal cavity and maxillary sinus simultaneously. MIDDLE MEATUS ANTROSTOMY It is done as a part of FESS, after uncinectomy . Maxillary ostium lies above the inferior turbinate and posterior to lower third of uncinate process. Once localized, it is enlarged anteriorly with a backbiting forceps or posteriorly with a through cut-straight forceps.

16. Preferred view in x ray to view maxillary sinuses- Waters view( occipitomental view)

17. FRONTAL SINUS- DEVELOPMENT The frontal sinus is the most variable sinus in terms of size and shape. Pneumatization of the frontal bone begins during the 16 th week of gestation originating from the anterior ethmoid complex. At birth , the frontal sinuses appear only as a small blind pocket that is difficult to distinguish from anterior ethmoidal cells on imaging. With gradual pneumatization, the frontal sinuses are seen in most radiological studies by the age of 8 years. Significant frontal pneumatization does not occur until early adolescence and continues until 18 years of age. Although still developing, the relative proportions of the frontal sinus have reached adult ratios by age 10-12 years and just prior to second growth spurt.

18. FRONTAL SINUS- ANATOMY The frontal sinus is situated above and deep to the supraorbital margin. It lies between the inner and outer tables of the lower part of frontal bone. The shape and size of this loculated sinus vary ( very large to absent). It is about 24mm high and 16mm deep The bilateral frontal sinuses are often asymmetric. The intervening bony septum , which is thin and often obliquely placed, may be deficient in some cases. A very large sinus may extend into the roof of the orbit. Arterial supply: Supraorbital, supratrochlear arteries Nerve supply: Supraorbital, supratrochlear nerves

19. RELATIONS OF FRONTAL SINUS Anterior wall of the sinus is related to the forehead skin Floor is in relation with orbit Posterior wall relations are meninges and frontal lobe of brain .

20. Drainage of the frontal sinus is through its ostium into the frontal recess. The frontal sinus, its ostium and the frontal recess form an hour glass structure. The anterior wall - anterior wall of the agger nasi cell. • The posterior wall - bulla ethmoidalis. • The lateral wall - lamina papyracea. • The medial wall - middle turbinate. • Superiorly the frontal recess opens via the frontal ostium into the frontal sinus.

21. The drainage of the frontal sinus varies depending on the superior attachment of the uncinate. When attached to lamina papyracea - it drain medial to the Infundibulum.In such cases the infundibulum ends as a blind recess called RECESSUS TERMINALIS. When attached to the middle turbinate or the cribriform - it drains into the Infundibulum.

22. FRONTAL SINUS TREPHINATION It is done in cases of complicated acute frontal sinusitis not responding to medical management and can also be done for chronic frontal sinusitis. A small verticle incision(1-1.5cm) is made below the medial end of the eyebrow and supraorbital rim. The periosteum is elevated and a drill is used to make a small window at the junction of the floor and anterior wall of the sinus. The sinus is irrigated and a drain is placed insitu.

23. Other surgical aapproaches to the frontal sinus include: Balloon Sinuplasty Lynch Howarth procedure Killians procedure Lothorp’s procedure Draf Frontal Sinus surgery Type 1: Ethamoidectomy and frontal sinusotomy Type 2: Enlargement of the frontal ostium Type 3: Bilateral frontal sinus enlargement, resection of part of the nasal septum, floor of the frontal sinus and inter-sinus septum.

24. Preferred view in x ray to view frontal sinus- Caldwell ‘s view

25. X ray of frontal sinus showing left frontal sinus mucocele- loss of scallops

26. frontal sinus showing osteitis 1. also called as pott’s putty tumour 2. shows egg shell crackling sign .

27. ETHMOID SINUS Development During the 9 th and 10 th weeks of gestation, a series of folds called ethmoturbinals that are separated from each other by corresponding grooves appear in the lateral wall of the nasal capsule. Fusion of these folds leads to the development of crests, each with an ascending and descending portion. All ethmoidal structures are present at birth and develop from these crests and the furrows between them. As a result, acute sinusitis in children often involves the ethmoid cavity which can extend laterally through the lamina papyracea causing orbital complications.

28. In order from anterior to posterior, the lamella include: FIRST: agger nasi(ascending portion) and uncinate process( descending portion) SECOND: bulla ethmoidalis THIRD: basal lamella of the middle turbinate FOURTH: superior turbinate FIFTH: supreme turbinate if present.

29. ETHMOID SINUS- ANATOMY Ethmoidal sinuses are thinwalled air cavities in lateral masses of ethmoid bone. They vary in number(3-18)and lie between upper third of lateral nasal wall and the medial wall of the orbit. Clinically they are divided into two groups: anterior group and the posterior group Anterior ethmoid group opens into the middle turbinate Posterior ethmoid group opens into the superior turbinate and some in sphenoethmoidal recess

30. BOUNDARIES ROOF : It is closed by the frontal bone, which forms the floor of anterior cranial fossa. LATERAL WALL : Lamina papyracea separates it laterally from the orbit. which shows depressions on its undersurface, called fovea ethmoidalis . FOVEA ETHAMOIDALIS is formed medially by the lateral / vertical lamella of the cribriform and laterally by the frontal bone.

31. AGGAR NASI CELLS These are the most anterior of anterior ethmoid cells,and lie in close proximity of frontal recess. present in the agger nasi ridge. Usually 1-3 in number. When well pneumatized they produce a distinct bulge anterior to anterior attachment of the middle turbunate .

32. 2. Ethmoid bulla – It is the largest and most consistent anterior ethamoid air cell. 2-3mm behind the bulla, the anterior ethamoidal artery in seen as a classical “ BREAKING OF MEDIAL ORBITAL WALL” . The artery may lie close to the skull base or may cross low within the anterior ethamoids in which case the orbitocranial canal with its bony mesentery is clearly seen. This is called the “ KENNEDY NIPPLE SIGN ”

33. 3. Supraorbital cells . – They are anterior ethamoid air cells extending superiorly and laterally over the orbital roof. *They can cause obstruction of the frontal recess. *They can be falsely identified as true frontal sinus leading to incomplete surgical dissection. *They are associated with a low postion of the anterior ethamoid artery because these cells pneumatize downward from the skull base behind the artery.

34. 4. Frontoethmoid cells – situated in the area of the frontal recess and may encroach the frontal sinus. They represent the cells of first ethmoturbinal that pneumatize above agger nasi towards the frontal sinus. KUHN classified the frontal cells into 4 types: Type 1- Single frontoethamoid cell above the agger nasi and below frontal sinus floor. Type 2- a tier of cells above the agger nasi Type 3 – Cell pneumatizing into the floor of the frontal sinus(FRONTAL BULLA) Type 4- Isolated frontal ethamoid cell within the frontal sinus.(LONER CELL)

35. WORMLAND further modified the Kuhn classification: Type 3 cells – frontoethamoid cells that fill less than 50% of the frontal sinus Type 4 cells- frontoethamoid cells filling greater than 50% of the frontal sinus. Identification of these frontal cells on pre-operative imaging prevents false assumption of complete sinusectomy .

36. BASAL LAMELLA : This bony insertion of middle turbinate into the skull base and lateral nasal wall separates anterior from posterior ethmoid cells. Grand lamella can be divided into three parts. Anterior one-third inserts into lamina cribrosa, middle one-third (oblique anterosuperior to posteroinferior course) into lamina papyracea and posterior one-third horizontal part inserts into lateral nasal wall.

37. Haller cells These ethmoid cells extend into the roof of maxillary sinus in the region of maxillary sinus ostium. These cells may remain asymptomatic or affect maxillary sinus ventilation and drainage resulting in recurrent or chronic maxillary sinusitis. They are present in 10% of population.

38. ONODI CELLS : These are posterior ethmoid cells and extend either laterally or superiorly along the sphenoid sinus. The optic nerve can lie within them. Onodi cells must be recognized during the endoscopic sinus surgery on posterior ethmoid to avoid optic nerve injury Arterial supply : Anterior ethmoidal sinuses are supplied by anterior ethmoidal arteries, Posterior ethmoidal sinuses are supplied by posterior ethmoid and sphenopalatine arteries. Nerve supply : Anterior ethmoidal sinuses are supplied by anterior ethmoidal nerves, Posterior ethmoidal sinuses are supplied by posterior ethmoid and sphenopalatine nerves.

39. SURGICAL APPROACHES EXTERNAL ETHMOIDECTOMY TRANSANTRAL ETHMOIDECTOMY(JANSEN HORGAN’S PROCEDURE) PATTERSON’S OPERATION

40. LATERAL OBLIQUE VIEW- RHESE VIEW

41. SPHENOID SINUS DEVELOPMENT The sphenoid sinus begins to develop in the twelfth week of gestation as an evagination from the sphenoethmoidalrecess . A small sphenoid sinus is present at birth with pro- gressive enlargement starting at age three during pneumatization of the sphenoid bone. Three pneumatization patterns are present in relation with sella turcica. These pneumatization patterns are important for surgical planning of transphenoid approaches to pituitary tumours. These include sellar (90%), pre- sellar (9%) and conchal (1%) type pneumatization patterns.

42. The sellar type is most common and describes sphenoid pneumatization posterior to the sella turcica. The pre sellar type describes sphenoid pneumatization up to the anterior sella and the conchal type describes a shallow bowl with minimal sphenoid pneumatization and trabecular bone between the sinus and sella . The sphenoid sinuses canal so pneumatize laterally into the pterygoid root resulting in the presence of a lateral sphenoid recess. This pneumatization pattern results in exposure of the neurovascular structures surrounding the sphenoid sinus.

43. ANATOMY The two sphenoid sinuses, one on each side are rarely symmet - rical . They occupy body of sphenoid bone and are separated by a thin bony septum, which is usually obliquely situated and may even be deficient. The ostium, which is situated in the upper part of anterior wall, drains into sphenoethmoidal recess. The anterior wall of sphenoid sinus is 7 cm away from nasal sill at 30 angle. An adult sphenoid sinus is about 2 cm high, 2 cm deep and 2 cm wide, but its pneumatization varies.

44. RELATIONS The relations are important during the endoscopic sinus surgery and transsphenoidal hypophysectomy. The extent and relations of sphenoid sinus depend upon the degree of pneumatization, which may extend into the wings of sphenoid, pterygoid plates and clivus

45. Anterior part: The superior relations are olfactory tract, optic chiasma and frontal lobe. The lateral wall relations are optic nerve, internal carotid artery and maxillary nerve. These structures may be dehiscent in the lateral wall of sinus. Posterior part: Roof of sinus is floor of sella turcica (pituitary gland fossa). Lateral wall is related to cavernous sinus, which contains internal carotid artery and CN III, IV, V and ophthalmic and maxillary divisions CN V (trigeminal).

46. TYPE TYPE 1 OPTIC NERVE COURSING ADJACENT TO SPHENOID SINUS WITHOUT INDENTATION OF THE WALL OF THE SINUS TYPE 2 OPTIC NERVE COURSING ADJACENT TO SPHENOID SINUS WITH INDENTATION OF THE SPHENOID SINUS WALL WWITHOUT CONTACT WITH THE POSTERIOR ETHMOIDAL CELLS TYPE 3 OPTIC NERVE COURSES THROUGH THE SPHENOID SINUS WITH 50% SURROUNDING AIR TYPE 4 OPTIC NERVE ADJACENT TO SPHENOID AND POSTERIOR ETHMOIDAL CELLS DELANOS CLASSIFICATION

47. • Differentiation between the posterior most ethmoid cell and the sphenoid sinus is one of the most common difficulties faced during endoscopic surgery. The following points help to identify the sphenoid sinus: SPHENOID SINUS POSTERIOR MOST ETHMOID CELL GLOBULAR PYRAMIDAL WITH APEX POSTERIORLY OPENS INFERIOR TO MAXILLARY RIDGE. OPENS ABOVE MAXILLARY RIDGE

48. SURGICAL APPROACHES TREPHINIG: Sphenoid sinus lies around 7cm deep from the nasal spine. A trochar and cannula is used to puncture the anterior bony wall. EXTERNAL TRANSETHMOIDAL SPHENOIDECTOMY: After external ethmoidectomy, anterior wall of sphenoid is exposed. The wall is fractured staying medially and inferiorly. The sinus wall is enlarged and diseased mucosa is removed.

49. TRANSPHENOIDAL APPROACH INDICATIONS: Intrasellar adenomas with limited sphenoid sinus extension Tumors confined to the sella Intrasellar cysts Pitutary apoplexy Pitutary abcess Sphenoid sinus mucocele TYPES: Trans-septal(midline) Trans-ethmoid(lateral) Trans-antral(oblique)

50. Trans antral approach Transethmoid approach

51. Arterial supply and nerve supply is same as that of posterior ethmoid sinus

52. LYMPHATIC DRAINAGE They drain into upper deep cervical nodes lateral retropharyngeal nodes either directly or through group of lymph nodes