Ct pns - Anatomical varients

Anatomical variation in coronal CT

1. Anatomical Variations of Paranasal Sinuses on Coronal CT-Scan in Subjects with Complaints Pertaining to PNS (concentrated on coronal CT) Presented by Dr. Liju Rajan , 2 nd year postgraduate Moderator Dr. CP DAS Dr. D Mohanty

2. The CT scan is the gold standard investigation in Functional Endoscopic Sinus Surgery preoperative cases and cannot be replaced by the MRI because it gives detailed bony anatomy of the area and serves as a “road map” for the operating surgeon A very basic paranasal sinus study would include bony and soft tissue windows of 3 mm cuts taken anterior to posterior in the coronal plane

3. Timing of CT Acute sinusitis adequately treated ( 3 weeks after course of antibiotics and NSAIDS) Chronic inflammatory diseases- maximised medical therapy It is advisable to use topical nasal decongestant before CT, or atleast blow the nose and clear secretions Role of CT to define PNS anatomy to identify regional disease in medical non-responders

4. Coronal Scan Most of the anatomical details can be seen well in coronal sections. Because this plane is almost identical to that approached by endoscopes Best displays Osteo -Meatal Unit Uncinate Process & Ethmoidal Bulla lie on a vertical plane

5. CT Patient Positioning

6. 1 st Cut Soft tissue over frontal bone Nasal bone Nasal Septum Nasal ala

7. Frontal bone proper Nasal bone Nasal Septum bony and cartilaginous part Nasal ala

8. Frontal Sinus with septae Nasal bone Nasal Septum bony Frontal process of maxilla

9. Septal tubercle

10. Well developed frontal sinus with intact floor False frontal septum disappearing Inferior turbinates

11. Maxillary sinus starts appearing. Well developed frontal sinus

12. 1 st cell appearing in scan. Agger nasi cell Well developed frontal septum with intact floor Middle turbinate starts come into the view Nasolacrimal system comes into view

13. Floor of frontal sinus is missing. Frontal recess Aggar Nasi cell not seen. Frontal recess present posterior to aggar nasi cells First part of middle turbinate in saggital plain getting attached to the roof Concha

14. Bulla ethmodalis Concha bullosa Uncinate process Hiatus semilunaris inferialis Infundibulum Triangular shaped maxillary sinus Pneumatised crista galli Supraorbital cell Well developed olfactory fossa Keros type2

15. Uncinate insertion and frontal recess drainage Osteomeatal complex

16. Haller cell or infraorbital cell

17. Ant ethmoidal artery Another land mark for starting of posterior ethmoidal cells and basal lamella Loss of sharpness of triangular shape of maxillary sinus

18. Ground lamella – transcission 2 nd part Superior turbinate Posterior frontanalle

19. Changes while going from ant ethmoid to post ethmoid Orbit – more smaller and squire Maxillary sinus- from triangular to oval Larger and fewer air cells Flatter and thicker skull base Past Ground lamella Past ant ethmoidal.a Presence of sup turbinate

20. Middle turbinate inserts into medial wall of maxilla

21. Inferior orbital fissure

22. Differentiate between posterior ethmoids and sphenoids Posterior ethmoids C complete septum will be seen Clear view of inferior and middle turbnate Sphenoid In ter sphenoidal septum Turbinates not clear

23. Choana Sphenoid sinus Greater wing of sphenoid Vidian cannal Foramen rotendum Ptregoid process Medial and latral ptregoid plates Optic nerve Buldge of carotid artery Medial ptregoid plates forming lateral wall of choana

24. Septal Deviations There may be gross septal deviations as well as mild Bony deviations can be clearly seen and studied Sometimes may be associated with concha bullosa , ITH or a pneumatised septum or may be associated with osteomeatal unit

25. Agger Nasi Cell 1 to 3 in number and may vary Some times these cells may be hypoplastic Some times prominent which causes changes in superior attachment of uncinate and also bulge in middle turbinate

26. Uncinate Process The uncinate process may be hypoplastic or laterally bent. In this case the infundibulum is a narrow space, which may be difficult to enter Sometimes will be well developed and resemble anterior wall of bulla. Sometimes more medially rotated and present like a duplication of middle turbinate Upper attachment of uncinate process

27. Uncinate getting attached to medial wall of orbit

28. Uncinate getting attached to skull base

29. Uncinate getting attached to middle turbinate

30. Uncinate lying free without attachment

31. Pneumatised Uncinate Process

32. Middle Turbinate Concha bullosa the pneumatisation of middle turbinate pneumatized from either the frontal recess, the agger nasi cell, anterior ethmoid cells or the middle meatus Or a isolated cell Large concha may impair drainage of PNS

33. Pneumatisation of vertical lamella of middle turbinate

34. Middle turbinate shows a latral bent instead of medial bent Can block infundibulum

35. A normally curved middle turbinate may curl upon itself to produce a concavity within it. This concavity is called the turbinate sinus

36. Ethmoidal Bulla The ethmoidal bulla is usually the largest and most constantly pneumatized anterior ethmoid cell hypoplastic or rarely even a solid non-pneumatized Some cases very prominent and may push uncinate or middle meatus compromising infundibulum or middle meatus

37. Usually bulla extend upto skull base if not the space present is suprabullar recess In some cases bulla will not extend up to ground lamella the space is called retrobullar recess Suprabullar recess and retro bullar resess togother form sinus latralis grunwald It drains into a semilunar space hiatus semilunaris superioralis

38. Ethmoidal air cells Infraorbital cell or haller cell Compromise the maxillary sinus drainage

39. The anterior ethmoid cells may migrate into the frontal recess area where they are then named the frontal cells. These are of four types — Type I: A single cell above the agger nasi cell. — Type II: Two or more cells above the agger nasi cell. — Type III: (Frontal bulla) A cell which extends well into the frontal sinus. Single massive cell pneumatizing cephalad into frontal sinus — Type IV: An isolated “loner cell” within the frontal sinus.

40. Ground Lamella The ground lamella of the middle turbinate, which separates the anterior and posterior ethmoid cells, is not always in a coronal plane May bulge into anterior ethmoid or posterior ethmoid and have convexity vise versa It may show dehiscences or be partially deficient in which case infection can pass from anterior to posterior ethmoids

41. Some times may get pneumatised to form multiple septae

42. Some cases the 2 nd part of middle turbinate directly get attached to medial wall of maxillary sinus. Thus maxillary sinus behaves as 2 one part as posterior ethmoids and other as maxillary sinus in terms of drainage and disease

43. Superior/Supreme Turbinate

44. Olfactory Fossa

45. Sphenoid sinus It may be present as a small pit in a predominantly non-pneumatized sphenoid bone- conchal type. It may extend upto the anterior wall of the sella turcica— Presellar type It may pneumatize the entire sphenoid body below and behind the sella turcica, so that the pituitary forms a distinct bulge in its posterosuperior wall— Sellar type

46. Inter sphenoidal may not divide sphenoid equally Septum may get attached to vital structures like Optic Nerve and Carotid artery

47. The sphenoid sinus may show extensive pneumatization laterally into the pterygoid processes and the greater wing of sphenoid. The maxillary and vidian nerves can then be seen prominently within these lateral recesses of the sphenoid

48. Maxillary Sinus The maxillary sinus is fairly constant in its pattern of pneumatization and drainage. Occasionally it may be hypoplastic or asymmetric. Rarely it may be completely absent Accessory ostia may be present in the anterior and posterior fontanelle in 25 percent of the cases May get pneumatised extensively and encroach on alveolar process of teeth Infra orbital nerve is dehesent and lie submucosally

49. Anatomical Variations of Paranasal Sinuses on Coronal CT-Scan in Subjects with Complaints Pertaining to PNS Journal Proper IJARS - Intrenational journal of anatomy radiology and surgery

50. MATERIALs AND METHODS This prospective study was performed in the Department of Radiodiagnosis, Mysore Medical College and Research Institute (KR Hospital) Mysore Total 100 patients who were referred form ENT OPD and wards from December 2013- July 2015 (1/12/2013 to 31/7/2015) with complaints pertaining to PNS were included in the study Patients were subjected to Coronal CT-scans of PNS using GE SYSTEMS-Hi Speed Dual-Slice CT. For CT examination patient was positioned in prone position with neck extended and angulation was perpendicular to hard palate.

51. Imaging was done from posterior margin of sphenoid sinus to anterior margin of frontal sinus. Thickness was 5mm slices with 3mm retro reconstruction.

52. The images were reviewed using bone and soft tissue windows and the details were analyzed : 1. Septum Deviation 2. Agger nasi pneumatized 3. Bulla Ethmoidalis 4. Uncinate process 5. Middle turbinate: pneumatisation 6. Maxillary sinus septation 7. Pneumatized superior turbinate 8. Supraorbital cell 9. Haller cell 10. Onodi cell 11. Frontal sinus 12. Cribriform Plate 13. Extramural sphenoid pneumatization 14. Other findings: Inflammatory sinus disease acute, chronic or allergic. If present, in which sinus?

53. Statistical Analysis Results were cross tabulated. Frequencies descriptive statistics were the statistical methods used. Level of significance of findings was assessed by Chi-square test

54. DISCUSSION Nasal cavity and para nasal sinuses together form a single anatomical and functional unit. Congenital anomalies and normal anatomical variations in this region are a rule rather than exception. Conventional X-rays don’t provide adequate information because of structural superimposition. There has been tremendous advances in the surgical treatment of sinusitis in recent years, particularly in Functional Endonasal Endoscopic Surgery (FESS), which requires the clinician to have a precise knowledge of nasal sinus anatomy and anatomical variants, many of which are detectable only by the use of CT.

55. Deviated Nasal Septum In a study of 110 subjects by Perez- Pinas J Sabate et al., [1], 80 subjects showed DNS. Most were non traumatic deviations of the septum (64 cases, 72%); the numbers of left and rightward deviations were similar, with a slight predominance of the former In our study 62% of patients showed deviated nasal septum and also showed slight predominance to the left side (29%) as compared to right side (23%). On statistical basis p values were also significant (p < 0.001).

56. Occurrence of Special Cells Presence of agger Nasi cells in this study is 26%

57. The optic nerve is in close relation with Onodi cells when present, accurate delineation of optic nerve is important in preoperative planning. The presence of Onodi cells is the most important factor limiting posterior extent of endoscopic clearance.

58. Septations in PNS According to John Earwaker , maxillary sinus showed septations in about 19 cases out of 800 patients studied. According to Abdullah BJ et al., out of 70 patients studied 68.9% showed septations in the sphenoid sinus In our study frontal sinus showed septations in about 31%.Maxillary sinus showed septations in about 19%. Sphenoid sinus showed septations in about 49%.

59. Frequency of Variations of Middle Turbinate In our study 43% of the cases showed concha bullosa [Table/Fig-14,15] out of which bilateral is the maximum of about 41% followed by right side of about 32% and least is on the left side of about 25%. Presence of a concha bullosa does not suggest a pathological finding. However, in the setting of chronic sinus disease, resection of the concha bullosa should be considered to improve paranasal sinus access

60. Orientation of the U ncinate Process Earwaker observed horizontal orientation of the uncinate process, unilaterally or bilaterally in 19% of cases, the variant was associated with an enlarged ethmoidal bulla and, in some cases, with contralateral septal deviation. Vertical orientation of the process which appeared enlarged or deformed was observed in 32% of patients In our study 43% of cases showed horizontal orientation [Table/Fig-18] of the uncinate process (with 82% of the cases associated with enlarged ethmoidal bulla) and 57% cases showed vertical orientation of the uncinate process(with 8.7% of the cases associated with enlarged ethmoidal bulla

61. Cribriform Plate Soraia Ale Souza et al.,[20] study showed Keros type II as the most common variant (73.3%) followed by type I in 26.3% and type III in 0.5% of cases. However, in our study Type I is commonest. The type of cribriform plate is important in predicting the intra operative complications during FESS

62. CONCLUSION Direct coronal CT is the imaging modality of choice for the evaluation of the anatomical variations in paranasal sinuses Coronal CT-scan provides more detailed information of the posterior sinus variations. Among the special cells, Aggernasi cell is the most common type Septations in paranasal sinuses is most common in sphenoid sinus Vertical orientation of uncinate process is the most common variety Type I variety of the cribriform plate is the most common type.