Characterization of Sphenoid Sinus in Sudanese Population Using Computed Tomography

ABSTRACT Sphenoid sinus is surrounded by critical structures and this can make sphenoid sinus surgeries very dangerous. The aims of this research were to study the anatomical relationships between the sphenoid sinus and their important adjacent neurovascular structures using the multiplanar reconstruction technique and to measure some important surgical distances of sphenoid sinus including, roof, bottom, posterior wall, anterior wall, in terms of their relevancy to the Sudanese patients. Coronal and sagittal CT scans of 201 patients attending Radiology Department of Royal Care Hospital in Sudan, between June 2012 and July 2014 were reviewed regarding the anatomical variations of the sphenoid sinus. The study assessed pneumatization of pterygoid process (PP), anterior clinoid process (ACP), and greater wing of sphenoid (GWS); the study also examined protrusion and dehiscence of internal carotid artery (ICA), optic nerve (ON), maxillary nerve (MN), and vidian nerve (VN) into the sphenoid sinus cavity. Moreover Characterization of the sphenoid sinus and seven horizontal and vertical measurements were evaluated. Pneumatization of (ACP), (GWS) and (PP) were seen in 13.9%, 34.8% and 40.3% patients respectively. Protrusion of the (ICA), (ON), (MN) and (VN) were noticed in 25.4%, 3%, 27.9% and 42.3% patients respectively; dehiscence of these structures was encountered in 12.4%, 15.9%, 45.3% and 55.2% patients respectively. Statistically, there was a significant association between (ACP) pneumatization and (ICA) protrusion and (ON) dehiscence (p = 0.003), also a significant association between (GWS) pneumatization and (MxN) protrusion and (MxN) dehiscence (p = 0.003) was noted. VI Significant association between (PP) and (VN) protrusion and (VN) dehiscence (p = 0.004) was also noted. The mean length of vertical lines from the center of sphenoid ostium to the roof and bottom were 9.9 ± 3.3 mm, 10.7 ± 3.4 mm respectively. When the sphenoid ostium was located superior to the lowest point of the sella, the line from the center of the sphenoid sinus ostium to the posterior wall of the sinus was 16.4 ± 4.7 mm and when was located inferior, the line was 18.4 ± 4.7 mm on average. The mean length of line 4 from the lowest point of the sella to the anterior wall of sphenoid sinus was 16.4 ± 3.7 mm. The line from anterior wall to posterior wall of sphenoid sinus lining skull base was 10.6±3.4mm mm. The maximum depth was 24.5 ± 6.7 mm and the maximum width was 17.3 ± 5.7mm. The differences in the sphenoid sinus measurements take place between males and females. The knowledge on the dimentions, anatomic variations and morphology of the sphenoid sinus and its related structures is important in order to avoid the surgical complications when entering the pituitary gland and sella turcica. The study provides essential anatomical information of the sphenoid sinus for Sudanese subjects and its impact in the clinical surgical practice.

List of Contents

I ……………………..………………………...………….…………..… الآیــة

Dedication ………………………………..………………….…………..…II

Acknowledgement………………….…….…………………………..….…III

Abstract (English) ……….…………….....………………………….…...…V

Abstract (Arabic)………………..…………………………………….…..VII

Lis of Contents……………….…………………….……………..……..... IX

List of Table………………………………………….…………………. XIII

List of Figure……………………………………………………….....….XIV

List of Abbrivation…………………………….………………….……... XV

1.0 Chapter one ……..…..………………………………..……………….. 1

1.1 Introduction …………………………...….…...……….…………..……1

1.2 Problem of the Study …………………………….…….………………..5

1.3 Objective of the Study…………………….……….….…………………5

1.3.1General Objectives………………………………….……….…………5

1.3.2 Specific Objective…………...….………….………………………….5

2.0 Chapter Two: Litreture Reviews …….…..……………………..……….6

2.1 An Overview of the History of Paranasal Sinus ……….……………….6

2.2 Embryology of sphenoid Sinus ……………..…………………..………9

2.3 Phsiology of sphenoid Sinus ……………….………………………….11

2.4 Anatomy of sphenoid Sinus ……….…………….…………………….13

2.4.1 Sphenoid sinus ……...………………..………………………………13

2.4.2 Vascular supply ………………….………..…………………………15

2.4.3 Innervation ………………………………………..…………………15

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2.4.4 Sphenoid Bone …………….………………….…………….……….15

2.4.4.1 Normal Anatomy………………...…………………………………16

2.4.4.2 Sphenoid Body …………………………….………………………16

2.4.4.3 Greater Wing ………….……………………..…………………….17

2.4.44 Lesser Wing …………………………………..…………….….….. 17

2.4.4.5 Pterygoid Process …………...…………………….……………… 18

2.4.4.6 Foraminal Anatomy ……………...……………………….…..…. . 18

2.4.5 Pneumatization of the sphenoid sinus ……….……………….…….. 22

2.4.6 Internal Sphenoid sinus Anatomy …………………..……………….29

2.4.7 Sphenoethmoidal cells (Onodi cells) ………………….……………. 37

2.4.8 The sphenoid sinus ostia and the intersphenoid septum …………… 40

2.5 Pathology of Sphenoid Sinuses ………………………………………. 43

2.6 Absence of sphenoidal sinuses ………………….……………………. 48

2.7 Surgical Approaches to the Sphenoid Sinus ………………...……….. 51

2.7.1 Indications …………………....…………………………………….. 52

2.7.2 Surgical Approaches …….…………………….…………………… 53

2.7.2.1 External Transorbital–Transethmoid Approach ……..….…..……. 54

2.7.2.2 Transantral–Transethmoid Approach ………….…………………. 54

2.7.2.3 Transpalatal Approach ……………….………………….……….. 55

2.7.2.4 Transnasal Approaches ………………..…………………………. 56

2.7.2.4.1 Transnasal – Transseptal Approach ……………………....……. 56

2.7.2.4.2 Transnasal – Nontransseptal Approaches ……………..………... 57

2.7.2.5 Transnasal – Transethmoid Approach …………………….……… 57

2.7.2.6 Direct Transnasal-Nontransethmoid Sphenoidotomy …...……….. 58

2.7.2.7 Functional Endoscopic Sinus Surgery ……………….…………… 58

2.7.2.7.1 Pathophysiology of Sinusitis ………………………….………... 63

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2.7.2.7.2 Initial Evaluation and Treatment ……………………….………. 64

2.7.2.7.3 Candidates for Sinus Surgery ……………………………………66

2.7.2.7.4 Nonendoscopic, 'Conventional' Sinus Surgery vs. FESS ….…… 67

2.7.2.7.5 Surgical Technique ……...……………………………………… 68

2.7.2.7.6 Postoperative Care ……………………………………………… 69

2.7.2.7.7 Outcome ……………...………………………………….………69

2.7.2.7.8 Complications ……………...…………………………………… 70

2.7.2.7.9 Limitations of FESS ……………………………………...…….. 71

2.7.2.7.9.1 Acute Severe Ethmoid and Frontal Sinusitis …………….…… 71

2.7.2.7.9.2 Nasal and Sinus Malignancies ……….……………………….. 71

2.8 Computer Tomography and PNS …..………………………………… 72

2.8.1 Basic Concepts ………...…………………………………………… 73

2.9 Previous Studies ………..…………………………………………….. 76

3.0 Chapter Three: Materials and Methods ……….…………………...84

3.1 Materials ………………………..…………………………………….. 84

3.2 Data Collection & Analysis ……………………..……………..…...… 85

3.2.1 Data collection …………..…………………………………..……….85

3.2.2 Statistical analysis ……………………………...…………..………..88

4.0 Chapter Four: Result ……………………...……………………..…..89

4.1 Table & Graphs ……………..…………………………………..……..92

5.0 Chapter Five ……………..…………………..…………………….. 112

5.1 Discussion …………………...……………………………………….112

5.1.1 Anterior clinoid process ……………………...…………………… 112

5.1.2 Greater wing of sphenoid ……………………...………………….. 113

5.1.3 Pneumatization of the pterygoid process ………………….………. 114

5.1.4 Internal carotid artery …………………...………………………… 115

5.1.5 Optic nerve …………………………………………………………117

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5.1.6 Maxillary nerve …………………………………………………….119

5.1.7 Vidian nerve ………………………………………………………..120

5.1.8 PosteriorEthmoid Cell …………………………..………………… 120

5.1.9 Classification of the Sphenois Sinus ……………………………… 121

5.1.10 Measurement of the Sphenoid Sinus ………………….…………. 122

5.2 Conclusion …………………………...……………………………… 127

5.3 Recommendation ………………………………...………………….. 129

References ……..………...………………………………………..……. 130

Appendix …………...……..……………………………………….…… 150