Diseases of the paranasal sinuses Ehab ZAYYAN, MD, PhD

1. Diseases of the paranasal sinusesEhab ZAYYAN, MD, PhD

2. Anatomy

3. Paranasal sinuses • Cavities found in the interior of the maxilla, frontal, sphenoid and ethmoid bones. • The function of the sinuses is to act as resonators of the voice and to reduce the weight of the skull.

5. Paranasal sinuses

6. Maxillary sinuses • The maxillary sinus drains into the middle meatus

7. Frontal sinuses • Two in number • 15 % of humans have a single frontal sinus • 5 % of humans has no frontal sinus. • Each frontal sinus opens into the middle meatus

8. Sphenoidal sinuses • Two in number • Lie within the body of the sphenoid bone • At the center of the skull • Each sinus opens into the sphenoethmoidal recess → superior meatus

9. Ethmoidal sinuses • Separated from the orbit via a thin plate called the lamina papracea. • Air cells: 4- 17 (average: 9) in each side • Divided into 2 groups: • Anterior group: opens into the middle meatus • Posterior group: opens into the superior meatus

11. Relations of the ethmoids: • Anterior: orbit and nasolacrimal duct • Posterior: sfenoid sinus, orbital apex, optic nerve • Lateral: orbit • Superior:skull base

14. lateral nasal wall • Superior, middle and inferior conchae. • The area below each concha is called meatus: superior, middle and inferior meatus

18. Embryology • Ethmoid sinuses: 0- 12 y • Frontal sinus: 6- 20 y • Maxillary sinus: 0 - 3 y 7 - 12 y • Sphenoid sinus: 3- 20

20. Histology • The nasal vestibule is lined with stratified squamous epithelium with vibrissae, sweat glands, and sebaceous glands. • The mucous membrane lines the nasal cavity except the vestibule. There are two types of mucous membranes: 1. Olfactory mucosa 2. Respiratory mucosa

21. 1. olfactory mucous membrane: lines the superior surface of the superior concha and the sphenoethmoidal recess. It also lines the corresponding part of the nasal septum

22. 2. The respiratory mucous membrane: • Pseudostratified ciliated, columnar epithelial cells, goblet cells, and submucosal glands • Its function is to warm, moisten and clean the inspired air. • Warming: venous plaxus in the submucosa • Moisture: mucous by the glands and goblet cells • Ciliary action….

23. Physiology The mucous membrane consists of two layers: • Gel layer: thick viscous elastic layer • Sol layer: serous layer between the cilia • Daily mucous secretion: 600 – 1800 cc • Contains a lot of substances mainly lysozymes and immunoglobulins.

24. Ciliary movements: • 50- 300 cilia/ cell • 8-20 beat/ second • The movement is towards the natural ostium not towards the gravity. For maximum ciliary activity: • Humidity: >85% • Temperature: 18- 40 degree C • pH: 7- 8

25. The sinus mucosa consists of pseudostratified ciliated, columnar epithelial cells, goblet cells, and submucosal glands that produce a protective mucous blanket. • The mucosal blanket traps bacteria and noxious materials, which are carried by ciliary motion to the ostium and into the nose for elimination. • The orientation of the cilia within a given sinus is specific as secretions are propelled towards the natural sinus ostia and from there to the nasopharynx and oropharynx where they are subsequently cleared by swallowing. • This mucosa is similar to that found in the nose and tracheobronchial tree

26. For normal function • Normal ventilation • Normal drainage • Ciliary movements

27. Examination of the paranasal sinuses • Palpation • Transillumination • Nasal cavity regular and endoscopic examination • Radiologic examination: - Sinus Water x- ray - Coronal sinus CT

28. Anterior rhinoscopy

29. Posterior rhinoscopy

33. Frontal sinus

34. Sinonasal imaging • Plain sinus radiographs: • Sinus opacifications • Air-fluid level • Mass • Fractures

36. Water view • Best for maxillary sinuses and orbital rims • Blow-out fractures

37. Computed tomography • Excellent views of the sinuses • Coronal section • Best for osteomeatal complex and ethmoidal disease

38. MRI • Excellent soft tissue definition • Neoplastic disease evaluation • Fails to demonstrate bone • Expensive • Claustra- phobia

39. Pathophysiology of sinusitis

40. Osteomeatal complex • The most commonly infected structure in the sinuses • Can be obstructed and inflammed easily with even minimal edema • Can not be examined by anterior rhinoscopy but with endoscopy • Can not be evaluated by conventional radiology but needs CT

41. Osteomeatal complex

42. Factors negatively affecting the mucociliary activity • Dryness of air • Cigarette • Temperature • Hypoxia • Hypercapnia • Hypertonic/ hypotonic fluids • Dehydration • pH changes • Cystic fibrosis • Primary ciliary dyskinesia • Drugs ( phenylphrine, adrenaline, lidocaine, atropine, antihistaminic). • Infections • Anatomic obstruction (septum, turbinate,..) • Foreign body • Nasal polyps

43. Hypoxia ↓ Vasodilatation Ciliary dysfunctionMucous gland ↓ dysfunction ↓ Stasis ↓ ↓ Transudation Accumulation of thick ← thick fluid secretions in the sinuses ↓ Bacterial growth

44. Anatomic variations Foreign body Mucociliary dysfunction Allergy Infections Local inflammation ↓ Obstruction of the osteomeatal complex ↓ Sinusitis

45. Osteomeatal complex obstruction, ↓ Decreased ventilation of the sinuses, Decreased drainage of the sinuses ↓ pO2 decrease, pCO2 increase, mucous stasis ↓ Inflammation and viscous mucous, ciliary movement slowing ↓ Stasis and proteolytic enzymes ↓ Ciliary damage ↓ Anaerobic microrganisms ↓ More damage……

46. Pathophysiological stages of sinusitis • Initial phase • Ostium obstruction phase • Bacterial phase • Chronic phase

47. 1.Initial phase • Edema and hyperemia of the sinus mucosa • Transudate accumulation and serous fluid • Reversible • If the ostium is not obstructed it resolves spontaneously

48. 2. Ostium obstruction phase • Sinus drainage and ventilation decreases • The secretion becomes thicker and more viscous • Ventilation decreases more, pO2 pressure ↓, CO2 ↑ • A good media for anaerobes develop

49. 3. Bacterial phase • Rapid bacterial growth • Anaerobic bacterial growth • Local inflammation • Viscosity increases • Ciliary activity decreases • If not treated chronic changes start

50. 4.Chronic phase • Immune activities stop • Irreversible changes occur • Mucosal destruction • Ciliary activity stops • The irreversibla changes usually affect some of the mucosa, so if surgery (FESS) is performed, the rest of the mucosa can be saved and start functioning….