June 2014, a ppt for DLO and MS ENT postgraduate students lecture by Prof Dr.G.Gananathan MS DLO FICS, then HOD & Prof of MMC, on endoscopic and ct relevence to lateral wall of nose and paranasal sinus.

1. Dr.G.Gananathan M.S, D.L.O.,F.I.C.S.,
Director & Professor
Upgraded Institute of Otorhinolaryngology
Madras Medical College, Chennai-03

2. 
 A systemic approach to reading a CT PNS includes
 Evaluation of patient’s sinus anatomy with its
variations
 Determinig the presence of disease
 Looking for potential areas of occlusionof drainage
pathways
Computer Tomography of Paranasal Sinuses

3. 
 To master FESS
 Perfect anatomy
 Familiarization of radiological landmarks
 3D reconstruction
 Cross sectional anatomy of FESS
 Handling of scope and instruments
 Not to panic when entering neighbouring areas
 Management of bleeding

4. 
 Ask for 3 planes-coronal, axial and sagittal
 Axial view- Patient’s hard palate is perpendicular to the CT
scanner table , so the External Auditory Canal is in line with
the infra-orbital rim.
 Coronal view- Patient’s hard palate is parallel to the scanner
table.
 Soft tissue and bone window settings
 Screening CT – 5-10mm , 1-2mm, 0.5mm
 Settings 1700-2300 HU , centre around +100 to +300 with
130 KV collimation of 2 x 1.5mm with rotation time of 1
second
Protocol of CT

5. 
 A patient undergoing FESS has to get a CT prior to the
procedure after completion of maximal medical therapy.
 The scans are read twice :
 once to study the anatomy and its variations and
 then again to study the pathology
 It is advisable to start reading the scans from the scout
view and then read it frame by frame without jumping
erratically
 The navigation is complementary to the CT allowing the
surgeon to orient himself in different planes intra-op
When to Order CT

6. Scout
film
Frontal Sinus &
Inferior turbinate
First cut Following Scout Film
- Nasal bone, Nasal septum &
- Alar cartilage

7. Frontal Recess and T sign
Nasofrontal beak, Nasolacrimal duct

8. Uncinate Process
(dotted line)
Crista galli &
Suprabullar recess

9. Anterior Ethmoidal Artery
Basal Lamella &
Lamina Papyracea

10. Posterior Skull Base and Inferior
Orbital fissure
Orbital Apex,
Sphenoidal Os &
Planum Sphenoidale

11. Onodi cell, Vidian canal,
Foramen Rotundum ,
Intersphenoidal septum,
Anterior clinoid process &
medial and lateral
pterygoid plates
Foramen Ovale &
sphenoid sinus

12. AXIAL CUTS
showing
Sphenopalatine
Foramen,
Nasolacrimal duct,
Globe, optic nerve
Lamina papyracea
And medial and
Lateral rectii.
Endoscopic view
Showing
sphenopalatine artery,
Crista ethmoidale,
Orbital fat,
Medial rectus,
Widened sphenoidal
ostium.

13. Frontal Recess in Axial Cuts
Axial cuts
Showing
Transition from
frontal sinus to
Frontal recess.
Viewed from top
Downwards.
Anterior wall is
Thicker.
(Naso-Frontal
Beak )

14. Frontal Recess
Agger Nasi Cell &
Concha bullosa

15. Frontal Air Cells
Type I (Bipatite agger cell) Type II
• Anterior & posterior group
• Anterior group - 4 Types

16. 
Frontal Air Cells
Type III (arrowheads) Type IV

17. Posterior- group -Supra Bullar cell

18. Posterior Frontal group-Frontal Bullar & Supra-orbital cells

19. 
Crista Galli
Interfrontal cell

20. Concha Bullosa

21. 
Uncinate Process- Attachments
Recess
terminalis

22. 
Anterior Ethmoidal
Artery

23. Haller cell

24. Onodi cell
d NO- dehiscent optic nerve

25. Lamina
Papyracea
&
Types of
Maxillary
Sinus
Hypoplasia

26. Infra orbital entry

27. LOCR-Lateral
Optico
Carotid
Recess
Fungal Rhino
Sinusitis

28. Type
IV
Frontal
cell

29. JNA-
Infra
Temporal
Fossa,
cavernous
sinus &
Superior
Orbital
fissure

30. Optic nerve-
White arrow

31. Fibrous Dysplasia of Ethmoid Sinus

32. Esthesioneuroblastoma

33. Fibrosarcoma
of Sphenoid sinus

34. Inverted Papilloma

35. Esthesio-
neuroblast
oma

36. Nerve
Marker
In
Navigation
Assisted
surgery

37. 
 Fresh cadaver dissection platform to fine tune skills
 Fresh frozen preferred over formalin preserved as
tissues are more pliable and anatomical details are
closest to living tissues
 Nasal Endoscopy – 3 passes
Cadaver Dissection

39. 
 Note the following
structures
 Inferior turbinate
 Middle turbinate
 Axilla of middle turbinate
 Uncinate process , Bulla
ethmoidalis
 Accessory ostia
 Tubal elevation,
Eustachian tube
 Fossa of Rosenmuller
 Superior turbinate,
Sphenoidal os

40. 
3 Passes
First Pass
Second Pass
Third pass

41. 
 Steps
 Lateralisation of Inferior turbinate at the level of
anterior end of middle turbinate using Freer’s elevator
(this increases room for manipulation in middle
meatus)
 Indentify the free border of uncinate process
 Identify junction of the upper 2/3rdand loer 1/3rd of
the uncinate process (corresponds
Uncinectomy

43.  Steps
 Mucosa of the medial surfaces of the horizontal portion of
the uncinate is debrided away.
 Lower portion of uncinate bone is dissected away with
sickle knife.
 The mucosa of the lateral surface of uncinate is retained. A
vertical cut is made at its anterior end.
 A scissor is used to cut the mucosa , flush with the roof of
the maxillary sinus as far as the accessory ostium
 The inferiorly based uncinate flap is now draped over the
raw surface created over the superior aspect of the inferior
turbinate.
Middle Meatal Antrostomy

45. 
 Boundaries
 Anteriorly : agger nasi
 Posteriorly: anterior ethmoidal artery
 Medially : middle turbinate
 Laterally : lamina papyracea
Frontal Recess

47. 
Anterior Ethmoid
 The bulla is the largest
anterior ethmoid air cell
 6 walls
 Anterior wall
 Medial wall-related to the
lateral wall of Hiatus
Semilunaris Superioris
 Lateral wall- lamina payracea
 Posterior wall- related to
retrobullar recess
 Superior wall – could be
attached to skull base /
related to suprabullar recess
 Inferior wall

49. 
 Anterior ethmoidal neurovascular bundle running
obliquely from posterior to anterior , and lateral to
medial.
 Small portion of anterior fovea between posterior
wall of frontal sinus and anterior ethmoidal artery.

50. 
 Boundaries
 Anteriorly : ground lamella
 Posteriorly : anterior wall of sphenoid
 Laterally : lamina payracea
 Superiorly : posterior skull base
 Medially : superior turbinate
 Steps
 Identify ground lamellaand gentally slide Blakesley forceps
along the horizontal attachment of middle turbinate.
 Perforate the basal lamella medially and inferiorly using the
forceps.
 Remove all cells till the posterior skull base is identified.
 The skull base descends inferiorly towards the posterior aspect.
Posterior Ethmoid

51. 
 Intermediate approach
 Follow the inferior wall of bulla towards posterior end of
middle turbinate.
 Use the debrider directed medially taking care not to
damage the septal mucosa.
 The anterior end of superior turbinate is identified.
 Push superior turbinate gently laterally and identify the
sphenoid os.
 Using forceps resect the inferior third of superior turbinate.
 Sphenoid os is visualized now.
 Using Stammberger mushroom punch forceps sphenoid os
is widened.
Sphenoid Sinus

52.  Following structures are seen in sphenoid sinus
 Orbitel apex
 Optic nerve
 Internal carotid artery
 Sellar floor
Structures in Sphenoid

53. Skull base

54.  Structures identified in Skull Base
 Posterior ethmoidal neurovascular
bundle
 Posterior fovea
 Anterior ethmoidal neurovascular
bundle
 Anterior fovea
 Frontal recess