Nose and paranasal sinuses COI Disclosure

Normal anatomy, IFA classification

• no conflict of interest regarding this presentation
& variations relevant for surgery:
„the checklist“

Bernhard Schuknecht1, Daniel Simmen2 and Hansruedi Briner 2

1Medical Radiological Institute Zurich CH

2ENT and Plastic Surgery Centre Klinik Hirslanden Zurich CH

bschuknecht@mri-roentgen.ch

European Course in Head and Neck Neuroradiology Nov 3, 2021 10:45-11:15

Normal anatomy? = anatomic variations ! If you go to the mountain often enough,

frontal sinus –ethmoid - sphenoid you will meet the tiger chinese proverb

frontal beak
depth of frontal sinus
position of ethm. roof
Onodi cell

lack of consensus with respect to the clinical significance of anatomic variations !

ї uniform acceptance regarding the relevance for endoscopic surgery !!

ZH paranasal sinus CT protocoll

Zürich paranasal sinus CT protocol
how scan axial alveolar process - top of frontal sinus ;>WљͿ
їlow dose acquistion, eff. mAs 90-120 (dose ~ 0.1 mSVͿ
їreconstruction of data Ϭ͘ϲŵŵїϯƉůĂŶĞƐΛϬ͘ϳϱŵŵ͕ how : iv contrast*:
ї bone window ,ϳϬŚ͕W 3200/ C 700
їsoft tissue window ,ϯϬƐϬ͘ϳϱїϯŵŵax/cor W 300/ C 100 • not required for preop. assessment of anatomy
їnavigation data: axial including nose, front, ears • acute inflammation with complications
correct pat. positioning and plane orientation !
• suspicion of tumor (inverted papilloma, neoplasmͿ
•al
• vascular lesions (angiofibroma, vascular malformations Ϳ

• (unilateral lesions͊Ϳ

sagittal coronal axial

 persistent mucosal swelling,
Paranasal sinus – CT ± navigation !! chronicity of disease?
anterior ostiomeatal complex disease

When: in chron. rhinosinusitisc s symptoms >12 weeks

ff maximal + optimal conservative tx
ї visualize drainage pathways + anatomy
ї assess persistent/recurrent unilateral disease
rarely in acute rhinosinusitis symptoms < 12 weeks
їidentify complications ;DZ͍Ϳ
їverify location and extension
їreassure diagnosis (insuff tx responseͿ
in neoplasm w. osseus erosion or tu of bone /cartilage origin
in suspected inverted papilloma treatment: culture or empirically driven antibiotics for 2 w posterior ostiomeatal complex disease
topical steroid for ϯǁor systemic steroids for ϱdays

well considered indication + good technique + communication

= best radioprotection the nose and septum are part of the exam !
How?

Radiologist

Lens protection device Ø navigation

Lense dose CT 0.1 - 0.5 mSv Rhinologist
CBCT 0.05- 0.3 mSv

Nasal cavityїmiddle meatus Anatomy coronal + osteomeatal complex

obstruction of ostiaї stasis of secretions Ethmoid roof = fovea ethmoidalis
їpropagation of infection/inflammation Olfactory fossa
Cribriform plate – lateral lamella
Middle turbinate vertical lamella
Inferior turbinate
Perpendicular lamina
Olfactory rim
Agger nasi
Ethmoid bulla
Frontal recess
Haller – infraorbital - cell
Ostiomeatal complex їmiddle meatus
• frontal sinus ostium +frontal recess
Concha bullosa Haller cells Maxillary sinus pneumatisation Hypoplastic maxillary sinus • ethmoid infundibulum
+pneumatized vertical lamella
• hiatus semilunaris
 Anatomy sagittal plane : osteomeatal complex
Middle turbinate
obstruction of ostia ї stasis of secretions
їpropagation of infection/inflammation
Frontal sinus beak- depth of frontal sinus
Frontal ostium- recess
Olfactory fossa
Cribriform plate ground lamella
Middle turbinate vertical/basal lamella
Inferior turbinate vertical lamella
Agger nasi
Ethmoid bulla
Uncinate process

posterior ostiomeatal complex

• spheno-ethmoid recess- sphenoid sinus
• superior meatus - posterior ethmoid –Onodi- cells
Transition of vertical to horizontal ground lamella separates ant. and post. ethmoid

1. attachment of uncinate process

8 –point preoperative CT checklist : ƚLJƉĞ;ůĂƚĞƌĂůͿ type B1 type B2 medial
= universal description of anatomic variations irrespective of the surgery planned

• uncinate process
• ethmoid roof
• ant. ethmoid artery
• lamina papyracea
• optic nerve
• internal carotid artery
• bony defects/dehiscences 
• ethmoid cells ĺIURQWDOsinus + sphenoid.

How to identify uncinate proc. attachment ? A vs B: different configuration of frontal sinus outflow
RT
Ouflow of frontal sinus јdistance
frontal beak- post wall
їŚŝŐŚfovea ethm.
Rt side type A
lateral

maxillary ostium
direct drainage
via frontal recess
LT
LT
Lt side type B љdistance
medial frontal beak- post wall
їlow fovea ethm.

ї indirect drainage
via ethmoid +
anterior
hiatus semilunaris
їcor plane
Ouflow of maxillary sinus Anatomic features related to maxillary sinus
uncinate process + Haller cells ֞ ostium
narrow
ostium

free infraorbital nerve ~ zygomatic recess silent ƐŝŶƵƐ;ůƚͿ͕atelectatic ostium lacrimal recessus= surgical route

position of orbital floor

+ Haller cells

wide
ostium

accessory ostium ??? neoplasm Underwood ƐĞƉƚƵŵ;ƐŝŶƵƐůŝĨƚͿ

2. position of ethmoid roof ֞ right

Identification ant. ethmoidalis artery Ÿ: „v“ configuration
3. course of ant. ethmoid artery

integrated course
canal of AEA

left

free course
canal of AEA

2. ethmoid roof ֞ cribriform plate ethmoid roof ֞ cribriform plate

Stankiewicz JA, Chow JM. The Low Skull Base: An invitation to disaster marked asymmetry ~ 7% !
American Journal of Rhinology 2004; 18 35–40 meningo-encephalocele

Keros type
1: 1-3mm
2: 4-7mm
3: 8-16mm

susceptible to injury of ethmoid artery susceptible to injury of ethmoid roof- dura Variation? meningocele, arachnoid herniation? MR exam!
 34. lamina papyracea Ÿ ethmoid 5. optic nerve ֞ ethmoid/sphenoid sinus
sagittal

Posttraumatic bone intact bony dehiscence (= point ϳchecklistͿ „intrasphenoid“ optic nerve position ? ? = internal carotid artery = point 6 checklist

6. internal carotid artery ֞ sphenoid sinus 7. osseous defects

commonly w ~ polyposis

bony dehiscence = point ϳchecklist

International Frontal Sinus Anatomy Classification (IFAC) International Frontal Sinus Anatomy Classification (IFAC)
Wormald PJ, Hosemann W, Callejas C, Siow JK, et al. The Internationals Frontal Sinus Anatomy Classification ;/&ͿĂŶĚClassification of the Extent of Endoscopic &ƌŽŶƚĂů^ŝŶƵƐ^ƵƌŐĞƌLJ;&^^Ϳ͘Int Forum Allergy Rhinol. 2016
Wormald PJ, Hosemann W, Callejas C, Siow JK, et al. The Internationals Frontal Sinus Anatomy Classification ;/&ͿĂŶĚClassification of the Extent of Endoscopic &ƌŽŶƚĂů^ŝŶƵƐ^ƵƌŐĞƌLJ;&^^Ϳ͘Int Forum Allergy Rhinol. 2016
classifying all cells as either anterior or posterior or medial or lateral
8. ethmoid cells: classifying all cells as either anterior or posterior or medial
agger nasi cell supra agger cell supra agger frontal cell

Supraorbital ethmoid cell ;ůĂƚ͘Ϳ

Supra bulla cell Supra bulla frontal cell Frontal septal cell ϵϱ%

49%
Ϯϱй

89%
Ϯϳй

Suprabulla
Supr
p ab
aabu
abul
bul
bu
bu
ullllaa cell
cel
cce
ell
el
ellll 9%

28%

Sommer F. et al. European Arch Oto-Rhino-Larngol ϮϬϭϵ͖Ϯϳϭ͗ϯϵ-46

 If you go to the mountain often enough,
Preoperative CT checklist : you will meet the tiger

• uncinate process ¥
• ethmoid roof ¥
• ant. ethmoid artery ¥
• lamina papyracea ¥
• optic nerve ¥
• internal carotid artery ¥
• osseous defects ¥ 
• ethmoid cells їĨƌŽŶƚĂůƐ͘ ¥ έϔΣϟ΍ ργϭΎϣ΋΍ΩεϳόϳϝΎΑΟϟ΍ΩϭόλΏΎϬϳϥϣ
Who is afraid to climb mountains will stay in a hole forever (arab proverb)