Preoperative check-list of CT-scan

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Preoperative check-list of CT-scan Powered By Docstoc
					  How to read a CT-scan
          before
endoscopic nasal and sinus
         surgery

         J.S. Lacroix, MD, PhD
      Rhinology-Olfactology Unit
     Clinic of Otorhinolaryngology
      University Hospital Geneva
               Switzerland

         Bangkok, Nov. 2009
                          Step 1

                   Correct orientation

Orientation of coronal (frontal) slides : antero-posterior

       Orientation of axial slides : bottom to top

        Orientation of sagittal slides : right - left
    coronal, sagittal, axial

  Coronal
                            Sagittal
antero-posterior
                            right-left




                 Axial
               bottom-top
Coronal CT




             Maxillary sinuses
             Ethmoid sinus
             Nasal cavity
Sagittal CT




              Frontal sinuses
              Ethmoidal sinuses
              Sphenoidal sinus
              Nasal cavity
                  Step 2

Identification of the anatomical structures.

            Are they normal ?
             Anatomic variants

                     Very frequent
      The presence of anatomic variants, alone or in
   combination, does not represent a disease state per se


Equal prevalence of patients with and without nasal and sinus
   disease in the presence of the same anatomic variant


 All anatomic variants should be identified
               before surgery
     Septal deviation
Coronal CT     Coronal CT




                                Hypoplastic
                                  middle
                                 turbinate
                                                Large
                                               middle
                                              turbinate


              Middle meatus
              Inferior meatus
The physiopathological mechanisms of septal deformities

   Ossification of the perpendicular plate and vomer




 1-3 years                                 10-17 years
Anatomical structures of the nasal septum
   Vomeral spur



1. Perpendicular plate of the ethmoid
2. Vomer
3. Dislocated sphenoidal process of
   the cartilaginous septum
4. Impression in the inferior turbinate
                        Septal spurs
                                 Axial CT
 Coronal CT

                                                         Coronal CT




                                                                 Bridging spur
 Frequently encountered at the junction of the perpendicular
 plate of the ethmoid and the vomer : sphenoid process

May compress or invaginate the middle or inferior turbinates. When the turbinate
mucosa swells with the normal nasal cycle or inflammation, it is impaled on the spur,
setting up a cycle of facial pain or headache and local neurogenic inflammation. A
septal spur may occasionally produces a complete bridge.
Lateral nasal wall

1.   Inferior turbinate
2.   Middle turbinate
3.   Superior turbinate
4.   Agger nasi
5.   Supreme turbinate
The turbinates

The lamelar type


The spongiotic type


The bullous type
Size variations of the middle turbinate

     Coronal CT                               Coronal CT




     50 % of middle turbinates abdnormalities are
        associated with chronic rhinosinusitis
    Turbinate and septal contact when the turbinate
    mucosa swells with the normal nasal cycle and
         may induce neurogenic inflammation.
     Pneumatized middle turbinate
 Axial CT
                                   Coronal CT




                                   Air cell in the vertical lamella:
                                   concha neck air cell
Air cell in the bulbous segment:
concha bullosa cell
  Paradoxical bending of the middle turbinate

Coronal CT




Most commun                       Paradoxical bending turbinate
Convex configuration medially     Concave configuration medially
Concave configuration laterally   Convex configuration laterally
Pneumatization of the superior turbinate

                    Coronal CT




      Could it cause headache?
      Enlargement of the superior turbinate due to pneumatization,
      may induce mucosal contact, and mechanical
      stimulation of sensory nerves and may induce pain.
      However, only 50 % of success after surgery !
Uncinate process
    Height : 1-4 mm
    Length : 14-22 mm
                             Coronal CT

         Coronal CT




 Medially rotated uncinate
                               Pneumatized
 Frontal bulla cell (suprabullar cell)
 Anterior ethmoid air cell extending upwards (intramural ethmoid
 air cell)

sagittal                    axial                         coronal
      Frontal recess




    May be small and only narrow the floor of the frontal sinus.
    May be elevated and narrow significantly the frontal recess
    May be prominent and bulge into the frontal sinus
 Frontal sinus extension
 Pneumatization of the orbital plate of the frontal bone




ant                                  post
         Coronal CT
                     Frontal sinus




       No frontal sinus drainage compromise
Agger nasi (AN) cell                                             Coronal CT

                    Sagittal CT



                                                 Lacrymal   AN
                                                 fossa




Frontal recess
The most anterior of the ethmoid cells. Forms the floor of the frontal
recess. It reaches the lacrymal fossa inferio-laterally, and is
Antero-laterally arched by the nasal bone. A large agger nasi can narrow
the frontal recess.

Its posterior-medial wall usually gives rise to the anterior uncinate process
 The endo-sinuses recesses:
Important to be localized when
planing surgery for fungus ball
   inverted papilloma, etc…
         Maxillary sinus recesses
Coronal CT      Palatine recess                        Axial CT




                                      Infraorbital recess of
                                      The maxillary sinus



Coronal CT              Sagittal CT          Axial CT




      Alveolar recesses
      (roots of the premolar
      and molar teeth)                       Zygomatic recess
      Sphenoid sinus recesses
          Sagittal view
                                            Coronal anterior view



ant
                          post                               Sphenoid
       Sphenoid sinus            Temporal          Orbital
                                                   wall
                                                             sinus
                                 bone


                                            Maxillary
                                            bone

              Rostrum
              Septum, vomer
              Sup or inf clivus
              Lesser wing
              Greater wing
              Pterygoid process
Sphenoid sinus recesses


        Sagittal CT           Sagittal CT




Septal recess         Inferior clival recess
      Sphenoid sinus recesses
                           Coronal CT




Lesser wing

Greater wing

Pterygoid process                   Coronal CT


Anterior clinoid process
      Foramen rotundum
      (maxillairy nerve)

     Optic nerve
Vulnerability of the carotid canal
      Internal carotid artery bulges
         into the sphenoid sinus
            Axial CT   Axial CT


                              Sphenoid
                              sinus
                              surgery

                                  septum
   Internal septation of the
        sphenoid sinus
      Axial CT
                      Coronal CT




Presellar segment of the internal carotid artery
Vulnerability of the carotid canal
            Dehiscent carotid canal

                                      Sphenoid
 Axial CT                  Axial CT   sinus
                                      surgery
Vulnerability of the carotid canal

    Normal          Hypoplasia or aplasia
   sphenoid         of the sphenoid sinus
     sinus         Carotid canal bulges into the posterior
                                  ethmoid
  Axial CT
                                    Posterior
                                    ethmoid
                                    surgery

         Ethmoid        posterior
                        ethmoid
        Normal
        sphenoid
        sinus
 Vulnerability of the optic nerve
1 Onodi cell (bulging of the optic canal into the posterior ethmoid)
2 Pneumatization of the lesser wing of the sphenoid bone
3 Pneumatization of the anterior clinoid process of the sphenoid bone



                                   Coronal CT         2                Coronal CT
                                                                                    3
     Sagittal CT       1


 Posterior                            Sphenoid
                                                                    Sphenoid
 ethmoid                              sinus
                                                                    sinus
 surgery                              surgery
                                                                    surgery

                                            Encasement of the optic nerve
                                              within the sphenoid sinus
      Optic nerves
Vulnerability of the optic nerve
   Onodi cell                                      Sagittal CT

 Axial CT


                                                        Sinus
                                                        sphenoid
                         Posterior
                         ethmoid
                         surgery                 Coronal CT




       Posterior ethmoid cell, with prominent superior or lateral
     pneumatization to the sphenoid sinus, and a bulge of the optic
                             canal into it.
Vulnerability of the optic nerve

     Axial CT

             Sphenoid
             sinus
             surgery




      1                         2
                                    Coronal CT
                                                    2

1. Bulging of the optic nerve
   into the sphenoid sinus               Sphenoid
2. Dehiscent optic canal                 sinus
                                         surgery
      Vulnerability of the orbit
                                 Haller cells

Coronal CT


                                            Anterior
                                            ethmoid
                                            endoscopy




        Anterior ethmoid air cells that extend along
                the medial floor of the orbit
    Vulnerability of the orbit

                                            Coronal CT
Axial CT

                               orbite
 orbit                                  Uncinectomy




           Uncinate process is very close to the
                 infero-medial orbit wall.
           Vulnerability of the orbit

Lamina papyracea localized medial to
the maxillary sinus ostium

                            Coronal CT                   Coronal CT

                                                                                    orbit




                                             Fusion of the uncinate process to the
                                             medial orbital wall
                                             (usually associated with ipsilateral hypoplastic
(Ex :maxillary sinus hypoplasia;reduced      maxillary sinus)
ethmoid transverse diameter i.e. children)
         Vulnerability of the orbit

Coronal CT         Axial CT                    Axial CT
                              Anterior
                              ethmoid
                              endoscopy




                                                           coronal




Dehiscent lamina    Thin medial orbital wall    Dehiscent lamina
papyracea           (lamina papyracea)          papyracea
Vulnerability of the nasolacrymal duct
Agger nasi cell can invade the lacrymal bone
and impinge on or encircle the nasolacrymal duct


            Coronal CT



                                     Anterior
                                     ethmoid
                                     endoscopy




                                          Axial CT
Vulnerability of the anterior skull base

 Low cribriform plate: below the upper third of the vertical
 orbital plate
                                     Coronal CT



     orbit


                           Risk of penetration into the
                           anterior cranial fossa during
 Usually associated with   ethmoid endoscopic surgery
 hypoplastic middle
 turbinate(s)
             Conclusions


      When all anatomic variants
   have been identified and localized,
endoscopic nasal and sinus surgery can
            be performed
        under safe conditions.
Thank you for your attention
  and welcome to Geneva
Switzerland June 20-24 2010




         June 20-24

				
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