Lysbilde 1

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CT bihuler
Heidi Beate Eggesbø Radiologisk avdeling Aker
Universitetssykehus
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• Normal utvikling
• Pneumatiserings varianter
• Anatomiske varianter
• Inflammatoriske mønstre

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Ethmoid sinus development

• Arise as numerous evaginations from the nasal
  cavity in the 35th fetal months
• Fluid-filled at birth
• Air-filled during the 1th year
• The adult ethmoid sinuses contain 318 cells each
  side

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Maxillary sinus development

• Maxillary sinuses develop in successive stages
• Rapidly until the age of 23 yrs
• Then a slower evolution is seen until the age of
  6-7 yrs
• A second acceleration of development occur after
  the age of 7-8 yrs
• Adult size reached by the age of 12 years

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Sphenoid sinus development
Presphenoid anterior to the sella
turcica Basisphenoid below the sella turcica
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Frontal sinus development
When the ethmoid recess passes the superior
orbital rim is it defined as frontal sinus This
usually occurs at the age of 6 yrs
Libersa C (1981),  Weiglein A (1992)
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Variations in development
Hyperpneumatization Hypoplasia Aplasia
Frontal sinus aplasia 4-5 Frontal sinus
hypoplasia 20 Maxillary sinus hypoplasia 6 -
10 Sphenoid sinus hypoplasia rare
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Ostiomeatal complex (OMC)

• -Refers to the final common drainage pathways of
  the maxillary, anterior ethmoid, and frontal
  sinuses

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Ostiomeatal complex (OMC)
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Mucociliary drainage routes
Maxillary sinus
Frontal sinus
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Functional Endoscopic Sinus Surgery (FESS)Main
goal enlarge the natural sinus ostia
Uncinectomy
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Pneumatisation variants
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Pneumatisation variants

• Excessive pneumatisation of the surrounding bone
• Same mucosal surface and undergo same
  inflammatory changes as the other sinuses

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Agger nasi cells
Frontal recess
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Concha bullosa
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Infraorbital (Haller) cells
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Large ethmoid bulla
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Less common pneumatisation variants
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Anatomical variantsto report on prior to surgery
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Maxillary sinus hypoplasia
? Increased risk for orbital penetration
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Reduced ethmoid tranverse diameter
? Increased risk for orbital penetration
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Ethmoid roof
Normal
Deep
Increased sloping and asymmetry
? Increased risk for cranial penetration
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The olfactory fossa Keros classification
? Increased risk for cranial penetration
(Keros, 1965 / Stammberger et al. 1995)
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Sphenoid sinus variants