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Paranasal Sinuses


Paranasal sinus (PNS)

Status at birth

1st radiological evidence

Best radiological view

Adult size

Drains into




4-5 months

Waters view / Occipitomental / Nose-chin position

15 years

Middle meatus

Largest PNS, capacity of 15 ml in an adult, antrum of Highmore



1 year

Caldwell view

Size increases until teens

Anterior & middle

Ethmoid = middle meatus,


Ethmoid = superior meatus

Number varies from 3 to 18



6 years

Caldwell view

7 years,

Middle meatus

6-7 ml capacity



4 years

Water’s view with open mouth

Between 15 years to adult age

Sphenoethmoidal recess

2.2 cm x 2 cm x 2.2. cm


Also know:

  1. Streptococcus pneumoniae is the most common organism implicated to acute sinusitis in both adults and children
  2. In children with cystic fibrosis, most common organism implicated to sinusitis is staphylococcus aureus.
  3. Chronic sinusitis is most commonly associated with s. aureus and coagulase negative staphylococci.
  4. Curvularia lunata,Aspergillus fumigatus, and Bipolaris and Drechslera species cause allergic fungal sinusitis.A fumigatus and dematiaceous fungi most commonly cause sinus mycetoma.
  5. Wegner's granulomatosis is the most common granulomatous sinusitis with maxillary sinus most commonly involved.
  6. Acute sinusitis almost always involves single sinus with ethmoid sinus being most common in children and maxillary in adults.
  7. Maxillary sinus is the most common location of chromic sinusitis in both children and adults closely followed by ethmoid sinus.
  8. Mucous retention cyst (different from mucocele) is most commonly found at maxillary sinus.
  9. Most common site of mucocele is frontal sinus (60%), least common at sphenoid sinus.
  10. Squamous cell carcinoma is the most common malignant tumor of sinuses with maxillary sinus most commonly involved (80%)
  11. Most common site of adenocarcinoma of sinus is ethmoid sinus.
  12. Brain abscess is the most common intracranial complication of sinusitis (as a whole)
  13. Meningitis is the most common intracranial complication of acute sinusitis.
  14. Orbital complication is the most common extracranial an overall complication of sinusitis

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