Development of paranasal and mastoid sinuses: a computed tomographic pilot study.

Paranasal sinus and mastoid disease in children is an important potential source of intracranial sepsis. Cranial computed tomographic (CT) scans are a primary imaging modality for assessment of the paranasal sinuses and mastoids. Radiographic assessment of paranasal sinus development has largely been confined to plain radiographs and polytomographic examination. We report a pilot, quantitative analysis of 30 CT scans obtained from patients without known ear, nose, or throat disease, and aged from 3 weeks to 13.8 years. Ethmoid, sphenoid, and mastoid sinus development was assessed by a "pneumatization index" (PI) derived from each CT scan. At all ages, the rank order of sinus development was ethmoid greater than mastoid greater than sphenoid. Individual developmental rates showed considerable variation. In the newborn, mastoid and sphenoid sinus development was minimal, whereas ethmoid sinuses showed substantial aeration. The data suggest that, for children older than 5 years of age, an ethmoid sinus PI less than or equal to 0.714 is highly suspicious of paranasal sinus disease.