Normal sellar variations in frontal tomograms.

Frontal tomograms of 100 normal sellae were examined. The sellar floor was usually flat or had a smooth central depression of less than 2 mm. Six per cent had a marked central depression. In such cases, the lateral angles of the sellar floor, usually rounded, may be sharp, so that the diagnosis of intrasellar lesions cannot be based on such alterations. Where one or more septa divided the sphenoid sinus asymmetrically, sellar floor configuration was modified in 21% of cases. The normal sellar floor may have a slope of up to 8 degrees, making analysis of subtle contour variations difficult.