Some Aspects of the Asymmetric Enlargement of Sella Turcica

An ordinary lateral view of the sella turcica will usually demonstrate whether it is enlarged, although asymmetric enlargement may easily be overlooked. The anterior wall and floor of the sella, on account of their shape and extension forwards, may produce several antero-inferior convex outlines. This appearance is often called a double floor (even if more than two outlines are present). A double floor formation in a true lateral view is considered evidence of asymmetry of the sellar floor, but there are exceptions. The sellar floor may even in normal cases be markedly convex downwards in the frontal plane, and in such cases a double floor may be apparent, even if the sella is symmetric, if the roentgen beam is tangential to different parts of the floor (Fig. 1). There are also, in the immediate neighbourhood of the floor, structures, such as the carotid sulcus, septa and walls of the sphenoid sinus that may have contours parallel to it and produce a false appearance of a double floor (Fig. 2). The absence of signs of a double floor does not, however, rule out asymmetry or asymmetric enlargement. A single contour of the floor may imply that a part of the latter is of such a shape that it is not struck tangentially by the beam and consequently is not depicted in the lateral view (Fig. 3). A high degree of decalcification may also be another reason for the asymmetric part of the floor not being shown. MAYER in some cases of asymmetric sellar enlargement with