A Study on the Normal Position of Angiographic Sylvian Point: Part 1 : Determination of the Position by Angle and Quotient

ABSTRACT

A method for determining the normal position of the angiographic sylvian point in the lateral angiographic projection has been devised by author. The position of the angiographic sylvian point has been determined by the angle between two lines from the anterior clinoid process to internal occipital protuberance and to angiographic sylvian point, and the quotient of the measured distance from the anterior clinoid process to angiographic sylvian point to that from the anterior clinoid process to inner table of parietal bone. The 95% confidence limits for mean vlaue of the angle are 50.09+/-.90 and of the quotient 0.47+/-.008. The angiographic sylvian point seems to become lower with advancing age, but remains stationary after growth is completed. The quotient value calculated is independent of skull dimensions. It is assumed that the author's method for estimating the position of the angiographic sylvian point is relatively accurate since the position is determined by the dual components of angle and quotient.