Atherosclerosis denotes a pathologic process primarily affecting the intima of larger arteries and characterized by focal thickening in which stainable lipids can be demonstrated.1-3The lesions have shown at one extreme almost exclusive fibrous composition with little lipid material; while at the other extreme, they may contain lipid accumulations of massive proportions.4-6Within the intracranial cavity, true atherosclerotic changes are seen chiefly along the vessels of the circle of Willis. Because of the nature of these changes, they are readily visible to the naked eye even in the earliest stages of their development. In spite of a very extensive literature on atherosclerosis, there is still considerable difference of opinion regarding the mechanisms involved in its etiology.7-11One of the great difficulties in evaluating the available medical literature with regard to specific etiologic factors in this degenerative arterial disease is the fact that investigators have used different recording and