White matter hyperintensities (WMH) are associated with intracranial atherosclerosis rather than extracranial atherosclerosis

There is increasing evidence for an association between WMH and large-artery atherosclerosis. We evaluated 268 patients with acute ischemic stroke to assess the relationship between intracranial (IC) atherosclerosis and WMH. The patients were classified into three groups according to the location of the stenosis; IC, extracranial (EC), and non-stenosis (NS) group. WMH were rated using the semiquantitative method of Scheltens and coworkers. The IC group had significantly more WMH score in comparison with the other groups after controlling age. The linear regression analysis showed that age was the factor most strongly associated with the total score of WMH; and the location of stenosis was positively related to WMH, especially in deep white matter. Our data show that IC stenosis is associated with WMH, indicating that IC stenosis, rather than EC stenosis, is likely to cause white matter lesions. These findings raise the possibility that occlusion of penetrating arteries, embolism to border-zone areas and a hemodynamic mechanism associated with IC stenosis leads to the formation of white matter lesions.