Periventricular hyperintensity lesions and dementia in multiple cerebral infarction

To examine the relationship between the presence of periventricular hyperintensity (PVH), as shown on MR-T2 weighted images, and both ischemia and dementia, regional cerebral blood flow (rCBF), oxygen extraction fraction (OEF), cerebral metabolic rate of oxygen (CMRO2), and cerebral blood volume (CBV) were determined by positron emission computed tomography using the 15O and 11CO inhalation technique. Thirty-three patients with subcortical cerebral infarction were classified according to the presence of PVH: the PVH (+) group with severe PVH (n=17) and the PVH (-) group without PVH (n=16). In the PVH (+) group of patients with no association of dementia and the PVH (-) group, both decreased rCBF and increased OEF were significantly observed in the frontal cingulate gyrus and PVH area, when compared with the normal controls. In the PVH (+) group of dementia patients, on the other hand, rCBF was significantly decreased in the PVH lesion and each cortical region; and CMRO2 was significantly decreased and OEF was increased in the PVH lesion and all cortical regions, especially the frontal cingulate gyrus. Moreover, the PVH(+) group had a significantly decreased rCBF and rCBF/CBV ratio in PVH lesion. These results showed that 'compensated hypoperfusion' existed in PVH lesion and cortical regions, especially the frontal cingulate gyrus, in multiple infarction patients without dementia and that 'ischemic hypoperfusion' was observed when associated with dementia. These changes, which seemed to be caused by cerebroarteriosclerosis, not only preceded the occurrence of mental deterioration, but also still persisted after dementia had occurred. PVH also reflected severe ischemic changes of the brain in multiple cerebral infarction, irrespective of the association of dementia. (N.K.)