Mechanism for decreased cortical oxygen metabolism in patients with leukoaraiosis: Is disconnection the answer?

Cerebral blood flow and metabolism are decreased in the cerebral cortex in patients with dementia of the Binswanger type. Decreased cortical metabolism may be explained by a disconnection of neuronal fibers in the cerebral deep white matter. This theory, however, has not been tested. Cerebral circulation and oxygen metabolism were measured by positron-emission tomography (PET) to examine mechanisms underlying decreased cortical oxygen metabolism in patients with extensive deep white matter lesions. Examinations with the use of PET were performed on 6 patients with dementia of the Binswanger type and 9 control subjects with hypertension. Cerebral cortex oxygen extraction fraction (OEF) was compared between the 2 groups of patients. Cortical OEF was higher in patients with dementia of the Binswanger type than in hypertensive control subjects. The result is consistent with the view that primary cortical hypoperfusion plays a role, at least in part, as a pathogenesis of impaired cortical metabolism in hypertensive patients with extensive deep white matter lesions.