MRI and SPECT studies of dural arteriovenous fistulas presenting as pure progressive dementia with leukoencephalopathy: a cause of treatable dementia.

We report two patients with dural arteriovenous fistulas (DAVFs) who presented with pure progressive dementia. Both patients showed only slowly progressive dementia, without headache, papilledema and other neurologic signs associated with diffuse white matter changes in MRI. MR cerebral angiography showed sigmoid sinus DAVFs that were mainly supplied by the occipital artery, together with retrograde filling of the superior sagittal and straight sinus and dilated cortical veins. SPECT studies showed extensive blood flow reduction in the occipital and parieto-occipital areas and right temporal lobe in one patient. Selective embolization for treatment of the DAVF improved cognitive function associated with the abnormal white matter MRI signal. MRI and SPECT showed that severity of dementia correlated with diffuse white matter changes and regional cerebral blood flow. Our cases suggest that gradually impaired cerebral circulation due to venous hypertensive encephalopathy could be involved in slowly progressive dementia with leukoencephalopathy resulting from a DAVF. DAVFs may be particularly important for differential diagnosis in elderly patients with pure progressive dementia. Thus, early diagnosis of DAVFs and treatment by endovascular surgery is important as treatable or reversible dementia.