Neuropathological aspects of dementias resulting from abnormal blood and cerebrospinal fluid dynamics.

In a large autopsy series of elderly individuals, organic dementia was attributed to (pre-) senile atrophy in 52.8%, to cerebrovascular disease in 22.5%, while 13.6% were of mixed senile and vascular origin, and 1.3% showed communicating hydrocephalus with meningopathies or were of undetermined origin. A survey is given of the morphological criteria of dementia resulting from disorders of cerebral blood supply and CSF circulation. The anatomic basis of vascular dementias are: atherosclerotic encephalopathy with lacunar state or multiple infarcts; granular cortical atrophy resulting from local microcirculation disorders; hypertensive cerebrovascular disease with the common "mixed" cortico-subcortical type, and the rare Binswanger's subcortical type. Atypical cerebral hemorrhage in old individuals rather results from congophilic (amyloid) angiopathy than from hypertensive arteriosclerosis. Multiple infarct dementia may also result from thrombotic microangiopathy, thromboembolic disease or cerebral vasculitides. The anatomical features of dementia associated with communicating "normal-pressure" hydrocephalus (NPH) are meningopathy at the basis or on the convexity, and fibrosis of the choroid plexus and/or arachnoid villi of post-inflammatory or undetermined origin, and other non-specific changes (periventricular gliosis). This condition is also associated with hypertensive cerebrovascular disease and Alzheimer's disease. Cerebral biopsies in NPH as well as in other types of hydrocephalus show enlarged extracellular spaces with otherwise normal neuropil probably resulting from increased transcapillary filtration. In some cases of "idiopathic" NPH no causative anatomical changes are found. The relationship between cerebral tissue changes, abnormal blood and CSF dynamics in these conditions remains to be clarified.