Neuropathological changes in chronic adult hydrocephalus: cortical biopsies and autopsy findings.

BACKGROUND The cortical changes resulting from chronic hydrocephalus in adults are not well defined. METHODS Retrospective analysis of twenty-one patients (age 64-88 years) with a clinical diagnosis of "normal pressure hydrocephalus" who underwent cortical biopsy at the time of intracranial pressure monitoring or shunt insertion, and eight patients who were biopsied but not shunted. Eleven brains (age 26-92 years), seven from patients who could be considered to have "normal pressure hydrocephalus", were also examined following autopsy. Age- and sex-matched control brains with small ventricles and no history of dementia were compared to the hydrocephalic brains. Senile plaques and neurofibrillary tangles were assessed semiquantitatively and a non-parametric statistical analysis was employed. RESULTS Five biopsies exhibited both senile plaques and rare neurofibrillary tangles, while two had only neurofibrillary tangles. Neurofibrillary tangles were more prevalent in hydrocephalic brains than in controls. There was no difference in the prevalence of senile plaques between the two groups. Grumose bodies in the substantia nigra were identified in five autopsy brains, a prevalence higher than in control brains. CONCLUSIONS These pathological features are not specific for hydrocephalus; however, they suggest that long-standing ventriculomegaly is associated with degenerative brain changes in sites beyond the periventricular white matter. The presence of senile plaques in cortical biopsies from hydrocephalic patients does not appear to be a contraindication to shunting; however a prospective study in patients undergoing intracranial pressure monitoring would better address the issue.