Neurofibrillary tangles in the dementia of "normal pressure" hydrocephalus.

Routine neuropathological examination could not explain the dramatic improvement exhibited by one patient with "normal pressure" hydrocephalus after shunting. The improved patient contrasted remarkably with the unchanged condition of four others also shunted successfully. The five brains were analysed by quantitative morphometry to determine the degree of neurofibrillary tangle formation in mesial temporal neurons. The density of tangle-bearing nerve cells in the four unimproved cases was markedly greater than in age-matched control brains from nineteen normal subjects, and fell in the same range as that of eight dements with neuropathologically confirmed Alzheimer's disease. The density of the one who recovered was within normal limits. The duration of dementia before shunting, and the total duration of dementia in these five patients rank in the same order as their degree of neurofibrillary formation. Furthermore, a positive linear correlation exists between the Tangle Indices and the total duration of dementia. The data suggest that early diagnosis may improve the chances of reversing the dementia of normal pressure hydrocephalus before histological alterations prove too severe.