[Normal pressure hydrocephalus. Part 2. The evaluation of severity of cerebral dysfunction by measurement of "barrier ratio" and regional cerebral blood flow (author's transl)].

In the previous study, quantitative analysis of RI ventriculography was reported in fifty-three cases with chronic communicating hydrocephalus. In this study, according to the same criteria as that of previous report, fifty-three cases were divided into two groups, namely NPH group (twenty-seven cases) and control group, which were considered as mere chronic communicating hydrocephalus without and NPH chalacteristics. (twenty-six cases). Results of "barrier ratio (B.R.)" measurement and regional cerebral blood flow study in these cases are as follows: 1) "Barrier ratio" using of 99mTcO4-: Concerning about B.R. of 99mTcO4- there was no significant difference between NPH and control group. However it tends to be that shunt surgery is not so effective in NPH cases in which B.R. shows abnormally low value. 2) rCBF by 133Xe clearance method: Regional cerebral blood flow was diffusely decreased in NPH patients, especially in its frontal area, suggesting the frontal area would be more severely damaged in NPH cases. These findings leads us to the conclusion that whether the shunt surgery might be effective or not depends on severity of cerebral dysfunction and the cerebral dysfunction is clearly evaluated by RI technique mentioned above.