[Normal pressure hydrocephalus. Part 1. Dynamic study of CSF circulation in patients with normal pressure...

To clarify the pathogenesis of normal pressure hydrocephalus (NPH), quantitative measurement of CSF dynamics was attempted using RI techniques. In this study results concerning RI ventriculography and RI transfer test from CSF to plasma were reported. "Barrier ratio" and regional cerebral blood flow study in NPH will be reported elsewhere. Fifty-three patients with chronic communicating hydrocephalus wer devided into two groups. Thus, twenty-seven cases were diagnosed as NPH according to clinical symptoms and signs, and others were considered as mere chronic communicating hydrocephalus without any NPH characteristics. Results are as follows: 1) 169Yb--DTPA ventriculography; In NPH group, there was longer retention of RI injected into lateral ventricle, and RI activity was not detected in the cisterna magna 60 minutes after the injection. These findings show remarkable delay of CSF flow in NPH patients. 2) Transfer test of 169Yb--DTPA from CSF to plasma; Immediately after the RI injection, Transfer ratio of RI activity from CSF to plasma was measured. It was revealed that intraventricular RI was more rapidly transfered to plasma in NPH group compared with in the control group, suggesting accelerated trans-ependymal absorption of RI in NPH group.