Two types of curves for transfer of RIHSA from cerebrospinal fluid to plasma in patients with normal pressure hydrocephalus

Abstract

✓ Adult patients suffering from progressive dementia and showing enlargement of cerebral ventricles without elevation of cerebrospinal fluid (CSF) pressure received intrathecal injections of radioisotopes. By plotting subsequent blood radioactivity at intervals, two types of curves were obtained. Group A showed a rapid rise of activity followed by a high plateau; Group B showed a slow but continuous rise of activity. In patients in whom intrathecal radioisotope scans were also performed, the concentration of radioactivity was mainly sagittal in Group A, whereas ventricular radioactivity persisted in Group B. It is proposed that the diminished rate of transfer in Group B is due to either diminished rate of absorption or of formation of CSF, or both. The estimation of the rate of transfer of isotope from CSF to plasma provides a supplementary aid in the diagnosis of normal-pressure hydrocephalus.