Abstract
We have studied CSF dynamics after subarachnoid hemorrhage (SAH) and normal pressure hydrocephalus (NPH) with the morphological alternation of the intracranial distribution of RI and clearance of intracranial RI.
The radionuclide used was 1 mCi of 189Yb-DTPA. Scintiphotos of the head were taken at 1, 3, 6, 24, 48 and 72 hours after RI injection into the lumbar intrathecal space, and clearance curves were made by plotting the time (seconds) required for 50, 000 counts when each scintiphoto was taken. The curve showed an initial descending part representing increase in radioactivity in the head, followed by an ascending part representing loss of radioactivity. The materials studied were 123 RI-cisternographies applied to 88 cases of SAH, of which 72 were ruptured aneurysm. The remaining 16 cases were primary SAH. Normal control study was made on 20 cases of epilepsy, minor head injury and cerebral infarction. Morphological changes of scintiphotos were classified into 2 major groups, i.e., ventricular retention of RI (within 24 hours and beyond 24 hours), and subarachnoid block(unilateral and bilateral). The clearance curve also changed in 2 ways; one was a tendency of a shift in the base of the curve to the right, i.e. delay in establishing maximum counting rate, and the other was a decrease of ascending gradient after the base of the curve. These changes in clearance curve seemed to represent disturbance of CSF circulation and absorption. CSF dynamics after SAH were evaluated along with the patients' condition and RI-cisternographical changes, and the conclusions were as follows :
1. RI-cisternographical changes take 3 weeks after SAH to become stable, therefore, this examination should be done after this 3 week period.
2. Intracranial surgery of aneurysm does not influence CSF dynamics on RI-cisternography.
3. Ventricular retention of RI beyond 24 hours suggests NPH, even more so when combined with bilateral subarachnoid block.
4. RI-cisternography should be repeated on a patient suspected of NPH because ventricular retention within 24 hours and beyond 24 hours changes each other according to improvement or deterioration of the clinical features.
5. RI-cisternography is a most useful and safe tool both for evaluation of CSF dynamics after SAH and for diagnosis of NPH, which is definitely represented by ventricular retention of RI beyond 48 hours and by bilateral
subarachnoid block. However, accurate diagnosis and treatment of suspected NPH cases should be made by a comprehensive study of other examinations such as saline infusion test, pneumoencephalography and EEG.
