Abstract
Measurements such as intracranial pressure-volume index (PVI), out flow resistance (Ro), and absorption pressure (Abs) of the cerebrospinal fluid were utilized for intracranial bio-mechanical analyses of four infants who suffered from hydrocephalus prior to insertion of a ventriculoperitoneal (V-P) shunt and 4 infants suffering from malfunction of a previously inserted V-P shunt. Changes in parameters immediately before and 14 days after insertion of a V-P shunt and before and after revision of a malfunctioning shunt were compared. Further, to clarify the clinical significance, in infantile hydrocephalus, of changes in bio-mechanical parameters, measurement results also were compared with the outcome of V-P shunts by assessing changeg in pre-and post- operative reduction in size of the frontal horn of the lateral ventricles (frontal horn index ; FHI), and also by Watanabe's method of neurological evaluation.
Among 7 infants whose Ro and Abs prior to shunting were abnormally high when compared with normal values reported by other investigators, values such as FHI, Ro and Abs tended to return, after the V-P shunt insertion, toward normal values in association with marked improvement of neurological status. The results appear to indicate that high Ro and Abs values recorded prior to surgery are factors predicting good functional outcome of a hydrocephalic infant after V-P shunt insertion. It should be noted, however, that in 3 out of the 7 cases, both preoperative and postoperative PVI values were found to be higher than the predicted PVI values reported by Shapiro. We speculate that, in such cases, intracranial compliance may have under-gone an irreversible change due to a degenerative change in the brain substance secondary to progressing hydrocephalus. Based on literary investigation in regard to this matter, we gained the impression that there exists an indication for a V-P shunt in these cases, although further investigation is required.
