Biochemical Investigation of Normal Pressure Hydrocephalus in the Assessment of Shunt Effectiveness

Abstract

It is well known that, among patients of normal pressure hydrocephalus (NPH), there is a group in which a shunting procedure had no effect on improving clinical signs (shunt-ineffective group). To differentiate the shunt-effective group from the shunt-ineffective group, we performed measurements of cerebrospinal fluid (CSF) levels of uric acid (UA) and gamma-aminobutyric acid (GABA) in patients of NPH. We investigated the age-related CSF levels of UA and GABA in the normal subjects and compared them with those in the patients of NPH including the shunt-ineffective group and other related states, that is, multi-infarct dementia (MID) and patients with full recovery after subarachnoid hemorrhage (SAH) due to the ruptured aneurysm. In the normal subjects, CSF UA levels of second and over seventh decades were significantly higher than those of third, fourth, and fifth decades. On the other hand, CSF GABA levels of second and over seventh decades were significantly lower than those of the others. In the patients of MID, CSF UA levels were much higher and CSF GABA levels were much lower in comparison with the normal controls. These results suggested that, in the aged normal subjects, some degree of brain damage is responsible for high CSF UA levels and low CSF GABA levels. There was no difference in the values of CSF UA and GABA between normal subjects and the patients with full recovery after SAH. In the patients of NPH, CSF UA levels were low in general, while CSF GABA levels were all high. After the shunting operation, CSF UA and GABA levels became normal in the shunt-effective group.(ABSTRACT TRUNCATED AT 250 WORDS)