Abstract
Shunt function tests were carried out 52 times in 32 cases of suspected malfunction of ventriculoperitoneal or ventriculoatrial shunt. Shunt function tests consisted of radioisotope (RI) study (flow study and shuntgraphy), CSF pressure measurement, and infusion test. The first was performed in all cases, the second in half, and the last in eight.
In the majority of the cases it was not enough to evaluate the shunt function by RI study alone as about 45% of the 21 cases which showed an abnormal flow pattern and abnormal shuntgraphy were found either by surgery or infusion test to actually have patent shunt systems. Such cases were regarded as false positive. All of the three cases which showed abnormal delayed flow pattern and high CSF pressure (above 150 mmH2O) were found by surgery to have shunt blockage. In addition to RI study, measurement of CSF pressure in the valve was necessary to correctly evaluate shunt functioning. Nine cases which showed delayed flow pattern and low or normal CSF pressure were classified by surgery and/or infusion test into two groups, i.e. the shunt-obstructed group (3 cases), and the shunt-patent group (6 cases). As the opening pressure of the shunt system was revealed by the infusion test, this test was very important in evaluating shunt patency for these cases.
