Artikel
The role of the craniospinal compliance with shunt indication
Die Rolle der kraniospinalen Compliance bei der Shuntindikation
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Veröffentlicht: | 11. April 2007 |
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Gliederung
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Objective: Recently MRI examinations pointed at a central role of the Compliance with the hydrocephalus genesis, while an elevation of the resistance to outflow (ROF) is seemingly only an epiphenomenon of a reduced compliance. The objective of this prospective study was to elaborate whether this new sight of the hydrocephalus pathophysiology may be proven with clinical data.
Methods: 180 patients with chronic hydrocephalus of various origins were examined. A dynamic infusion test, - a variant of a constant-flow infusion test which provides the ROF as well as the Pressure Volume Index (PVI) -, was performed in all patients, but was not used for shunt indication. The shunt indication was based on long-term ICP monitoring. 125 patients were shunted using gravitational valves. The follow-up was 4.6 1.8 years. Statistics: Spearman-, Kruskal-Wallis-, Wilcoxen-U-test.
Results: ROF alone had a positive predictive value (PPV) of 75% and a negative predictive value (NPV) of 40%, a sensitivity of 96% with a specificity of 7% at a critical value of 13 mmHg/ml x min. With a critical value of 18 mmHg/ml x min the NPV and sensitivity became worse, the increase of the PPV minimal and the specificity (26%) was clinically irrelevant. Similar to an isolated assessment of the PVI independent of different assumed critical value (22ml/30ml), the PPV and, - with a critical value of 30ml -, the sensitivity were in an acceptable clinical range, but specificity and NPV were unacceptable from a clinical viewpoint. Only a combined assessment and a logical “OR” combination of both values at a critical value of the PVI of 30ml and of the ROF of 13mmHg/ml x min provided clinically satisfying predictive values: sensitivity =97%, specificity =88%, PPV=80%, NPV=60%.
Conclusions: The results suggest that the recent neuroradiological idea of the hydrocephalus pathophysiology should be correct, because a combined assessment of both PVI and ROF provides the best prediction for successful shunting.