BACKGROUND: Hydrocephalus results from inadequate passage of cerebrospinal fluid (CSF) from its point of production within the cerebral ventricles to its point of absorption into systemic circulation. Aims: The objective of this study was to investigate the disorders of CSF absorption by arachnoid villi during the different phases of hydrocephalus. MATERIALS AND METHODS: Silicone oil was injected into the fourth ventricle of 15 canines as an experimental group. Saline solution (0.9% NaCl) was injected in another nine canines as a control group. In order to block CSF transport through the cribriform plate, an external ethmoidectomy was performed in five dogs from experimental group and three dogs from control group at three days (acute stage), two weeks (sub-acute stage), and 12 weeks (chronic stage) respectively. Tritiated water was injected into the canines' cortical subarachnoid space and blood levels were measured at intervals of 1 h, 4 h, 8 h, 16 h and 48 h respectively. Time-concentration curve of tritiated water was drafted. The area under the curve (AUC) was calculated for variance analysis and t-testing. Results: In the chronic group, the tritiated water concentration rose slowly to a peak at 16 h. It was significantly lower than other groups at 1h, 4h, 8h and 16 h, but was higher than other groups at 48 h. Analysis of the AUC showed significant differences among all the groups (P<0.01). There were no significant differences in the AUC between control groups, the acute group, and the sub-acute group (P>0.05); however, the AUC of the chronic group was significantly lower than other groups (P<0.05). CONCLUSIONS: The CSF absorption ability of arachnoid villi is significantly damaged in a long-term state of hydrocephalus.
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