Impact of Shunt Placement on CSF Dynamics.

Background: CSF dynamics are disturbed in chronic hydrocephalus (NPH). We hypothesise that these alterations reflect a disturbance of intracranial compliance. The aim of our study is to investigate the variations in intracranial hydrodynamics in NPH after ventricular shunt surgery.
Patients and Method: We included 14 patients with definite NPH. All patients improved after ventriculoperitoneal shunting. The patients underwent an analysis of intracranial haemodynamics by phase-contrast MRI (pcMRI) preoperatively, at 6 months postoperatively, and at 1 year postoperatively. We analysed the dynamics of intraventricular CSF at the level of the aqueduct of Sylvius (SV _AQU ) and CSF at the level of the high cervical subarachnoid spaces (SV _CERV ). We calculated the ratio between SV _AQU and SV _CERV , called CSF _RATIO , which reflects the participation of intraventricular pulsatility in overall intracranial CSF pulsatility.
Results: SV _AQU significantly ( p = 0.003) decreased from 240 ± 114 μL/cc to 214 ± 157 μL/cc 6 months after shunt placement. Six months after shunt placement, SV _CERV significantly ( p = 0.007) decreased from 627 ± 229 μL/cc to 557 ± 234 μL/cc. Twelve months after shunt placement, SV _CERV continued to significantly ( p = 0.001) decrease to 496 ± 234 μL/cc. CSF _RATIO was not changed by surgery.
Conclusions: CSF dynamics are altered by shunt placement and might be a useful marker of the shunt's effectiveness-especially if pressure values start to rise again. The detection of changes in CSF dynamics would require a reference postoperative pcMRI measurement for each patient.
Competing Interests: The authors declare no conflicts of interest.