Cerebrospinal fluid dynamics in chronic obstructive hydrocephalus before and after successful endoscopic third ventriculostomy

OBJECTIVE: to describe cerebrospinal fluid dynamics in chronic obstructive hydrocephalus before and after successful endoscopic third ventriculostomy (ETV). MATERIALS AND METHODS: 8 patients (7-21 years old) with chronic obstructive hydrocephalus due to tectal plate glioma were investigated before and after successful ETV. Apart from clinical and MRI assessment ICP-monitoring (ICP0) and intraventricular infusion studies were performed as well as upright ICP (ICP90) was investigated preoperatively and on 1st and 7th postoperative days (POD). Dynamic changes were assessed using Wilcoxon matched pairs test. RESULTS: There were no complications. MRI demonstrated functional ventriculostomy and reduced ventricle size in all cases. At follow-up all ETV's were considered clinically successful. By the 7th POD ICP0 showed tendency to reduction (p = 0.07) and ICP90 reduced significantly (p = 0.02). Significant reduction of Rcsf was evident by the 1st POD (p = 0.03) and was maintained until the 7th POD (p = 0.02). Elastance coefficient and compliance (as measured during infusion study) didn't change significantly in relation to ETV. In all the 3 cases when computerized ICP monitoring was used reduction of ICP pulse amplitude (AMP), AMP/ICP slope and RAP was noted by the 7-th POD which most probably reflects reduction of intracranial elastance. CONCLUSION: Effect of ETV in chronic obstructive hydrocephalus cannot be explained exclusively by its influence on ICP0; clinical improvement can possibly be attributed also to normalization of ICP90 and Rcsf, reduction of intracranial elastance and increase of cerebral blood flow reserve capabilities. There may be a pathophysiological ground for ETV in obstructive hydrocephalus with normal ICP.