Comparison of ventricular steady-state infusion with bolus infusion and pressure recording for differentiating between arrested and non-arrested hydrocephalus

Abstract

In 6 years 26 adult patients with chronic communicating or non-communicating hydrocephalus underwent ventricular fluid pressure (VFP) recording, including intraventricular steady-state and bolus infusion tests. Patients were treated with a shunt when steady-state infusion yielded a csf outflow resistance (Rcsfs) greater than 10 mm Hg/ml/min; the success rate was 83%. The main purpose of the study was to compare Rcsfs with outflow resistance obtained by bolus infusions (Rcsfb), pressure-volume index (PVI) and VFP. Rcsfs was higher than Rcsfb, particularly when resistance was high and the degree of disturbance of csf dynamics was reflected by Rcsfs better than by Rcsfb. The PVI showed a roughly inverse relationship with the Rcsfs but was not helpful in differentiating arrested from non-arrested hydrocephalus. Rcsfs and VFP correlated better than expected. A high Rcsfs was associated with an elevated VFP and a normal Rcsfs with a normal VFP. VFP only varied when Rcsfs exhibited a mild to moderate increase. It is concluded that steady-state infusion remains the most reliable method for the prediction of the result of shunting. We recommend shunting when Rcsfs is greater than 10 mm Hg/ml/min. Bolus infusions provide valuable data on brain elastance and additional information on csf outflow resistance. VFP recording is certainly worthwhile because infusion tests can be omitted when VFP is clearly elevated and useful information is obtained when Rcsf is borderline.