Work

A Lumped Parameter Model Suggests That Infusion Studies Overestimate the Cerebrospinal Fluid Outflow Resistance in Normal Pressure Hydrocephalus

Year: 2024

Type: article

Abstract: Background/objectives: Cerebrospinal infusion studies indicate the cerebrospinal fluid outflow resistance (Rout) is elevated in normal pressure hydrocephalus (NPH). These studies assume the CSF formation rate (CSFfr) does not vary during the infusion. If the CSFfr were to increase during the infusion, then the Rout would be overestimated. Previous estimates of the CSFfr in NPH sug-gested a low figure. More recent estimates of the CSFfr suggest it is increased, indicating it probably varies with measurement technique. This would bring the estimation of Rout into doubt. A previous paper using a lumped parameter model suggested the CSFfr could vary with the capillary transmural pressure (TMP) in this disease, suggesting a possible solution to this problem. The current study investigates the possibility that the intracranial pressure manipulation occurring during an infusion study may vary the capillary TMP and CSFfr. Methods: A lumped parameter model previously developed to describe the hydrodynamics of NPH was modified to investigate the effect of CSF pressure manipulation during infusion studies, to describe how the CSFfr could vary depending on the technique used. Results: The model indicates the capillary transmural pressure is normal in NPH and increases during an infusion study. CSF drainage at the end of an infusion study similarly increases the capillary TMP, and presumably the CSFfr by increasing the interstitial fluid production. Conclusions: The model suggests that infusion studies and draining CSF increases the CSFfr in NPH compared to earlier techniques. Allowing for the increase in CSFfr suggests infusion overestimates the Rout by between 23-33%.

Source: Brain Sciences

DOI: 10.3390/brainsci14121242

Authors: Grant Alexander Bateman, Alexander Robert Bateman

Institutions: John Hunter Hospital, University of Newcastle Australia, UNSW Sydney

Language: English

Topic: Cerebrospinal fluid and hydrocephalus

Subfield: Cellular and Molecular Neuroscience

Field: Neuroscience

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $2,501