Abstract
Abstract
Introduction
Disproportionately enlarged subarachnoid space hydrocephalus (DESH) and resistance to CSF outflow (R
out
) are two of the most consistent diagnostic and prognostic markers in normal pressure hydrocephalus, yet it remains unclear whether they reflect a common pathophysiological process. A plausible link is that tightness of the high convexities adjacent to the superior sagittal sinus (SSS), the principal CSF outflow region, compromises CSF drainage and thereby increases R
out
. To test this hypothesis, we investigated the association between parasagittal high-convexity CSF volume near the SSS and R
out
in subjects undergoing MRI and CSF infusion testing.
Methods
We conducted a retrospective study of 621 individuals (581 with ventriculomegaly and 40 without), investigated with CSF infusion testing and brain MRI. Parasagittal high convexity CSF volumes were quantified using a semi-automated segmentation approach, focusing on anatomically defined high convexity regions. R
out
was derived from lumbar CSF infusion testing using standardised protocols. Associations between parasagittal CSF volume and R
out
were evaluated using correlation analyses, with additional assessment of demographic and structural confounders.
Results
An inverse relationship was observed between parasagittal high convexity CSF volume and R
out
(N = 621, Spearman Rho =-0.42, p Conclusions
A localised relationship exists between parasagittal high-convexity morphology and resistance to CSF outflow. The regional specificity of this association suggests that DESH and R
out
may reflect a shared pathophysiological mechanism, which becomes apparent only when examined at anatomically strategic sites along the CSF outflow pathway.