CO 2 as an engine for neurofluid flow: Exploring the coupling between vascular reactivity, brain clearance, and changes in tissue properties.

Elisabeth C van der Voort, Yunjie Tong, Eva E van Grinsven, Jaco J M Zwanenburg, Marielle E P Philippens, Alex A Bhogal

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The brain relies on an effective clearance mechanism to remove metabolic waste products for the maintenance of homeostasis. Recent studies have focused on elucidating the forces that drive the motion of cerebrospinal fluid (CSF), responsible for removal of these waste products. We demonstrate that vascular responses evoked using controlled manipulations of partial pressure of carbon dioxide (PaCO 2 ) levels, serve as an endogenous driver of CSF clearance from the brain. To demonstrate this, we retrospectively surveyed our database, which consists of brain metastases patients from whom blood oxygen level-dependent (BOLD) images were acquired during targeted hypercapnic and hyperoxic respiratory challenges. We observed a correlation between CSF inflow signal around the fourth ventricle and CO 2 -induced changes in cerebral blood volume. By contrast, no inflow signal was observed in response to the nonvasoactive hyperoxic stimulus, validating our measurements. Moreover, our results establish a link between the rate of the hemodynamic response (to elevated PaCO 2 ) and peritumoral edema load, which we suspect may affect CSF flow, consequently having implications for brain clearance. Our expanded perspective on the factors involved in neurofluid flow underscores the importance of considering both cerebrovascular responses, as well as the brain mechanical properties, when evaluating CSF dynamics in the context of disease processes.

Original languageEnglish
Article numbere5126
JournalNMR in Biomedicine
Volume37
Issue number8
Early online date25 Feb 2024
DOIs
Publication statusPublished - Aug 2024

Keywords

  • peritumoral edema
  • BOLD MRI
  • cerebral blood volume
  • cerebrospinal fluid
  • cerebrovascular reactivity

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