Anesthetics Modulate Cerebrospinal Fluid Efflux Pathways in Mice by Changing the Perineural and Perivascular Spaces

Motivation: Anesthesia could affect neurofluid circulation, but its impact on cerebrospinal fluid (CSF) drainage remains unclear. Goal(s): We aimed to clarify the detailed CSF efflux pathways from the brain to the periphery under different anesthetics. Approach: We performed dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and structure MRIs in mice under three anesthesia protocols (isoflurane alone (ISO), isoflurane plus dexmedetomidine (DEXI), and ketamine/xylazine (K/X)). Results: ISO significantly accelerates CSF outflow via the nasopharyngeal lymphatic plexus but slows it through the paraspinal space compared to DEXI and K/X. For the jugular ganglion, K/X significantly retards CSF outflow relative to DEXI and ISO. Impact: Different anesthesia protocols could affect the CSF outflow pathways, and the CSF volume changes under different anesthesia protocols are the potential mechanism.