Impaired Macroscopic Cerebrospinal Fluid Flow by Sevoflurane in Humans during and after Anesthesia

Area of Science:

• Neuroscience
• Anesthesiology
• Physiology

Background:

• The glymphatic system model posits that cerebrospinal fluid (CSF) flow drives brain waste clearance.
• Glymphatic transport is enhanced during sleep, but anesthetic effects in humans remain poorly understood.
• Existing animal research shows varied anesthetic impacts on CSF flow, necessitating human studies.

Purpose of the Study:

• To investigate the impact of sevoflurane anesthesia on human CSF flow.
• To assess CSF flow and brain connectivity changes during and after sevoflurane administration.

Main Methods:

• Functional magnetic resonance imaging (fMRI) in 16 healthy subjects before, during, and after sevoflurane anesthesia.
• CSF flow indexed by fMRI signal fluctuations in basal cisternae.
• Global gray matter functional connectivity and gray matter-CSF coupling measured using fMRI signal correlations.

Main Results:

• Sevoflurane decreased cisternal CSF flow amplitude.
• Anesthesia disrupted global cortical blood oxygenation level-dependent (BOLD) and functional connectivity.
• Impaired connectivity and gray matter-CSF coupling persisted post-anesthesia.

Conclusions:

• Sevoflurane anesthesia impairs macroscopic CSF flow by disrupting global brain activity.
• These impairments linger after regaining consciousness.
• Further research is needed to link these findings to postoperative neurocognitive symptoms, especially in vulnerable populations.