Brain white matter lesions and postoperative cognitive dysfunction: a review

Area of Science:

• Neuroscience
• Gerontology
• Anesthesiology

Background:

• Postoperative cognitive dysfunction (POCD) is a significant complication, particularly in aging patients.
• Current understanding implicates neuroinflammation and neurodegeneration (amyloid-beta, tau) in POCD pathophysiology.
• White matter lesions (WML), linked to chronic cerebral hypoperfusion and cognitive decline, are increasingly recognized as a POCD risk factor.

Purpose of the Study:

• To investigate the hypothesis that perioperative vital sign changes contributing to reduced cerebral blood flow may exacerbate POCD in patients with pre-existing WML.
• To explore an additional mechanism for POCD beyond neuroinflammation and neurodegeneration.

Main Methods:

• Utilized a rat model of chronic cerebral hypoperfusion, inducing global WML without neuronal damage, analogous to vascular dementia in the elderly.
• Previous studies in this model demonstrated neuronal damage from hypocapnia or hypotension.
• The current hypothesis extends these findings to human POCD in WML patients.

Main Results:

• The study builds upon prior findings showing that hypocapnia or hypotension can cause neuronal damage in specific brain regions (caudoputamen, hippocampus) in a rat model.
• This model exhibits global cerebral WML, mirroring conditions seen in elderly individuals with vascular dementia.
• The research highlights the critical role of cerebral blood flow in the context of WML and POCD.

Conclusions:

• Perioperative vital sign fluctuations reducing cerebral blood flow may represent a significant, previously underappreciated mechanism contributing to POCD.
• This mechanism is particularly relevant for patients with existing white matter lesions (WML) and compromised cerebral perfusion.
• Further research is warranted to validate these findings and explore therapeutic interventions targeting perioperative hemodynamics in at-risk populations.