Cerebrovascular reactivity in obstructive sleep apnea: A systematic review using BOLD MRI

Area of Science:

• Neuroimaging
• Cardiovascular Science
• Sleep Medicine

Background:

• Obstructive sleep apnea (OSA) is a significant risk factor for stroke and cognitive decline.
• The impact of OSA on cerebrovascular reactivity (CVR) and the utility of BOLD MRI in assessing these changes remain unclear.

Purpose of the Study:

• To systematically synthesize BOLD MRI studies of CVR in adults with OSA.
• To resolve discrepancies regarding OSA's effects on CVR and BOLD MRI's consistency.

Main Methods:

• Searched five databases for human studies on BOLD CVR in OSA.
• Included studies with hypercapnia- or breath-hold-evoked BOLD CVR.
• Performed risk-of-bias assessment and random-effects pooling of PETCO2-referenced data.

Main Results:

• Six studies met inclusion criteria (4 case-control, 2 CPAP trials).
• Pooled data showed higher global CVR in OSA patients than controls.
• Alternative metrics indicated regionally reduced reactivity, highlighting dissociations between BOLD and perfusion CVR.

Conclusions:

• BOLD CVR in OSA is heterogeneous, not uniformly reduced.
• PETCO2-referenced BOLD MRI is a marker of cerebrovascular dysregulation in OSA.
• This provides a framework for CVR standardization, risk stratification, and CPAP response monitoring.