Impaired cerebrovascular reactivity in obstructive sleep apnea: a case-control study

Area of Science:

• Neurology
• Cardiovascular Science
• Sleep Medicine

Background:

• Obstructive sleep apnea (OSA) is a known stroke risk factor.
• Cerebrovascular hemodynamic changes during apnea are not well understood.
• Hypercapnia during apnea may compromise cerebral blood flow (CBF) due to reduced CO2 vasodilatory response.

Purpose of the Study:

• To investigate the effect of the apnea-hypopnea index (AHI) on cerebrovascular response to CO2.
• To evaluate if OSA severity influences the brain's ability to regulate blood flow during changes in CO2 levels.

Main Methods:

• Compared 11 OSA patients with 16 healthy controls.
• Utilized arterial spin labeling (ASL) and BOLD MRI to assess cerebrovascular responses.
• Included hypercapnia and breath-holding tasks to measure CO2 reactivity.

Main Results:

• CBF response to CO2 was significantly impaired with increasing AHI, indicating reduced reactivity in more severe OSA.
• OSA patients showed a significantly reduced CO2 response in white matter CBF compared to controls.
• No significant differences were found in BOLD response to CO2 or breath-holding tasks between groups.

Conclusions:

• Cerebrovascular CO2 reactivity, measured by CBF, is impaired with increasing OSA severity.
• These findings contribute to understanding the link between OSA and increased stroke risk.