Chapter 35 - Neuroimaging of autonomic dysfunction and ventilatory control in obstructive sleep apnea

Summary

This chapter summarizes functional neuroimaging findings from a variety of autonomic and respiratory challenges the author's group has performed in people with obstructive sleep apnea (OSA). A cold pressor challenge involves exposing a body region to a cold stimulus, which elicits a sympathetic activation that leads to a vasoconstriction and a blood pressure increase. The Valsalva maneuver is an autonomic challenge involving straining by forceful expiration against a closed glottis, and the tasks elicit a sequence of blood pressure and heart rate responses mediated through a coordination of autonomic regulatory activity. The inspiratory and expiratory loading tasks led to a degree of dyspnea in most subjects, as did the Valsalva maneuver to a lesser extent. An abnormal pattern in OSA is altered insular functional neuroanatomy in response to autonomic stimuli, as seen with higher-resolution functional magnetic resonance imaging (fMRI) in response to the Valsalva maneuver.