Inspiratory loading elicits aberrant fMRI signal changes in obstructive sleep apnea

• Published in: Respiratory physiology & neurobiology Vol. 151; no. 1; pp. 44 - 60
• Main Authors: Macey, Katherine E., Macey, Paul M., Woo, Mary A., Henderson, Luke A., Frysinger, Robert C., Harper, Rebecca K., Alger, Jeffry R., Yan-Go, Frisca, Harper, Ronald M.
• Format: Journal Article
• Language: English
• Published: Amsterdarm Elsevier B.V 28.03.2006; Elsevier
• Subjects: Adult; Autonomic; Biological and medical sciences; Blood Pressure - physiology; Brain - blood supply; Brain - physiopathology; Brain Mapping; Broca's area; Cerebellum; Cluster Analysis; Disorders of higher nervous function. Focal brain diseases. Central vestibular syndrome and deafness. Brain stem syndromes; Dyspnea; Electroencephalography; Heart Rate - physiology; Humans; Image Processing, Computer-Assisted - methods; Inhalation - physiology; Limbic; Magnetic Resonance Imaging - methods; Male; Medical sciences; Middle Aged; Nervous system (semeiology, syndromes); Neurology; Oxygen - blood; Sleep Apnea, Obstructive - physiopathology; Time Factors; Cerebellum; Broca's area; Dyspnea; Limbic; Autonomic; Human; Inspiration; Nervous system diseases; Central nervous system; Sleep disorder; Respiratory system; Motor control; Nuclear magnetic resonance imaging; Obstruction; Encephalon; Apnea; Sleep; Autonomic nervous system; Sleep wake cycle; Respiration; Neurological disorder; Inspiratory resistive load; Functional imaging
• ISSN: 1569-9048; 1878-1519
• DOI: 10.1016/j.resp.2005.05.024

We hypothesized that neural processes mediating deficient sensory and autonomic regulatory mechanisms in obstructive sleep apnea (OSA) would be revealed by responses to inspiratory loading in brain regions regulating sensory and motor control. Functional magnetic resonance imaging (fMRI) signals and physiologic changes were assessed during baseline and inspiratory loading in 7 OSA patients and 11 controls, all male and medication-free. Heart rate increases to inspiratory loading began earlier and load pressures were achieved later in OSA patients. Comparable fMRI changes emerged in multiple brain regions in both groups, including limbic, cerebellar, midbrain, and primary motor cortex. However, in OSA subjects, altered signals appeared in primary sensory thalamus and sensory cortex, supplementary motor cortex, cerebellar cortex and deep nuclei, cingulate, medial temporal, and insular cortices, right hippocampus, and midbrain. Signal delays occurred in basal ganglia. We conclude that areas mediating sensory and autonomic processes, and motor timing, are affected in OSA; many of these areas overlap regions of previously demonstrated gray matter loss.