Functional magnetic resonance imaging responses to expiratory loading in obstructive sleep apnea

• Published in: Respiratory physiology & neurobiology Vol. 138; no. 2; pp. 275 - 290
• Main Authors: Macey, P.M, Macey, K.E, Henderson, L.A, Alger, J.R, Frysinger, R.C, Woo, M.A, Yan-Go, F, Harper, R.M
• Format: Journal Article
• Language: English
• Published: Amsterdarm Elsevier B.V 14-11-2003; Elsevier
• Subjects: Adult; Biological and medical sciences; Blood Pressure; Brain Mapping; Case-Control Studies; Cluster Analysis; Disease, obstructive sleep apnea; Exhalation - physiology; Heart Rate; Humans; Magnetic Resonance Imaging; Male; Mammals, humans; Medical sciences; Methods, magnetic resonance imaging; Middle Aged; Non tumoral diseases; Otorhinolaryngology. Stomatology; Physical Stimulation; Respiration; Respiratory Mechanics; Sleep Apnea, Obstructive - physiopathology; Sleep, obstructive apnea, neural mechanisms; Time Factors; Upper airways, patency; Upper respiratory tract, upper alimentary tract, paranasal sinuses, salivary glands: diseases, semeiology; Methods, magnetic resonance imaging; Mammals, humans; Disease, obstructive sleep apnea; Sleep, obstructive apnea, neural mechanisms; Upper airways, patency; Human; obstructive apnea; Pathophysiology; Upper respiratory tract; Disease; obstructive sleep apnea; Mammals; magnetic resonance imaging; Sleep; Sleep disorder; Expiration; Nuclear magnetic resonance imaging; Obstruction; patency; Apnea; Sleep; humans; Methods; neural mechanisms; Upper airways; Sleep wake cycle; Respiration; Functional imaging
• ISSN: 1569-9048; 1878-1519
• DOI: 10.1016/j.resp.2003.09.002

Obstructive sleep apnea (OSA) is characterized by diminished upper airway muscle phasic and tonic activation during sleep, but enhanced activity during waking. We evaluated neural mechanisms underlying these patterns with functional magnetic resonance imaging procedures during baseline and expiratory loading conditions in nine medication-free OSA and 16 control subjects. Both groups developed similar expiratory loading pressures, but appropriate autonomic responses did not emerge in OSA cases. Reduced neural signals emerged in OSA cases within the frontal cortex, anterior cingulate, cerebellar dentate nucleus, dorsal pons, anterior insula and lentiform nuclei. Signal increases in OSA over control subjects developed in the dorsal midbrain, hippocampus, quadrangular cerebellar lobule, ventral midbrain and ventral pons. Fastigial nuclei and the amygdala showed substantially increased variability in OSA subjects. No group differences were found in the thalamus. OSA patients show aberrant responses in multiple brain areas and inappropriate cardiovascular responses to expiratory loading, perhaps as a consequence of previously-demonstrated limbic, cerebellar and motor area gray matter loss.