Global and Regional Brain Non-Gaussian Diffusion Changes in Newly Diagnosed Patients with Obstructive Sleep Apnea.
OBJECTIVE
Obstructive sleep apnea (OSA) patients show brain structural injury and functional deficits in autonomic, affective, and cognitive regulatory sites, as revealed by mean diffusivity (MD) and other imaging procedures. The time course and nature of gray and white matter injury can be revealed in more detail with mean kurtosis (MK) procedures, which can differentiate acute from chronic injury, and better show extent of damage over MD procedures. Our objective was to examine global and regional MK changes in newly diagnosed OSA, relative to control subjects.


METHODS
Two diffusion kurtosis image series were collected from 22 recently-diagnosed, treatment-naïve OSA and 26 control subjects using a 3.0-Tesla MRI scanner. MK maps were generated, normalized to a common space, smoothed, and compared voxel-by-voxel between groups using analysis of covariance (covariates; age, sex).


RESULTS
No age or sex differences appeared, but body mass index, sleep, neuropsychologic, and cognitive scores significantly differed between groups. MK values were significantly increased globally in OSA over controls, and in multiple localized sites, including the basal forebrain, extending to the hypothalamus, hippocampus, thalamus, insular cortices, basal ganglia, limbic regions, cerebellar areas, parietal cortices, ventral temporal lobe, ventrolateral medulla, and midline pons. Multiple sites, including the insular cortices, ventrolateral medulla, and midline pons showed more injury over previously identified damage with MD procedures, with damage often lateralized.


CONCLUSIONS
Global mean kurtosis values are significantly increased in obstructive sleep apnea (OSA), suggesting acute tissue injury, and these changes are principally localized in critical sites mediating deficient functions in the condition. The mechanisms for injury likely include altered perfusion and hypoxemia-induced processes, leading to acute tissue changes in recently diagnosed OSA.
Department of Anesthesiology, University of California at Los Angeles. Los Angeles, CA.
Sudhakar
S
Tummala
Department of Anesthesiology, University of California at Los Angeles. Los Angeles, CA.
Jose
J
Palomares
Department of Medicine, University of California at Los Angeles. Los Angeles, CA.
Daniel W
DW
Kang
Department of Anesthesiology, University of California at Los Angeles. Los Angeles, CA.
Bumhee
B
Park
UCLA School of Nursing, University of California at Los Angeles. Los Angeles, CA.
Mary A
MA
Woo
Department of Neurobiology, University of California at Los Angeles. Los Angeles, CA.|The Brain Research Institute, University of California at Los Angeles. Los Angeles, CA.
Ronald M
RM
Harper
Department of Anesthesiology, University of California at Los Angeles. Los Angeles, CA.|The Brain Research Institute, University of California at Los Angeles. Los Angeles, CA.|Department of Radiological Sciences, University of California at Los Angeles. Los Angeles, CA.|Department of Bioengineering, University of California at Los Angeles. Los Angeles, CA.
Rajesh
R
Kumar
D015992:Body Mass Index; D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D003071:Cognition; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D012890:Sleep; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000473:pathology* / Q000503:physiopathology*
acute injury; diffusion kurtosis imaging; hypoxia; obstructive sleep apnea