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Brain white matter changes in CPAP‐treated obstructive sleep apnea patients with residual sleepiness
Author(s) -
Xiong Ying,
Zhou Xiaohong Joe,
Nisi Robyn A.,
Martin Kelly R.,
Karaman M. Muge,
Cai Kejia,
Weaver Terri E.
Publication year - 2017
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.25463
Subject(s) - fractional anisotropy , psychomotor vigilance task , obstructive sleep apnea , medicine , epworth sleepiness scale , white matter , diffusion mri , continuous positive airway pressure , somnolence , corpus callosum , nuclear medicine , polysomnography , magnetic resonance imaging , apnea , pathology , radiology , sleep deprivation , adverse effect , circadian rhythm
Purpose To investigate white matter (WM) structural alterations using diffusion tensor imaging (DTI) in obstructive sleep apnea (OSA) patients, with or without residual sleepiness, following adherent continuous positive airway pressure (CPAP) treatment. Possible quantitative relationships were explored between the DTI metrics and two clinical assessments of somnolence. Materials and Methods Twenty‐nine male patients (30–55 years old) with a confirmed diagnosis of OSA were recruited. The patients were treated with CPAP therapy only. The Psychomotor Vigilance Task (PVT) and Epworth Sleepiness Scale (ESS) were performed after CPAP treatment and additionally administered at the time of the magnetic resonance imaging (MRI) scan. Based on the PVT results, the patients were divided into a nonsleepy group (lapses ≤5) and a sleepy group (lapses >5). DTI was performed at 3T, followed by an analysis using tract‐based spatial statistics (TBSS) to investigate the differences in fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (λ 1 ), and radial diffusivity (λ 23 ) between the two groups. Results A higher MD ( P < 0.05) was observed in the sleepy group than the nonsleepy group in the whole‐brain TBSS analysis in the WM. The increased MD (17.8% of the fiber tracts; P < 0.05) was caused primarily by an elevated λ 23 . Axial diffusivity (λ 1 ) exhibited no significant difference ( P > 0.17). The alterations in FA or MD of individual fiber tracts occurred mainly in the internal/external capsule, corona radiata, corpus callosum, and sagittal stratum regions. The FA and MD values correlated with the PVT and ESS assessments from all patients (R ≥ 0.517, P < 0.05). Conclusion Global and regional WM alterations, as revealed by DTI, can be a possible mechanism to explain why OSA patients with high levels of CPAP use can have differing responses to treatment. Compromised myelin sheath, indicated by increased radial diffusivity, can be involved in the underlying WM changes. Evidence level : 1 J. MAGN. RESON. IMAGING 2017;45:1371–1378