White matter alterations in patients with obstructive sleep apnea: a systematic review of diffusion MRI studies

Background: Obstructive sleep apnea (OSA) is a common sleep disorder, which causes wide range of neurological and psychiatric symptoms. Several studies demonstrated structural and functional brain alterations using magnetic resonance imaging (MRI) techniques. Recently, diffusion-based brain MRI studies in patients with OSA showed changes in diffusion measures that represent various impairments of white matter (WM) integrity. The various finding may be due to diffusion indices employed for detection of neural impairment at the microstructural level, phase of the disease and the goals of studies. Objectives: We aimed to identify a common abnormal WM pattern across the previous studies. Methods: We reviewed related literature in EMBASE, Scopus and PubMed databases and identified 13 studies that meet our selection criteria. Results: The current data pointed to WM integrity changes in corpus callosum, cingulate cortex, corti-cospinal tract, insular cortex, basal ganglia, and limbic sites. These regions mainly contribute in mood, autonomic and cardiovascular regulation. Conclusion: Widespread use of diffusion magnetic resonance imaging (dMRI) parameters provides insight into the pathophysiology of OSA, stage of the disease and planning appropriate treatments in future. (c) 2020 Elsevier B.V. All rights reserved.