Early Detection of Brain White Matter Damage in Patients with Severe OSA

Abstract

Objectives: Obstructive sleep apnea (OSA) is commonly associated with neuropsychological sequelae, presumably induced by brain injury resulting from intermittent hypoxia. Newer magnetic resonance imaging modalities allow a more accurate examination of fiber integrity of the brain microstructure. Diffusion tensor imaging (DTI) is sensitive to the microstructure of brain tissue. This study is to evaluate the integrity of white matter in OSA patients with DTI. Methods: The subjects underwent a polysomnography study to determine the severity of OSA and DTI scans to detect fiber integrity. Fractional anisotropy (FA), a measure of fiber integrity, was derived from the diffusion tensor, resulting in a whole brain FA map. The FA maps were compared using voxel-based statistics to determine differences between severe OSA and control groups, with age and sex as a covariate. The correlation between FA value and clinical severity was performed. Results: Twenty patients with severe OSA (apnea/hypopnea index, AHI >30/h) and 14 sex- and age-matched healthy volunteers (AHI <5/h) were recruited. The exploratory group-wise comparison showed that severe OSA patients exhibited reduced FA values in several brain clusters, including the white matter underlying amygdala, superior temporal gyrus, inferior parietal lobule, precuneus, postcentral gyrus, anterior cingulate gyrus, claustrum, insula, basal ganglia, tapetum, and cerebral peduncle compared with controls. The FA values were negatively correlated with clinical disease severity. Conclusions: This study indicates that OSA patients have impaired white matter integrity in vulnerable regions, associated with increased disease severity. The findings likely represent the pathological process of the brain in OSA patients.