Nocturnal Hypoxemia Is Associated with White Matter Hyperintensities in Patients with a Minor Stroke or Transient Ischemic Attack

Study Objectives: Obstructive sleep apnea (OSA) is a risk factor for stroke, which is modulated by accompanying nocturnal hypoxemia. White matter hyperintensities (WMH) share many of the same risk factors as stroke. The purpose of this study was to investigate whether OSA and nocturnal hypoxemia are associated with white matter disease in patients with minor stroke and transient ischemic attack. Methods: Patients with minor stroke or TIA were recruited. Level 3 diagnostic sleep testing was used to diagnose OSA and quantify nocturnal hypoxemia. Significant OSA was defined as respiratory disturbance index >= 15, and nocturnal hypoxemia was defined as oxyhemoglobin saturation < 90% for >= 12% of total monitoring time. WMH were assessed and quantified on FLAIR MRI. The volume of WMH was compared between those with and without significant OSA and between those with and without nocturnal hypoxemia. Results: One hundred nine patients were included. Thirty-four (31%) had OSA and 37 (34%) had nocturnal hypoxemia. Total WMH volume was significantly greater in the OSA than in the non-OSA groups (p = 0.04). WMH volume was also significantly higher in the hypoxic than the non-hypoxic groups (p = 0.001). Mutivariable analysis with adjustment for age, hypertension, and diabetes showed that nocturnal hypoxemia was independently associated with WMH volume (p = 0.03) but OSA was not (p = 0.29). Conclusions: We conclude that nocturnal hypoxemia, predominantly related to OSA, is independently associated with WMH in patients who present with minor ischemic stroke and TIA and may contribute to its pathogenesis.