Case control study of cerebrovascular damage defined by magnetic resonanceimaging in patients with OSA and normal matched control subjects

Study Objectives: To assess whether MRI detectable evidence of silent cereb rovascular disease is more prevalent in patients with obstructive sleep apn ea (OSA) when compared to carefully matched control subjects. Design and Setting: Case-control study of patients with OSA attending a spe cialist sleep clinic and matched control subjects drawn from the normal com munity. Participants: Forty-five sleep clinic patients with moderate to severe OSA and excessive daytime sleepiness, matched to 45 control subjects without ex cessive sleepiness or evidence of OSA on a sleep study. Matched variables i ncluded age, body mass index (BMI), alcohol and cigarette consumption, trea ted hypertension, and ischaemic heart disease. Interventions: N/A Measurements and Results: All subjects underwent 24-hour ambulatory blood p ressure recordings (before treatment in OSA patients) and sagittal T1, axia l T2, and coronal dual echo cerebral MRI imaging to detect clinically silen t abnormalities related to hypertensive cerebrovascular disease; areas of h igh signal foci in deep white matter (DWM), lacunae, and periventricular hy perintensity. Lacunae/high signal foci in DWM and/or periventricular hyperi ntensity were present in 15 (33%) OSA subjects and 16 (35%) controls, despi te significant increases in mean daytime diastolic blood pressure (4.6mmHg, p<0.05), and both nighttime diastolic (7.2mmHg, p<0.001) and systolic bloo d pressures (9.2mmHg, p<0.05) in OSA subjects. These data exclude more than a 17% excess prevalence of MRI detected minor cerebrovascular disease in t he OSA patients, with 95% confidence. Conclusions: Sub-clinical cerebrovascular disease is prevalent in both clin ic patients with OSA and their matched control subjects. Despite the increa sed arterial blood pressures, there is, however, no apparent excess of MRI- evident subclinical cerebrovascular disease in patients with OSA compared t o appropriately matched control subjects.