Sleep architectural dysfunction and undiagnosed obstructive sleep apnea after chronic ischemic stroke

Abstract Objective/Background Sleep-wake dysfunction is bidirectionally associated with the incidence and evolution of acute stroke. It remains unclear whether sleep disturbances are transient post-stroke or are potentially enduring sequelae in chronic stroke. Here, we characterize sleep architectural dysfunction, sleep-respiratory parameters, and hemispheric sleep in ischemic stroke patients in the chronic recovery phase compared to healthy controls. Patients/Methods Radiologically confirmed ischemic stroke patients (n=28) and matched control participants (n=16) were tested with ambulatory polysomnography, bi-hemispheric sleep EEG, and demographic, stroke-severity, mood, and sleep-circadian questionnaires. Results Twenty-eight stroke patients (22 men; mean age=69.61±7.4 years) were cross-sectionally evaluated 4.1±0.9 years after mild-moderate ischemic stroke (baseline NIHSS: 3.0±2.0). Fifty-seven percent of stroke patients (n=16) exhibited undiagnosed moderate-to-severe obstructive sleep apnea (apnea-hypopnea index >15). Despite no difference in total sleep or wake after sleep onset, stroke patients had reduced slow-wave sleep time (66.25 min vs 99.26 min, p=0.02), increased time in non-rapid-eye-movement (NREM) stages 1-2 (NREM-1: 48.43 vs 28.95, p=0.03; NREM-2: 142.61 vs 115.87, p=0.02), and a higher arousal index (21.46 vs 14.43, p=0.03) when compared to controls. Controlling for sleep apnea severity did not attenuate the magnitude of sleep architectural differences between groups (NREM 1-3=ηp2>0.07). We observed no differences in ipsilesionally versus contralesionally scored sleep architecture. Conclusions Fifty-seven percent of chronic stroke patients had undiagnosed moderate-severe obstructive sleep apnea and reduced slow-wave sleep with potentially compensatory increases in NREM 1-2 sleep relative to controls. Formal sleep studies are warranted after stroke, even in the absence of self-reported history of sleep-wake pathology.