Objective: To analyze the prevalence of sleep-disordered breathing in patients with acute ischemic stroke and the influence of the characteristics of the stroke and time of onset.
Patients and methods: Polysomnography was performed with an Autoset Portable Plus II in 139 patients within 72 hours of the onset of symptoms. Standard polysomnographic data, signs and symptoms related with sleep apnea-hypopnea syndrome (SAHS) prior to ischemic stroke, vascular risk factors, and characteristics and onset time (day/night) of ischemic stroke were recorded. The polysomnographic data were compared with results published for subjects of a similar age in the general population.
Results: The mean age was 73.6 (SD 11.1) years (59% of the patients were men). Prior to the stroke, 64.7% of the patients snored, 21.6% presented repetitive sleep apneas, and 35.6% had daytime sleepiness. The mean apnea-hypopnea index (AHI) was 29.1 (17.9) episodes/hour, the obstructive component of which was 20.1 (15.7) episodes/hour. Five patients presented Cheyne-Stokes breathing. The AHI (for all cut-points from 5 to 50), chronic snoring, and daytime sleepiness were significantly greater than those published for the general population. The stroke characteristics showed no significant differences between daytime and nighttime onset. Nighttime stroke (60.4%) was associated with a significantly higher AHI (33.3 compared to 24.7 episodes/ hour) mainly because of obstructive apneas. Nighttime stroke was also associated with a greater nighttime desaturation and a greater probability of SAHS symptoms prior to stroke (odds ratio, 2.62). In contrast, there were no differences in vascular risk factors between daytime and nighttime stroke onset.
Conclusion: The prevalences of sleep-disordered breath- ing with clinical signs and symptoms of SAHS were high in this population of patients with acute ischemic stroke. Patients with nighttime stroke had more obstructive sleep-disordered breathing and a higher clinical probability of obstructive SAHS before stroke. These findings support the hypothesis that obstructive SAHS is a risk factor for ischemic stroke, particularly for strokes presenting at night.