Abstract
Background&Purpose: Sleep apnea (SA) is an increasingly recognized stroke risk factor. Little is known about the relationship between SA and sleep-related ischemic stroke (SIS). As part of our prospective study of early in-hospital overnight sleep studies in stroke patients, we aimed to evaluate the proportion and severity of SA in patients with SIS. Subjects&Methods: We prospectively (11/2009-05/2011) performed overnight sleep studies in consecutive patients with acute cerebral ischemia without known SA during their hospital stay (<5 days) to determine the presence of SA, defined as an apnea-hypopnea-index (AHI) ≥5/h. Demographics, clinical and sleep-related variables were collected at baseline. Sleep-related ischemic stroke was defined as the presence of stroke symptoms on awakening (wake-up stroke, WUS) or symptom-onset within 1 hour of awakening from nocturnal sleep. Functional outcome was assessed using the modified Rankin Scale at discharge and 180 days. Baseline demographics were analyzed using chi-square and Wilcoxon rank sum test. Correlations were used to examine the relationship between the outcome of interest and collected variables, and logistic regression was used to predict SIS or WUS. Results: Of 61 patients who met the inclusion criteria, 56 had analyzable sleep studies (18% TIA; 54% women; mean age 64±8 years; mean BMI 27.2±3.9; median baseline NIHSS score 1 point, range 0-15; median Epworth Sleepiness Scale score 5 points, range 0-13; mean AHI 23.6±19.3/h). SIS was found in 19 (34%) patients including 14 (25%) WUS. Nearly 91% (51/56) had SA; 32% (18/56) mild, 30% (17/56) moderate, and 29% (16/56) severe. There were no significant differences in baseline characteristics between SIS and non-SIS patients except for gender (males 26% vs. 57%, p=.03) and atrial fibrillation (32% vs. 5%, p=.008). Functional outcome at discharge (p=.24) and 6 months (p=.35) did not differ between SIS and non-SIS patients. When comparing SIS and non-SIS patients, no differences were found regarding the presence (95% vs. 89%, p=.49) or severity (e.g., severe SA: 32% vs. 27%, p=.69) of SA. Similarly, there were no differences in the presence (100% vs. 88%, p=.17) or severity (e.g., severe SA: 32% vs. 29%, p=.66) of SA when comparing WUS and non-WUS patients. AHI did not prove to be a significant independent predictor of SIS (p=.45) or WUS (p=.56). Conclusions: The similar proportions and severity of SA in our patients with sleep-related and non-sleep-related ischemic strokes may be due to the overall high prevalence of SA (91%) in the entire study population, which highlights the importance of early screening for SA in all ischemic stroke patients. As the majority of our patients had mild strokes, these findings warrant further investigation in a moderate-to-severe stroke population.
Published Version
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