Signs and symptoms of sleep apnea and acute stroke severity: is sleep apnea neuroprotective?

Abstract

Background: In animal models, brief periods of hypoxemia render the brain tolerant to subsequent ischemic insults. Sleep apnea leads to frequent episodes of nocturnal hypoxemia and may induce ischemic tolerance. Snoring and daytime sleepiness are cardinal symptoms of sleep apnea. We undertook this study to determine differences in stroke severity and early neurologic course in patients at risk for sleep apnea as determined by a sleep questionnaire.

Methods: Patients admitted with acute ischemic stroke completed the Berlin questionnaire. The Berlin questionnaire examines habitual snoring, daytime sleepiness, presence of hypertension, and body mass index (BMI) and classifies patients into a high or low risk for sleep apnea group. National Institutes of Health Stroke Scale (NIHSS) score was determined on admission and day 5 of hospitalization. Age, sex, cardiovascular risk factors, BMI, and stroke mechanism were determined prospectively.

Results: We enrolled 190 patients with a mean age of 60 years and 53% were men. The Berlin questionnaire classified 103 patients (54%) at high risk for sleep apnea. The median NIHSS score on admission and day 5 of hospitalization did not differ between the two groups after multivariate analysis. Examined separately, we found no effect of snoring, daytime sleepiness, or BMI on acute stroke severity and outcome.

Conclusion: We found that a large number of patients admitted with acute ischemic stroke were at high risk for having sleep apnea. We were not able to show that a constellation of symptoms and features highly suggestive of sleep apnea influenced stroke severity or early neurologic course after acute ischemic stroke.