Purpose of review
A growing number of studies suggest that there is a close relationship between sleep-disordered breathing (SDB) and stroke. Since the prevalence of SDB is high among acute stroke patients and since oxygen desaturations are potentially dangerous, SDB may influence not only stroke risk, but also stroke outcome and recurrence. This review summarizes recent data on this issue, pointing out existing evidence but also defining issues that still need to be clarified.
Recent studies further supported the hypothesis of a link between SDB and stroke: (1) although stroke occurs most frequently in the morning hours, i.e. shortly after awakening, stroke events take place predominantly during sleep in SDB patients; (2) a large cross-sectional study confirmed the association of SDB not only with coronary heart disease but also with stroke; (3) several works suggest that SDB may increase stroke risk through various mechanisms including blood pressure swings, endothelial dysfunctions, prothrombotic coagulation shifts, pro-inflammatory states, increased platelet aggregation and atherosclerosis; (4) one study in acute stroke patients demonstrated that SDB is associated with early neurological worsening although not with final stroke outcome; (5) treatment trials with continuous positive airway pressure (CPAP) have demonstrated mild reductions of diastolic and systolic blood pressure in SDB patients, an effect that is expected, however unproven, to decrease stroke risk.
Despite considerable progress regarding our understanding about the role of SDB in vascular disease, further studies are needed to determine whether cerebrovascular morbidity is related to SDB independent of associated vascular risk factors, whether SDB has indeed a negative impact on stroke progression and whether CPAP treatment ameliorates stroke outcome.