Habitual snoring, sleep apnoea, and stroke prevention

Sleep-disordered breathing and stroke: chicken or egg?

The bidirectional interaction between sleep-disordered breathing (SDB) and stroke has been the subject of many studies. On the one hand, different forms of SDB, and especially obstructive sleep apnea, increase the risk of stroke either directly or indirectly by influencing other known cardiovascular risk factors such as arterial hypertension and arrhythmias. On the other hand, stroke itself can cause either de novo appearance of SDB, aggravate a pre-existing SDB, or trigger a transition from one type of pathological SDB pattern into another. In this review, we discuss some aspects of this "chicken or egg" relationship.

Night time versus daytime transient ischaemic attack and ischaemic stroke: a prospective study of 110 patients

OBJECTIVE

Ischaemic stroke occurs only in 20%-40% of patients at night. The aim of the study was to compare sleep and stroke characteristics of patients with and without night time onset of acute ischaemic cerebrovascular events.

METHODS

A consecutive series of 110 patients with transient ischaemic attack (n=45) or acute ischaemic stroke (n=65) was studied prospectively by means of a standard protocol which included assessment of time of onset of symptoms, sleep, and stroke characteristics. An overnight polysomnography was performed after the onset of transient ischaemic attack/stroke in 71 patients. Stroke and sleep characteristics of patients with and without cerebrovascular events occurring at night (between midnight and 0600) were compared.

RESULTS

A night time onset of transient ischaemic attack or stroke was reported by 23 (21%) of 110 patients. Patients with daytime and night time events were similar in demographics; risk factors; associated vascular diseases; clinical and polysomnographic sleep characteristics (including severity of sleep apnoea); and stroke severity, aetiology, and outcome. Only the diastolic blood pressure at admission was significantly lower in patients with night time events (74 v 82 mm Hg, p=0.01).

CONCLUSIONS

Patients with night time and daytime transient ischaemic attack/stroke are similar in sleep and stroke characteristics. Diastolic hypotension may predispose to night time cerebrovascular events. Factors not assessed in this study probably account for the circadian variation in the frequency of transient ischaemic attack and acute ischaemic stroke.