Papers selected for this review were identified by searches of PubMed, MEDLINE, and our personal files. Abstracts were not considered in this review. Search terms included “sleep apnoea”, “sleep-disordered breathing”, “obstructive sleep apnoea”, “stroke”, “transient ischaemic attack”, “cardiovascular” and “cerebrovascular” diseases. The searches were done on Feb 25, 2004, and included articles dating back to 1980.
ReviewObstructive sleep apnoea and stroke
Section snippets
Overview of obstructive sleep apnoea
Sleep-disordered breathing comprises snoring, upper airway resistance syndrome, obstructive sleep apnoea, central apnoea, and central hypoventilation. Among these disorders obstructive sleep apnoea has been investigated extensively in regard to the association with stroke and cerebral haemodynamics. For this reason, obstructive sleep apnoea, referred to as sleep apnoea, will be discussed in this review.
Sleep apnoea is repeated closure of the upper airway during sleep and is associated with a
Sleep apnoea as a cause of systemic hypertension
Autonomic and haemodynamic responses to sleep apnoea are complex and include the effects of apnoea, hypoxia, hypercapnia, changes in intrathoracic pressure, and arousal. Individual episodes of sleep apnoea cause acute surges in heart rate and blood pressure at apnoea termination (figure 1). The magnitude of these changes in blood pressure may be as large as a 40 mm Hg rise in mean arterial pressure.20 These acute rises in blood pressure during apnoea seem to be driven by chemoreceptor responses
Snoring and stroke
As with sleep-disordered breathing and hypertension, early epidemiological studies that examined the relationship between sleep-disordered breathing and cerebrovascular disease used self-reported snoring as the primary exposure variable. Most of these studies clearly show an association between snoring and stroke (table 1). They also show that the strength of this association is similar to traditional risk factors for stroke such as hypertension, smoking, atrial fibrillation, and
Sleep apnoea and stroke
Overnight polysomnography is the gold-standard diagnostic test for sleep apnoea. Several cross-sectional and case-control studies have used overnight polysomnography to more precisely define sleep apnoea, in an attempt to sort out whether it is patients with sleep apnoea who account for the apparent increased risk of snoring with stroke (table 2). These studies have focused on sleep apnoea both as a consequence of stroke and as a risk factor for stroke.
Functional outcome after stroke
The presence of sleep apnoea in the setting of stroke is associated with unfavourable clinical course including early neurological worsening, delirium, depressed mood, impaired functional capacity, impaired cognition, and a longer period of hospitalisation and rehabilitation.5, 12, 44, 45, 46, 47 In one study,12 the functional status—as assessed by the Barthel index, a multifaceted scale measuring mobility and activities of daily living—in patients with stroke together with evidence of sleep
Sleep apnoea, cognitive impairment, and white-matter disease
Epidemiological studies, primarily in middle-aged adults, have shown associations between sleep apnoea and deficits in neurocognitive function, particularly attention and concentration.48, 49 These deficits may, in part, be mediated through the excessive daytime sleepiness associated with sleep apnoea. However, even after adequate therapy for sleep apnoea, some neurocognitive deficits such as impairment in executive function and manual dexterity can persist.50, 51 The residual deficits may, in
Therapy for sleep apnoea in stroke
An early study that gives some insight into the effect of treatment of sleep apnoea on the risk of myocardial infarction and stroke was a retrospective cohort study of patients diagnosed with sleep apnoea by use of polysomnography in the 1970s before the availability of CPAP when the only known definitive therapy for sleep apnoea was tracheostomy.53 7 years of follow-up was provided on 198 patients of which 71 received tracheostomy (then thought effective treatment) and 127 received the
Pathophysiological mechanisms
There are likely multiple mechanisms by which sleep apnoea may lead to the development of stroke. During sleep apnoea, repetitive episodes of airway occlusion result in hypoxaemia, hypercapnia, and significant changes in intrathoracic pressure, and arousal from sleep. These effects elicit autonomic, haemodynamic, coagulopathic, and vascular injury processes that serve as plausible mechanisms by which sleep apnoea may cause stroke (figure 4).
Conclusion
Sleep apnoea is strongly associated with increased risk of stroke independent of known cardiovascular risk factors. If causal, even a moderately high risk of stroke coupled with the high prevalence of sleep apnoea could have significant public-health implications. The mechanisms underlying this risk of stroke are multifactorial and include hypertension, changes in cerebral haemodynamics, paradoxical embolism through PFO, cardiac arrhythmias, increased hypercoagulability, and increased
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Neurological effects of respiratory dysfunction
2022, Handbook of Clinical NeurologyCitation Excerpt :The broad range of health consequences is attributed to the impact of sleep fragmentation, cortical arousal, and hypoxemia by stimulating sympathetic overactivity, release of acute phase reactants, reactive oxygen species, exacerbate insulin resistance and lipolysis, and augment prothrombotic and proinflammatory state (Dewan et al., 2015; Ferini-Strambi et al., 2017). Relationships between OSAHS and cognition, neurodegenerative disorders, stroke, epilepsy, and headache are well established (Lanfranchi and Somers, 2001; Society, 2004; Yaggi and Mohsenin, 2004; Johnson and Johnson, 2010; Gaig and Iranzo, 2012; Kristiansen et al., 2012; Pornsriniyom et al., 2014; Ding et al., 2016; Stranks and Crowe, 2016; Ferini-Strambi et al., 2017). In addition, OSAHS is an independent risk factor for stroke.
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