Sleep-Disordered Breathing and Stroke
Research into sleep-disordered breathing (like sleep apnea) has increased awareness of the association between sleep disorders and stroke and TIA.
- As many as 63% of stroke and TIA patients also experience sleep-disordered breathing (SDB).
- Stroke and TIA patients are five times more likely to suffer from sleep-disordered breathing than controls.
- Stroke sufferers with SDB have worse functional outcomes and higher mortality after one year compared to controls.
Obstructive Sleep Apnea
Sleep-disordered breathing is a general term for any type of breathing disruption that occurring during sleep, of which the most common is obstructive sleep apnea. Obstructive sleep apnea is characterized by:
- Loud, intermittent snoring
- Fragmented sleep
- Apneas and hypopneas, which can interfere with gas exchange
- Oxygen desaturations, which cause arousals from sleep
- In severe cases, patients may experience arousals from sleep hundreds of times each night
Symptoms of Sleep-Disordered Breathing Linked with Stroke
People with sleep apnea and other sleep disorders experience a number of symptoms that may predispose them to stroke. Recent studies suggest:
- Repetitive drops in nighttime blood oxygen levels caused by SDB can cause long-term hypoxia, putting an individual at a much greater risk for stroke because of the stress it places on the heart and brain.
- SDB arousals lead to increased blood pressure and heart rate, placing patients at an increased risk for stroke, especially during sleep when their cardiovascular systems are already stressed.
- SDB is associated with an increased post-stroke mortality. Even though SDB has not been conclusively proven to cause stroke, the literature suggests that the cause-effect relationship is biologically plausible.
Shared Risk Factors
Stroke and sleep apnea share many of the same risk factors. Older stroke and TIA patients with a high body mass index (BMI), diabetes and/or severe stroke are more likely to suffer from sleep apnea. Other risk factors include:
- Hypertension – Recent studies have found SDB to be an independent risk factor for high blood pressure, one of the leading risks for stroke. Having high blood pressure increased the risk of stroke by 4 to 6 times.
- History of snoring – Snoring is one of the most common symptoms and is associated with strokes that occur during sleep or within the first 30 minutes after waking.
- Heart disease – Researchers suspect that acute hemodynamic events associated with SDB increase cardiac workload and may increase cardiovascular morbidity and mortality.
- Age – Risk of stroke and incidence of sleep apnea and other sleep disorders increases with age, most commonly affecting men over the age of 55.
- Obesity – People with a high BMI are likely to have other stroke risk factors, such as high cholesterol, high blood pressure, and diabetes.
Recognizing and Diagnosing Sleep-Disordered Breathing in Stroke Patients
The NSA recommends that all acute stroke facilities and stroke rehabilitation programs include screening for sleep apnea and sleep-disordered breathing. Recognizing sleep problems in stroke survivors is often challenging because the symptoms associated with them are often attributed to stroke. Obtaining a complete sleep history from family members will help determine whether sleep problems were present prior to the stroke or developed after the stroke
The Importance of Treatment
Patients with SDB have a significant disadvantage in the struggle to recover from stroke. They develop compounded attention and concentration deficits that impair their abilities to perform activities of daily living and acquire new skills. Untreated SDB in any population leads to:
- Excessive daytime sleepiness
- Impaired cognitive functioning
- Memory loss
- Intellectual deterioration
The Impact of Sleep-Disordered Breathing on Post-Stroke Rehabilitation
- Excessive daytime sleepiness, fatigue and impaired cognitive functioning associated with sleep problems, combined with the deficits caused by stroke, may have specific adverse effects on the outcome of post-stroke rehabilitation.
- Excessive daytime sleepiness and fatigue may reduce the patient’s ability and motivation to participate in rehabilitation programs, resulting in poor compliance and impeded recovery.
- Sleep-disordered breathing in stroke patients is associated with higher mortality at one year and poor functional outcomes in survivors.
Benefits of Treating Sleep-Disordered Breathing
Benefits of treating SDB include:
- Improved blood pressure control
- Reduced cardiovascular morbidity and mortality
- Improved quality of life