Direct link between stroke and obstructive sleep apnea
Another cause of cerebrovascular diseases, in particular stroke, has been identified and proven – a symptom of obstructive sleep apnea. The presence of obstructive sleep apnea in a patient increases the risk of stroke by 2–8 times compared with persons without sleep breathing disorders . The presence of severe sleep apnea significantly worsens the course of a stroke. Disability due to a stroke ranks first among diseases that cause disability.
In a stroke, brain damage occurs due to a decrease or cessation of the provision of its limited area with blood and oxygen. Periodic obstructive sleep apnea causes pronounced fluctuations in cerebral blood flow, and at certain times there may be a critical decrease in cerebral perfusion and the onset of a stroke.
Respiratory arrest and lack of oxygen are a stress reaction accompanied by activation of the sympathoadrenal system and an increase in blood pressure. Hypercapnic acidosis and sudden respiratory efforts also contribute to an increase in pressure. Patients with sleep apnea have a higher level of blood pressure, especially at night, which is unfavorable in terms of the development of cerebrovascular diseases. The most formidable form is an acute violation of cerebral circulation – a stroke.
When studying the parameters of cerebral hemodynamics in patients with sleep apnea, a significant decrease in the volumetric blood flow velocity in the internal carotid artery and total volumetric cerebral blood flow was shown. If we consider that a violation of the supply of oxygen to the brain coincides with an increase in blood pressure and hypoxemia, it becomes clear why obstructive sleep apnea becomes the direct cause of a stroke. In addition, obstructive sleep apnea has been shown to be the cause of early carotid atherosclerosis, which tends to progress and lead to stroke.
There is also an inverse relationship between stroke and obstructive sleep apnea, which in this case is already a complication of a stroke. The appearance of obstructive sleep apnea syndrome after a brain accident aggravates the patient’s condition and is an unfavorable prognostic sign. It is recommended to conduct a more thorough examination of patients who have suffered a violation of cerebral circulation, with complaints of snoring, intermittent sleep and fatigue. Excessive drowsiness and weakening of mental abilities, characteristic of obstructive sleep apnea syndrome, complicate the rehabilitation of such a patient.
From the foregoing, it follows that the prevention of stroke depends on the accuracy of diagnosis and detection of cases of sleep apnea. And it is extremely important to get tested for sleep apnea for patients who have already had a stroke, because if breathing is not corrected, the chances of a second stroke increase. There is a higher mortality rate in patients with cerebrovascular accidents and untreated sleep apnea. Studies conducted over 10 years have concluded that mortality due to acute brain attacks is 3 times higher in patients with sleep apnea compared to patients without breathing disorders during sleep.
The main method for diagnosing obstructive sleep apnea syndrome is polysomnography (performed in the clinic and at home), which allows you to clarify the diagnosis, the severity of the disease and the need for adequate therapy. CPAP therapy is by far the most effective method for correcting breathing disorders during sleep.