To understand whether snoring contributes to an increased risk of ischemic brain infraction, the University of Finland funded a study conducted by Dr. Heikki Palomaki. Under his guidance, the case-control study was done with 177 male patients within the age of 16-60 years that had acute brain infraction, as diagnosed by medical professionals. 

Know About Ischemic Brain Infraction

Ischemic brain infraction or ischemic stroke is a neurological disorder which occurs due to disrupted flow of blood in the brain. This happens due to the issues with the blood vessels. With the lack of proper blood supply, the oxygen deprived brain cells die off leaving the individual with various neurological disorders. As per the study, various factors were considered for the multiple logistic regression analysis. These included:

  • coronary heart disease
  • heavy drinking (>300 g/wk)
  • Hypertension
  • Occasional/habitual snoring

Though the brain infraction ratio was 2.13, but using the McNemar’s test, the probability of the connection increased if the individual had a sleep apnea, obesity and daytime drowsiness. As per the studies done, the reason for snoring as a key factor for ischemic stroke is possible due to obstructive sleep apnea which is more among snorers. 

As mentioned in the Lancet, 1985 by M. Koskenvuo, J. Kaprio, M. Partinen, H. Langinvainio, S. Sama, K. Heikkila – “Snoring as a risk factor for hypertension and angina pectoris” habitual snoring is associated with coronary heart disease. However, recent epidemiological studies have shown that snoring can lead to brain infraction during sleep or shortly after waking up. Additionally, it was seen in multiple studies that obstructive sleep apnea has a detrimental effect on the cardiovascular health. 

The key aspect that can be seen in the association of snoring and brain infraction is similar to the risk factors for stroke. These include sleep apnea and snoring. Age, obesity, alcohol consumption and smoking are red flags for coronary heart disease and arterial hypertension. 

Methods of the study

The study 177 male patients that were admitted to the Meilahti University Hospital in Helsinki. All of them had confirmed brain infraction as per the neurologist.  For each patient, an age matched male control from the same hospital was selected that had no history of ischemic cerebrovascular issues. 

Both controls and patients were examined for potential risk factors for brain infractions for snoring risk. Detailed history of the medical conditions was obtained from the group, clinical and laboratory exams after a follow up. The data collection was about:

  • Hypertension
  • Coronary heart disease
  • Diabetes
  • Smoking
  • Alcohol consumption
  • Sleep habits and patterns

The snoring history was categorized as habitual snoring (always/nearly always), occasional and non-snorers. Thus, habitual snorers were categorized as snorers and rest were done as non-snorers, for the study. After the results were tabled using the BMDP, there were risk variants for brain infraction that were similar in the case-control pairs. This was determined further by the McNemar’s test. 

Based on binomial distribution, the 95% confidence interval of the OR was computed. While the independent effect of the risk factors was established using stepwise logical regression analysis with the dependent variable- the brain infraction. To get the correct individual OR from the multitude of analysis, the variables were gleaned from risk factors such as:

  • coronary heart disease
  • hypertension 
  • diabetes mellitus
  • BMI as greater than 27 kg/m2
  • Consumption of cigarettes per day (greater than 10/non-smokers)
  • Alcohol consumption (heavy drinkers/occasional/abstainers)

Case Study Result

As per the results of this specific study wherein the average age of the male participants was 49 years, the mean age of the age matched 177- men of the control group was also 49 years. As per the clinical presentation and symptoms of 16 patients or 9% showed cardiogenic embolic infarction. In 76.35 or 135 patients the infraction was in the carotid while in 23.7% or 42 patients, it was localized in the vertebrobasilar artery. 

The common risk factors for brain infractions were matched in the case-control groups. These included snoring, hypertension, diabetes and coronary heart disease. As per the multiple logistic regression analysis, coronary heart disease, drinking over 300 g/wk, and snoring became the risk factors. 

It was seen that brain infraction and snoring have an association and was found among all sub-groups of tested patients. The association was more between cardiogenic embolism and snoring. 

Current study discussed

As per this study, it was found that 52.3% of the men were snorers so the OR for habitual snoring and brain infraction was 2.13. Additionally, 32% of the control group were snorers. In a prospective study of 4,388 men within the age group of 40-69 years, there was seen an association of coronary heart disease and stroke with heavy snorers and non-snorers as 2.38. Among 1294 snorers, there were 16 cases of strokes while there was no case among the group of 480 non-snorers. 

Additionally, it has been seen that heart diseases and hypertension have been precursors of brain infraction. While obesity and the consumption of alcohol have a dual effect as these are two contributors to sleep apnea and snoring while are risk factors for brain strokes. 

As per the multiple logistic regression analyses, there were no variables that led to snoring becoming a risk for brain infraction. The only cause seems to be that heavy snoring leads obstructive sleep apnea which can lead to poor blood circulation and oxygen levels. That is why OSA is associated with cardiac arrhythmias as mentioned in the American Journal of Medicine in “Cardiac arrhythmias and conduction disturbances in the sleep apnoea syndrome” by Dr. WP Miller.

Relation Between Snoring, Sleep Apnea and Brain Stroke

Thus, snoring is particularly associated with cardiogenic embolism while there have been noticeable hypotensive periods in relation to sleep apnea.  Thus, consistence with sleep apnea, due to hemodynamic mechanisms, there is an increased risk of ischemic stroke that suffer with cardiac issues. As per the results, individuals that just snored but did not suffer with sleep apnea were at little risk of brain infraction. Conversely, sleep apnea could be a result of brain infraction, if the lesion was situated in the area of vertebrobasilar circulation. Vertebrobasilar ischemia has been seen to be triggered by instances of obstructive sleep apnea. As per this study’s result, obstructive sleep apnea syndrome in stroke patients is 5.2% higher than other estimates. 

Although an independent factor for triggering stroke and cardiac issues, heavy alcohol consumption in turn leads to increased episodes of snoring. The results were clear as they were done in a clinical environment and can be said that the risks are inter-dependent and can be factored in as a cause for brain infraction.

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