Previous studies have shown that untreated sleep apnea may increase risk for heart attack or stroke. Interestingly, though, it has also been suggested that having a stroke may actually worsen sleep apnea. How can this be so if apneas occur in the upper airway? Although apneas do typically occur due to an excess amount of tissue in the airway, the brain may also contribute. This is because breathing regulation occurs in the brainstem, which is the region of the brain that is connected directly to the spine. In theory, then, if a stroke were to occur in this area, sleep apnea severity may be worse than if a stroke occurred in a non-breathing related part of the brain. This theory has been recently investigated.
Using a large population of 355 subjects, a research team set out to compare sleep apnea severity in those with a brainstem stroke in comparison to those with a non-brainstem related stroke. These subjects were pulled from an existing database that aims to document and monitor all existing stroke sufferers in the area. Subjects were contacted and asked to do an overnight sleep study in their own home using a portable breathing monitoring device. The apnea hypopnea index (AHI) was then compared between the two groups to see which had more severe sleep apnea.
Results showed that overall, having a stroke in the brainstem led to 3 times the odds of having sleep apnea (an AHI greater than 10 per events per hour). There was an overall higher AHI in those with a brainstem stroke, suggesting the stroke may precede the severity. Interestingly, the size of the stroke did not matter, meaning even a small amount of damage in that location led to an increased risk and severity of sleep apnea.
These results are both interesting and scary. On one hand, it is interesting that excess weight is not the only contributing factor to sleep apnea. Clearly, sleep apnea is a complex beast. On the other hand, because we are unable to control the brain location of stroke, there isn’t too much we can do about it! However, early prevention against stroke is key. As mentioned, having sleep apnea can increase the risk for stroke. In addition, having excess weight can also increase this risk. Therefore, by trying to stay fit, you can prevent the occurrence of sleep apnea and maybe even the occurrence of stroke. Regardless of what may come, PAP treatment, such as CPAP, remains to be effective even in those who have stroke-worsened apnea. The message, as always, is clear – seek an apnea treatment, and stay treated!
Source: Brown, D. L., McDermott, M., Mowla, A., De Lott, L., Morgenstern, L. B., Kerber, K. A. & Lisabeth, L. D. (2014). Brainstem infarction and sleep-disordered breathing in the BASIC Sleep Apnea Study. Sleep Medicine.