Silent strokes more common in people with sleep apnea

People who snore and gasp during sleep, waking frequently during the night, a common condition called sleep apnea, may have an increased risk of silent strokes, a new study suggests.

The study, presented Wednesday at the 2012 American Stroke Association's International Stroke Conference in New Orleans, is not the first to find a connection between sleep apnea and strokes, but it is one of the first to explore the relationship between sleep apnea and silent strokes –– strokes that occur in the past without a history of corresponding stroke symptoms. The researchers, led by Jessica Kepplinger, MD, a stroke fellow at Dresden University in Dresden, Germany, evaluated a total of 56 patients for the presence of sleep apnea over an 18-month period. All participants had previous histories of strokes, average age 67. Each study participant completed a battery of tests overnight attached to devices to detect changes in breathing patterns. Of the 56 patients, ninety-one percent (51 of 56) periodically stopped breathing while they slept, meeting the criteria for sleep apnea. Participants also underwent magnetic resonance imaging (MRI) and computerized tomography (CT) scans to look for evidence of damage to the brain caused by stroke. Scans found that just over half of the study participants with sleep apnea had areas of tissue death –– evidence, Kepplinger tells WebMD, of silent stroke.

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A Sleep Study patient at Princess Alexandra Hospital, Australia who during the study stopped breathing for as much as 20 seconds.

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Lee Schwamm, MD, vice chair of neurology at Massachusetts General Hospital in Boston, told MedPage Today that this study is important because it tells us that breathing disorders are more common after stroke than we previously expected.” But it also raises a number of questions that deserve further study —in particular “is abnormal breathing during sleep a long-term problem in these patients? Or will it go away? And is abnormal breathing a risk factor that leads to stroke? Or is it a consequence of stroke?” Schwamm asks. The authors acknowledge that their study had important limitations, particularly in relation to patient selection. For example, the study involved a mostly white population, so the results may not be generalizable to people of other races. “Demographic characteristics in our study are comparable to western European populations, but our findings may not be entirely generalizable to other populations with diverse ethnicities such as in the U.S.,” Kepplinger said. In the meantime, Kepplinger hopes that their results show that sleep apnea deserves the same amount of attention as a risk factor for having a stroke as the medical community does now for high blood pressure. “Risk factors for stroke such as … smoking can be changed through lifestyle modifications, but sleep apnea is widely neglected as a risk factor that can be changed,” Kepplinger said. “All stroke patients should be screened for sleep apnea.” Do you are someone you know have sleep apnea? What should more people understand about living with sleep apnea?