Infection Worsens Stroke Damage

Having a viral or bacterial infection when experiencing a stroke may lead to an increased risk of brain damage, according to recent study.

The study, published in the Annals of Neurology, not only connected infection to an increased risk of brain damage following a stroke, but they also explained this phenomenon, finding evidence that suggests that inflammation of the brain caused by the immune system in response to the infection makes the brain more vulnerable to permanent damage.

According to the study, researchers were able to determine this after analyzing stroke outcomes in lab rats infected with Streptococcus pneumoniae -- an infection most commonly seen in patients at risk of stroke.

In a comparative model, the researchers were able to determine that rats infected with S. pneumoniae --- which earned an auto-inflammatory response as part of the immune systems efforts to fight off the infection -- experienced strokes that were 50 to 90 percent more damaging, compared to strokes in similar mice who were not infected.

According to the researchers, the extensive damage in these strokes was caused primarily by hemorrhaging of blood vessels in the brain. Normally, blood platelets in the blood would work to stop bleeding after injury in the brain. However, when the immune system is fighting infection molecule called  inteleukin-1 is used as part of the inflammation response. Blood platelets, which are drawn to the interleukin-1 molecules, then wind up exacerbating the brain damage that they were designed to stop.

According to the study, when an infected mice group was given an anti-inflammatory soon after suffering from  a stroke, they displayed risk of damage similar to the non-infected group, showing that inflammation above all else is the culprit behind an increased risk of post-stroke damage.

The study was published in the Annals of Neurology, the official journal of the American Neurology Association and the Child Neurology Society, on April 14.