People under the age of 50 who suffer a head or neck injury are at an increased risk of suffering a stroke, the results of a new study suggest.

US researchers analysed the health records of 1.3 million patients - all under the age of 50 - who had been treated in emergency departments (EDs). Around 11 in every 100,000 suffered a stroke within one month of their hospitalisation.

However, the researchers found that those who had suffered an injury to their head or neck had a three-fold increased risk of suffering an ischaemic stroke.

Ischaemic storkes are caused by a sudden blockage in the blood vessels supplying blood to the brain. Up to 90% of strokes are ischaemic.

"These findings are important because strokes after trauma might be preventable," noted Dr Christine Fox of the University of California San Francisco.

According to the researchers, one cause of ischaemic stroke is a tear in the blood vessels of the neck or head that lead to the brain. This can be a source of clots that go on to cause a stroke. However, if these tears could be diagnosed at the time of an injury, the patient could be given anti-clotting treatment to help prevent the stroke.

Meanwhile, the study also found that the average age of those who suffered a stroke after a head or neck trauma was 37.

Details of these findings were presented at the American Stroke Association's International Stroke Conference 2014 in San Diego.