A simple blood test that can detect evidence of concussion up to a week after a head injury has been developed.
Researchers discovered that a biomarker released by the brain when the head is injured stays in the bloodstream for seven days.
They say the breakthrough could greatly expand the window for diagnosing concussions, especially in patients who experience a delayed onset of symptoms.
Study lead author Dr Linda Papa, an emergency medicine physician at Orlando Health in the United States, said: “Symptoms of a concussion, or a mild to moderate traumatic brain injury, can be subtle and are often delayed, in many cases by several days.
“This could provide doctors with an important tool for simply and accurately diagnosing those patients, particularly children, and making sure they are treated properly.”
Almost all concussions in children are diagnosed only by symptoms, which are either observed – such as vomiting or loss of balance – or symptoms reported by the child, such as blurred vision or headaches.
Dr Papa said: “If patients are not diagnosed properly and treated appropriately, it could lead to long-term problems.”
Untreated, or under-treated traumatic brain injuries sucha s concussions, can lead to prolonged bouts with headaches, dizziness, memory loss and depression.
Dr Papa said: “This test could take the guesswork out of making a diagnosis by allowing doctors to simply look for a specific biomarker in the blood””
The biomarker Papa analysed is known as a glial fibrillary acidic protein (GFAP). These proteins are found in glial cells, which surround neurons in the brain, and when an injury occurs, the GFAP are released.
Dr Papa said that what makes them unique is that they pass the blood-brain barrier and enter the bloodstream, making them easy to detect with the new test.
“Not only were they present in the bloodstream, we were able to detect measurable levels of GFAP up to a week after the injury,” said Dr Papa.
The researchers, whose findings were published in the journal Neurology, analysed nearly 600 patients for three years.
When cross-checked with scans, the blood test was able to detect mild to moderate traumatic brain lesions with up to 97 per cent accuracy in patients 18 years and older.
The blood test also indicated which patients were in need of life-saving neurosurgery.
Dr Papa said that suggests that the blood test could be used by clinicians for up to a week after injury to detect brain injury which is important because many patients with concussion may not seek medical attention for several days after being injured.
She said the blood test could also dramatically cut the need for computerised tomography (CT) scans. Currently, CT scans are the most precise way to diagnose brain lesions, but are expensive and are associated with radiation exposure.
Dr Papa said: “Physicians really want to minimise the amount of CTs in patients, especially children, who are a lot more sensitive to radiation and the side effects that can come with it.
“Fortunately, this simple blood test appears to give us nearly the same information as a CT scan.”
Dr Papa analysed 152 children within six hours of sustaining a concussion, or mild to moderate traumatic brain injury. The results showed that the blood test was able to detect brain injuries with 94 per cent accuracy, nearly as effective as state-of-the art CT scans.
She added: “This could ultimately change the way we diagnose concussions, not only in children, but in anyone who sustains a head injury.
“We have so many diagnostic blood tests for different parts of the body, like the heart, liver and kidneys, but there’s never been a reliable blood test to identify trauma in the brain. We think this test could change that.”