Brain Injury in Stroke Patients can be Measure by Blood Biomarker

From mild symptoms and a fast recovery to permanent impairment, a stroke may have a wide range of effects. The scale for assessing disease severity does not correspond well with damage to the brain tissue. Markers of tissue damage will therefore, allow better prediction of outcomes and the creation of treatment. Now a group has found that a blood biomarker, a protein known as neurofilament light (NFL), can assess the degree of brain damage from various kinds of strokes and predict patient prognosis.

                  

The title of the paper is "Plasma neurofilament light predicts mortality in patients with stroke".

In neurons located in the brain, the NFL protein is abundant. NFL is released into cerebrospinal fluid and then the blood if nerves are damaged after a stroke or from other neurological disorders. According to the research team, the amount of NFL released is indicative of neuron damage in the brain. Stroke is a leading cause of death, but from acute and non-disabling to serious long-term disability, symptoms differ widely.

It is crucial for patients and their loved ones to estimate the seriousness of a stroke and how well a person is expected to recover,' said Tania Gendron, PhD, assistant professor at the Mayo Clinic in Florida and the paper's first author. It is also critical for their care to accurately predict a patient's prognosis, as it informs decisions on treatment and recovery. We tried to decide whether the amount of NFL in the blood of patients could be used to assess their prognosis after a stroke, whether it is an ischemic stroke, occurring when a clot prevents blood flow to the brain, or a hemorrhagic stroke, occurring when a weak blood vessel bursts and bleeds into the brain.

To measure NFL concentrations in blood collected from 314 patients after a stroke and in blood from 79 healthy individuals, researchers used an investigative blood test. The patients had either acute cerebral infarction (N = 227), subarachnoid aneurysmal haemorrhage (N = 58), or intracerebral nontraumatic haemorrhage (N = 29). In addition, the team validated the findings of nontraumatic intracerebral haemorrhage in two independent cohorts of patients with (N = 96 and N = 54) due to the scarcity of blood biomarker studies for this deadliest type of stroke." This analysis allowed the scientists to determine whether NFL after a stroke is elevated. They also investigated whether NFL levels are indicative of the severity of the stroke and eventual recovery.

For all stroke forms, the researchers found that NFL levels were higher.

In addition to the neurological, functional, or cognitive status of the patients at the time their blood was obtained, the researchers explored associations between NFL levels and the degree of brain injury. The study also investigated whether by accurately predicting post-stroke outcomes and survival, NFL levels could foresee future recovery. Similar methods were used to test NFL as a prognostic biomarker in two additional groups of stroke patients (total of 150) and 48 healthy controls to validate their findings; they also found that patients with lower NFL levels increased day-to-day function six months after stroke.

We find that NFL blood levels predict the severity of stroke,” said Leonard Petrucelli, PhD, a professor of neuroscience at the Florida Mayo Clinic. We find that higher NFL levels predict worse functional results and shorter post-stroke survival times. For ischemic stroke and hemorrhagic stroke, we found this to be the case. As a positive prognostic biomarker for stroke, our research establishes NFL.

Brain imaging is currently used to assess damage from a stroke. While an NFL blood test is not yet available in the clinical environment, researchers hope that doctors will be able to minimise the use of imaging in the future, using an NFL blood test instead to help assess the best course of action, as well as boosting clinical trials with better matched groups of patients based on the degree of brain injury and severity of symptoms.

The authors noted that identifying precisely when blood NFL levels begin to associate with long-term outcomes in the aftermath of stroke would be one crucial step in clinical translation.

"We hope that our findings will eventually improve how patients are handled in clinical trials using NFL biomarkers to allow therapeutic effects to be identified more quickly and accurately," said James Meschia, MD, a neurologist at the Mayo Clinic in Florida. Our results will also help us plan rehabilitation needs better for patients who need it most and for the longer term.