Swedish study shows blood test may help in evaluating epilepsy

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Researchers from Sweden have discovered higher levels of immune proteins in patients’ blood both before and after an epileptic seizure.

The results of their study, published February 20 in Heliyon, indicate that these epilepsy biomarkers could be identified using a simple blood test.

Epilepsy is abnormal brain activity that causes temporary loss of behavior and movement control. The condition can be congenital, or may be caused by a brain tumor, stroke, or infection and can cause different symptoms depending on where in the brain the episode occurs. Inflammation processes that start as an immune response can also induce a seizure.

Distinguishing epilepsy from other conditions can be challenging. For example, psychogenic nonepileptic seizures -- a psychiatric, often underdiagnosed condition that manifests itself through clinical symptoms -- can be mistaken for epilepsy. As a result, this chronic condition is often inappropriately treated with epilepsy medication. Determining whether patients are suffering from epilepsy or psychogenic seizures is resource-intensive, requiring several days of hospitalization with continuous video, electroencephalogram (EEG) surveillance, and medical staff.

To meet the urgent need to distinguish between the two conditions more easily, and more accurately diagnose a patient seeking medical care after a suspected seizure, the Sweden-based researchers sought possible biomarkers for epilepsy within the immune system.

The team accepted 56 carefully selected patients into their study for three to five days of in-hospital video-EEG monitoring; 12 control subjects were also included.

The 56 patients were divided into groups based on observed seizure semiology and EEG findings. Patients with either temporal or frontal lobe epilepsy, or both, and psychogenic nonepileptic seizures had their blood sampled upon hospital admission and after video-EEG verified seizures. In comparing epileptic seizures with psychogenic nonepileptic seizures, the researchers discovered that levels of five inflammation markers -- all proteins -- were acutely elevated in people who had experienced actual epileptic seizures.

These markers served as so-called fingerprints since the inflammation-related proteins showed different reaction patterns. Patients with temporal and frontal lobe epilepsy showed raised levels of one of the five proteins, called interleukin-6 (IL-6), in their blood serum even before a seizure, a value that was further raised directly after the seizure.

Patients with psychogenic nonepileptic seizures, however, showed no change in their serum IL-6 levels. The researchers concluded that if a blood test following a seizure shows no elevation in the patient’s immunological response, there is a greater chance of it being a psychogenic seizure. This can provide medical staff with an initial indication upon which to base a patient’s further assessment.

“The next stage is to repeat our studies on a broader and less homogenous patient group, where we investigate the fingerprint in adults with epilepsy,” said study leader Christine Ekdahl Clementson, associate professor at Lund University, in a statement. “We also want to see whether the biomarkers respond in the same way in children, where the causes of epilepsy are more often genetic.”

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