Spread of seizures can be suppressed

Sufficient pressure inside the brain could prevent seizures from spreading throughout the brain, Carnegie Mellon researchers have found. This discovery has the potential to completely alter how drug-resistant epilepsy is treated.

Epilepsy is among the most common neurological disorders, affecting young and old people alike. Many seizure disorders exist, but all are considered forms of epilepsy. Although the majority of seizure disorders can be treated with medicine, a few strains of epilepsy are drug-resistant. These strains of epilepsy can only be treated with surgery, where surgeons remove tissue to eliminate or minimize seizures

Dr. Bin He, the Department Head of Biomedical Engineering, and his lab recently published a study in the Annals of Neurology journal alongside researchers from the Mayo Clinic. The study, “Multiple Oscillatory Push-Pull Antagonisms Constrain Seizure Propagation”, describes what may be an important and promising biomarker in the future, finding that focal seizures — seizures which arise from a single point — are able to be regulated by the brain’s push-pull dynamics.

According to the researchers, an imbalance of excitation-inhibition activity in epileptic networks may allow for the secondary generalization of focal seizures. These researchers speculate that medical professionals could determine whether a seizure will propagate throughout the brain by looking at imbalances between inhibition and excitation of firing of neurons.

"People thought that the spread of seizures mainly depends on where seizures originate in the brain, but the propagation of a seizure is actually regulated by the surrounding tissues, which includes that seizure onset zone. By using an array of electrophysiological recordings, we found that it's not moving outward necessarily; it depends on how much 'pull' a patient receives from the surrounding tissue towards the seizure onset zone, and how much 'push' propagates from the seizure onset zone in the same patient. If that pull is weak, then it's going to spread. If that pull is strong, then we can contain the seizure where it is and prevent it from spreading,” said Dr. He in a press release.

Currently, medical professionals are aware that drug-resistant focal epilepsy is a network disease, where seizures originate at a single point then propagate throughout the entire brain, spreading alongside differing neuron oscillation frequencies. However, the exact manner in which different networks lead to the spreading of focal seizures remains a mystery.

The researchers contrasted fast and slow brain rhythms, as well as many frequencies of brain activity. They analyzed the rhythmic bands of functional networks, performing analyses of how low and high brain rhythms interact. They used a recently popularized technique known as cross-frequency directionality to analyze 24 focal drug-resistant epilepsy patients. In doing so, they discovered that propagation of seizures in the brain is dependent on a so-called push-pull antagonism control mechanism, which may indicate connections in the epileptic network and may also suppress the seizures.

Dr. He explained, "This finding will have important implications, and suggests that future treatment options should consider interventions not only upon seizure onset zones, but also the surrounding tissues. Further delineation of critical network nodes may assist the development of treatments for epilepsy using neuromodulation."