The use of a technique known as responsive neurostimulation (RNS) can help to treat epilepsy. RNS detects the oncoming seizures and uses an electrical current as a means to stop that seizure from developing. Patients that utilize RNS find that they tend to have fewer seizures. This technique has been used for some time, but it is only recently that researchers have been able to develop a better understanding of just why this happens.
Researchers at the University of Pittsburgh School of Medicine and the University of Pittsburgh Medical Center have recently reported some new evidence in the field. A report in JAMA Neurology from the researchers found that RNS has the power to remodel the brain, making it less likely that the patient will have seizures. The researchers were looking at the brain signatures of these patients and were using them as a guide. The goal is to be able to optimize the use of neurostimulation as a means of treating other patients, helping them to reduce the number of seizures they are suffering.
One of the researchers, Mark Richardson, MD, Ph.D., an associate professor at Pittsburgh’s School of Medicine, has said that currently, doctors simply wait to see whether the patients’ seizures drop after neurostimulation. He says that there is not a way to predict who will respond to this type of treatment and that there is “currently much more data recorded on these RNS devices than we currently have the ability to analyze.”
Patients who have received the RNS implant will have their baseline brain activity recorded for a month. This is so that the doctors will be able to get a better understanding of characteristics of the patient’s seizure patterns. Then, they use the information that has been gathered to “train” the RNS device, so that it can respond properly when there is a seizure initiating.
Researchers believed that they would find the electrical stimulation would acutely stop the seizure. That’s not what they discovered though. They saw that this happened in only about 5% of the samples. However, it wouldn’t explain the 60% to 70% of patients who were responding to the treatment.
They developed a theory that the stimulation was able to change the neuron networks in the brain instead. They believe that the changes help to ensure that full seizures will not occur, at least not as often. Richardson said, “In epilepsy, brain networks get recruited to fire hyper-synchronously. What we think we’re doing when we stimulated is to desynchronize, over time, making it harder for the whole seizure network to come online.”
The lead author on the study, Vasileios Kokkinos, Ph.D., who is a neurosurgery instructor, wanted to test the hypothesis. The researchers from the Brain Modulation Laboratory compiled RNS data from 11 patients who suffered from focal epilepsy. They were treated at the University of Pittsburgh Comprehensive Epilepsy Center between 2015 and 2017 and were followed for up to two years.