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Post-Ictal Rhythmic Thalamic Activity in the Central Media Nucleus May Play a Role in Seizure Termination in Drug-Resistant Epilepsy

Post-Ictal Rhythmic Thalamic Activity in the Central Media Nucleus May Play a Role in Seizure Termination in Drug-Resistant Epilepsy 1024 677 Jessica Nye, PhD

Investigators from Nationwide Children’s Hospital are the first to describe post-ictal rhythmic thalamic activity (PIRTA) in the central media nucleus (CMN) during focal onset seizure.

“When this paper was published, it was a period where understanding the role of the center of the thalamus and seizures was a novel thing,” says senior author Ammar Shaikhouni, MD, PhD, surgical director of the Epilepsy Surgery Program at Nationwide Children’s and assistant professor at The Ohio State University (OSU) College of Medicine. “The thalamus, which lies in the middle of the brain and has a role in sleep and coordination of activity along the entire cortex, could be a hub for seizure networks. In theory, we could potentially treat seizure by interfering with the seizure activity that passes through it, or is coordinated by it.”

In a paper published in the Journal of Clinical Neurophysiology by lead author Kristen Arredondo, MD, the investigators recruited five patients with drug-resistant epilepsy and bilateral or hemibody tonic-clonic seizures who underwent stereo-electroencephalography monitoring between 2020 and 2021.

All of the patients had frontal-onset seizures that progressed to full body seizures. A rhythmic activity at 1.5 to 2.5 Hz delta frequency was observed in the CMN during seizure termination and the suppression of background activity.

“When the seizure starts, it may start in one spot, but once it gets into the thalamus we found out that it generalizes across the entire brain, and at the end of the seizure, we saw what we call the post-ictal rhythmic thalamic activity,” says Dr. Shaikhouni.

Given these observations, the study authors speculate that the CMN could have a role in seizure termination and/or recovery, making it a potential candidate as a target for deep brain stimulation (DBS).

“There’s a large unmet need for patients who continue to have debilitating seizures despite trying different medicines. The CMN potentially provides hope for giving them better seizure control,” says second author Adam P. Ostendorf, MD, medical director of the Epilepsy Surgery Program at Nationwide Children’s and associate professor at OSU College of Medicine. “But we still don’t know a lot about how best to use it. This paper describes a very unique, and potentially important activity in the thalamus. I think we need more articles like this that describe what’s going on in there. Our goal is to try to better understand and predict which patients are going to benefit or do worse with DBS.”

Research into the role of the CMN in drug-resistant epilepsy has continued at Nationwide Children’s since the publication of this paper online in 2023.

Dr. Shaikhouni concludes, “We’re still in the infancy of understanding how we can use DBS to change the course of disease. It’s taken us five years to get 25 patients studied so far. I think we need a lot of data from a lot of sites so we can give patients better odds so that they can make better decisions. Nationwide Children’s is a great place [for this research] because of the collaboration with people inside and outside the institution who have interest in the role of cortical thalamic circuits in both normal and abnormal physiology.”

 

Reference:

Arredondo K, Ostendorf AP, Ahrens S, Beatty CW, Pindrik J, Shaikhouni A. Post-ictal Rhythmic Thalamic Activity of the Centromedian Nucleus. Journal of Clinical Neurophysiology. 2024:1;41(4):326-333.

Image credit: Adobe Stock

About the author

Jessica Nye, PhD, is a freelance science and medical writer based in Barcelona, Spain. She completed her BS in biology and chemistry and MS in evolutionary biology at Florida State University. Dr. Nye studied population genetics for her doctorate in biomedicine at University of Pompeu Fabra. She conducted her postdoctoral research on the inheritance of complex traits at the Autonomous University of Barcelona.