Distinct Seizure Networks involving differing thalamic nuclei after Corpus Callosotomy
Abstract number :
3.416
Submission category :
9. Surgery / 9B. Pediatrics
Year :
2025
Submission ID :
1228
Source :
www.aesnet.org
Presentation date :
12/8/2025 12:00:00 AM
Published date :
Authors :
Presenting Author: Sarah Pedroza, PA-C – Children's Hospital of Orange County
Jordan Davies, MD – Children's Hospital of Orange County
Joffre Oyala, MD – Childrens Hospital of Orange County
Donald Phillips, MD, MPH – Children's Hospital of Orange County; UC Irvine School of Medicine
Maija Steenari, MD – Childrens Hospital of Orange County, CA
Julia Hunter, BS – Children's Hospital of Orange County
Rationale: The thalamus functions as a critical relay station in the propagation of seizures within the network theory of epilepsy. Thalamic nuclei have been targeted with neuromodulation therapies, both RNS and DBS, with the specific target often chosen based upon seizure semiology and/or etiology. For example, thalamic treatment in generalized epilepsy often targets the centromedian nucleus (CM), and thalamic treatment of focal epilepsy often targets anterior nucleus of the thalamus (ANT)(Gouveia. Historically, when bilateral thalami are targeted in modulation treatment, the same nucleus is targeted on each side. Invasive stereo-encephalography (SEEG) has been used to sample bilateral thalamic nuclei in order to personalize the modulatory targets for the seizure network (Wu, 2023). In this case report, we present findings from SEEG sampling of bilateral thalami in a patient with multiple bilateral seizure foci and history of corpus callosotomy.
Methods: This case report describes a 22-year-old male with chromosome 15 duplication syndrome and LGS manifesting as medically refractory generalized tonic-clonic and myoclonic seizures starting at 7 years old. He underwent corpus callosotomy at 15, reducing seizure severity and frequency by ~50%, but daily seizures persisted. A VNS was implanted at 19, with modest initial seizure frequency reduction. Seizure frequency worsened to >10 seizures/per day. The patient underwent SEEG with 16 10-contact electrodes placed bilaterally in cortical and thalamic regions.
Results: During two days of invasive monitoring, over 80 electroclinical seizures were captured, originating independently from the right and left hemispheres, each with distinct semiology. From the left hemisphere, semiology was characterized by leftward eye deviation and stiffening of left hemibody, followed by right clonic activity with occasional evolution into generalized tonic-clonic activity. Electrographically, the seizure onset was best localized to the left SMA contacts with thalamic involvement most predominantly left CM. From the right hemisphere, semiology was characterized by rightward eye deviation and stiffening of left hemibody with secondary generalization. Electrographicallyto the right ANT> right CM > right pulvinar.
Conclusions: This is a 22-year-old male with medically refractory epilepsy consistent with LGS, status post corpus callosotomy and VNS, who underwent SEEG monitoring. Results show independent seizure networks from the left and right hemispheres with distinct semiology, onset, and thalamic involvement. The left hemisphere seizures relayed predominantly through CM and the right hemisphere seizures relayed predominantly through ANT. It is possible that the previous corpus callosotomy allowed SEEG resolution of these networks, which otherwise may have been obscured by rapid secondary generalization. This case suggests possible utility in bilateral thalamic SEEG sampling, to better define individualized seizure networks, which may guide tailored neuromodulation strategies in complex and/or multifocal epilepsies.
Funding: None
Surgery