Characteristics of Ictal Thalamic EEG in Pediatric-onset Neocortical Focal Epilepsy
Abstract number :
1.161
Submission category :
3. Neurophysiology / 3C. Other Clinical EEG
Year :
2022
Submission ID :
2204041
Source :
www.aesnet.org
Presentation date :
12/3/2022 12:00:00 PM
Published date :
Nov 22, 2022, 05:23 AM
Authors :
Benjamin Edmonds, MD – UCLA; Makoto Miyakoshi, Ph.D. – Assistant Project Scientist, Institute for Neural Computation, UC San Diego; Samuel Ahn, MD – Epilepsy Fellow, UCLA; H. Westley Phillips, MD – Chief Resident, Neurosurgery, UCLA; Raman Sankar, MD, PhD – Chief of Pediatric Neurology, Pediatric Neurology, UCLA; Aria Fallah, MD, MS – Pediatric Neurosurgeon, Neurosurgery, UCLA; Joyce Matsumoto, MD – Interim Chief of Pediatric Neurology, Pediatric Neurology, UCLA; Hiroki Nariai, MD, PhD – Assistant Professor, Pediatric Neurology, UCLA
Rationale: There is increasing interest in targeting the thalamus with neurostimulation in patients with medication-resistant epilepsy. However, utilization of responsive neurostimulation (RNS) requires accurate detection of ictal activity. Therefore, in this study, we investigated ictal EEG changes in the centromedian (CM) and anterior nucleus (AN) of the thalamus in pediatric-onset neocortical focal epilepsy.
Methods: Patients with pediatric-onset medication-resistant neocortical epilepsy who underwent intracranial stereotactic EEG study with thalamic coverage were identified. Ictal EEG changes at the thalamic channels during habitual seizures were analyzed with both visual and quantitative computational analyses in a bipolar configuration. Cortical onset was defined by expert visual analysis. Ictal thalamic EEG onsets of beta and gamma frequencies were quantified relative to cortical onset using amplitude analysis. Statistically significant augmentation was called when the amplitudes exceed over mean plus two standard deviations than baselines, defined as 60 to 30 seconds prior to the cortical onset.
Results: Forty habitual seizures were analyzed across nine patients (age at thalamic recording 2-25 yo, median age 18 yo, 4 males, 5 females). Seizure types included epileptic spasms, focal motor, startle induced myoclonic, focal tonic, focal impaired awareness, and focal motor to bilateral tonic-clonic. Seizures with bilateral onset were noted in 3 patients. On visual analysis (Figure 1), there were ipsilateral EEG changes seen in nearly all seizures at the CM nucleus by 97% (29/30), while 86% (31/36) of seizures at the AN showed ictal changes. In the contralateral CM, 100% (4/4) of seizures showed ictal EEG changes, while in the contralateral AN, 71% (5/7) of the seizures showed ictal EEG changes. The most common thalamic ictal EEG change was low-voltage fast activity (76%). With quantitative EEG analysis (Figure 2) of 38 habitual seizures, statistically significant augmentation of ictal beta (gamma) activity was noted by 93.9% (84.8%), 83.3% (50.0%), 100.0% (90.9%), and 83.3% (100%) at the ipsilateral CM, contralateral CM, ipsilateral AN, and contralateral AN respectively. The mean onset latencies (in seconds) [and 95% CI] of beta activity relative to the cortical onset was -2.5 [-12.0 to 20.6], 13.2 [-53.5 to 32.2], 0.53 [-6.3 to 15.5], and -5.3 [-20.1 to 7.1] at the ipsilateral CM, contralateral CM, ipsilateral AN, and contralateral AN, for gamma activity, it was -4.1 [-8.0 to 7.9], -11.7 [-39.9 to 5.9], -0.35 [-8.4 to 17.3], and 2.0 [-25.3 to 16.2] respectively. Six of nine patients subsequently received RNS implant (3 cortical, 2 bithalamic CM, 1 cortico-thalamic coverage).
Conclusions: We demonstrated that the ictal thalamic EEG changes were consistently observed in AN and CM. Our findings suggest that thalamic recording reliably detects habitual seizures around the timing of the cortical onset, indicating thalamic stimulation using RNS (closed-loop system) is feasible in this population.
Funding: Epilepsy Foundation Greater Los Angeles, UCLA Children’s Discovery and Innovation Institute, NINDS 5R01NS047293-16, Gift by The Swartz Foundation
Neurophysiology