Thalamic Recordings in Children Undergoing SEEG

Overview

Stereoelectroencephalography (SEEG) forms a key part of the pre-surgical evaluation in children who may be candidates for epilepsy surgery. It can help delineate the location of the putative epileptogenic zone, guiding further treatments including resective, disconnective and ablative epilepsy surgery techniques. However, less than 35% of children undergoing SEEG end up becoming seizure free following further treatment. Open and closed loop stimulation of thalamic nuclei via deep brain stimulation (DBS) and responsive neurostimulation (RNS) are emerging treatment options for epilepsy. Thalamic target nuclei vary between studies and there are currently no gold standard personalised methods for choosing a target. This stems from the limited systematic neurophysiological recordings from thalamic nuclei; investigators currently do not understand the ictal and interictal thalamic signatures of involvement in epilepsy and do not understand how functional connectivity can be altered within and between patients. In this prospective study, the investigators aim to recruit 30 patients undergoing SEEG as part of their pre-surgical evaluation for drug resistant epilepsy at Great Ormond Street Hospital over a period of 3 years. Once recruited, the investigators will target 3 nuclei bilaterally in each patient - the anterior, centromedian and pulvinar nuclei - using additional SEEG electrodes. Following clinical recording, the investigators will conduct two stimulation experiments, the first using single pulse electrical stimulation to measure effective connectivity between the thalamus and cortical regions and the second to study the effects of simulated DBS currents on cortical local field potential signatures. This study will lay the foundation for a personalised approach to thalamic neuromodulation for drug-resistant epilepsy by identifying neurophysiological biomarkers of thalamic involvement in epilepsy, paving the way for closed loop neuromodulation strategies that aim to optimise response using these biomarkers.

Interventions

• Procedure Additional electrodes into bilateral anterior, centromedian and pulvinar thalamic nuclei
  The centromedian, anterior and pulvinar nuclei on each side will be chosen as target for new electrodes; up to 6 additional electrodes may be added but, where possible, existing electrode trajectories will be extended to facilitate recording. At the beginning of the recording process, usually within the first 24-48 hours of implantation, we will conduct 2 study-specific stimulation experiments: 1. Single pulse electrical stimulation (SPES): 2. N-of-1 trials of simulated DBS: We will simulate h

Primary outcome measures

• Ictal thalamic involvement [Time frame: Hospital discharge (maximum one month from SEEG implantation)]
• Epileptogenicity index [Time frame: Hospital discharge (maximum one month from SEEG implantation)]
• Interictal power distribution [Time frame: Hospital discharge (maximum one month from SEEG implantation)]
• Single pulse electrical stimulation (SPES): [Time frame: Hospital discharge (maximum one month from SEEG implantation)]

Secondary outcome measures (1)

• Incidence of bleeding [Time frame: Hospital discharge (maximum one month from SEEG implantation)]

Eligibility criteria

Inclusion criteria

• All children undergoing SEEG as part of their pre-surgical evaluation at GOSH
• Participants/parents/legal guardian provide informed consent for inclusion

Exclusion criteria

1\) Lack of informed consent

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

N/A

Model

Single group

Masking

Open label

Primary purpose

Basic science

Study locations

United Kingdom · 1 center

• Great Ormond Street Hospital for Children — London

Identifiers

NCT: NCT06453759 · 23BI31

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗