Thalamic Recordings in Children Undergoing SEEG

NCT06453759 | Recruiting

• 1 other identifier: 23BI31
• Study Type: interventional
• Target: 30
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Focal Epilepsy

Outcome Measures

Primary Outcomes (4)

• Ictal thalamic involvement

  Experienced neurophysiologists will assess, during ictal activity, whether each of the nuclei are involved in the seizure and, if so, the latency between first cortical contact onset and thalamic nucleus onset.

  Hospital discharge (maximum one month from SEEG implantation)

• Epileptogenicity index

  We will quantify ictal involvement by measuring the epileptogenicity index in each nucleus.

  Hospital discharge (maximum one month from SEEG implantation)

• Interictal power distribution

  To assess interictal signatures, we will assess power at different frequencies in the nuclei using the 'fitting oscillations \& one over f' (FOOOF) method.

  Hospital discharge (maximum one month from SEEG implantation)

• Single pulse electrical stimulation (SPES):

  We will systematically conduct SPES from all cortical and thalamic contacts and record responses in all other contacts. This measures the effective connectivity.

  Hospital discharge (maximum one month from SEEG implantation)

Secondary Outcomes (1)

• Incidence of bleeding

  Hospital discharge (maximum one month from SEEG implantation)

Study Arms (1)

Thalamic SEEG

EXPERIMENTAL

The centromedian, anterior and pulvinar nuclei on each side will be chosen as target for new electrodes.

Procedure: Additional electrodes into bilateral anterior, centromedian and pulvinar thalamic nuclei

Interventions

Additional electrodes into bilateral anterior, centromedian and pulvinar thalamic nuclei PROCEDURE

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 high (130Hz) and low (6Hz) frequency DBS currents from each pair of thalamic nuclei (always bilateral) and record spontaneous interictal neuronal activity in all other cortical contacts for 15 minutes. We will also record SPES from each of the cortical contacts.

Thalamic SEEG

Eligibility Criteria

• Age: 2 Years - 20 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64)

You may qualify if:

• All children undergoing SEEG as part of their pre-surgical evaluation at GOSH

You may not qualify if:

• \) Lack of informed consent

Sponsors & Collaborators

• Great Ormond Street Hospital for Children NHS Foundation Trust: lead

Study Sites (1)

Great Ormond Street Hospital for Children

London, WC1N 3JH, United Kingdom

RECRUITING

MeSH Terms

Conditions

Epilepsies, Partial

Condition Hierarchy (Ancestors)

Epilepsy; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases

Central Study Contacts

Aswin Chari, PhD

CONTACT

07726780817; aswin.chari.18@ucl.ac.uk

Martin Tisdall, MD

CONTACT

martin.tisdall@gosh.nhs.uk

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: May 24, 2024
• First Posted: June 12, 2024
• Study Start: September 1, 2025
• Primary Completion (Estimated): August 1, 2028
• Study Completion (Estimated): December 1, 2028
• Last Updated: February 2, 2026

Record last verified: 2026-01

Locations

GB (1)