Thalamic Recordings in Children Undergoing SEEG

ConditionFocal Epilepsy

Trial statusRecruiting

Trial phaseNot applicable

Trial typeInterventional

Biological sexAll

Age2-20

SponsorGreat Ormond Street Hospital for Children NHS Foundation Trust

About this trial

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.

Eligibility criteria

This trial does not accept healthy volunteers

Qualifiers

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

Participants/parents/legal guardian provide informed consent for inclusion

Disqualifiers

None

Trial design

Design model

Single group

Treatments tested in this trial

Additional electrodes into bilateral anterior, centromedian and pulvinar thalamic nuclei
Procedure/Surgery
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.

Treatment groups

30 Participants

are divided into 1 treatment group

Group A: Thalamic SEEGExperimental treatment 1 intervention

Trial outcomes

Primary outcomes

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.

Time frame