Evaluation of ANT-DBS Neuromodulation with Sensing Electrodes (EANSkE)

In patients with medically refractory epilepsy who are not eligible for
surgical treatment, neuromodulation including deep brain
stimulation (DBS) remains as a last resort. However, a good response (> 50%
seizure reduction) is achieved in only approximately
70% of patients.
To date, the effects of the stimulation parameters (voltage, frequency, pulse
width, and cycling on stimulation) are still poorly understood and no *optimal*
set of stimulation parameters is defined. Optimizing stimulation settings for
each patient individually is an important aspect of DBS for epilepsy.
Currently, this is a very complex task and adjustment of stimulation parameters
is based on trial and error and heavily rely on patient seizure diaries. Until
now, no biomarkers exist that can guide in this procedure. Recent advances in
DBS hardware allow recording of the local field potentials (LFPs) of the
neuronal tissue around the electrode. We hypothesize that the combination of
this technique with network analysis of resting state fMRI and 64-channel EEG
can provide insight in the brain circuits involved in the disturbed brain
dynamics and can result in a significant improvement in response evaluation of
individual patients with DBS for epilepsy. Analyzing the direct response to DBS
stimuli in the EEG (DBS evoked potentials) can also contribute to this.

The primary goal of the study is to identify biomarkers from LFPs recorded from
the DBS electrodes that are associated with treatment response to DBS in
patients with epilepsy. If these biomarkers exist, these can potentially be
used to guide treatment therapy as an alternative of seizure diaries in future
patients.

We propose a prospective observational cohort study.

The risks of participating in this observational study are very minimal. The
study has no influence on the implantation of the DBS system nor on programming
the stimulation settings.
Patients will be followed starting from 2 months pre-operative until 24 months
postoperative. LFPs will be recorded from the implanted DBS electrodes 1 or 2
days post-operative (during hospital admission) and at 6 additional study
visits (1,3,6,12,18 and 24 months postoperative).
Reading-out LFPs from DBS electrodes that already are implanted, can be
performed contactless and is without any risk for the patient.
In addition, we will record 64-channel EEG at baseline (before DBS
implantation), 1 or 2 days postoperative (during hospital admission), and at 12
and 24 months postoperative. During the EEGs recorded at 12 and 24 months
follow-up, the DBS settings will be varied to eanable measuring DBS evoked
potentials. MRI scans (anatomical, DTI and fMRI) will be made twice, at
baseline and 12 months postoperative. Patients will be asked to keep diaries of
their perceived seizures during the study period. We will also ask all patients
to fill four questionnaires about psychological well-being at baseline and at
12 and 24 months post-operative.
If we can find biomarkers that can be used in the evaluation of treatment
response to DBS therapy these can be used for optimal individual DBS
programming in future patients. Therefore, the risk and burden for the
participating capacitated adults are in proportion with the potential value of
the study,