Ultra snelle hersengolven bij mensen met epilepsie

Rationale:

Background: A new biomarker is needed to establish prognosis in focal epilepsy. High frequency oscillations (HFOs) seem a good candidate biomarker, but HFOs are currently used in intracranial electroencephalography (iEEG). When measured with subdural grids, this is called corticography. HFOs can also be measured non-invasively using scalp EEG and magnetoencephalography (MEG). This is a very recent discovery which needs more research before we can draw conclusions on HFOs. Non-invasive HFO analysis will improve early identification of a focal epilepsy generator, and will be available in all patients.

Hypothesis: HFOs recorded non-invasively with MEG and scalp EEG are biomarkers of ictogenesis and disease activity like iEEG HFOs.



Objective:

Primary objective of this study is to improve identification of epileptic HFOs in EEG and MEG, by using combined MEG-EEG recordings and to compare these with HFOs in corticography. Secondary objective is to study the relation of non-invasively recorded HFOs with the number of seizures and cognitive test results before and after surgery.



Study design:

Prospective observational study



Study population:

Patients with drug-resistant focal epilepsy who will undergo epilepsy surgery with intraoperative corticography in the UMCU and will get a clinical MEG registration, and patients with drug-resistant focal epilepsy who will undergo epilepsy surgery with pre-operative corticography in the UMCU, regardless whether they get a clinical MEG registration or not. All patients are six years of age or older. In total we will include 30 patients.



Intervention (if applicable):

Not applicable



Main study parameters/endpoints:

The parameter we study is HFOs. We will compare the number and distribution of HFOs recorded with different techniques (corticography and simultaneous MEG and scalp EEG), look at how the extent of brain tissue generating HFOs correlates to seizure frequency, and investigate if there is a correlation between the number of HFOs remaining after surgery and the number of postoperative seizures and cognitive functioning, and compare these measures between the different techniques.

We hypothesize that HFOs recorded non-invasively with MEG and scalp EEG are biomarkers of disease activity like iEEG HFOs

EEG and MEG will take place before surgery, right after inclusion. Surgery will follow within 2 week- 3 months and followed by MEG and EEG in 6 weeks to 6 months.

Surgical outcome and cognitive outcome are determined 1 year after surgery.

EEG, MEG and ECoG before and after resection.

EEG and ECoG are part of the standard clinical work-up.

Pre-operative MEG is part of standard clinical work-up for some patients.

Patients will undergo extra post-operative MEG and sometimes pre-operative MEG together with simultaneous EEG.