We want to address the following questions:How reliable is EEG-fMRI for epileptic source localization in difficult cases?Is EEG-fMRI able to replace intracranial EEG studies?
ID
Source
Brief title
Condition
- Seizures (incl subtypes)
Synonym
Research involving
Sponsors and support
Intervention
Outcome measures
Primary outcome
Cortical area (gyral location, surface delineation) of the epileptic source.
Difference (location, surface) between predicted source with EEG-fMRI and gold
standard (intracranial EEG).
Secondary outcome
Successful seizure outcome after 1 year postresection.
Background summary
Epilepsy surgery is an effective treatment for patients with focal epilepsy who
do not respond to anti-epileptic drugs. In the Netherlands, the National Dutch
Taskforce on Epilepsy Surgery deals with all applications for epilepsy surgery,
and consists of the 4 epilepsy centres and 3 academic hospitals. The UMC
Utrecht is the oldest and still most important surgical centre. The Taskforce
has a fixed diagnostic work-up for all patients and a central database that is
supported by the UMC.
Essential to epilepsy surgery is the localization of the epileptic focus in the
brain. In problematic cases, MRI, EEG findings and clinical seizure description
do not converge and the localization of the focus is unclear. This often leads
to further diagnostic tests (PET, ictal SPECT) and ultimately seizure
monitoring using intracranial (implanted, subdural) electrodes. In spite of
many technical advances, there still is a continuing need for such invasive
recordings.
We recently introduced in the Netherlands a new technique of epileptic source
localization, so-called EEG-correlated functional MRI (EEG-fMRI; see METC
04-276). The technique is based on detecting the BOLD effect (Blood Oxygen
Level Dependent) by MRI. Differences in magnetic properties of oxygenated
versus desoxygenated haemoglobin lead to signal intensity changes with (focal)
brain activity. Therefore, an activated versus and inactivated state has to be
defined. Only after averaging and statistical leveling the very small
differences can be visualized. Until recently, fMRI paradigms consisted of
repetitive tasks performed by a person at command. This cannot be used for
epileptic activity which by definition occurs at random and can only be
detected by EEG. Using the technical innovation that makes it possible to
record EEG within the MRI scanner, it is possible to combine both and do
off-line analysis with the occurrence of interictal spikes in the EEG as a
trigger (activated state) for fMRI.
Using this technique we first investigated patients who had been rejected for
epilepsy surgery (METC 05-250). This led to new insights in a number of these
patients, and reconsideration of epilepsy surgery in a few of them. The current
study is a logical step towards validation of EEG-fMRI as a source localizing
tool, by comparing its results with the gold standard of intracranial EEG.
Study objective
We want to address the following questions:
How reliable is EEG-fMRI for epileptic source localization in difficult cases?
Is EEG-fMRI able to replace intracranial EEG studies?
Study design
All intracranial electrode implantations in the Netherlands take place in the
UMC Utrecht, in about 10 patients a year.
All these patients with focal epilepsy who are implantation candidates will be
asked to participate in the study and to undergo EEG-fMRI prior to implantation.
Results from the EEG-fMRI study will be analyzed and a source localization will
be provided, independent from the results of other tests. This source
localization will be taken into account in the planning of the electrode
placement.
After implantation, the position of the electrodes intracranially will be
determined by coregistration of postimplantation CT with preoperative 3D T1 MRI
cortical rendering. The location of the epileptic source(s) by the intracranial
recordings will be projected on the 3D T1 MRI rendering, together with the
predicted source(s) by EEG-fMRI.
Localization differences will be expressed in neurosurgical terms as gyral
distance.
Study burden and risks
EEG-fMRI has been shown to be safe and of minor discomfort. The patient only
needs to lie still. Discomfort from lying on the occipital electrodes can be
relieved by a special vacuum pillow that also fixes head position. Noise during
scanning is tempered by ear plugs.
EEG-fMRI might result in different hypotheses regarding the epileptic source,
and thus to adaptation of the implantation strategy. In some cases, this will
lead to a more extensive implantation. This is probably associated with a small
increased risk of infection and hemorrhage, the two major complications of
intracranial electrode implantations.
Heidelberglaan 100
3584 CX Utrecht
NL
Heidelberglaan 100
3584 CX Utrecht
NL
Listed location countries
Age
Inclusion criteria
all patients who are to undergo intracranial EEG evaluation (electrode implantation) in the UMCU, as part of the diagnostic protocol as decided by the National Dutch Taskforce on Epilepsy Surgery
Exclusion criteria
A lack of interictal spiking in the standard EEG, defined as less than 10 spikes per hour. Contraindications for MRI, such as claustrofobia or presence of a pacemaker etc.
Design
Recruitment
Followed up by the following (possibly more current) registration
No registrations found.
Other (possibly less up-to-date) registrations in this register
No registrations found.
In other registers
| Register | ID |
|---|---|
| CCMO | NL18352.041.07 |