Epilepsy surgery: Exactly defining the operation area
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Detecting better techniques

Taking away brain tissue is extremely precarious work. When such a procedure is done, the neurosurgeon must know exactly where to safely remove what tissue. For patients for whom epilepsy surgery might be an option, seizure detection – a lengthy and extensive EEG examination in combination with continuous video monitoring – is one of the first steps in the often long preparatory process on the road to possible brain surgery. An MRI-scan and neuro-psychological examinations are also part of the process. For many patients, these examinations offer insufficient certainty to determine if and how epilepsy surgery could be done. In these cases, more complex techniques are required.

Specialists in Kempenhaeghe aim to refine examination methods and combinations thereof. Goal is to – as exactly as possible - define the location in the brain that must be operated on in order to get the patient free of seizures, using as few invasive procedures as possible. Multiple scientific research projects currently focus on this subject. Part of these is initiated by the Academic Center for Epileptology. In other, often international projects, the Center participates.

An interesting project is the cooperation of Kempenhaeghe specialists with ScanNexus and experts of the University of Technology Eindhoven. In part of the patients for whom there is a clear idea of where the epilepsy originates, no deviations are found on the MRI images. Studies are currently underway to determine if more subtle deviations can be made visible when stronger MRA magnets are being used and/or automated post-processing is done.

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Improving and linking EEG and MRI

Interesting is the simultaneous deployment of EEG and functional MRI. It already takes place on a small scale as part of pre-surgical examinations. After technical problems were overcome, the two technologies can now be linked. As a result, epileptic discharges in the EEG are related to changing brain activity measured with functional MRI. The advantage of this combination is that it allows to search deep in the brain for the source of the epileptic discharges. This makes this combination a powerful instrument for preparing deep registrations (also called stereo-EEG or intracranial registration). Scientific research into this subject is also underway.

The combined application of EEG-MRI requires further improvement, as artefacts appear. These are ‘false’ outcomes cause by electrical disturbances that are the result of movement of the wires, or the patient’s breathing or heartbeat. Projects with, amongst others, the University of Technology Eindhoven aim to reduce this noise.

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The meaning of MEG

EEG examinations are still the golden standard in the diagnosis of epilepsy. But in some patients, it results in a diffuse image, when the brain activity is hard to follow. A magneto-encephalogram (MEG) may be an alternative to localize the epilepsy source.

A large-scale patient study of the Amsterdam Universitair Medisch Centrum – where the MEG center is located -, the Academic Center for Epileptology Kempenhaeghe, the Universitair Medisch Centrum Utrecht, the University Maastricht and SEIN shows that MEG can better localize the epilepsy source than EEG. This technology can thus contribute to more efficient, cost-effective and patient-friendly diagnostics.

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Studies on new treatment methods

In addition to scientific research on determining the epilepsy source, researchers also work on related studies on new treatment methods for people who do not qualify for epilepsy surgery.

An example is Deep Brain Stimulation, an already known treatment method that, however, has only been used for epilepsy since a few years. At this moment this treatment is possible in ACE Kempenhaeghe/MUMC+ only.

Another example is thermo-coagulation, a relatively new and unknown treatment method in the Netherlands. Together with Maastricht UMC+, Kempenhaeghe has considerable experience with this method in the Netherlands. The advantage of thermo-coagulation is that a complex extra brain operation is unnecessary. Before the treatment, electrodes are placed in various directions deep in the brain, as part of already scheduled diagnostics. Via this so-called stereo EEG deviations in the brain are localized exactly. This search may take several weeks. When it is determined where the lesions are that cause the epilepsy, the areas that cause the epilepsy, deep in the brain, can in some patients be turned off by dispensing current. Directly after this, we measure if the epileptic brain activity had disappeared and the electrodes are removed.