Changes in intracortical excitability after successful epilepsy surgery
Claus Henning Läppchen1, Bertram Feil, Susanne Fauser
1Epilepsy Centre, University Hospital Freiburg, Breisacher Str. 64, D-79106 Freiburg, Germany.
Epilepsy Research
|February 26, 2008
Summary
Epilepsy surgery alters brain networks, affecting inhibition and excitability remotely. These changes, measured by transcranial magnetic stimulation, highlight the widespread impact of epileptic foci removal.
Area of Science:
- Neuroscience
- Epileptology
- Clinical Neurophysiology
Background:
- Interictal activity from epileptic foci can cause remote brain effects.
- The impact of epilepsy surgery on cortical networks is not well understood.
Purpose of the Study:
- To assess changes in intracortical inhibition and excitability after successful epilepsy surgery.
- To investigate remote effects of epileptic foci and their surgical removal.
Main Methods:
- Focal transcranial magnetic stimulation (TMS) was used in 22 patients before and after surgery.
- Measured parameters included motor thresholds (MT), contralateral cortical silent periods (CSP), and motor evoked potential (MEP) amplitudes.
- Stimulation was performed on both focal and non-focal hemispheres.
Main Results:
- Postsurgical MT was higher in the focal hemisphere compared to the non-focal hemisphere.
- Contralateral cortical silent periods (CSP) were shorter in the non-focal hemisphere postsurgically.
- Paired-pulse stimulation showed reduced motor evoked potential (MEP) amplitudes in the non-focal hemisphere postsurgically.
Conclusions:
- Epilepsy surgery significantly alters brain inhibition and facilitation, particularly in the non-focal hemisphere.
- Transcranial magnetic stimulation provides evidence for remote network changes following epileptic focus removal.
- These excitability changes may relate to functional impairments in focal epilepsy patients.
