Combining MEG and MRI with neuronavigation for treatment of an epileptiform spike focus in the precentral region: a technical case report.
BACKGROUND
Epileptic foci are often located in the vicinity but not necessarily within the boundaries of intra-axial brain tumors. Resection of these tumors is based on two major goals: first, maximizing tumor removal without provoking new neurologic deficits, and second, minimizing epileptic seizure activity. Magnetic source imaging (MSI) depicts the generators of magnetic fields overlaid on individual magnetic resonance (MR) images. Established application areas are lesions located adjacent to or partly within the sensory and motor cortex, or in the depth of the brain, necessitating a surgical approach through functionally highly relevant cortical regions. Magnetoencephalography (MEG) is also applicable for epileptiform spike foci recording during interictal activity.


METHODS
A patient with a recurrent glioma close to the Rolandic cortex scheduled for epilepsy and tumor surgery was investigated with MSI. The MSI data showed an epileptiform spike focus outside the tumor boundaries. The resulting MSI images were integrated into our neuronavigation system. This procedure allowed for the preoperative identification of the sensory and motor cortex, the precise localization of the epileptiform spike focus, and careful planning of the surgical procedure. In this case, we were able to safely resect the recurrent tumor and the epileptiform spike focus under general anesthesia using MSI-based neuronavigational guidance but no conventional intraoperative mapping techniques.


CONCLUSIONS
Magnetic source imaging can be a valuable, noninvasive method for planning and performing tumor resections in high-risk brain regions, especially if an epileptiform spike focus has to be localized and included into the resection strategy.
Duffner
Frank
F
University Hospital for Neurosurgery, Hoppe-Seyler-Strasse 3, D-72076 Tubingen, Germany.
Freudenstein
Dirk
D
Schiffbauer
Hagen
H
Preissl
Hubert
H
Siekmann
R
R
Birbaumer
Niels
N
Grote
Ernst H
EH
D001932:Brain Neoplasms / Q000150:complications / Q000175:diagnosis / Q000601:surgery*; D004827:Epilepsy / Q000209:etiology*; D005910:Glioma / Q000150:complications / Q000175:diagnosis / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation