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Contact: Julie Poupart
info@can-acn.org
Canadian Association for Neuroscience

New imaging techniques used to help patients suffering from epilepsy

Toronto, May 23 2013 - New techniques in imaging of brain activity developed by Jean Gotman, from McGill University's Montreal Neurological Institute, and his colleagues lead to improved treatment of patients suffering from epilepsy. The combination of electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) leads to more precise localization of the areas generating epileptic seizures, giving neurosurgeons a better understanding of the optimal ways of intervention, if appropriate. These results were presented at the 2013 Canadian Neuroscience Meeting, the annual meeting of the Canadian Association for Neuroscience - Association Canadienne des Neurosciences (CAN-ACN).

Epilepsy is a brain disorder in which a person has repeated seizures. These seizures are episodes of abnormal brain activity, in which the brain sends out abnormal signals. Seizures can often be controlled using medication. In an estimated 40% of patients, however, drugs do not control seizures well, and for some of these people surgery to remove the abnormal brain cells that cause the seizures can be considered.

Before brain surgery can be performed, doctors and surgeons must determine if the point of origin of the seizures, which can be viewed as brain activity spikes, is discrete, and if it can be removed without damaging other important brain areas. Dr. Gotman and his colleagues developed a new imaging technique, combining EEG, which delivers excellent information on the timing of the spikes but is not always capable of precisely locating the source of the discharge, with fMRI, which allows to very precisely localize this activation in the brain.

EEG- fMRI, while technically challenging, since the strong magnetic field required for fMRI can interfere with the recording of the minute electrical currents emitted by brain cells, is useful for patients in whom precise localization of the focal point, or point of origin of seizures, was not well defined. It is also important for a better understanding of how epileptic discharges affect brain function.

Citation from Dr. Gotman: "Combing EEG and fMRi is a unique method to define non-invasively in the whole brain the regions involved in epileptic discharges. It is a complex tool but it is likely to play an increasing role among the methods currently used to localize the source of epileptic activity"

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This research is supported by the Canadian Institutes of Health Research.

About the Canadian Association for Neuroscience:

The Canadian Association for Neuroscience is the largest association dedicated to the promotion of all fields of neuroscience research in Canada. The association has been organizing a yearly annual meeting since 2007. Learn more about our meeting at: http://www.can-acn.org/meeting2013

Please contact Julie Poupart, Communications Director for the Canadian Association for Neuroscience, for further information, to receive a press pack, or to request an interview with a neuroscientist

Facts:

Approximately 0.6% of the Canadian population has epilepsy. Each year, an average of 15,500 people learn that they have epilepsy. Seventy-five to eighty percent of patients are diagnosed before the age of 18, 55% before the age of 10, and 44% before age 5.

EEG: Electroencephalography is a test to measure the tiny electrical signals that brain cells use to communicate with one another. These signals are also called impulses. fMRI: The functional Magnetic Resonance Imaging technique used by Dr Gotman relies on the fact that the magnetic properties of hemoglobin, the molecule carrying oxygen in blood, differ when it is carrying oxygen (a form called oxyhemoglobin, nonmagnetic) and after it has "delivered" oxygen to cells (a form called deoxyhemoglobin, magnetic). When a brain region is activated, it uses oxygen and the concentration of deoxyhemoglobin initially increases, before being compensated by an increase in blood flow, resulting in a decrease in deoxyhemoglobin. These differences can be very precisely localized by fMRI. This method is known as BOLD contrast, which stands for Blood Oxygen Level-Dependent contrast.

References:

Dr. Jean Gotman's website: http://apps.mni.mcgill.ca/research/gotman/

Recent publications by Dr. Gotman: http://www.ncbi.nlm.nih.gov/pubmed/?term=gotman+j%5BAuthor%5D

Epilepsy Canada, Epilepsy Facts webpage: http://www.epilepsy.ca/en-CA/Facts/Epilepsy-Facts.html)

Epilepsy: http://www.nlm.nih.gov/medlineplus/ency/article/000694.htm)

fMRI: http://www.radiologyinfo.org/en/pdf/fmribrain.pdf

EEG: http://www.nlm.nih.gov/medlineplus/ency/article/003931.htm



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