POTENTIAL CONTRIBUTION OF BILATERAL MAGNETIC SOURCE IMAGING TO THE EVALUATION OF EPILEPSY SURGERY CANDIDATES

THE CURRENT PROCEDURES that are used to evaluate candidates for epilep sy surgery are time-consuming, costly, and often invasive. Magnetic so urce imaging (MSI), the combination of magnetoencephalography and anat omic imaging modalities, has shown promise as an efficient noninvasive means of localizing and characterizing seizure sources for possible r esection. However, MSI has been limited by the inability to conduct si multaneous bilateral monitoring. In this study, a newly developed dual -magnetometer system was employed to record bilaterally the interictal activity in 30 candidates for epilepsy surgery. A standard monitoring protocol that included concurrent electroencephalographic recording a nd required a 2- to 3-hour examination period for each patient was dev eloped. As a first step in a series of studies, the resultant MSI indi cations were compared with the information available from standard mag netic resonance imaging and concurrent electroencephalographic results . In 83% of the cases, this MSI protocol provided new information abou t the location of interictal epileptic activity that could be directiv e for subsequent patient care. Based on these results, it seems that M SI may become a cost-effective early step in epilepsy surgery evaluati on. To continue the development on this basis, a study intended to val idate the accuracy of MSI indicated by comparison with invasive electr oencephalography has been initiated.