Value of electroencephalography/functional magnetic resonance imaging localizing epileptic foci in focal epilepsy

Abstract

To explore the diagnostic value of simultaneous electroencephalography/ functional magnetic resonance imaging ( EEG-fMRI) for epileptic foci in focal epilepsy of normal brain structure. The normal structural images of EEG-fMRI and resting state-fMRI (RS-fMRI) with 3. OT high-field MR system were performed for 15 focal epileptic patients from April 2013 to July 2014. On EEG-fMRI, epileptiform discharges were regarded as nerve stimulation. And off-line analysis yielded the blood oxygen level-dependent (BOLD) responses related to epileptiform discharges. The relationship was analyzed between BOLD activation reaction and electroencephalography-clinical symptomatology position. And the electroencephalography-clinical symptomatology position was selected as a major indicator of judging the degree of concordance. The involved lobes were temporal (n = 7), frontal (n = 5) and frontotemporal (n = 3). On EEG-fMRI, all patients demonstrated BOLD responses related to epileptiform discharges. Compared with electroencephalography-clinical symptomatology position, 12 cases (12/15) were fully concordant and 3 cases (3/15) partially concordant. Three patients had BOLD responses in accordance with electroencephalography-clinical symptomatology position on RS-fMRI. And the detection rate of BOLD responses was higher for EEG-fMRI than that for RS-fMRI. The BOLD responses related to epileptiform discharges may help locate noninvasively the epileptogenic region of focal epilepsy and provide additional useful information for preoperative evaluations of epilepsy.