Reproducibility of EEG–fMRI Results in a Patient With Fixation-Off Sensitivity

Abstract

Blood oxygenation level-dependent (BOLD) activation associated with interictal epileptiform discharges in a patient with fixation-off sensitivity (FOS) was studied using a combined electroencephalography-functional magnetic resonance imaging (EEG-fMRI) technique. An automatic approach for combined EEG-fMRI analysis and a subject-specific hemodynamic response function was used to improve general linear model analysis of the fMRI data. The EEG showed the typical features of FOS, with continuous epileptiform discharges during elimination of central vision by eye opening and closing and fixation; modification of this pattern was clearly visible and recognizable. During all 3 recording sessions EEG-fMRI activations indicated a BOLD signal decrease related to epileptiform activity in the parietal areas. This study can further our understanding of this EEG phenomenon and can provide some insight into the reliability of the EEG-fMRI technique in localizing the irritative zone.

Assessment of Event-Related EEG Power After Single-Pulse TMS in Unresponsive Wakefulness Syndrome and Minimally Conscious State Patients

“…This approach allows defining the time course of the slow and fast oscillations and evaluating the rhythms modifications as well as the TMS-locked response. Accordingly, waveletbased techniques are being increasingly used for processing non-stationary EEG recordings with respect to oscillatory behavior (Samar et al 1999) as well as for evaluating the effects of a magnetic (Manganotti et al 2012(Manganotti et al , 2013aRosanova et al 2009) or electric stimulation (Formaggio et al 2013), during robot-assisted motor performance (Formaggio et al 2015), and during EEG-functional magnetic resonance imaging co-registration (Formaggio et al 2011(Formaggio et al , 2014Storti et al 2010).…”

Altered brain rhythms and functional network disruptions involved in patients with generalized fixation-off epilepsy

“…9 Patient 1, only-closed brain network (red-yellow) from single-ICA analysis (Fig. 3middle row) and subbeta1 activation map in EEG-informed closed-eyes rsfMRI series (greenblue) (z>2.3, slices are displayed according to the neurological convention from fMRI: a) to study individual frequency bands in the EEG power spectrum (Klimesch 1999;Michels et al 2010), b) to analyze EEG microstates (Yuan et al 2012), c) to obtain specific EEG patterns using ICA (Formaggio et al 2013); to use parallel ICA approaches (Wu et al 2010). Instead of predefined EEG band frequencies in an EEG-informed fMRI approach.…”

“…The scarce previous EEG-fMRI findings related to FoS analyzed a single asymptomatic adult (Krakow et al 2000) and patients with occipital paroxysms (Di Bonaventura et al 2005;Formaggio et al 2013;Iannetti et al 2002). These studies used mainly a block-design with two conditions: openedeyes and closed-eyes.…”

“…The EEG data were used to define the start and end of the FoS-related EEG abnormalities during the closed-eyes condition. A more refined EEG-informed fMRI was used by Formaggio et al (Formaggio et al 2013), where the altered brain rhythm in the EEG was extracted by ICA and the subject-specific Hemodynamic Response Function (HRF) was computed prior to the statistical analysis using GLM.…”

Spatial and Temporal EEG-fMRI Changes During Preictal and Postictal Phases in a Patient With Posttraumatic Epilepsy

“…Because EEG-fMRI recording during epileptic seizures is associated with technical challenges and safety issues, the majority of studies are performed during the interictal state or in epileptic patients presenting with nonmotor seizure types (ie, fixation-off sensitivity studies). 20 Recording of ictal motor events is therefore usually serendipitous. The aim of our study was to determine preictal and postictal BOLD signal modifications in a patient with posttraumatic epilepsy, presenting with a complex motor partial seizure inside the scanner, and compare them with the interictal BOLD activation.…”