Ictal brain hemodynamics in the epileptic focus caused by a brain tumor using functional magnetic resonance imaging (fMRI)

Abstract

Using functional magnetic resonance imaging (fMRI) we were able to observe, in detail, ictal brain hemodynamics during epileptic seizure caused by a brain tumor. A 53-year-old man was experencing partial motor seizures of the left side of his face and neck. In a brain MR image a mass lesion was found in the subcortical area of the right frontal lobe. We found focal spikes in his right hemisphere, though dominantly in C4 and T4 regions. fMRI investigations were carried out at 1.5 T (GE Signa Horizon) using gradient-echo echo-planar neuroimaging. We were able to perform the ictal examination twice. The activated regions were focalized and clearly found only on the lateral side of the tumor base. The region was in agreement with the epileptic focus examined using an electrocorticogram (ECOG). The signal intensity in the seizure focus rapidly increased 30 seconds before the convulsion was observed. After the end of the convulsion it also took 30 seconds to restore the signal intensity to the baseline value. fMRI is a very useful tool for various studies such as the identification of the epileptic focus, the mechanism of epileptic seizure, and so on.

Sequential analysis of fMRI images: A new approach to study human epileptic networks

“…This propagation pattern was similar to the early propagation pattern assessed by invasive subdural electrodes. Ictal fMRI showed that even focal seizures activated a large network of remote interconnected cortical and subcortical brain regions, as had also been shown in previous ictal SPECT, SISCOM (O’Brien et al., 2000; Shin et al., 2001; Van Paesschen, 2004), and ictal‐fMRI studies (Jackson et al., 1994; Detre et al., 1995; Krings et al., 2000; Kubota et al., 2000; Morocz et al., 2003; Salek‐Haddadi et al., 2003; Federico et al., 2005; Archer et al., 2006; Di Bonaventura et al., 2006; Kobayashi et al., 2006b). The expected increase in signal in the frontoparietal areas and basal ganglia in the left hemisphere (Ramsey et al., 1996; Haslinger et al., 2002), contralateral to the hand used to press the seizure‐button, probably did not interfere in the interpretation of the results obtained after sequential analysis, as activations related to press the button did not reach sufficient significance to be displayed in the activation maps seizure‐related, so they were neglected.…”

“…Nevertheless, in contrast to fMRI studies aimed at evaluating physiologic functions, for which it is essential to perform enough trials under each experimental condition to produce a reliable signal change (given that these changes are very small), the changes in BOLD signal intensity related to epileptic seizures are larger and more sustained than those typically seen related to physiologic conditions. They are also larger and more sustained than those seen in combined electroencephalography (EEG)-fMRI studies of interictal events (Lemieux et al, 2001;Benar et al, 2002;Makiranta et al, 2005), ranging between a 3% and 45% signal increase (Krings et al, 2000;Kubota et al, 2000;Salek-Haddadi et al, 2002;Morocz et al, 2003). Therefore, our working hypothesis was that those changes could be reliable, sustained, and sufficiently consistent to allow us to subdivide and analyze the seizure dataset in consecutive and independent epochs.…”

“…35 fit in time and space with the initial clusters of activation obtained from the GLM (30s and 10 s before the clinical onset, respectively). Epilepsia ILAE initial clinical symptoms reported by the patient inside the scanner by 10-40 s. Those changes in BOLD signal could reflect a change in neuronal activity or some energy-consuming phenomenon that occurred seconds to several minutes prior to the emergence of clinical symptoms (Krings et al, 2000;Kubota et al, 2000;Federico et al, 2005;Makiranta et al, 2005;Brevard et al, 2006). Interestingly, on each registered seizure (pre-and postsurgery) the first observed change, even before the occurrence of the initial increase in BOLD signal seizure-related, was a transient and widespread decrease in signal involving the frontoparietal association areas; including the frontal mesial region, precuneus, and posterior cingulate gyrus, which are part of the ''default mode network'' of brain function (Fig.…”

“…Functional magnetic resonance imaging (fMRI) has been shown to provide valuable information concerning the localization of regions generating interictal epileptiform activity (Detre et al., 1996; Lemieux et al., 2001; Benar et al., 2002; Al Asmi et al., 2003; Archer et al., 2003a; Aghakhani et al., 2004; Bagshaw et al., 2004; Aghakhani et al, 2006; Bagshaw et al, 2006; Kobayashi et al., 2006a;Salek‐Haddadi et al., 2006), prolonged bursts of interictal epileptiform discharges (Detre et al., 1995; Bagshaw et al., 2005; Hamandi et al., 2007), and even focal epileptic seizures (electrographic and clinical seizures) (Jackson et al., 1994; Detre et al., 1995; Krings et al., 2000; Kubota et al., 2000; Morocz et al., 2003; Salek‐Haddadi et al., 2003; Federico et al., 2005; Archer et al., 2006; Di Bonaventura et al., 2006; Kobayashi et al., 2006b). However, these studies have shown widespread blood oxygenation level–dependent (BOLD) changes, reflecting both the ictal onset zone as well as those structures involved in seizure propagation, precluding a precise delineation of the cortical area from which the seizures are arising.…”

Ictal EEG‐fMRI in localization of epileptogenic area in patients with refractory neocortical focal epilepsy

“…Many studies using EEG‐fMRI have been focused on the noninvasive identification of the irritative zone (Al‐Asmi et al., ; Hamandi et al., ; Gotman et al., ; Salek‐Hadaddi et al., ; Thornton et al., ; Donaire et al., ), detecting BOLD signal changes in 40–80% of patients and revealing some degree of concordance with the presumed epileptic generator in 50–100% of the cases. However, there are few large case series reporting patients with ictal EEG‐fMRI, taking into account the intrinsic difficulty in performing this test during the ictal period (Jackson et al., ; Detre et al., ; Krings et al., ; Kubota et al., ; Salek‐Hadaddi et al., ; Mórocz et al., ; Salek‐Hadaddi et al., ; Federico et al., ; Archer et al., ; Di Bonaventura et al., ; Kobayashi et al., ; Liu et al., ; Tyvaert et al., ; Donaire et al., ,b; Salek‐Haddadi et al., ; Thornton et al., ; Fernández et al., ; Chaudhary et al., ). Most of the studies correlated the BOLD activations in the ictal EEG‐fMRI with the results from structural neuroimaging tests (Kobayashi et al., ; Tyvaert et al., ) or with invasive examinations (Thornton et al., ; Chaudhary et al., ).…”