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

Abstract

The combined use of electroencephalography (EEG) and functional magnetic resonance imaging (EEG-fMRI) in epilepsy allows the noninvasive hemodynamic characterization of epileptic discharge-related neuronal activations. The aim of this study was to investigate pathophysiologic mechanisms underlying epileptic activity by exploring the spatial and temporal distribution of fMRI signal modifications during seizure in a single patient with posttraumatic epilepsy. EEG and fMRI data were acquired during two scanning sessions: a spontaneous critical episode was observed during the first, and interictal events were recorded during the second. The EEG-fMRI data were analyzed using the general linear model (GLM). Blood oxygenation level-dependent (BOLD) localization derived from the preictal and artifact-free postictal phase was concordant with the BOLD localization of the interictal epileptiform discharges identified in the second session, pointing to a left perilesional mesiofrontal area. Of note, BOLD signal modifications were already visible several seconds before seizure onset. In brief, BOLD activations from the preictal, postictal, and interictal epileptiform discharge analysis appear to be concordant with the clinically driven localization hypothesis, whereas a widespread network of activations is detected during the ictal phase in a partial seizure.

Correspondence between large‐scale ictal and interictal epileptic networks revealed by single photon emission computed tomography (SPECT) and electroencephalography (EEG)–functional magnetic resonance imaging (fMRI)

“…The unpredictable occurrence of seizures is another explanation for the scarcity of such recordings. Reports of EEG‐fMRI studies, related to focal seizures and spikes within the same subject, are even more exceptional and confined to case reports or small case series (of patients with malformation of cortical development, hypothalamic hamartoma, posttraumatic epilepsy). Congruent (pre)ictal and interictal EEG‐fMRI activity has been found in most, but not all, patients.…”

Isolated aphasic status epilepticus: CT perfusion, SPECT and EEG reveal neurovascular coupling and support the differential diagnosis

“…and seizures [3,4]. Storti et al observed hyperperfusion using an EEG/fMRI method during an ictal epileptic event in a post-lesional epilepsy patient [13]. Arterial spin labelling may be advantageous as neither contrast agent nor ionizing radiation exposure are required, while CT-based perfusion imaging is more available and less-time consuming in emergency settings.…”

Resting-State Functional MRI/PET Profile as a Potential Alternative to Tri-Modality EEG-MR/PET Imaging: An Exploratory Study in Drug-Refractory Epilepsy

“…In an EEG–RS-fMRI study, in the preictal, postictal, and interictal states, the lateralization to SOZ was maintained. 13 In the two cases with bilateral MTS, the lateralization with sMRI, PET, and RS-fMRI was similar as they represented the same brain state.…”

“… 13 The post-ictal period is affected by type, duration, and number of seizures. EEG–RS-fMRI studies have shown widespread BOLD changes before clinical onset and after clinical resolution of the seizure 13 and the postictal showed either abrupt return, stuttering, or no return to baseline. The timescale is in milliseconds, seconds, or minutes for EEG–RS-fMRI/PET, hence the variability across these modalities.…”

“…[10][11][12] EEG-PET studies in the postictal phase have shown that although we expect a postictal hypometabolism and normal EEG baseline, 10% had persistent hypermetabolism on PET and only 31% showed a normal EEG baseline after 12 to 24 hours. 13 The post-ictal period is affected by type, duration, and number of seizures. EEG-RS-fMRI studies have shown widespread BOLD changes before clinical onset and after clinical resolution of the seizure 13 and the postictal showed either abrupt return, stuttering, or no return to baseline.…”