Different Neuronal Networks Are Associated with Spikes and Slow Activity in Hypsarrhythmia

Abstract

SUMMARYPurpose: West syndrome is a severe epileptic encephalopathy of infancy characterized by a poor developmental outcome and hypsarrhythmia. The pathogenesis of hypsarrhythmia is insufficiently understood. Methods: We investigated eight patients with infantile spasms and hypsarrhythmia (group I) and 8 children with complex partial seizures (group II) using simultaneous recordings of electroencephalogram (EEG) and functional MRI. Hemodynamic responses to epileptiform discharges and slow wave activity (EEG delta power) were analyzed separately. Results: In group I (mean age, 7.82 ± 2.87 months), interictal spikes within the hypsarrhythmia were associated with positive blood oxygenation leveldependent (BOLD) changes in the cerebral cortex (especially occipital areas). This was comparable with cortical positive BOLD responses in group II (mean age, 20.75 ± 12.52 months). Slow wave activity in group I correlated significantly with BOLD signal in voxels, which were localized in brainstem, thalamus, as well as different cortical areas. There was no association between BOLD effect and EEG delta power in group II. Moreover, as revealed by group analysis, group I differed from group II according to correlations between BOLD signal and slow wave activity in putamen and brainstem. Conclusions: This study demonstrates that multifocal interictal spikes and high-amplitude slow wave activity within the hypsarrhythmia are associated with the activation of different neuronal networks. Although spikes caused a cortical activation pattern similar to that in focal epilepsies, slow wave activity produced a hypsarrhythmia-specific activation in cortex and subcortical structures such as brainstem, thalamus, and putamen. KEY WORDS: West syndromeHypsarrhythmia -EEG-fMRI-Blood oxygenation level-dependent (BOLD) responses-Occipital cortex-Basal ganglia.

Neuronal Networks in West Syndrome as Revealed by Source Analysis and Renormalized Partial Directed Coherence

“…Studies on functional neuroimaging mostly with PET technology in West syndrome have revealed putamen, brainstem and various cortical regions playing an important role in the pathogenesis of hypsarrhythmia (Chugani et al, 1990, Haginoya et al, 2000, Hrachovy et al, 1981, Morimatsu et al, 1972, Metsahonkala et al, 2002, Neville, 1972, Satoh et al, 1986, Hrachovy and Frost, 2003. Using simultaneous EEG-fMRI recordings, Siniatchkin et al (2007) have demonstrated recently, that the high-amplitude slow cortical activity in hypsarrhythmia is associated with positive BOLD effects in putamen and brainstem, and that multifocal epileptiform discharges are correlated with positive BOLD effects in occipital cortex and various other cortical areas.…”

“…In order to evaluate the specificity of pathogenetic mechanisms of hypsarrhythmia, these infants were compared with children suffering from complex partial seizures. In order to validate the results obtained with DICS, we compared the results of electrical source imaging with EEG -fMRI results obtained previously from the same data sets of EEG-fMRI recordings (Siniatchkin et al, 2007).…”

“…Gradient artifacts as a result of electromagnetic distortion of the EEG through static and dynamic magnetic field during MR data acquisition and ballistocardiogram artifacts were removed using the averaged artifact subtraction (AAS) method described by Allen et al (2000Allen et al ( , 1998. After artifact correction, the data were down-sampled to 250 Hz and were low-pass filtered at 75 Hz (Siniatchkin et al, 2007).…”

“…The detailed description of simultaneous EEG and fMRI recordings, the protocol of MR artifact correction of the EEGs and fMRI analysis with the general linear model and canonical haemodynamic response function is presented in our previous publication (Siniatchkin et al, 2007).…”

Epilepsy‐related brain networks in ring chromosome 20 syndrome: An EEG‐fMRI study

“…EEG-fMRI studies have recently contributed to the understanding of the epileptic networks involved in different epileptic encephalopathies (EEs). To date, studies have been published in continuous spike-and-wave during sleep (CSWS), Lennox-Gastaut syndrome (LGS), and West (WS) syndromes, [11][12][13][14] revealing the existence of specific networks involved during the pathologic activity in such conditions. In [r (20)] syndrome, we recently showed that the typical theta-delta rhythm is generated within the frontoparietal cortices, suggesting a dysfunction of the premotor/sensorimotor systems.…”