Topographical EEG analysis of rolandic spikes

Value of combined video EEG and polysomnography in clinical management of children with epilepsy and daytime or nocturnal spells

PURPOSE

Sleep disorders are common in epilepsy. Additionally, events of staring, jerking, or nocturnal behaviors are common presentations in neurology or sleep practice. Moreover, sleepiness and nocturnal awakenings are common symptoms in children with epilepsy and differentiation form ongoing seizures and sleep disorders is needed. However, limited data exist for the best evaluation methods. This study evaluated the usefulness of combined video electroencephalography (EEG) and polysomnography (PSG) studies (vEEG/PSG).

METHODS

Polysomnography custom database was searched for combined vEEG/PSG studies, performed from July 2010 to April 2014, which identified 240 studies. From chart review, data were collected for presenting symptoms, sleep disorder and epilepsy/neurology diagnoses, and EEG and PSG results.

RESULTS

Most common indications for performing combined vEEG/PSG were correlating sleep events with seizure occurrence, evaluating sleepiness, nocturnal awakenings and nocturnal events. Sleep physician evaluation and/or PSG were abnormal in 94% of the studies. The EEG was abnormal in 53% and events or seizures were recorded in 40% of the studies. Hence, vEEG/PSG addressed the diagnostic questions. Additionally, as compared to children with epilepsy, a significantly larger number of children with spells/parasomnia had a normal sleep evaluation including a normal PSG (9 Vs 37%, p = 0.00003).

CONCLUSIONS

This study demonstrates that combined video EEG and polysomnography is useful in addressing the common management questions in children with epilepsy and suspicious nocturnal events. Additionally, sleep disorders are more common in children with epilepsy than parasomnia. Hence sleep evaluation is important in children with epilepsy. Further prospective studies are needed.

Delayed convergence between brain network structure and function in rolandic epilepsy

Introduction: Rolandic epilepsy (RE) manifests during a critical phase of brain development, and has been associated with language impairments. Concordant abnormalities in structural and functional connectivity (SC and FC) have been described before. As SC and FC are under mutual influence, the current study investigates abnormalities in the SC-FC synergy in RE.

Methods: Twenty-two children with RE (age, mean ± SD: 11.3 ± 2.0 y) and 22 healthy controls (age 10.5 ± 1.6 y) underwent structural, diffusion weighted, and resting-state functional magnetic resonance imaging (MRI) at 3T. The probabilistic anatomical landmarks atlas was used to parcellate the (sub)cortical gray matter. Constrained spherical deconvolution tractography and correlation of time series were used to assess SC and FC, respectively. The SC-FC correlation was assessed as a function of age for the non-zero structural connections over a range of sparsity values (0.01–0.75). A modularity analysis was performed on the mean SC network of the controls to localize potential global effects to subnetworks. SC and FC were also assessed separately using graph analysis.

Results: The SC-FC correlation was significantly reduced in children with RE compared to healthy controls, especially for the youngest participants. This effect was most pronounced in a left and a right centro-temporal network, as well as in a medial parietal network. Graph analysis revealed no prominent abnormalities in SC or FC network organization.

Conclusion: Since SC and FC converge during normal maturation, our finding of reduced SC-FC correlation illustrates impaired synergy between brain structure and function. More specifically, since this effect was most pronounced in the youngest participants, RE may represent a developmental disorder of delayed brain network maturation. The observed effects seem especially attributable to medial parietal connections, which forms an intermediate between bilateral centro-temporal modules of epileptiform activity, and bear relevance for language function.

Combined spike-related functional MRI and multiple source analysis in the non-invasive spike localization of benign rolandic epilepsy

OBJECTIVE

To localize the irritative zone in children by combined spike-related fMRI and EEG multiple source analysis (MSA) in children with benign rolandic epilepsy.

METHODS

Interictal spikes were averaged and localized using MSA, and source locations were displayed in the anatomical 3D-MRI in 11 patients (5-12 yrs, median 10). Interictal spikes were additionally recorded during the fMRI acquisition (EEG-fMRI), and the fMRI sequences were correlated off-line with the EEG spikes.

RESULTS

MSA revealed an initial central dipole in all patients, including the face or hand area. A second dipolar source was mostly consistent with propagated activity. BOLD activations from EEG-fMRI, consistent with the locations of the initial dipoles, were found in four patients. We found additional large areas of BOLD activations in 3 of these subjects extending into the sylvian fissure and the insula. These were identified as propagated activity by MSA using the short time differences in the source waveforms.

CONCLUSIONS

MSA provided reliable localization of the spike onset zone in all children with benign rolandic epilepsy. Using the combination of EEG-fMRI and MSA we were able to discriminate the spike onset zone from propagated epileptiform source activity, using the spatial resolution of the EEG-fMRI technique and the temporal resolution of the MSA. However, the sensitivity of the EEG-fMRI technique was low and further improvements of the technique are warranted.

SIGNIFICANCE

This study shows that a combination of EEG-fMRI and MSA may be a powerful tool to describe the irritative zone of patients with idiopathic focal epilepsies. Clinical studies in patients with non-idiopathic focal epilepsies may clarify whether both techniques can be used as complementary clinical tools to localize the onset of interictal epileptic activity in focal epilepsies.

[Benign childhood epilepsy with centrotemporal spikes: high and low central focus]

Twenty children with benign childhood epilepsy with centrotemporal spikes were studied. Anamnesis, neurological exam, "Columbia" Scale (1993) application and digital electroencephalogram were carried out. The digital electroencephalogram was recorded with electrodes according to 10-20 international system, and a supplementary electrode, between C3 and T3 or C4 and T4-C5 or C6, respectively, at the side with a higher number of spikes. The averaging of the spikes was carried. Localization and the laterality of the spikes were analyzed. Seizures involving a superior limb occurred in a higher proportion of cases with spikes of maximum negativity in C3, C4. Independent epileptiform activity, different from centrotemporal, was more frequent in the cases were the maximum negativity of the spikes occurred in C3 or C4 regions. There are clinical and electroencephalographic differences according to the localization of the discharges

EEG-related functional MRI in benign childhood epilepsy with centrotemporal spikes

The localization of epileptic foci is an important issue in children with extratemporal epilepsies. However, the value of noninvasive methods such as the EEG-assisted functional magnetic resonance imaging (fMRI) has not been sufficiently investigated in children. As a model of extratemporal epilepsies, we studied 7 patients aged 5 to 12 (median 10) years with benign childhood epilepsy and centrotemporal (rolandic) spikes. Interictal spikes were recorded during the fMRI acquisition on a MR-compatible battery-powered digital EEG system with 16 channels. The fMRI sequences were correlated off-line with the EEG spikes and analyzed with the software Statistical Parametrical Mapping SPM99. The fMRI results demonstrated the spike-related activation in the perisylvian central region in three patients; we could not demonstrate fMRI activation despite active spiking in 2 patients, and 2 patients did not produce sufficient spikes for fMRI analysis. We currently consider the spike-related fMRI as a research tool that localizes epileptic activity in selected patients. Further improvements of the technique are necessary to allow a clinical application of this method.