Electroclinical significance of rolandic spikes and dipoles in neurodevelopmentally normal children

Ripples on rolandic spikes: A marker of epilepsy severity

OBJECTIVE

Children with rolandic spikes may or may not have seizures, ranging from benign rolandic epilepsy to severe atypical rolandic epilepsy. We investigated whether ripples (80-250 Hz), superimposed on rolandic spikes in surface electroencephalography (EEG), can differentiate between different entities.

METHODS

In this cohort study we analyzed the EEG studies of children with rolandic spikes without other EEG or magnetic resonance imaging (MRI) abnormalities. They were divided into the following three groups: (1) rolandic spikes but no epilepsy, (2) typical rolandic epilepsy, and (3) atypical and symptomatic rolandic epilepsy. Ripples superimposed on rolandic spikes were marked in 10 minutes of EEG, and compared to the number of seizures before the EEG. Receiver operating characteristic (ROC) curves were constructed to determine the predictive value of ripples and spikes for having epilepsy (groups 2 and 3) and for differentiating benign courses (groups 1 or 2) from atypical and symptomatic epilepsy (group 3). Ripples were also marked in the time frequency spectrum of averaged rolandic spikes.

RESULTS

Ripples were found in 13 of 22 children. Children without epilepsy showed no ripples, except for a single child with only one ripple. The number of ripples showed a significant positive correlation with the number of seizures (ρ = 0.70, p = 0.001), whereas spikes had a borderline significant correlation (ρ = 0.43, p = 0.05). Presence of more than two ripples was a predictor for having seizures (area under the curve [AUC] 0.84), whereas spikes could not predict having seizures (AUC 0.53). More than five ripples predicted the difference between benign courses and atypical and symptomatic epilepsy (AUC 0.91, sensitivity 63%, specificity 100%). Ripples in the time frequency spectra appeared in all children and were not related to seizures.

SIGNIFICANCE

Absence of ripples on top of rolandic spikes predicts a relative benign clinical entity, whereas in the presence of several ripples, the child is likely to have more seizures than classical rolandic epilepsy, and pharmacologic treatment might be needed.

Patterns of interictal spike propagation across the central sulcus in benign rolandic epilepsy

It has been reported that the rolandic area generating spikes is hyperexcitable, and that rolandic spikes propagate across the central area. However, the pattern of rolandic spike propagation and how the dipolar distribution of the spikes is related to the propagation pattern have not yet been studied. Thirty-nine EEGs from 27 patients with benign rolandic epilepsy (BRE) were examined. Sequential topographic mapping in 4-ms steps was used to analyze the pattern of spike propagation. The locations of maximum negative foci, the presence and distribution of the dipolar field, and the propagation pattern were examined. Dipoles were present in 23 (85.2%) out of 27 patients and in 43 (72.9%) out of 59 foci. Thirty-two foci (54.2%) in 20 patients demonstrated a propagation pattern. The typical pattern consisted of propagation from central to mid-temporal locations across the central sulcus. Most spike foci exhibiting a propagation pattern had a dipolar distribution (87.5%; p=0.008). These results suggest that rolandic spikes originate from sulcal or gyral cortices on either side of the central sulcus, and that spike propagation can ensue by intracortical spreading across the central sulcus.

[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

Magnetoencephalographic analysis of bilaterally synchronous discharges in benign rolandic epilepsy of childhood

The purpose of this study was to examine the spatial and temporal relationship between bilateral foci of bilaterally synchronous discharges in benign rolandic epilepsy of childhood (BREC) using a whole-scalp neuromagnetometer. We simultaneously recorded interictal magnetoencephalographic (MEG) and electroencephalographic (EEG) signals in six children with BREC. Interictal spikes were classified into three groups: bilaterally synchronous discharges (BSDs), unilateral discharges on right side (UD-R), and unilateral discharges on left side (UD-L). We used equivalent current dipole (ECD) modelling to analyse the cortical sources of interictal spikes. Both BSDs and UDs were found in Patients 1-4, whereas only UDs were identified in Patients 5 and 6. The ECDs of interictal spikes were located in rolandic regions, 10-20mm anterior and lateral to hand somatosensory cortices. Multi-dipole analysis of BSDs showed two ECDs in homotopic motor areas of the hemispheres. During BSDs, the right-sided activation preceded the left-sided activation by 15-21 milliseconds in Patients 1 and 2. In Patients 3 and 4, the activation occurred 17-20 milliseconds earlier in the left than the right hemisphere. Within the same hemisphere, the sources of BSDs and UDs were located in similar areas. In conclusion, our results imply the cortical epileptogenicity in bilateral perirolandic areas in BREC. The sequential activation during BSDs in both hemispheres suggest the existence of synaptic connections, possibly via the corpus callosum, between bilateral irritative foci.

Time-related configuration change in benign focal epileptiform discharges of childhood: from a dipole to a negative monopole in a patient with generalized epilepsy

The case of a 6-year-old child with generalized epilepsy and benign focal epileptiform discharges (BFEDs) of childhood is presented. During his first EEG, performed when he was 6 years old, the patient had three staring episodes accompanied by bursts of 3-Hz spike-and-wave complexes. Interictally, frequent BFEDs were seen, configured as dipoles with a right temporal negativity and a right frontal positivity. The patient was administered ethosuximide and the staring spells disappeared. On follow-up EEG performed 2 years later, no generalized discharges were seen. However, the EEG again showed frequent spikes with a characteristic morphology of BFEDs. This time they were not configured as dipoles, but as monopoles with a maximum negativity over the right frontal region. The change in the generator's orientation over time (from a horizontal to a vertical dipole) is discussed, as well as the prognostic implications of the morphology and configuration of focal spikes. In addition, the authors review the coexistence of BFEDs and 3-Hz spike-and-wave complexes in their patient database.

Normal EEG in very premature infants: reference criteria

OBJECTIVES

Objectives were to precise EEG criteria of normality in very premature infants.

METHODS

The neonatal electroencephalograms (EEGs) of 17 neurologically normal very premature infants recorded at a conceptional age (CA) of 26-28 weeks have been analyzed. The normality of the infants was defined as normal neonatal cranial ultrasound scans and normal neurological outcome at a minimum postnatal age of 2 years.

RESULTS

All tracings were discontinuous. The bursts (amplitude >/=30 microV) were interhemispherically synchronous and lasted up to 3 min. The interburst intervals lasted up to 46 s. EEG patterns consisted mainly of slow waves (</=3 Hz), with high amplitude (up to 300 microV), occipital predominance and superimposed alpha, beta and theta rhythms. High amplitude theta rhythms predominated on temporal areas, beta rhythms were mainly central, whereas alpha rhythms were central and occipital. Sleep state differentiation began as early as 26 weeks CA. On a given trace, the existence of more mature graphoelements than expected for the CA reflected a normal increasing maturation.

CONCLUSIONS

EEG has constant and reproductible patterns in normal very premature infants. This can constitute a basis for the determination of EEG criteria for neurological prognosis in infants of 26-28 weeks CA.

Modern electroencephalography: its role in epilepsy management

Epilepsy is the area in which electroencephalography is probably of greatest potential clinical value, and yet is most abused. In general, the sensitivity of the waking interictal EEG for detecting epilepsy and its specificity for distinguishing epilepsy from other episodic disorders are both very limited, and routine examination for diagnostic screening or follow up is of little value. However, as this review attempts to demonstrate, EEG is of crucial importance for answering specific, clearly defined questions which commonly arise in the management of seizure disorders, especially so, when non-routine and if necessary complex investigations are undertaken, to address the problems of individual patients.

Localization analysis of neuronal activities in benign rolandic epilepsy using magnetoencephalography

Benign epilepsy of childhood with rolandic spikes (BECRS) is an electroclinical syndrome characterized by partial sensorimotor seizures with centrotemporal spikes. We report a detailed localization analysis of spontaneous magnetic brain activities in seven BECRS patients using magnetoencephalography (MEG). All patients had BECRS diagnosis with typical seizures and electroencephalographic findings and five patients had minor psychomotor deficits. MEG was recorded over both parieto-temporal regions using a 2x37-channel biomagnetic system. The collected data were digitally bandpass-filtered (2-6, 14-30, or 1-70 Hz) to analyze slow- and fast-wave magnetic activities and rolandic spikes. Slow-wave activity was increased in four hemispheres of three patients. Increased fast-wave activity was found in all five patients with minor neuropsychological deficits. The presence of increased fast-wave magnetic brain activity appeared to cause functional anomalies in the higher brain function processes. In the spike analysis, the dipoles of rolandic spikes which constantly manifested anterior positivity in direction were concentrated in the superior rolandic region in four cases and the inferior rolandic region in three cases. The localizations of increased slow- and fast-wave activities were identical with those of the spikes. The seizure profiles were frequently characterized by the spike locations. Source localizations of the focal brain activities and rolandic spikes by MEG will contribute to the different diagnosis and pathophysiological elucidation of BECRS.