Changes in EEG foci with age in childhood partial epilepsies

Interictal epileptiform discharges vary across age groups

OBJECTIVE

To investigate whether the occurrence and morphology of interictal epileptiform discharges (IEDs) in scalp-EEG change by age.

METHODS

10,547 patients who had a standard or sleep deprived EEG recording reported using the SCORE standard were included. 875 patients had at least one EEG with focal IEDs. Focal IED morphology was analyzed by age using quantitative measures in EEGLAB and by visual classification based on the SCORE standard. We present distributions of IED measures by age group, with medians, interquartiles, 5th and 95th percentiles.

RESULTS

Focal IEDs occurred most frequently in children and elderly. IED morphology and localization depended on age (p < 0.001). IEDs had higher amplitudes, sharper peaks, larger slopes, shorter durations, larger slow-wave areas and wider distributions in children. These morphological characteristics diminished and the IEDs became more lateralized with increasing age. Spike asymmetry was stable across all age groups.

CONCLUSIONS

IEDs have age-dependent characteristics. A spike detector, human or computer, should not operate with the same set of thresholds for patients at various age. With increasing age, focal IEDs are less sharp, have lower amplitudes, have less prominent slow-waves and they become more lateralized. Our findings can help EEG readers in detecting and correctly describing IEDs in patients of various age.

SIGNIFICANCE

EEG readers should always consider patient age when interpreting interictal epileptiform discharges.

Tantrums, Emotion Reactions and Their EEG Correlates in Childhood Benign Rolandic Epilepsy vs. Complex Partial Seizures: Exploratory Observations

We explored associations between EEG pathophysiology and emotional/behavioral (E/B) problems of children with two types of epilepsy using standard parent questionnaires and two new indicators: tantrums recorded by parents at home and brief, emotion-eliciting situations in the laboratory. Children with Benign Rolandic epilepsy (BRE, N = 6) reportedly had shorter, more angry tantrums from which they recovered quickly. Children with Complex Partial Seizures (CPS, N = 13) had longer, sadder tantrums often followed by bad moods. More generally, BRE correlated with anger and aggression; CPS with sadness and withdrawal. Scores of a composite group of siblings (N = 11) were generally intermediate between the BRE and CPS groups. Across all children, high voltage theta and/or interictal epileptiform discharges (IEDs) correlated with negative emotional reactions. Such EEG abnormalities in left hemisphere correlated with greater social fear, right hemisphere EEG abnormalities with greater anger. Right hemisphere localization in CPS was also associated with parent-reported problems at home. If epilepsy alters neural circuitry thereby increasing negative emotions, additional assessment of anti-epileptic drug treatment of epilepsy-related E/B problems would be warranted.

A study on spike focus dependence of high-frequency activity in idiopathic focal epilepsy in childhood

Objective

Spike foci in benign epilepsy with centrotemporal spikes (BECTS) are related to seizure semiologies, but this relationship is inconspicuous in Panayiotopoulos syndrome (PS). We analyzed spike‐associated high‐frequency activity (HFA) and its relationship to spike foci in the electroencephalograms (EEGs) of patients with BECTS and PS in order to elucidate the pathophysiology of these epileptic syndromes.

Methods

In 35 patients with BECTS and 29 with PS, focal spikes in scalp sleep EEGs were first classified by clustering according to their characteristics, including shape and distribution. For each patient, three or fewer spike clusters were investigated by time‐frequency spectral analysis and single‐dipole analysis using a realistic three‐dimensional head model to explore the relationships between the presence or absence of spike‐associated HFA and the distribution of estimated spike sources.

Results

A total of 159 spike clusters were analyzed (96 in BECTS and 63 in PS). HFA was detected in 73 spike clusters (76.0%) in BECTS and 37 (58.7%) in PS, with a significant difference in the proportion of spike clusters with HFA (p = 0.024 by Fisher's exact test). In BECTS, spikes had relatively uniform distributions, but the proportion of spikes with associated HFA was significantly higher in the spike group with dipoles in the perirolandic areas (42 of 49) than in that with dipoles outside of the perirolandic areas (23 of 36; p = 0.037). In PS, The proportion of spikes with associated HFA was significantly higher in the spike group with dipoles in the occipital lobes (20 of 26) than in that with dipoles outside of the occipital lobes (13 of 33; p = 0.020).

Significance

The proportion of spike‐associated HFA was higher in BECTS than in PS. Particular pathophysiological meaning was indicated in spikes with dipoles in the perirolandic areas in BECTS and in spikes with dipoles in the occipital lobes in PS owing to the high proportions of spike‐associated HFA in these areas.

Migration of epileptic spike foci in encephalograms may correlate with a better outcome in pediatric epilepsy

Epileptic spike foci in children can be fixed in specific brain regions or migrate over time. We analyzed 969 encephalograms from 463 epileptic children to determine outcome differences between those with fixed foci (FF) and those with migrated foci (MF) on at least three encephalograms over 3years. All epileptic spike foci were classified as frontal, temporal, central, parietal, or occipital. Migration directions were divided into anterior, posterior, lateral, and unclassified. Seventy-nine cases met the inclusion criteria: 24 (30%) FF and 55 (70%) MF. More patients in the FF than in the MF group required multiple antiepileptic drugs (P=0.004), and had abnormal image findings (P=0.014), mental retardation (P=0.035), and worse seizure control (P=0.047). Seizure frequency (P=0.007; correlation coefficient=0.56) and the number of prescribed drugs (P=0.047; correlation coefficient=0.372) were more significant in the FF group than in the MF group. When we compared only whether the cases were symptomatic or cryptogenic, we found the same outcome trends. In comparisons of only idiopathic epileptic patients, the FF group had non-significantly different outcomes compared with those in the MF group. When we compared 16 cases of benign childhood epilepsy with centrotemporal spikes (BECTs) and 8 Panayiotopoulos syndrome (PS), the cases with BECTs had more FF (38% vs. 0%, P=0.03). We conclude that outcomes may not correlate as well in FF cases as they do in MF cases. Idiopathic epilepsy warrants more study.

Age-dependent spike localization in various epileptic syndromes

The electroencephalograms from 276 patients with localization-related epilepsy were analyzed to compare the distribution of spike foci in different age groups. Patients were divided into five groups according to spike location in the frontal, central, temporal, occipital, or multiple cortical regions. The age of peak incidence was earliest in patients with occipital foci, followed by those with central foci and then those with frontal foci. A bimodal age distribution of patients with temporal foci was observed. Symptomatic patients frequently exhibited multiple and frontal foci, and a large number of idiopathic patients had central, temporal, and occipital foci. Multiple foci were detected in 27.5% of idiopathic patients. Age-related spike localization was uniformly observed, regardless of the epileptic syndrome. The analysis of these data indicates that there are two types of multiple foci, one correlated with organic lesions and the other with an idiopathic, functional nature.

Brain maturation-related spike localization in Panayiotopoulos syndrome: magnetoencephalographic study

Focal spike activities in Panayiotopoulos syndrome involve all brain regions in electroencephalography, and commonly reveal multiple foci, often through occipital predominance. To investigate correlations between developmental brain maturation and spike origin in Panayiotopoulos syndrome, we evaluated age-related or duration-related magnetoencephalographic spike localization in 25 patients with Panayiotopoulos syndrome. Regarding age at examination, patients with frontal spikes were significantly older than patients with spikes on rolandic, parieto-occipital, or calcarine sulci. Occipital spikes were classified into two subgroups, located at the calcarine sulcus and parieto-occipital sulcus. Both calcarine and parieto-occipital localizations were seen in patients around the same age. Follow-up magnetoencephalography was performed on three patients, and demonstrated shifting localization or disappearance of magnetoencephalographic spikes. These results suggest that the location of spike discharges is not directly related to seizure symptoms, but instead indicates maturation-related cortical hyperexcitability in patients with Panayiotopoulos syndrome.

EEG in children with early-onset benign occipital seizure susceptibility syndrome: Panayiotopoulos syndrome

PURPOSE

We analyzed sequential changes in the localization of EEG foci along with age to identify a specific EEG pattern, and the relation between the clinical manifestations and the EEG pattern in patients with Panayiotopoulos syndrome (PS).

METHODS

The subjects were 76 children, who had been followed up >2 years with repeated EEG examinations at 6-month intervals. Analysis of EEG findings included the determination of localization of spike foci, as a function of age, by using cross-sectional data, and the identification of subgroups with homogeneous EEG patterns. Then we compared certain clinical features among these subgroups.

RESULTS

In the cross-sectional EEG study, the occipital EEG spike focus was most frequently seen between ages 2 and 5 years. Independent and synchronous frontopolar and occipital spikes (Fp-O spikes) and centroparietotemporal (CPT) EEG spike foci had increased incidences between ages 4 and 7 years, and between ages 6 and 10 years, respectively. We subclassified the 76 patients into the following five subgroups based on the evolutional changes in epileptic EEG foci, which frequently showed shifting, multiplications, and generalization: (a) persistent occipital focus group (O group), (b) Fp-O spikes group (Fp-O pattern group), (c) generalized EEG pattern group, (d) CPT foci group (CPT group), and (e) no epileptic EEG focus group. The Fp-O group showed the latest age at onset of epilepsy. The generalized EEG pattern group had the highest frequency of seizures as well as recurrences of status epilepticus (SE), as well as the longest active seizure period among the five groups.

CONCLUSIONS

These results indicated that the EEG foci in most of patients with PS are frequently shifting location, multiplying, and propagating diffusely with age, rather than persistently localizing in the occipital region. In addition, the EEG patterns showed a certain trend and roughly corresponded to certain clinical characteristics. However, the prognosis of the seizures appeared to be favorable regardless of the EEG pattern.

Study on the early-onset variant of benign childhood epilepsy with occipital paroxysms otherwise described as early-onset benign occipital seizure susceptibility syndrome

PURPOSE

We studied the early-onset variant of benign childhood epilepsy with occipital paroxysms (EVBCEOP) proposed by Panayiotopoulos, to confirm whether his five criteria are sufficient to delineate EVBCEOP as a new epileptic syndrome, as well as to predict a good outcome prospectively at the time of the first examination.

SUBJECTS

The subjects were 649 children with localization-related epilepsies (LREs) observed in our hospital for >4 years.

METHODS

We applied the International Classification of Epilepsies and Epileptic Syndromes to the 649 patients and identified patients who had EVBCEOP from among those with nonspecific idiopathic LRE. The inclusion criteria were to satisfy all five criteria and all but one criterion (i.e., either ictal vomiting or occipital EEG paroxysms). We were blind as to the outcomes and selected patients who satisfied the following three of the five criteria at the time of the first examination, (a) normal development before the onset, (b) epilepsy onset age between 2 and 8 years, and (c) occipital EEG foci. We attempted to determine whether the outcome can be predicted prospectively, and whether the presence or absence of ictal vomiting affects the prognosis.

RESULTS

We identified 19 patients who satisfied all five criteria, 22 who exhibited all but occipital EEG foci, and 21 who exhibited all but ictal vomiting. The incidence of status convulsivus was higher in those with ictal vomiting than in those without ictal vomiting (p < 0.05). Interictal EEG performed every 6 months showed shifting and multiplication of EEG foci in 42 and 52% of all subjects, respectively. We identified 57 patients, 42 (74%) of whom were in remission by age 12 years. The number of patients who experienced remission did not differ significantly between those with (76%, n = 25) and without (72%, n = 32) ictal vomiting (p > 0.05).

CONCLUSIONS

Nosologically, EVBCEOP appears to constitute the earliest form of idiopathic epileptic syndrome different from classic BCEOP. However, its clinical spectrum, ranging from the absence of ictal vomiting to a combination of extraoccipital and multifocal EEG foci, is broad, such that further prospective study is expected to reveal the exact prerequisite criteria for determining the border of this epileptic syndrome and for clarifying the clinical spectrum within this syndrome.