Interictal Epileptogenic Activity Research Articles

Language regression as a manifestation of epilepsy

Introduction: Childhood epileptic encephalopathies are age-dependent brain disorders in which ictal and interictal epileptogenic activity is the apparent cause of progressive cognitive and neuro-psychological impairment. Case report: A previously healthy four-year-old boy presented to the Emergency Department with a history of receptive and expressive language regression with four days of evolution, associated with seizure onset. Clinical features and electroencephalographic findings led to diagnosis of Landau-Kleffner syndrome. The boy was treated with valproate, clobazam, and prednisolone, with language improvement. Discussion/Conclusion: Landau-Kleffner syndrome is a rare epileptic encephalopathy with pathognomonic sudden aphasia, epilepsy, and paroxysmal electroencephalographic abnormalities. The condition should be suspected in children with normal development who show a deterioration of established language skills. Early diagnosis and treatment are important to improve outcome.

Epilepsy after congenital zika virus infection: EEG and neuroimaging features

PurposeTo describe epilepsy after congenital Zika virus infection (ZIKV) and its relationship with structural neuroimaging findings. MethodsThis was a cross-sectional study in children (aged 13–42 months) who were born with microcephaly due to ZIKV infection between 2015–2017. Patients underwent a brain imaging scan (magnetic resonance) and a video-EEG study. ResultsAmong the patients (n = 43), 55.8 % were male, 88.4 % were born at term, mean head circumference at the birth was 29.7 ± 1.8 cm, and 44.8 % were infected in the first trimester of pregnancy. Neuroimaging was moderately abnormal in 30.2 % and severely abnormal in 46.5 % of patients. Early seizures (<6 months of age) were observed in 41.9 %. EEG background was abnormal when asleep or awake in 72.1 % and during sleep in 62.8 %. The interictal epileptogenic activity was recorded on 41/43 of the EEGs and was predominantly multifocal (62.8 %). An ictal EEG was obtained in 22 patients and 31.8 % had more than one seizure type. Sleep EEG (background) patterns, interictal epileptogenic activity (p = 0.046), interictal discharge localization (p = 0.015), type of ictal epileptogenic activity (p = 0.002), and localization of ictal discharge (p = 0.024) were significantly different between neuroimaging groups. The mild neuroimaging group had a higher chance of having more frequently normal sleep EEG patterns, no interictal epileptogenic activity and a further increase in the probability of walking without limitations, and less neurodevelopment delay. ConclusionIn patients with congenital Zika virus syndrome, epilepsy tended to be early and refractory. EEG features correlated with degree of neuroimaging abnormalities.

Analysis of tissue Doppler parameters and 24-hour heart rate variations in children with newly diagnosed untreated idiopathic epilepsy in interictal period

IntroductionCardiac mortality has increased in patients with epilepsy. Although majority of cardiac autonomic and ventricular function abnormalities were detected in ictal and postictal period, interictal epileptogenic activity may induce the autonomic imbalance as well. In our study, we aimed to investigate the interictal, subclinical cardiac changes in terms of cardiac autonomic balance via 24-hour Holter electrocardiography (ECG) and ventricular functions by tissue Doppler echocardiography (TDI) in children with newly diagnosed untreated idiopathic epilepsy. Material and methodsThirty children with newly diagnosed untreated idiopathic epilepsy (12 males, 18 females; mean age: 125.13 ± 35.2 months) (patient group) and 40 healthy, age and body mass index (BMI)-matched children (18 males, 22 females; mean age: 129.43 ± 38.5 months) (control group) were enrolled. Included patients underwent 24-hour Holter electrocardiographic and tissue Doppler echocardiographic study. ResultsTime domain measures were found significantly lower in the patient group. Mean high frequency (HF) values were significantly lower, and mean low frequency (LF) and mean LF/HF parameters were significantly higher in the patient group. Mean isovolumetric contraction time (ICT), isovolumetric relaxation time (IRT), and myocardial performance index (MPI) values were significantly higher, and mean ejection time (ET) values were significantly lower among the patients with untreated idiopathic epilepsy. ConclusionWe found that patients with untreated newly diagnosed epilepsy have a significant subclinical deterioration of left ventricular functions, and they also showed changes in heart rate variability (HRV) regarding the sympathovagal imbalance in interictal period. These findings can be related with increased cardiac mortality.

Sleep EEG patterns in infants with congenital Zika virus syndrome.

To describe sleep EEG patterns of neonates, and infants with microcephaly due to congenital Zika virus (ZikV) syndrome. A descriptive case series of EEGs performed in a cohort of neonates with microcephaly monitored from October 2015 to February 2016 at a University Hospital in Northeast Brazil. Infants were investigated following an established protocol that includes EEG, neuroimaging studies, PCR and specific antibodies for ZikV detection. EEGs (n=37) from 37 infants were reviewed. Age at investigation varied from 1 to 5months (mean=2.6). Diffuse low voltage (n=7), background asymmetry (n=6) and modified hypsarrhythmia with or without burst-suppression (n=11), were the main background abnormalities identified. Interictal EEG abnormalities were identified in 23 recordings (62%) and localized as focal frontal (n=8) or occipital (n=2) spikes/sharp, multifocal spikes/sharp waves (n=13). Electrographic seizures without clinical manifestation were identified in 4 recordings and characterized as focal pseudo rhythmic pattern. Further findings were focal high amplitude slow waves that were registered in the frontal (n=3) or occipital (n=1) regions. Different types of EEG abnormalities were encountered with a predominance of interictal epileptogenic activity and hypsarrhythmia. Sleep EEGs in congenital Zika virus syndrome are consistently abnormal even in infants who have not yet developed epilepsy.

Respiratory disorders during sleep in patients with epilepsy: effect of ventilatory therapy on EEG interictal epileptiform discharges

Objective: Sleep disorders are common and may coexist with a variety of diseases, including epilepsy, with important implications for the clinical management of the latter. Sleep fragmentation and deprivation, and hypoxia associated to sleep disordered breathing (SDB) may contribute to the occurrence of seizures. On the other hand, antiepileptic drugs may worsen SDB by reducing the muscle tone of the upper airways, and increasing the arousal threshold. There is evidence indicating that treatment of the SDB can reduce both frequency and intensity of seizures. This study aimed at further understanding the relationship between SDB and epilepsy, particularly the influence of SDB on epileptogenicity – as evaluated by a quantitative analysis of interictal epileptogenic activity. Methods: Eight consecutive patients affected by partial epilepsy associated to SDB (OSAS or an association between chronic obstructive pulmonary disease – COPD – and snoring) underwent two nocturnal polysomnographies (PSG) – before and after ventilatory therapy with CPAP (in 6 patients with OSAS) or oxygen (in two patients with COPD and snoring). Spiking was quantified during the first sleep cycle in both PSG studies, and spiking rates were calculated both for the entire sleep cycle and for each separate sleep phase (NREM 1, NREM 2, NREM 3–4, REM and wake time after sleep onset – WASO). Results: In all patients, the improvement of the SDB after ventilatory treatment – as demonstrated by a reduction of the respiratory disturbances index (RDI) – was associated to a reduction of spiking rates, both in the entire cycle and in relationship to slow wave sleep. This reduction was particularly marked in patients with higher spiking rates in baseline conditions. Conclusion: Our data show that SDB treatment reduces the interictal epileptogenic activity, suggesting that SDB plays a role in increasing epileptogenicity. Further studies will be necessary to clarify the mechanisms whereby this reduction in epileptogenicity occurs, although improved sleep stability seems to play an important role. The presence of an underlying SDB in patients with refractory epilepsy should be investigated.

Reliability of automatic and visual analysis of interictal spikes in lateralising an epileptic focus during video-EEG monitoring

We evaluated 2 h of two night recordings of surface EEG of 10 patients with drug-resistant focal epilepsy using video-EEG monitoring, giving 40 h of EEG. The raw data of the automatic spike analysis according to the Gotman algorithm was visually corrected by rejecting false detections. Furthermore, the complete EEG recordings were analysed independently visually by two experienced electroencephalographers. For each method we analysed the total count of detections and the topographical distribution (left-right) of spikes. The total number of detections was significantly higher (243%) in the raw data and significantly lower after elimination of false detections (57%) in comparison to conventional analysis (100%). Lateralisation was concordant between the methods in 9 10 patients. The extent (<75%, 75–90%, ≥90%) was concordant in 80% between the two human raters. The automatic analysis with elimination of false detections was concordant with each of the human raters in 60% of patients. Extent of concordance was dependent of the total number of spikes with patients having more spikes being more reliably lateralised. Our results suggest that visually corrected automatic spike analysis is an economical method to use interictal epileptogenic activity as an independent indicator of the side of the epileptogenic focus in the setting of non-invasive presurgical evaluation. This is especially true in patients with many spikes.

Review of autonomic dysfunction, cardiac arrhythmias, and epileptogenic activity.

Similarities in autonomic dysfunction associated with arrhythmias and death in animal models for digitalis toxicity, myocardial infarction, psychotropic toxicity, and epileptogenic activity are reviewed. When intravenous (IV) pentylenetetrazol was given to anesthetized cats, autonomic dysfunction was associated with both interictal and ictal epileptogenic activity. The autonomic dysfunction was manifested by the fact that autonomic cardiac nerves did not always respond in a predictable manner to changes in blood pressure, the development of a marked increase in variability in mean autonomic cardiac nerve discharge, and the appearance of a very large increase in the variability of the discharge rate of parasympathetic nerves first and then secondly in sympathetic discharge. The altered autonomic cardiac nerve discharge was associated with interictal epileptogenic activity and arrhythmia, which may contribute to sudden unexplained death in patients with epilepsy. Since phenobarbital (20 mg/kg, IV 60 min prior to pentylenetetrazol) exhibited anticonvulsant, but not antiarrhythmic and neural depressant activity, phenobarbital does not appear to be the ideal agent to prevent the autonomic dysfunction associated with epileptogenic activity in this animal model.

Effects of ketamine on EEG activity in cats and monkeys

The effects of intravenously administered Ketamine were studied in 28 cats and 6 monkeys. In cats, Ketamine initially induced generalized high voltage beta activity followed by generalized slow waves. These slow waves were called Ketamine complexes (KCs) and had two different morphological appearances suggestive either of polyspike-slow wave complexes or of delta waves intermixed with beta activity. Often it was morphologically uncertain if KCs represented spikes-slow waves or a combination of beta-delta waves. In monkeys, Ketamine induced theta and beta rhythms and at higher doses, quasi-periodic slow wave complexes. The effect of Ketamine on neocortical and hippocampal epileptogenic foci was studied in 16 cats. Ketamine consistently suppressed focal seizures but was ineffective in modifying interictal epileptogenic activity both at the primary and mirror focus. It was concluded that Ketamine had no epileptogenic properties. Ketamine affects the central nervous system at many levels in different ways. It simultaneously excites and depresses different systems and disrupts normal cortical and subcortical physiological activities.