Ictal Central Apnea Is Predictive of Mesial Temporal Seizure Onset: An Intracranial Investigation

OBJECTIVE

Ictal central apnea (ICA) is a semiological sign of focal epilepsy, associated with temporal and frontal lobe seizures. In this study, using qualitative and quantitative approaches, we aimed to assess the localizational value of ICA. We also aimed to compare ICA clinical utility in relation to other seizure semiological features of focal epilepsy.

METHODS

We analyzed seizures in patients with medically refractory focal epilepsy undergoing intracranial stereotactic electroencephalographic (SEEG) evaluations with simultaneous multimodal cardiorespiratory monitoring. A total of 179 seizures in 72 patients with reliable artifact-free respiratory signal were analyzed.

RESULTS

ICA was seen in 55 of 179 (30.7%) seizures. Presence of ICA predicted a mesial temporal seizure onset compared to those without ICA (odds ratio = 3.8, 95% confidence interval = 1.3-11.6, p = 0.01). ICA specificity was 0.82. ICA onset was correlated with increased high-frequency broadband gamma (60-150Hz) activity in specific mesial or basal temporal regions, including amygdala, hippocampus, and fusiform and lingual gyri. Based on our results, ICA has an almost 4-fold greater association with mesial temporal seizure onset zones compared to those without ICA and is highly specific for mesial temporal seizure onset zones. As evidence of symptomatogenic areas, onset-synchronous increase in high gamma activity in mesial or basal temporal structures was seen in early onset ICA, likely representing anatomical substrates for ICA generation.

INTERPRETATION

ICA recognition may help anatomoelectroclinical localization of clinical seizure onset to specific mesial and basal temporal brain regions, and the inclusion of these regions in SEEG evaluations may help accurately pinpoint seizure onset zones for resection. ANN NEUROL 2024;95:998-1008.

Unrecognized Focal Nonmotor Seizures in Adolescents Presenting to Emergency Departments

BACKGROUND AND OBJECTIVES

Many adolescents with undiagnosed focal epilepsy seek evaluation in emergency departments (EDs). Accurate history-taking is essential to prompt diagnosis and treatment. In this study, we investigated ED recognition of motor vs nonmotor seizures and its effect on management and treatment of focal epilepsy in adolescents.

METHODS

This was a retrospective analysis of enrollment data from the Human Epilepsy Project (HEP), an international multi-institutional study that collected data from 34 sites between 2012 and 2017. Participants were 12 years or older, neurotypical, and within 4 months of treatment initiation for focal epilepsy. We used HEP enrollment medical records to review participants' initial diagnosis and management.

RESULTS

A total of 83 adolescents were enrolled between 12 and 18 years. Fifty-eight (70%) presented to an ED before diagnosis of epilepsy. Although most ED presentations were for motor seizures (n = 52; 90%), many patients had a history of nonmotor seizures (20/52 or 38%). Adolescents with initial nonmotor seizures were less likely to present to EDs (26/44 or 59% vs 32/39 or 82%, p = 0.02), and nonmotor seizures were less likely to be correctly identified (2/6 or 33% vs 42/52 or 81%, p = 0.008). A history of initial nonmotor seizures was not recognized in any adolescent who presented for a first-lifetime motor seizure. As a result, initiation of treatment and admission from the ED was not more likely for these adolescents who met the definition of epilepsy compared with those with no seizure history. This lack of nonmotor seizure history recognition in the ED was greater than that observed in the adult group (0% vs 23%, p = 0.03) and occurred in both pediatric and nonpediatric ED settings.

DISCUSSION

Our study supports growing evidence that nonmotor seizures are often undiagnosed, with many individuals coming to attention only after conversion to motor seizures. We found this treatment gap is exacerbated in the adolescent population. Our study highlights a critical need for physicians to inquire about the symptoms of nonmotor seizures, even when the presenting seizure is motor. Future interventions should focus on improving nonmotor seizure recognition for this population in EDs.

Clinical characteristics, seizure control, and delivery outcomes in pregnant women with focal and generalized epilepsies

OBJECTIVE

To prospectively investigate the course of epilepsy and assess seizure control during pregnancy in women with focal epilepsy (FE) compared with generalized epilepsy (GE), to ascertain the effects of epilepsy and its types on delivery and neonatal outcomes, and to compare adverse outcomes between pregnancies complicated by epilepsy and normal pregnancies.

METHODS

124 pregnant women with epilepsy (WWE) were enrolled in a prospective study. Obstetric and neonatal outcomes were compared with those of 277 healthy women in the control group.

RESULTS

Occurrence of seizures during pregnancy was more often in FE (77.1 %) compared with GE (50.0 %) (Odds ratio [OR] 2.08; 95 % confidence interval [CI] 0.97-4.46, p = 0.06); the overall seizure freedom was significantly higher in women with GE compared with women with FE (p = 0.0038). Poor seizure control one year prior to the pregnancy and nonadherence to treatment were significantly associated with presence of seizures during pregnancy (p < 0.0001). Compared with pregnancies of women without epilepsy, WWE were at increased risk of cesarean section (CS) (p < 0.0001) and preterm birth (p = 0.03). Offspring of mothers with epilepsy were at higher risks of Apgar scores at 5 min ≤7 (p < 0.0001) and perinatal hypoxia (p = 0.03) compared with infants of unaffected women. Seizures during pregnancy were significantly correlated with the higher rate of CS, Apgar scores at 5 min ≤7, and perinatal hypoxia (p = 0.0069; p = 0.0098; and p = 0.0045, respectively). The risks of adverse outcomes were not significantly increased in women with FE compared to women with GE.

CONCLUSION

Epileptic seizures in pregnancy are associated with increased risks of adverse delivery and neonatal outcomes. Hence, early assessment of seizure disorder, adequate seizure control prior to and during pregnancy, and effective treatment are required to prevent potential seizure-related complications and improve maternal and fetal outcomes.

Functional brain connectivity in children with focal epilepsy: A systematic review of functional MRI studies

Epilepsy is increasingly recognised as a brain network disorder and many studies have investigated functional connectivity (FC) in children with epilepsy using functional MRI (fMRI). This systematic review of fMRI studies, published up to November 2023, investigated profiles of FC changes and their clinical relevance in children with focal epilepsy compared to healthy controls. A literature search in PubMed and Web of Science yielded 62 articles. We categorised the results into three groups: 1) differences in correlation-based FC between patients and controls; 2) differences in other FC measures between patients and controls; and 3) associations between FC and disease variables (for example, age of onset), cognitive and seizure outcomes. Studies revealed either increased or decreased FC across multiple brain regions in children with focal epilepsy. However, findings lacked consistency: conflicting FC alterations (decreased and increased FC) co-existed within or between brain regions across all focal epilepsy groups. The studies demonstrated overall that 1) interhemispheric connections often displayed abnormal connectivity and 2) connectivity within and between canonical functional networks was decreased, particularly for the default mode network. Focal epilepsy disrupted FC in children both locally (e.g., seizure-onset zones, or within-brain subnetworks) and globally (e.g., whole-brain network architecture). The wide variety of FC study methodologies limits clinical application of the results. Future research should employ longitudinal designs to understand the evolution of brain networks during the disease course and explore the potential of FC biomarkers for predicting cognitive and postsurgical seizure outcomes.

Feasibility study of microburst VNS therapy in drug-resistant focal and generalized epilepsy

BACKGROUND

Vagus nerve stimulation (VNS) at low frequencies (≤30 Hz) has been an established treatment for drug-resistant epilepsy (DRE) for over 25 years.

OBJECTIVE

To examine the initial safety and efficacy performance of an investigational, high-frequency (≥250 Hz) VNS paradigm herein called "Microburst VNS" (μVNS). μVNS consists of short, high-frequency bursts of electrical pulses believed to preferentially modulate certain brain regions.

METHODS

Thirty-three (33) participants were enrolled into an exploratory feasibility study, 21 with focal-onset seizures and 12 with generalized-onset seizures. Participants were titrated to a personalized target dose of μVNS using an investigational fMRI protocol. Participants were then followed for up to 12 months, with visits every 3 months, and monitored for side-effects at all time points. This study was registered as NCT03446664 on February 27th, 2018.

RESULTS

The device was well-tolerated. Reported adverse events were consistent with typical low frequency VNS outcomes and tended to diminish in severity over time, including dysphonia, cough, dyspnea, and implant site pain. After 12 months of μVNS, the mean seizure frequency reduction for all seizures was 61.3% (median reduction: 70.4%; 90% CI of median: 48.9%-83.3%). The 12-month responder rate (≥50% reduction) was 63.3% (90% CI: 46.7%-77.9%) and the super-responder rate (≥80% reduction) was 40% (90% CI: 25.0%-56.6%). Participants with focal-onset seizures appeared to benefit similarly to participants with generalized-onset seizures (mean reduction in seizures at 12 months: 62.6% focal [n = 19], versus 59.0% generalized [n = 11]).

CONCLUSION

Overall, μVNS appears to be safe and potentially a promising therapeutic alternative to traditional VNS. It merits further investigation in randomized controlled trials which will help determine the impact of investigational variables and which patients are most suitable for this novel therapy.

Longitudinal evolution of electroencephalogram (EEG): Findings over five years of follow-up in children with Zika-related microcephaly from the Microcephaly Epidemic Research Group Pediatric Cohort (2015-2020)

OBJECTIVE

To assess the longitudinal evolution of EEG findings in children with Zika related-microcephaly (ZRM) and to evaluate the associations of these patterns with the children's clinical and neuroimaging characteristics.

METHODS

As part of the follow-up of the Microcephaly Epidemic Research Group Pediatric Cohort (MERG-PC) in Recife, Brazil, we performed serial EEG recordings in a subgroup of children with ZRM to evaluate changes in background rhythms and epileptiform activity (EA). Latent class analysis was used to identify patterns in the evolution of EA over time; clinical and neuroimaging findings were compared across the identified groups.

RESULTS

Out of the 72 children with ZRM who were evaluated during 190 EEGs/videoEEGs, all participants presented with abnormal background activity, 37.5% presented with an alpha-theta rhythmic activity, and 25% presented with sleep spindles, which were less commonly observed in children with epilepsy. EA changed over time in 79.2% of children, and three distinct trajectories were identified: (i) multifocal EA over time, (ii) no discharges/focal EA evolving to focal/multifocal EA, and (iii) focal/multifocal EA evolving to epileptic encephalopathy patterns (e.g., hypsarrhythmia or continuous EA in sleep). The multifocal EA over time trajectory was associated with periventricular and thalamus/basal ganglia calcifications, brainstem and corpus callosum atrophy and had less focal epilepsy, whereas the children in the trajectory which evolved to epileptic encephalopathy patterns had more frequently focal epilepsy.

SIGNIFICANCE

These findings suggest that, in most children with ZRM, trajectories of changes in EA can be identified and associated with neuroimaging and clinical features.

A splicing variation in NPRL2 causing familial focal epilepsy with variable foci: additional cases and literature review

NPRL2 (nitrogen permease regulator like 2) is a component of the GATOR1(GAP activity towards rags complex 1) proteins, which is an inhibitor of the amino acid-sensing branch of the mTORC1 pathway. GATOR1 complex variations were reported to correlate with familial focal epilepsy with variable foci (FFEVF). However, FFEVF caused by NPRL2 variants has not been widely explored. Here, we describe a variant, 339+2T>C, in NPRL2 identified by trio whole-exome sequencing (WES) in a family. This splicing variant that occurred at the 5' end of exon 3 was confirmed by minigene assays, which affected alternative splicing and led to exon 3 skipping in NPRL2. Our cases presented multiple seizure types (febrile seizures, infantile spasms, focal seizures, or focal to generalized tonic-clonic seizures). Electroencephalogram (EEG) showed frequent discharges in the left frontal and central regions. A favorable prognosis was achieved in response to vitamin B6 and topiramate when the patient was seven months old. Our study expands the phenotype and genotype spectrum of FFEVF and provides solid diagnostic evidence for FFEVF.

Interictal spike networks predict surgical outcome in patients with drug-resistant focal epilepsy

OBJECTIVE

To determine if properties of epileptic networks could be delineated using interictal spike propagation seen on stereo-electroencephalography (SEEG) and if these properties could predict surgical outcome in patients with drug-resistant epilepsy.

METHODS

We studied the SEEG of 45 consecutive drug-resistant epilepsy patients who underwent subsequent epilepsy surgery: 18 patients with good post-surgical outcome (Engel I) and 27 with poor outcome (Engel II-IV). Epileptic networks were derived from interictal spike propagation; these networks described the generation and propagation of interictal epileptic activity. We compared the regions in which spikes were frequent and the regions responsible for generating spikes to the area of resection and post-surgical outcome. We developed a measure termed source spike concordance, which integrates information about both spike rate and region of spike generation.

RESULTS

Inclusion in the resection of regions with high spike rate is associated with good post-surgical outcome (sensitivity = 0.82, specificity = 0.73). Inclusion in the resection of the regions responsible for generating interictal epileptic activity independently of rate is also associated with good post-surgical outcome (sensitivity = 0.88, specificity = 0.82). Finally, when integrating the spike rate and the generators, we find that the source spike concordance measure has strong predictability (sensitivity = 0.91, specificity = 0.94).

INTERPRETATIONS

Epileptic networks derived from interictal spikes can determine the generators of epileptic activity. Inclusion of the most active generators in the resection is strongly associated with good post-surgical outcome. These epileptic networks may aid clinicians in determining the area of resection during pre-surgical evaluation.

Regional abnormality of functional connectivity is associated with clinical manifestations in individuals with intractable focal epilepsy

We explored regional functional connectivity alterations in intractable focal epilepsy brains using resting-state functional MRI. Distributions of the network parameters (corresponding to degree and eigenvector centrality) measured at each brain region for all 25 patients were significantly different from age- and sex-matched control data that were estimated by a healthy control dataset (n = 582, 18-84 years old). The number of abnormal regions whose parameters exceeded the mean + 2 SD of age- and sex-matched data for each patient were associated with various clinical parameters such as the duration of illness and seizure severity. Furthermore, abnormal regions for each patient tended to have functional connections with each other (mean ± SD = 58.6 ± 20.2%), the magnitude of which was negatively related to the quality of life. The abnormal regions distributed within the default mode network with significantly higher probability (p < 0.05) in 7 of 25 patients. We consider that the detection of abnormal regions by functional connectivity analysis using a large number of control datasets is useful for the numerical assessment of each patient's clinical conditions, although further study is necessary to elucidate etiology-specific abnormalities.

Ictal EEG in patients with autistic spectrum disorder and epilepsy

OBJECTIVE

Autism spectrum disorder (ASD) is a neurodevelopmental disorder frequently associated with epilepsy and epilepsy is a leading cause of death in ASD patients. Despite growing interest in genetic, neurophysiological and clinical overlaps, data on ictal electroencephalographic (EEG) recordings in ASD are lacking since behavioral disorders often make it difficult to obtain EEG recordings. We examined ictal EEG features in a consecutive series of patients with ASD and epilepsy.

METHODS

We retrospectively identified 400 consecutive patients with ASD and epilepsy at our Level 4 Epilepsy center between 2015 and 2019; 45 had at least one EEG-recorded seizure captured. Demographics, age of nonfebrile seizure onset, age of ASD diagnosis, language, magnetic resonance imagining findings, genetic testing and EEG studies were reviewed. Seizures were classified by semiologic and electrographic features. Ictal findings were analyzed.

RESULTS

A total of 497 seizures were captured in 45 patients: 20 patients with focal onset epilepsy had 126 seizures (median: 1, range: 1-30), 17 patients with generalized onset epilepsy had 88 seizures (median: 2, range: 1-15), 7 patients with Lennox-Gastaut syndrome had 270 seizures (median: 12, range: 1-74) and one patient had both right hemisphere focal and generalized onsets (12 focal, 1 generalized).

SIGNIFICANCE

Our study is the first to analyze a large set of ictal data in patients with autism spectrum disorder, a population traditionally difficult to obtain ictal recordings. Our results confirm the diverse spectrum of seizure types and provide clinical-EEG correlates of seizures in ASD patients. Both focal-onset and generalized-onset seizures were recorded, confirming that ASD patients have higher rates of both focal and generalized epilepsy syndromes. Among patients with focal epilepsy, temporal and frontal onsets were frequent, suggesting the possibility of epilepsy surgery or brain stimulation. EEG to classify seizures and epilepsies is critical to determine therapeutic options and effort should be made to obtain EEGs in this heterogenous population.

High-density Electric Source Imaging of interictal epileptic discharges: How many electrodes and which time point?

OBJECTIVE

To assess the value of caudal EEG electrodes over cheeks and neck for high-density electric source imaging (ESI) in presurgical epilepsy evaluation, and to identify the best time point during averaged interictal epileptic discharges (IEDs) for optimal ESI accuracy.

METHODS

We retrospectively examined presurgical 257-channel EEG recordings of 45 patients with pharmacoresistant focal epilepsy. By stepwise removal of cheek and neck electrodes, averaged IEDs were downsampled to 219, 204, and 156 EEG channels. Additionally, ESI at the IED's half-rise was compared to other time points. The respective sources of maximum activity were compared to the resected brain area and postsurgical outcome.

RESULTS

Caudal channels had disproportionately more artefacts. In 30 patients with favourable outcome, the 204-channel array yielded the most accurate results with ESI maxima < 10 mm from the resection in 67% and inside affected sublobes in 83%. Neither in temporal nor in extratemporal cases did the full 257-channel setup improve ESI accuracy. ESI was most accurate at 50% of the IED's rising phase.

CONCLUSION

Information from cheeks and neck electrodes did not improve high-density ESI accuracy, probably due to higher artefact load and suboptimal biophysical modelling.

SIGNIFICANCE

Very caudal EEG electrodes should be used for ESI with caution.

A multi-scale cortical wiring space links cellular architecture and functional dynamics in the human brain

The vast net of fibres within and underneath the cortex is optimised to support the convergence of different levels of brain organisation. Here, we propose a novel coordinate system of the human cortex based on an advanced model of its connectivity. Our approach is inspired by seminal, but so far largely neglected models of cortico-cortical wiring established by postmortem anatomical studies and capitalises on cutting-edge in vivo neuroimaging and machine learning. The new model expands the currently prevailing diffusion magnetic resonance imaging (MRI) tractography approach by incorporation of additional features of cortical microstructure and cortico-cortical proximity. Studying several datasets and different parcellation schemes, we could show that our coordinate system robustly recapitulates established sensory-limbic and anterior-posterior dimensions of brain organisation. A series of validation experiments showed that the new wiring space reflects cortical microcircuit features (including pyramidal neuron depth and glial expression) and allowed for competitive simulations of functional connectivity and dynamics based on resting-state functional magnetic resonance imaging (rs-fMRI) and human intracranial electroencephalography (EEG) coherence. Our results advance our understanding of how cell-specific neurobiological gradients produce a hierarchical cortical wiring scheme that is concordant with increasing functional sophistication of human brain organisation. Our evaluations demonstrate the cortical wiring space bridges across scales of neural organisation and can be easily translated to single individuals.

The clinical significance of small sharp spikes: A retrospective study of 909 patients in epilepsy monitoring unit

OBJECTIVES

To determine the incidence and clinical significance of small sharp spikes (SSS) in the patient population of the adult Epilepsy Monitoring Unit (EMU).

METHODS

This is a retrospective study of EEG data and medical records from consecutive patients who underwent video-EEG recording in the adult EMU from March 2013 to February 2019. SSS, interictal epileptiform discharges (IEDs), and ictal patterns were identified.

RESULTS

Of the 909 patients reviewed, SSS were observed in110 (12.1 %) patients. Epilepsy was present in 101 of the 110 (91.8 %) patients with SSS and in 441 of the 799 (55.2 %) patients without SSS. The incidence of epilepsy was significantly higher in patients with SSS than in those without SSS (OR = 9.1, 95 % CI: 4.5-18.3, P < 0.01). The sensitivity of SSS for epilepsy was 18.6 % and the specificity was 97.5 %. The incidence of SSS was strongly correlated with the frequency of IEDs (OR 1.89; 95 %CI: 1.60-2.24, P < 0.01). When both present, SSS and IEDs were co-lateralized in the same hemisphere.

CONCLUSIONS

There is a statistically significant association between SSS and focal epilepsy. SSS have similar clinical implications to IEDs in the lateralization and localization of temporal lobe seizures. SSS can be an epileptiform EEG pattern for temporal lobe epilepsy.

Psychosis rarely occurs in patients with late-onset focal epilepsy

AIMS

We examined psychosis occurrence in patients with late-onset focal epilepsy.

SUBJECTS AND METHODS

Case records of consecutive patients with focal epilepsy without central nervous system (CNS) disease (n = 873) were retrospectively examined, with gender, age at epilepsy onset, duration of epilepsy, epilepsy type (temporal or extratemporal), and age at the initial examination used as clinical and demographic variables. Patients with onset ≤49 years old (control) were compared with those with late-onset.

RESULTS

In the control group (n = 775), 38 had a history of psychosis, while none in the late-onset group (n = 98) reported that (p = 0.016). Psychosis was only interictal in 32 and predominantly postictal in 6, while 2 patients showed both interictal and postictal psychosis. Duration of illness (p = 0.000001) and temporal lobe epilepsy (p = 0.000343) were significant determinants associated with psychosis. Gender (p = 0.210) and age at examination (p = 0.084) were found to be not contributory to psychosis.

DISCUSSION

The prevalence for a history of psychosis in the present cohort (2.5%) agrees well with that noted in previous studies, and duration of illness proved to be the most powerful determining factor leading to that. A keen awareness of unrecognized underlying CNS or metabolic disease is important when psychosis appears in patients with nonlesional late-onset epilepsy, which should lead to an in-depth investigation of possible underlying and still uncovered CNS disease.

Volumetric and Functional Activity Lateralization in Healthy Subjects and Patients with Focal Epilepsy: Initial Findings in a 7T MRI Study

BACKGROUND AND PURPOSE

In 30% of the patients with focal epilepsy, an epileptogenic lesion cannot be visually detected with structural MRI. Ultra-high field MRI may be able to identify subtle pathology related to the epileptic focus. We set out to assess 7T MRI-derived volumetric and functional activity lateralization of the hippocampus, hippocampal subfields, temporal and frontal lobe in healthy subjects and MRI-negative patients with focal epilepsy.

METHODS

Twenty controls and 10 patients with MRI-negative temporal or frontal lobe epilepsy (TLE and FLE, respectively) underwent a 7T MRI exam. T1 -weigthed imaging and resting-state fMRI was performed. T1 -weighted images were segmented to yield volumes, while from fMRI data, the fractional amplitude of low frequency fluctuations was calculated. Subsequently, volumetric and functional lateralization was calculated from left-right asymmetry.

RESULTS

In controls, volumetric lateralization was symmetric, with a slight asymmetry of the hippocampus and subiculum, while functional lateralization consistently showed symmetry. Contrarily, in epilepsy patients, regions were less symmetric. In TLE patients with known focus, volumetric lateralization in the hippocampus and hippocampal subfields was indicative of smaller ipsilateral volumes. These patients also showed clear functional lateralization, though not consistently ipsilateral or contralateral to the epileptic focus. TLE patients with unknown focus showed an obvious volumetric lateralization, facilitating the localization of the epileptic focus. Lateralization results in the FLE patients were less consistent with the epileptic focus.

CONCLUSION

MRI-derived volume and fluctuation amplitude are highly symmetric in controls, whereas in TLE, volumetric and functional lateralization effects were observed. This highlights the potential of the technique.

Nine-year prospective efficacy and safety of brain-responsive neurostimulation for focal epilepsy

OBJECTIVE

To prospectively evaluate safety and efficacy of brain-responsive neurostimulation in adults with medically intractable focal onset seizures (FOS) over 9 years.

METHODS

Adults treated with brain-responsive neurostimulation in 2-year feasibility or randomized controlled trials were enrolled in a long-term prospective open label trial (LTT) to assess safety, efficacy, and quality of life (QOL) over an additional 7 years. Safety was assessed as adverse events (AEs), efficacy as median percent change in seizure frequency and responder rate, and QOL with the Quality of Life in Epilepsy (QOLIE-89) inventory.

RESULTS

Of 256 patients treated in the initial trials, 230 participated in the LTT. At 9 years, the median percent reduction in seizure frequency was 75% (p < 0.0001, Wilcoxon signed rank), responder rate was 73%, and 35% had a ≥90% reduction in seizure frequency. We found that 18.4% (47 of 256) experienced ≥1 year of seizure freedom, with 62% (29 of 47) seizure-free at the last follow-up and an average seizure-free period of 3.2 years (range 1.04-9.6 years). Overall QOL and epilepsy-targeted and cognitive domains of QOLIE-89 remained significantly improved (p < 0.05). There were no serious AEs related to stimulation, and the sudden unexplained death in epilepsy (SUDEP) rate was significantly lower than predefined comparators (p < 0.05, 1-tailed χ2).

CONCLUSIONS

Adjunctive brain-responsive neurostimulation provides significant and sustained reductions in the frequency of FOS with improved QOL. Stimulation was well tolerated; implantation-related AEs were typical of other neurostimulation devices; and SUDEP rates were low.

CLINICALTRIALSGOV IDENTIFIER

NCT00572195.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that brain-responsive neurostimulation significantly reduces focal seizures with acceptable safety over 9 years.

Inappropriate Laughter in a Patient with Hypothalamic Hamartoma

MEDICAL IMAGE

Macroscale and microcircuit dissociation of focal and generalized human epilepsies

Thalamo-cortical pathology plays key roles in both generalized and focal epilepsies, but there is little work directly comparing these syndromes at the level of whole-brain mechanisms. Using multimodal imaging, connectomics, and computational simulations, we examined thalamo-cortical and cortico-cortical signatures and underlying microcircuits in 96 genetic generalized (GE) and 107 temporal lobe epilepsy (TLE) patients, along with 65 healthy controls. Structural and functional network profiling highlighted extensive atrophy, microstructural disruptions and decreased thalamo-cortical connectivity in TLE, while GE showed only subtle structural anomalies paralleled by enhanced thalamo-cortical connectivity. Connectome-informed biophysical simulations indicated modest increases in subcortical drive contributing to cortical dynamics in GE, while TLE presented with reduced subcortical drive and imbalanced excitation-inhibition within limbic and somatomotor microcircuits. Multiple sensitivity analyses supported robustness. Our multiscale analyses differentiate human focal and generalized epilepsy at the systems-level, showing paradoxically more severe microcircuit and macroscale imbalances in the former.

Optically pumped magnetoencephalography in epilepsy

We demonstrate the first use of Optically Pumped Magnetoencephalography (OP-MEG) in an epilepsy patient with unrestricted head movement. Current clinical MEG uses a traditional SQUID system, where sensors are cryogenically cooled and housed in a helmet in which the patient's head is fixed. Here, we use a different type of sensor (OPM), which operates at room temperature and can be placed directly on the patient's scalp, permitting free head movement. We performed OP-MEG recording in a patient with refractory focal epilepsy. OP-MEG-identified analogous interictal activity to scalp EEG, and source localized this activity to an appropriate brain region.

The FAST graph: A novel framework for the anatomically-guided visualization and analysis of cortico-cortical evoked potentials

BACKGROUND

Intracerebral electroencephalography (iEEG) using stereoelectroencephalography (SEEG) methodology for epilepsy surgery gives rise to complex data sets. The neurophysiological data obtained during the in-patient period includes categorization of the evoked potentials resulting from direct electrical cortical stimulation such as cortico-cortical evoked potentials (CCEPs). These potentials are recorded by hundreds of contacts, making these waveforms difficult to quickly interpret over such high-density arrays that are organized in three dimensional fashion.

NEW METHOD

The challenge in analyzing CCEPs data arises not just from the density of the array, but also from the stimulation of a number of different intracerebral sites. A systematic methodology for visualization and analysis of these evoked data is lacking. We describe the process of incorporating anatomical information into the visualizations, which are then compared to more traditional plotting techniques to highlight the usefulness of the new framework.

RESULTS

We describe here an innovative framework for sorting, registering, labeling, ordering, and quantifying the functional CCEPs data, using the anatomical labelling of the brain, to provide an informative visualization and summary statistics which we call the "FAST graph" (Functional-Anatomical STacked area graphs). The FAST graph analysis is used to depict the significant CCEPs responses in patient with focal epilepsy.

CONCLUSIONS

The novel plotting approach shown here allows us to visualize high-density stimulation data in a single summary plot for subsequent detailed analyses. Improving the visual presentation of complex data sets aides in enhancing the clinical utility of the data.

EEG Analysis in Structural Focal Epilepsy Using the Methods of Nonlinear Dynamics (Lyapunov Exponents, Lempel-Ziv Complexity, and Multiscale Entropy)

This paper analyzes a case with the patient having focal structural epilepsy by processing electroencephalogram (EEG) fragments containing the "sharp wave" pattern of brain activity. EEG signals were recorded using 21 channels. Based on the fact that EEG signals are time series, an approach has been developed for their analysis using nonlinear dynamics tools: calculating the Lyapunov exponent's spectrum, multiscale entropy, and Lempel-Ziv complexity. The calculation of the first Lyapunov exponent is carried out by three methods: Wolf, Rosenstein, and Sano-Sawada, to obtain reliable results. The seven Lyapunov exponent spectra are calculated by the Sano-Sawada method. For the observed patient, studies showed that with medical treatment, his condition did not improve, and as a result, it was recommended to switch from conservative treatment to surgical. The obtained results of the patient's EEG study using the indicated nonlinear dynamics methods are in good agreement with the medical report and MRI data. The approach developed for the analysis of EEG signals by nonlinear dynamics methods can be applied for early detection of structural changes.

Parry-Romberg syndrome in Kuwait. Neurological manifestations in 2 children

Parry-Romberg syndrome is a rare disorder with progressive hemifacial atrophy of unknown etiology. We reported 2 cases of progressive hemifacial atrophy with different neurological manifestations from Kuwait. The first case was a 14-year-old boy who initially presented with recurrent transient stroke-like episodes followed by focal seizures and hemifacial atrophy. Magnetic resonance imaging showed significant white matter changes and cerebral hemiatrophy. The second case was a 7-year-old girl who presented with complex partial seizures and hemifacial atrophy, her magnetic resonance imaging scan showed minimal changes in the hemiatrophy of the temporal cerebral lobe. Both patients' disease activity was well controlled with immunosuppressive therapy and anticonvulsants. Parry-Romberg syndrome should be considered in any child with unexplained neurological symptoms.

Cortical thickness in childhood left focal epilepsy: Thinning beyond the seizure focus

OBJECTIVE

Structural brain differences are found in adults and children with epilepsy, yet pediatric samples have been heterogeneous regarding seizure type, magnetic resonance imaging (MRI) findings, and hemisphere of seizure focus. This study examines whether cortical thickness and surface area differ between children with left-hemisphere focal epilepsy (LHE) and age-matched typically developing (TD) peers. We examined whether age differentially moderated cortical thickness between groups and if cortical thickness was associated with duration of epilepsy, seizure frequency, or neuropsychological functioning.

METHODS

Thirty-five children with LHE and 35 TD children completed neuropsychological testing and 3T MR imaging. Neuropsychological measures included general intelligence and executive functioning. All MRIs were normal. Surface-based morphometric processing and analyses were conducted using FreeSurfer 6.0. Regression analyses compared age by cortical thickness differences between groups. Correlational analyses examined associations between cortical thickness in these areas with neuropsychological functioning or epilepsy characteristics.

RESULTS

Left-hemisphere focal epilepsy displayed decreased cortical thickness bilaterally compared to TD controls across 6 brain regions but no differences in surface area. Moderation analyses revealed quadratic relationships between age and cortical thickness for left frontoparietal-cingulate and right superior frontal regions. Higher performance intelligence quotient (IQ) (PIQ) and verbal IQ (VIQ) and fewer parent reported executive function problems were associated with greater cortical thickness in TD children.

SIGNIFICANCE

Children with LHE displayed thinner cortex extending beyond the hemisphere of seizure focus. The nonlinear pattern of cortical thickness across age occurring in TD children is not evident in the same manner in children with LHE. These differences in cortical thickness patterns were greatest in children 8-12 years old. Greater cortical thickness was associated with higher IQ and fewer executive control problems in daily activities in TD children. Thus, differences in cortical thickness in the absence of differences in surface area, suggest cortical thickness may be a sensitive proxy of subtle neuroanatomical changes that are related to neuropsychological functioning.

Focal EEG abnormalities and focal ictal semiology in generalized epilepsy

In clinical practice, the diagnosis of focal vs generalized epilepsy dictates the management of the patient. The distinction between generalized and focal epilepsy is at times imperfect and some epilepsies have features that fall in between these two extremes. An example is the occurrence of focal interictal and focal ictal abnormalities in generalized epilepsies. As a part of the special issue on "The epileptogenic zone in pediatric epilepsy surgery", this focused narrative review will discuss different focal abnormalities seen in generalized epilepsy. An overlap of focal and generalized epileptiform abnormalities may support a continuum between focal and generalized epilepsy. When evaluating patients in the "gray zone", other factors such as ictal semiology, neuroimaging, genetic testing and functional deficits may need to be considered to reach an accurate diagnosis. Being aware of possible occurrence of focal clinical and EEG features in generalized epilepsy will help clinicians select more preferred AED (s), avoiding potential iatrogenic side effects and inappropriate consideration for epilepsy surgery.

Localizing non-epileptiform abnormal brain function in children using high density EEG: Electric Source Imaging of focal slowing

BACKGROUND

Electric Source Imaging (ESI) of interictal epileptiform discharges (IED) is increasingly validated for localizing epileptic activity. In children, IED can be absent or multifocal even in cases of a focal epileptogenic zone and additional electrophysiological markers are needed. Here, we investigated ESI of pathological focal slowing (FS) recorded on EEG as a new localizing marker in children with drug-resistant epilepsy.

METHODS

We selected 15 children (median: 12; range: 4-18yrs), with high-density EEG (hdEEG), presurgical evaluation and surgical resection. One patient had a non-lesional MRI. ESI of patient-specific focal slow activity was performed (distributed linear inverse solution and individual head model). The maximal average power in the band of interest was considered as the source of focal slowing (ESI-FS). The Euclidian distance between ESI-FS and the resection (5 mm margin) was compared to the localization of maximal ESI of interictal epileptiform discharges (ESI-IED), interictal FDG-PET and ictal SPECT/SISCOM.

RESULTS

In 9/15 patients (60%), ESI of focal slowing (ESI-FS) was inside or ≤5 mm from resection margins. The remaining 6/15 cases had distances ≤15 mm. In 9/15 patients with interictal spikes, the ESI-IED was concordant with the resection. 6/15 patients with concordant ESI-FS showed also interictal concordant ESI of IED; in 3/15 patients, ESI-FS but not ESI-IED was concordant with the resection. In 10/15 patients, ESI-FS was concordant with MRI lesion and for ESI-IED this concordance was on 8/15 patients. Maximal hypometabolism and SISCOM were concordant with the resection for 7/15 and 7/12, respectively.

CONCLUSION

These findings suggest that "non-epileptiform" EEG activity, such as focal slowing, could be a complementary useful marker to localize the epileptogenic zone. ESI-FS may notably be applied in young patients without focal interictal spikes or multifocal spikes. This potential new marker of brain dysfunction has potential applications to other neurological disorders associated with slow EEG activity.

Risk factors associated with drug resistant focal epilepsy in adults: A case control study

PURPOSE

Using an adult cohort of patients with focal epilepsy, we aimed to identify risk factors for development of drug-resistant epilepsy, which if identifiable would allow patients to receive appropriate counsel and earlier surgical treatment.

METHODS

This is a case-control study nested within a cohort, 146 adult patients with focal epilepsy were included. Definitions were used in accordance with ILAE criteria. The odds ratio and its confidence interval were calculated. We performed a logistic regression analysis.

RESULTS

Seventy-one [48.6%] patients met the criteria for drug-resistant epilepsy [cases] and 75 [51.4%] patients were controls. The mean age of patients was 44.5 ± 16.4 years. The most significant variables associated with developing drug-resistant epilepsy include younger age at diagnosis [18.75 vs. 32.2, p < 0.001], years of evolution of epilepsy [22.54 vs. 16.05, p < 0.001], number of AED [4.8 vs. 2.87, p < 0.001], complex partial seizures [51 vs. 35 OR 2.9, p = 0.002], having more than one seizure per month [51 vs. 38, p = 0.009], bi-temporal focus [14 vs. 4 p = 0.008] and mesial temporal sclerosis [23 vs. 11 p = 0.01]. Good response to first AED [7 vs. 29 OR 0.2, p = 0.001] and epilepsy secondary to encephalomalacia [8 vs. 20 OR 0.35, p = 0.018] might be protective factors against drug resistant epilepsy.

CONCLUSIONS

Longer time of epilepsy evolution, high frequency of seizures, complex partial seizure presentation, higher number of antiepileptic drugs, mesial temporal sclerosis and bitemporal epilepsy are predictive factors of subsequent pharmacoresistance.

Self-stimulation in an adult misdiagnosed with focal epilepsy

Self-stimulation is a normal part of development and a common behaviour in children before puberty, but very rare in adults. The stereotyped semiology can sometimes raise the suspicion of epilepsy. We present a 30-year-old patient who came to our epilepsy monitoring unit for differential diagnosis of nocturnal episodes, interpreted elsewhere as hypermotor status epilepticus associated with a known diagnosis of focal epilepsy and septo-optic dysplasia. The recorded events during video-EEG were consistent with psychogenic self-stimulating behaviour, which improved with psychotherapy. Disturbed sexual development with hypopituitarism and poor eyesight, androgen replacement therapy, alongside a protective environment provided by her parents, were the identified predisposing factors for this uncommon entity in an adult. [Published with video sequence].

Misdiagnosis and pitfalls in Panayiotopoulos syndrome

Panayiotopoulos syndrome (PS) is a frequent (6% among children of 1-15 years) and benign epileptic syndrome, characterized by predominantly autonomic symptoms (emesis, pallor, flushing, cyanosis, mydriasis/miosis, cardiorespiratory and thermoregulatory alterations, incontinence of urine and/or feces, hypersalivation, and modifications of intestinal motility) associated with simple motor focal seizures, which can be followed by secondary generalization. Panayiotopoulos syndrome can be extremely insidious, because it can mimic several condition, such as gastroenteritis, gastroesophageal reflux disease, encephalitis, syncope, migraine, sleep disorders, or even metabolic diseases. This peculiar pleiotropism should be kept in mind by child neurologists and pediatricians and general practitioners, because a wrong diagnosis may lead to inappropriate interventions. The consequences are high morbidity, costly mismanagement, and stress for children and their parents. The availability of electroencephalography (EEG) recording in pediatric Emergency Departments might be useful for a prompt and not-cost-consuming diagnosis. On the other hand, it is important to be aware of the possible, multifaceted, clinical presentations of PS and its clinical, radiological, and neurophysiological features in order to improve both recognition and management.

Characterizing the role of the structural connectome in seizure dynamics

How does the human brain's structural scaffold give rise to its intricate functional dynamics? This is a central question in translational neuroscience that is particularly relevant to epilepsy, a disorder affecting over 50 million subjects worldwide. Treatment for medication-resistant focal epilepsy is often structural-through surgery or laser ablation-but structural targets, particularly in patients without clear lesions, are largely based on functional mapping via intracranial EEG. Unfortunately, the relationship between structural and functional connectivity in the seizing brain is poorly understood. In this study, we quantify structure-function coupling, specifically between white matter connections and intracranial EEG, across pre-ictal and ictal periods in 45 seizures from nine patients with unilateral drug-resistant focal epilepsy. We use high angular resolution diffusion imaging (HARDI) tractography to construct structural connectivity networks and correlate these networks with time-varying broadband and frequency-specific functional networks derived from coregistered intracranial EEG. Across all frequency bands, we find significant increases in structure-function coupling from pre-ictal to ictal periods. We demonstrate that short-range structural connections are primarily responsible for this increase in coupling. Finally, we find that spatiotemporal patterns of structure-function coupling are highly stereotyped for each patient. These results suggest that seizures harness the underlying structural connectome as they propagate. Mapping the relationship between structural and functional connectivity in epilepsy may inform new therapies to halt seizure spread, and pave the way for targeted patient-specific interventions.

Slowing less than 1 Hz is decreased near the seizure onset zone

Focal slowing (<4 Hz) of brain waves is often associated with focal cerebral dysfunction and is assumed to be increased closest to the location of dysfunction. Prior work suggests that slowing may be comprised of at least two distinct neural mechanisms: slow oscillation activity (<1 Hz) may reflect primarily inhibitory cortical mechanisms while power in the delta frequency (1-4 Hz) may correlate with local synaptic strength. In focal epilepsy patients, we examined slow wave activity near and far from the seizure onset zone (SOZ) during wake, sleep, and postictal states using intracranial electroencephalography. We found that slow oscillation (0.3-1 Hz) activity was decreased near the SOZ, while delta activity (2-4 Hz) activity was increased. This finding was most prominent during sleep, and accompanied by a loss of long-range intra-hemispheric synchrony. In contrast to sleep, postictal slowing was characterized by a broadband increase of spectral power, and showed a reduced modulatory effect of slow oscillations on higher frequencies. These results suggest slow oscillation focal slowing is reduced near the seizure onset zone, perhaps reflecting reduced inhibitory activity. Dissociation between slow oscillation and delta slowing could help localize the seizure onset zone from interictal intracranial recordings.

Deep brain activities can be detected with magnetoencephalography

The hippocampus and amygdala are key brain structures of the medial temporal lobe, involved in cognitive and emotional processes as well as pathological states such as epilepsy. Despite their importance, it is still unclear whether their  neural activity can be recorded non-invasively. Here, using simultaneous intracerebral and magnetoencephalography (MEG) recordings in patients with focal drug-resistant epilepsy, we demonstrate a direct contribution of amygdala and hippocampal activity to surface MEG recordings. In particular, a method of blind source separation, independent component analysis, enabled activity arising from large neocortical networks to be disentangled from that of deeper structures, whose amplitude at the surface was small but significant. This finding is highly relevant for our understanding of hippocampal and amygdala brain activity as it implies that their activity could potentially be measured non-invasively.

Controlling seizure propagation in large-scale brain networks

Information transmission in the human brain is a fundamentally dynamic network process. In partial epilepsy, this process is perturbed and highly synchronous seizures originate in a local network, the so-called epileptogenic zone (EZ), before recruiting other close or distant brain regions. We studied patient-specific brain network models of 15 drug-resistant epilepsy patients with implanted stereotactic electroencephalography (SEEG) electrodes. Each personalized brain model was derived from structural data of magnetic resonance imaging (MRI) and diffusion tensor weighted imaging (DTI), comprising 88 nodes equipped with region specific neural mass models capable of demonstrating a range of epileptiform discharges. Each patient's virtual brain was further personalized through the integration of the clinically hypothesized EZ. Subsequent simulations and connectivity modulations were performed and uncovered a finite repertoire of seizure propagation patterns. Across patients, we found that (i) patient-specific network connectivity is predictive for the subsequent seizure propagation pattern; (ii) seizure propagation is characterized by a systematic sequence of brain states; (iii) propagation can be controlled by an optimal intervention on the connectivity matrix; (iv) the degree of invasiveness can be significantly reduced via the proposed seizure control as compared to traditional resective surgery. To stop seizures, neurosurgeons typically resect the EZ completely. We showed that stability analysis of the network dynamics, employing structural and dynamical information, estimates reliably the spatiotemporal properties of seizure propagation. This suggests novel less invasive paradigms of surgical interventions to treat and manage partial epilepsy.

Rapid and specific processing of person-related information in human anterior temporal lobe

The anterior temporal lobe (ATL), located at the tip of the human temporal lobes, has been heavily implicated in semantic processing by neuropsychological and functional imaging studies. These techniques have revealed a hemispheric specialization of ATL, but little about the time scale on which it operates. Here we show that ATL is specifically activated in intracerebral recordings when subjects discriminate the gender of an actor presented in a static frame followed by a video. ATL recording sites respond briefly (100 ms duration) to the visual static presentation of an actor in a task-, but not in a stimulus-duration-dependent way. Their response latencies correlate with subjects' reaction times, as do their activity levels, but oppositely in the two hemispheres operating in a push-pull fashion. Comparison of ATL time courses with those of more posterior, less specific regions emphasizes the role of inhibitory operations sculpting the fast ATL responses underlying semantic processing.

[DYSFUNKCJA AUTONOMICZNEGO UKŁADU NERWOWEGO W PADACZCE Dysfunction of the autonomic nervous system in epilepsy OPISY PRZYPADKU / CASE REPORTS]

Generalized or partial epileptic seizures may be accompanied by autonomic dysfunction. They may also take the form of self-inflicted seizures or be present during interictal period. Arrhythmias, resulting in haemodynamic disturbances in the circulatory system and prolonged hypoxia of the central nervous system, may itself provoke secondary episodes of seizure morphology. The doctor when diagnosing patients with epileptic seizures should always be aware of the potential for cardiogenic disorders. Consideration should be given to the effect of epilepsy on the structure of the autonomic nervous system, the effect of antiepileptic drugs, and the potential for mutations within the ion channels.

A Comparison of Evoked and Non-evoked Functional Networks

The growing interest in brain networks to study the brain's function in cognition and diseases has produced an increase in methods to extract these networks. Typically, each method yields a different network. Therefore, one may ask what the resulting networks represent. To address this issue we consider electrocorticography (ECoG) data where we compare three methods. We derive networks from on-going ECoG data using two traditional methods: cross-correlation (CC) and Granger causality (GC). Next, connectivity is probed actively using single pulse electrical stimulation (SPES). We compare the overlap in connectivity between these three methods as well as their ability to reveal well-known anatomical connections in the language circuit. We find that strong connections in the CC network form more or less a subset of the SPES network. GC and SPES are related more weakly, although GC connections coincide more frequently with SPES connections compared to non-existing SPES connections. Connectivity between the two major hubs in the language circuit, Broca's and Wernicke's area, is only found in SPES networks. Our results are of interest for the use of patient-specific networks obtained from ECoG. In epilepsy research, such networks form the basis for methods that predict the effect of epilepsy surgery. For this application SPES networks are interesting as they disclose more physiological connections compared to CC and GC networks.

Inappropriate Laughter and Behaviours: How, What, and Why? Case of an Adult with Undiagnosed Gelastic Seizure with Hypothalamic Hamartoma

Gelastic seizures (GS) are a rare form of epilepsy characterized by inappropriate, uncontrolled laughter. They are highly associated with abnormal cognitive development and behavioral problems in patients. Research has shown that GS can originate from hypothalamic hamartomas (HH), non- neoplastic masses consisting of gray matter with large and small neurons interspersed with glial nuclei. GS have also been observed in patients with frontal and temporal lobe lesions. The patient in this case report is a 40-year-old man with a past medical history significant for brain tumor, diabetes mellitus, and schizophrenia who presented with a long standing history of sudden, involuntary laughter occurring 2-3 times a week since 8 years old. Since the onset of these laughing spells the patient has displayed gradual cognitive impairment and increasing behavioral problems. Subsequent EEG (21-channel electroencephalogram) showed focal epileptiform activity in the right frontotemporal region and MRI studies revealed a mass arising from the hypothalamus suggestive of a HH. Other conditions should be considered in the differential diagnosis for laughing spells and distinguishing different causes can be challenging. As demonstrated by this case report, in patients with behavioral issues, especially those with inappropriate uncontrolled laughter, gelastic seizures need to be included in the differential diagnosis. Thus, a thorough workup should include neuroimaging with attention to the suprasellar region and EEG. Accurate, early diagnosis and patient education are critical in avoiding excessive and unnecessary treatments. This condition may be pharmacoresistant and is often associated with progressive cognitive and behavioral issues. Studies have shown a surgical treatment approach may be effective.

Theory of Mind impairment in focal versus generalized epilepsy

Theory of Mind (ToM) is a critical component of social cognition, and thus, its impairment may adversely affect social functioning and quality of life. Recent evidence has suggested that it is impaired in epilepsy. What is not clear, however, is whether it is related to particular types of epilepsy or other factors. We undertook the present study to explore ToM in patients with focal versus those with generalized epilepsy, the particular pattern of ToM deficits, and the potential influence of antiepileptic medication load. Our sample included 149 adults: 79 patients with epilepsy (34 with generalized epilepsy and 45 with focal epilepsy) and 70 healthy controls. Theory of Mind tasks included a) comprehension of hinting, b) comprehension of sarcasm and metaphor, c) comprehension of false beliefs and deception, d) recognition of faux pas, and e) a visual ToM task in cartoon form. We found significant ToM impairment in the group with focal epilepsy relative to the performance of both the healthy group and the group with generalized epilepsy on all tasks, with the exception of faux pas, on which the group with generalized epilepsy also performed more poorly than the healthy group. Additionally, early age at seizure onset, but not antiepileptic drug (AED) load, was associated with ToM performance. Our findings suggest that focal temporal and frontal lobe, but not generalized, epilepsies were associated with impaired ToM. This may reflect the neuroanatomical abnormalities in the relevant neuronal networks and may have implications for differential cognitive-behavioral interventions based on epilepsy type.

Neuronal Population Responses in the Human Ventral Temporal and Lateral Parietal Cortex during Arithmetic Processing with Digits and Number Words

Past research has identified anatomically specific sites within the posterior inferior temporal gyrus (PITG) and the intraparietal sulcus (IPS) areas that are engaged during arithmetic processing. Although a small region of the PITG (known as the number form area) is selectively engaged in the processing of numerals, its surrounding area is activated during both digit and number word processing. In eight participants with intracranial electrodes, we compared the timing and selectivity of electrophysiological responses in the number form area-surround and IPS regions during arithmetic processing with digits and number words. Our recordings revealed stronger electrophysiological responses in the high-frequency broadband range in both regions to digits than number words, with the difference that number words elicited delayed activity in the IPS but not PITG. Our findings of distinct profiles of responses in the PITG and the IPS to digits compared with number words provide novel information that is relevant to existing theoretical models of mathematical cognition.

[A case series of 4 epilepsy patients with promnesia]

Promnesia is a feeling of familiarity and foreknowledge and is a manifestation of simple partial seizures (focal aware seizures). It is similar to déjà vu and has been reported to be a rare symptom in patients with temporal lobe epilepsy. Here, we investigated the clinical characteristics in 4 patients with partial epilepsy presenting promnesia. Three out of 4 patients showed abnormal electroencephalography (EEG) and/or MRI findings in the temporal lobe. Furthermore, in 2 patients, promnesia was the only aura. It is important to actively obtain medical history of patients about promnesia because this is useful for identifying the epileptic focus. Further cases need to be analyzed to evaluate the sensitivity and specificity of promnesia for diagnosis and therapy of partial epilepsy.

The anti-seizure effects of IV 5α-dihydroprogesterone on amygdala-kindled seizures in rats

OBJECTIVE

The present study investigated the anti-seizure effects of 5α-dihydroprogesterone (DHP) in an animal model of human drug-resistant focal seizures with impaired awareness. DHP was administered via the intravenous (IV) route.

METHODS

Female Wistar rats were implanted with an electrode in the right basolateral amygdala. They were then kindled to 15 stage 5 seizures, stability tested, and cannulated in the jugular vein. Multiple doses of IV DHP were tested against focal electrographic seizures and secondarily generalized convulsions. The time-course of DHP's action was also examined.

RESULTS

The dose-response study, done at 5 min after injection, showed a dose-dependent suppression of both generalized and focal seizures, with an ED50 of 1.69 mg/kg for the generalized convulsive seizures and an ED50 of 3.48 mg/kg for the focal electrographic seizures. Ataxia, as rated by the Löscher ataxia scale, was also seen, with a TD50 of 3.57 mg/kg. The time-response study, done at the ED75 for focal seizure suppression, showed suppression of both generalized and focal seizures from immediately after injection to about 60 min post-injection.

SIGNIFICANCE

DHP has demonstrated anti-seizure effects in a drug-resistant model of human focal seizures with impaired awareness. Its analogs might be developed as new anti-seizure drugs.

Cumulative effect of transcranial direct current stimulation in patients with partial refractory epilepsy and its association with phase lag index-A preliminary study

There is an urgent need for alternative treatments for refractory epilepsy. We investigated the effect of two courses of cathodal transcranial direct current stimulation (tDCS) in nine patients with partial refractory epilepsy. A two-course treatment (1 month per course, with six sessions of stimulation per course within the first 2 weeks by 2-mA cathodal tDCS for 20 min) was administered to each patient. After the first course of tDCS, the average seizure frequency had decreased by 37.8 ± 21.9% compared with baseline (p = 0.001). After the second course, the average seizure frequency had decreased by 48.9 ± 31.2% compared with baseline (p = 0.002). Only seven of the nine patients maintained the same state of wakefulness in three electroencephalogram (EEG) recordings. We analyzed the EEG recordings of these seven patients on day 0 immediately posttreatment and on days 4 and 9 in the first course of tDCS. When compared with baseline, no significant change in the number of epileptiform discharges was observed. The day 9 phase lag index (PLI) decreased in five patients with seizure reduction after tDCS but increased in two patients without seizure reduction after tDCS. A significant negative correlation was observed between the day 9 PLI of alpha band and first-course seizure reduction (R² = 0.6515) (p = 0.028). The results revealed that tDCS may be considered as an alternative treatment option for patients with refractory epilepsy, and its effect might be cumulative after repeated stimulations and associated with a decrease in PLI.

Eslicarbazepine Acetate: A New Improvement on a Classic Drug Family for the Treatment of Partial-Onset Seizures

Eslicarbazepine acetate is a new anti-epileptic drug belonging to the dibenzazepine carboxamide family that is currently approved as adjunctive therapy and monotherapy for partial-onset (focal) seizures. The drug enhances slow inactivation of voltage-gated sodium channels and subsequently reduces the activity of rapidly firing neurons. Eslicarbazepine acetate has few, but some, drug–drug interactions. It is a weak enzyme inducer and it inhibits cytochrome P450 2C19, but it affects a smaller assortment of enzymes than carbamazepine. Clinical studies using eslicarbazepine acetate as adjunctive treatment or monotherapy have demonstrated its efficacy in patients with refractory or newly diagnosed focal seizures. The drug is generally well tolerated, and the most common side effects include dizziness, headache, and diplopia. One of the greatest strengths of eslicarbazepine acetate is its ability to be administered only once per day. Eslicarbazepine acetate has many advantages over older anti-epileptic drugs, and it should be strongly considered when treating patients with partial-onset epilepsy.

Severe neonatal hyperbilirubinemia induces temporal and occipital lobe seizures

To examine the origin of seizures induced by severe neonatal hyperbilirubinemia, The EEG characteristics of seizures were analyzed in newborns with and without severe neonatal hyperbilirubinemia. Fisher’s exact test was used to determine the specificity. In total, 931 patients had a total serum bilirubin (TSB) level of 340–425 μmol/L, only 2 of whom had seizures. Compared to patients with hyperbilirubinemia and a TSB level of 340–425 μmol/L, those with a TSB level >425 μmol/L had a significant risk of seizure (OR = 213.2, 95% CI = 113.0–405.8, P<0.001). Of all 28 patients with severe hyperbilirubinemia and seizure, 26 had seizures that originated in the temporal and/or occipital lobe. In seizure patients without severe hyperbilirubinemia, origination in the temporal/occipital and other lobes occurred in 19 and 117 cases, respectively. Compared to the risk of seizure origination in the temporal and/or occipital lobe in other diseases, the risk in patients with severe hyperbilirubinemia was increased by approximately 80 times (OR = 80.1, 95% CI = 28.3–226.4, P<0.001). Severe neonatal hyperbilirubinemia can selectively induce temporal and occipital lobe seizures. This is the first report of a new syndrome with the same etiology and electrophysiological features as epilepsy.

Dynamic interneuron-principal cell interplay leads to a specific pattern of in vitro ictogenesis

Ictal discharges induced by 4-aminopyridine in the in vitro rodent entorhinal cortex present with either low-voltage fast or sudden onset patterns. The role of interneurons in initiating low-voltage fast onset ictal discharges is well established but the processes leading to sudden onset ictal discharges remain unclear. We analysed here the participation of interneurons (n = 75) and principal cells (n = 13) in the sudden onset pattern by employing in vitro tetrode wire recordings in the entorhinal cortex of brain slices from Sprague-Dawley rats. Ictal discharges emerged from a background of frequently occurring interictal spikes that were associated to a specific interneuron/principal cell interplay. High rates of interneuron firing occurred 12 ms before interictal spike onset while principal cells fired later during low interneuron firing. In contrast, the onset of sudden ictal discharges was characterized by increased firing from principal cells 627 ms before ictal onset whereas interneurons increased their firing rates 161 ms before ictal onset. Our data show that sudden onset ictogenesis is associated with frequently occurring interictal spikes resting on the interplay between interneurons and principal cells while ictal discharges stem from enhanced principal cell firing leading to increased interneuron activity. These findings indicate that specific patterns of interactions between interneurons and principal cells shape interictal and ictal discharges with sudden onset in the rodent entorhinal cortex. We propose that specific neuronal interactions lead to the generation of distinct onset patterns in focal epileptic disorders.

Seizure Outcomes in Occipital Lobe and Posterior Quadrant Epilepsy Surgery: A Systematic Review and Meta-Analysis

BACKGROUND

Occipital lobe epilepsy (OLE) is an uncommon but debilitating focal epilepsy syndrome with seizures often refractory to medical management. While surgical resection has proven a viable treatment, previous studies examining postoperative seizure freedom rates are limited by small sample size and patient heterogeneity, thus exhibiting significant variability in their results.

OBJECTIVE

To review the medical literature on OLE so as to investigate rates and predictors of both seizure freedom and visual outcomes following surgery.

METHODS

We reviewed manuscripts exploring surgical resection for drug-resistant OLE published between January 1990 and June 2015 on PubMed. Seizure freedom rates were analyzed and potential predictors were evaluated with separate meta-analyses. Postoperative visual outcomes were also examined.

RESULTS

We identified 27 case series comprising 584 patients with greater than 1 yr of follow-up. Postoperative seizure freedom (Engel class I outcome) was observed in 65% of patients, and was significantly predicted by age less than 18 yr (odds ratio [OR] 1.54, 95% confidence interval [CI] 1.13-2.18), focal lesion on pathological analysis (OR 2.08, 95% CI 1.58-2.89), and abnormal preoperative magnetic resonance imaging (OR 3.24, 95% 2.03-6.55). Of these patients, 175 also had visual outcomes reported with 57% demonstrating some degree of visual decline following surgery. We did not find any relationship between postoperative visual and seizure outcomes.

CONCLUSION

Surgical resection for OLE is associated with favorable outcomes with nearly two-thirds of patients achieving postoperative seizure freedom. However, patients must be counseled regarding the risk of visual decline following surgery.

Insulinoma with a History of Epilepsy: Still a Possible Misleading Factor in the Early Diagnosis of Insulinoma

A delayed diagnosis of insulinoma remains a clinical issue. Hypoglycemic symptoms can mimic neuropsychiatric disorders such as epilepsy. A 27-year-old woman with a history of epilepsy and anti-epileptic drugs (AEDs) developed repeated seizures and neuropsychiatric symptoms after a 9-year asymptomatic interval. She had received transient treatment with AEDs before the possibility of hypoglycemia was considered. Following a clinical diagnosis of insulinoma, distal pancreatectomy was performed; her seizures didn't occur again. The early diagnosis of insulinoma requires vigilance not only for hypoglycemia in patients with neuropsychiatric symptoms but also for the possible masking effects of a history of epilepsy and preceding AED usage.