Ictal Recordings Research Articles

Probabilistic ictal EEG sources and temporal lobe epilepsy surgical outcome.

For patients with medication refractory medial temporal lobe epilepsy (MTLE), surgery offers the hope of a cure. However, up to 30% of patients with MTLE continue to experience disabling seizures after surgery. The reasons why some patients do not achieve seizure freedom are poorly understood. A promising theory suggests that epileptogenic networks are broadly distributed in surgically refractory MTLE, involving regions beyond the medial temporal lobe. In this retrospective study, we aimed to investigate the distribution of epileptogenic networks in MTLE using Bayesian distributed EEG source analysis from preoperative ictal onset recordings. This analysis has the advantage of generating maps of source probability, which can be subjected to voxel-based statistical analyses. We compared 10 patients who achieved post-surgical seizure freedom with 10 patients who continued experiencing seizures after surgery. Voxel-based Wilcoxon tests were employed with correction for multiple comparisons. We observed that ictal EEG source intensities were significantly more likely to occur in lateral temporal and posterior medial temporal regions in patients with continued seizures post-surgery. Our findings support the theory of broader spatial distribution of epileptogenic networks at seizure onset in patients with surgically refractory MTLE.

Role of ictal baseline shifts and ictal high-frequency oscillations in stereo-electroencephalography analysis of mesial temporal lobe seizures.

To assess the role of ictal baseline shifts (IBS) and ictal high-frequency oscillations (iHFOs) in intracranial electroencephalography (EEG) presurgical evaluation by analysis of the spatial and temporal relationship of IBS, iHFOs with ictal conventional stereo-electroencephalography (icEEG) in mesial temporal lobe seizures (MTLS). We studied 15 adult patients with medically refractory MTLS who underwent monitoring with depth electrodes. Seventy-five ictal EEG recordings at 1,000 Hz sampling rate were studied. Visual comparison of icEEG, IBS, and iHFOs were performed using Nihon-Kohden Neurofax systems (acquisition range 0.016-300 Hz). Each recorded ictal EEG was analyzed with settings appropriate for displaying icEEG, IBS, and iHFOs. IBS and iHFOs were observed in all patients and in 91% and 81% of intracranial seizures, respectively. IBS occurred before (22%), at (57%), or after (21%) icEEG onset. In contrast, iHFOs occurred at (30%) or after (70%) icEEG onset. The onset of iHFOs was 11.5 s later than IBS onset (p < 0.0001). All of the earliest onset of IBS and 70% of the onset of iHFOs overlapped with the ictal onset zone (IOZ). Compared with iHFOs, interictal HFOs (itHFOs) were less correlated with IOZ. In contrast to icEEG, IBS and iHFOs had smaller spatial distributions in 70% and 100% of the seizures, respectively. An IBS dipole was observed in 66% of the seizures. Eighty-seven percent of the dipoles had a negative pole at the anterior/medial part of amygdala/hippocampus complex (A-H complex) and a positive pole at the posterior/lateral part of the A-H complex. The results suggest that evaluation of IBS and iHFOs, in addition to routine icEEG, helps in more accurately defining the IOZ. This study also shows that the onset and the spatial distribution of icEEG, IBS, and iHFOs do not overlap, suggesting that they reflect different cellular or network dynamics.

Impact of sleep on the localizing value of video EEG in patients with refractory focal seizures – A prospective video-EEG with EOG and submental EMG study

ObjectivesTo examine the role of sleep and its stages on the localizing value of video EEG in the evaluation of refractory focal seizures. MethodsVideo-electroencephalographic (VEEG) evaluation with additional polygraphic recording was carried out for 70 consecutive patients with refractory focal epilepsy, undergoing pre-surgical evaluation, over a two-year period. Localization of video EEG for each seizure was made based on clinical, ictal and interictal data. Seizure localization in each patient was assessed for concordance with MRI and other imaging data (SPECT, PET) for both wake and sleep seizures. Interictal discharges in sleep and wake were similarly compared for concordance with imaging data. ResultsA total of 608 seizures were recorded in 70 patients, 289 in sleep. Overall, concordance with imaging data was found in 218 out of 322 wake seizures (67.8%) and in 157 out of 286 sleep seizures (54.8%) (p=0.0314). On analyzing the subset of patients with seizures recorded in both wake and sleep states (total 279 seizures recorded, 113 out of sleep), concordance was observed in 93 out of 166 (56%) wake seizures and in 80 out of 113 (70.7%) sleep seizures (OR 2.03, 95% CI 1.17 to 3.56; p 0.007). Interictal discharges were more common and more precisely localizing in sleep, mostly in stage N2. ConclusionsThis prospective VEEG-PSG study demonstrates the role of sleep versus wake state in the localizing value of different components of long-term VEEG recording for patients with medically refractory epilepsy. Our findings show that while wake state ictal EEG has more localizing value in a mixed group of patients, sleep ictal and interictal EEG is significantly more useful in patients who have seizures recorded both during wake and sleep states. In addition, interictal discharges recorded during NREM sleep have high localizing value. SignificanceThis is only the second study elucidating the effect of sleep on the localizing value of video-electroencephalographic evaluation of patients with medically refractory focal epilepsy; mainly revealing high value of sleep interictal discharges and that sleep ictal recording has two times higher localizing value than wake ictal recording, among patients in whom seizures are recorded in both states.

Ictal local field potential recordings in nucleus subthalamicus (STN) in a patient with idiopathic generalized epilepsy (IGE)

Rationale: For more than a decade STN has been discussed as a potential target for deep brain stimulation (DBS) and ictal recordings have been obtained in focal epilepsies (e.g. Loddenkemper et al., Journal of Clinical Neurophysiology, 2001). Recently, DBS of STN showed a beneficial effect in progressive myoclonus epilepsy, an epilepsy syndrome with a distinct seizure type: generalized myoclonic seizures (Vesper et al. Epilepsia 2007). Ictal field recordings from the STN were recorded simultaneously with surface electrodes in a patient with pharmacoresistant IGE.

Ictal local field potential recordings in anterior thalamus (ANT) and nucleus accumbens (NAC) in patients with temporal lobe epilepsy (TLE)

Rationale: Deep brain stimulation (DBS) of the ANT has recently been established as a therapeutic strategy for medically refractory focal epilepsy. However, the mechanistic underpinnings of this novel treatment option are still not sufficiently understood, partly because under normal clinical conditions the analysis of propagation of epileptic activity is restricted to information derived either from surface or intracranial EEG recordings restricted to the accessible cortical structures.

Localization of epileptogenic zones in Lennox–Gastaut syndrome (LGS) using graph theoretical analysis of ictal intracranial EEG: A preliminary investigation

Precise localization of epileptogenic zones is essential for the successful surgical treatment of refractory epilepsy including Lennox-Gastaut syndrome (LGS). The surgical resection areas are generally determined by epileptologists based on diverse neuroimaging modalities; however, exact epileptogenic zones cannot be accurately localized in many patients with LGS using the conventional methods. Therefore, new reliable algorithms are still required for enhancing the success rate of the resective epilepsy surgery. In the present study, we introduce an approach to localize epileptogenic zones in LGS based on the graph theoretical analysis of ical intracranial EEG (iEEG). Four patients with LGS who became seizure-free after the resective epilepsy surgery were selected. Before the surgery, their epileptogenic zones were delineated using EEG, iEEG, and several conventional imaging modalities. Phase locking value (PLV) analysis was applied to construct functional connectivity networks during ictal events, and then several graph theoretical indices including betweenness centrality (BC) were evaluated for each iEEG sensor to find the primary hubs of the ictal epileptic network. The graph theoretical index values were then overlaid on 3D individual cortical surface. The iEEG channels with high BC values coincided well with the surgical resection areas. Among various graph theoretical measures such as local efficiency, participation coefficient, and eigenvector centrality, only BC showed fair correspondence with the surgical resection areas. The primary hubs in the ictal epileptic networks coincided well with areas of surgical resection in LGS patients with successful surgical outcomes. This observation warrants further studies to determine if the graph theoretical network analysis of ictal iEEG recordings can serve as a new auxiliary tool to localize epileptogenic zones in LGS.

Ictal injury in psychogenic non-epileptic seizures

PurposeWhilst ictal injuries in psychogenic non-epileptic seizures (PNES) have been reported previously, very few studies have described the spectrum of ictal injuries in these patients. In the current study, we tried to determine the spectrum of reported ictal injuries associated with PNES and to investigate the possible associated risk factors. MethodsAll patients with PNES were recruited prospectively in the outpatient epilepsy clinic at Shiraz University of Medical Sciences, between 2008 and 2013. The diagnosis was made by clinical assessment and ictal video-EEG recordings. We asked all patients and their caregivers about history of any minor (e.g., tongue biting, bruises, and lacerations) or major (e.g., burns and fractures) physical injuries associated with their seizures, since their disease started. Clinical variables, factors potentially predisposing to PNES and video-EEG recordings of all patients were analyzed. ResultsTwo hundred and eleven patients were studied. Sixty-five patients (30.8%) reported injuries with one or more of their attacks. The most common type of reported injury was tongue biting. Lacerations, bruises, limb fractures, dental injury, and burn were also reported. ConclusionPNES commonly produce physical injuries. Despite the shibboleth that injuries rarely occur during PNES, mild injuries commonly happen and even severe injuries such as fractures and burns are not uncommonly reported in these patients. Patients with more dramatic seizure manifestations (e.g., urinary incontinence) were more likely to report ictal injuries.

Electrophysiological biomarkers of epilepsy.

In patients being evaluated for epilepsy and in animal models of epilepsy, electrophysiological recordings are carried to capture seizures to determine the existence of epilepsy. Electroencephalography recordings from the scalp, or sometimes directly from the brain, are also used to locate brain areas where seizure begins, and in surgical treatment help plan the area for resection. As seizures are unpredictable and can occur infrequently, ictal recordings are not ideal in terms of time, cost, or risk when, for example, determining the efficacy of existing or new anti-seizure drugs, evaluating potential anti-epileptogenic interventions, or for prolonged intracerebral electrode studies. Thus, there is a need to identify and validate other electrophysiological biomarkers of epilepsy that could be used to diagnose, treat, cure, and prevent epilepsy. Electroencephalography recordings in the epileptic brain contain other interictal electrophysiological disturbances that can occur more frequently than seizures, such as interictal spikes (IIS) and sharp waves, and from invasive studies using wide bandwidth recording and small diameter electrodes, the discovery of pathological high-frequency oscillations (HFOs) and microseizures. Of IIS, HFOs, and microseizures, a significant amount of recent research has focused on HFOs in the pathophysiology of epilepsy. Results from studies in animals with epilepsy and presurgical patients have consistently found a strong association between HFOs and epileptogenic brain tissue that suggest HFOs could be a potential biomarker of epileptogenicity and epileptogenesis. Here, we discuss several aspects of HFOs, as well as IIS and microseizures, and the evidence that supports their role as biomarkers of epilepsy.

Jeavons syndrome in China

ObjectivesJeavons syndrome (JS) is one of the underreported epileptic syndromes and is characterized by eyelid myoclonia (EM), eye closure-induced seizures or electroencephalography (EEG) paroxysms, and photosensitivity. In the Western populations, it has been reported to be characterized by focal posterior, occipital predominant epileptiform discharges (OPEDs) or frontal predominant epileptiform discharges (FPEDs) followed by generalized EDs in both interictal and ictal EEG recordings. However, it is not clear if there are different clinical manifestations between OPEDs and FPEDs. The clinical and electrographic presentations in the Chinese population are largely unknown. Here, we report the clinical and electroencephalographic features of 50 Chinese patients with JS and evaluate for the presence of different clinical features between patients with OPEDs and patients with FPEDs. MethodsWe identified 50 cases who met the Jeavons syndrome criteria from 4230 patients with epilepsy at Xijing Hospital, Xi'an, China from the period of January 2010 to November 2011. These patients underwent long-term 24-hour video-EEG recording. Brain imaging was performed using magnetic resonance imaging (MRI) or computerized tomography (CT). Webster IQ testing was performed to determine intellectual development. We reviewed and described the interictal abnormalities, ictal EEG pattern, and demographic, clinical, and neuroimaging findings of these 50 Chinese patients in Xi'an. We divided the 50 patients into two groups according to the predominance of EDs and analyzed their clinical features. ResultsTwenty-five of these 50 patients were male. Twenty-two out of 32 patients in the group with FPEDs were male, and 3/18 patients in the group with OPEDs were male. The median age of EMA–EM onset in FPEDs was 8years and that in OPEDs was 5.8years. Eyelid myoclonia occurred in all the 50 patients. Twenty-one out of 32 patients in the group with FPEDs had EM with absences, and 14/32 of them had EM with eyeball rolling up. Two out of 18 patients in the group with OPEDs had EM with absences, and only 1 of 18 had EM with eyeball rolling up. ConclusionEyelid myoclonia with or without absences or JS diagnosis is easily missed and underreported in China. As an IGE, either the frontal or the occipital lobe may initiate generalized spike-and-wave discharges (GSWDs) and generalized seizures (GSs). There may be two subtypes of JS with distinctive clinical and electroencephalogrphic features: a predominantly male group with frontal predominant epileptiform discharges, eyelid myoclonia, and eyes rolling up and a predominantly female group with occipital predominant epileptiform discharges with eyelid myoclonia alone.

Clinical Features of a Series of Non-Surgical Patients with Focal Cortical Dysplasia and Epilepsy

Most published series of patients with focal cortical dysplasia and epilepsy are surgical or pathological series of pediatric cases. Patients have a high frequency of seizure. The description of clinical features and the frequency patterns of non-surgical adult patients are less describe. We retrospectively reviewed the clinical records of adult patients (>18 years of age) that visited the Epilepsy Centre of the Ramos Mejía Hospital in the city of Buenos Aires between 2010 and 2012. We included all cases with confirmed diagnosis of epilepsy and MRI diagnosis of focal cortical dysplasia by standardized 1.5 T MRI. We analyzed the following variables: sex, age at seizure onset, seizure types, seizure frequency, presence of abnormal neurological exam, family history of epilepsy, existence of perinatal insults and electroencephalography or video-EEG with at least one ictal recording. We included 20 patients since 2010–2012. Mean age of our population was 25.9 years (9–46 years), 7 females, 13 males, they all had a negative family history of epilepsy, and only two patients had pathological neurological exam, both with mild contralateral paresis. Mean seizure onset age was 5.71 years (2 months–17 years) and the average frequency was 5.1 seizures per month (0–15). Two patients became seizure-free after adjusting antiepileptic drugs. Focal seizures were presented in the 100% of our population. The low frequency of seizure emphasizes the heterogeneity of these patients and the importance of the correct use of antiepileptic drugs schemes, as well as it can be dynamic over time. A proportion of medically resistant patients with cortical dysplasia are poor surgical candidates because the lesion cannot be completely identify or removed if it involves eloquent areas of the cortex. With the development of new drugs and the correct choice of treatment schedules is expected that more patients with focal cortical dysplasia would be treated successfully.

Prolonged psychogenic nonepileptic seizures or pseudostatus

PurposeThe purpose of this study was to determine if patients with episodes of prolonged psychogenic nonepileptic seizures or pseudostatus are different from those with psychogenic nonepileptic seizures (PNESs) without prolonged attacks regarding their demographic and clinical characteristics and factors potentially predisposing to PNESs. MethodsIn this prospective study, all patients with a clinical diagnosis of PNESs (based on ictal recordings) were recruited at the outpatient epilepsy clinic at Shiraz University of Medical Sciences from 2008 through 2013. The epileptologist interviewed all the patients. We compared the demographic and clinical characteristics of patients with PNES-status with those with PNES-only. ResultsTwo hundred and eleven patients were studied. Forty-nine patients (23.2%) reported episodes of PNES-status, and 162 patients (76.8%) did not report PNES-status. There were no significant differences between these two groups of patients regarding the demographic and clinical characteristics and factors potentially predisposing to PNESs. ConclusionPsychogenic nonepileptic seizure status (PNES-status) is relatively common among patients with PNESs. It seems that patients with PNES-status are not different from those with PNES-only, at least regarding the demographic and clinical characteristics and factors potentially predisposing to PNESs.

Widespread EEG Changes Precede Focal Seizures

The process by which the brain transitions into an epileptic seizure is unknown. In this study, we investigated whether the transition to seizure is associated with changes in brain dynamics detectable in the wideband EEG, and whether differences exist across underlying pathologies. Depth electrode ictal EEG recordings from 40 consecutive patients with pharmacoresistant lesional focal epilepsy were low-pass filtered at 500 Hz and sampled at 2,000 Hz. Predefined EEG sections were selected immediately before (immediate preictal), and 30 seconds before the earliest EEG sign suggestive of seizure activity (baseline). Spectral analysis, visual inspection and discrete wavelet transform were used to detect standard (delta, theta, alpha, beta and gamma) and high-frequency bands (ripples and fast ripples). At the group level, each EEG frequency band activity increased significantly from baseline to the immediate preictal section, mostly in a progressive manner and independently of any modification in the state of vigilance. Preictal increases in each frequency band activity were widespread, being observed in the seizure-onset zone and lesional tissue, as well as in remote regions. These changes occurred in all the investigated pathologies (mesial temporal atrophy/sclerosis, local/regional cortical atrophy, and malformations of cortical development), but were more pronounced in mesial temporal atrophy/sclerosis. Our findings indicate that a brain state change with distinctive features, in the form of unidirectional changes across the entire EEG bandwidth, occurs immediately prior to seizure onset. We postulate that these changes might reflect a facilitating state of the brain which enables a susceptible region to generate seizures.

Psychogenic non-epileptic seizures in Iran

PurposeWe investigated the demographic and clinical characteristics of psychogenic non-epileptic seizures (PNES) in patients in Iran. MethodsIn this prospective study, all patients with a clinical diagnosis of PNES (based on ictal recordings) were recruited at the outpatient epilepsy clinic at Shiraz University of Medical Sciences, from 2008 through 2013. The epileptologist interviewed all the patients. We investigated the demographic and clinical characteristics of PNES. ResultsTwo hundred and forty-nine patients were diagnosed as having PNES. Two hundred and eleven patients had video-EEG recordings available and included in the study. One hundred and forty-one (66.8%) were female and 70 (33.2%) were male. There were no significant differences between our patients and previous reports regarding the clinical and semiological characteristics of PNES. ConclusionPsychogenic non-epileptic seizures are relatively common at epilepsy clinics. It appears that an Islamic lifestyle (in Iran) has little influence on the clinical characteristics and manifestations of PNES, as we observed similar results as in most previous studies from other cultures.

WORK, REST AND PLAY; THE CLINICAL SPECTRUM OF NON–CONVULSIVE STATUS EPILEPTICUS

IntroductionNon–convulsive status epilepticus (NCSE) is defined as prolonged seizure activity in the absence of motor features or a change in behaviour and/or mental processes from baseline associated with continuous epileptiform...

Ictal kissing behavior: Neurological and psychodynamic overview

This study is based on the psychodynamic and neurological analysis of three Turkish patients who displayed ictal kissing automatism during their seizures. To unveil the probable underlying causes of their kissing behaviors, all patients underwent psychiatric interviews after being evaluated by ictal video-EEG recordings. The group consisted of two females (ages 35 and 29) and one male (age 26). In addition to prominent oral automatisms, each patient also displayed behaviors of kissing or blowing kisses to individuals at close proximity. Seizures were related to the right temporal lobe in two patients and the left temporal lobe in one patient. Magnetic resonance imaging showed mesial temporal sclerosis in two of the patients (one left, one right) and was normal in one. According to the DSM-IV-TR criteria, each of the three patients also suffered from major depression, while the psychodynamic interviews revealed traumatic childhood histories and intense unfulfilled affective needs.

Eating epilepsy: Phenotype, MRI, SPECT and video-EEG observations

Eating epilepsy is one of the rare forms of reflex epilepsy precipitated by eating. Previous studies have demonstrated lesions due to variable aetiology involving the temporolimbic and suprasylvian regions. To study anatomical correlates of reflex eating epilepsy using multimodality investigations (MR imaging, video-EEG and SPECT). Six patients (M:F=3:3; mean age: 20.7±4.9 years) with eating epilepsy were subjected to MRI of brain, video-EEG studies and SPECT scan. These were correlated with phenotypic presentations. Among the five patients with ictal recording of eating epilepsy during video-EEG, semiology was characterized by behavioural arrest followed by either flexion or extension of trunk and neck and two patients had speech arrest and four had salivation from angle of mouth. Another patient had EEG changes during "thought about eating". Four patients had perisylvian frontal lobe lesions and one had high frontal lesion on MRI. Ictal EEG (n=6) showed ictal rhythmic slowing/fast activity in parieto-temporal (n=2) or fronto-temporal (n=4) regions with subsequent secondary generalization in three. Ictal and interictal SPECT imaging showed changes in frontal lobe (n=1), anterior temporal lobe (n=1), and parieto-insular region (n=1) suggesting it to be seizure onset zone. Three of four patients with structural lesions in MRI had concordant ictal EEG and ictal SPECT changes. Lesions near the perisylvian region might play a major role in eating epilepsy.

Interictal estimation of intracranial seizure onset in temporal lobe epilepsy

ObjectivesTo evaluate the lateralizing and localizing values of interictal focal slow activity (IFSA), single pulse electrical stimulation (SPES) and 18FDG PET, in order to estimate their potential to complement ictal intracranial recordings and reduce prolonged monitoring in patients with temporal lobe epilepsy. MethodsThe study includes 30 consecutive patients with bilateral temporal subdural electrodes and focal seizure onset. IFSA, SPES and 18FDG PET when available, were visually assessed and their combined lateralization was based on the majority of the individual lateralizing tests. ResultsIn the 18 patients who had all three tests, lateralization was congruent with seizure onset areas in 15 (83%). When lateralized (15 patients), 18FDG PET was always congruent with intracranial seizure onset. In all 12 patients without 18FDG PET, lateralization combining IFSA and SPES was congruent with seizure onset, including two with bilateral independent seizure onset on subdural monitoring. 22 out of the 23 patients who had surgery enjoyed favorable outcome (Engel I or II). ConclusionIntracranial IFSA and SPES can reliably predict the side and site (mesial versus lateral temporal) of seizure onset when they lateralize to the same side. Significance18FDG PET can be useful in planning electrode implantation. During intracranial recordings, IFSA and SPES have the potential to reduce telemetry time, risks and costs.

Gender differences in manifestations of psychogenic non-epileptic seizures in Iran

PurposePsychogenic non-epileptic seizures (PNES) are more prevalent among women. We investigated the potential differences in demographic and clinical characteristics of PNES between women and men. MethodsIn this prospective study, all patients with a clinical diagnosis of PNES (based on ictal recordings) were recruited at the outpatient epilepsy clinic at Shiraz University of Medical Sciences, from 2008 through 2012. The epileptologist interviewed all the patients. We compared the demographic and clinical characteristics and seizure semiology of PNES between women and men. ResultsTwo hundred and twenty-two patients were diagnosed as having PNES. One hundred and eighty-eight patients had video-EEG recordings available and included in the study. One hundred and twenty-nine (69%) were female and 59 (31%) were male. There were no significant differences between women and men with PNES with regard to demographic, clinical and semiological characteristics. ConclusionWe did not observe any significant demographic differences between women and men with PNES. Likewise, seizure characteristics and semiology were very similar in both genders. It appears that an Islamic lifestyle (in Iran) has little influence on the sex ratio and clinical manifestations of PNES compared with the Western studies.

Dravet syndrome: New potential genetic modifiers, imaging abnormalities, and ictal findings

Dravet syndrome is an autosomal dominant epileptic encephalopathy of childhood, which is caused mainly by SCN1A and PCHD19 mutations. Although Dravet syndrome is well recognized, the causes of acute encephalopathy are still elusive, and reported data on ictal electroencephalography (EEG) and structural brain abnormalities are scarce. We studied 30 children who fulfilled the clinical criteria for Dravet syndrome. All patients were screened for SCN1A mutations and 25 for POLG mutations with bidirectional sequencing. Clinical data, including etiologic studies done as part of the clinical workup, were collected from hospital charts. Ictal video-EEG recordings and magnetic resonance (MR) images were reanalyzed by the authors. SCN1A mutations were found in 25 patients (83%). Two SCN1A mutation-negative patients had chromosomal translocations involving chromosomes 9 and X, and one had a mutation in PCDH19. Prolonged seizures were associated with acute encephalopathy in three SCN1A mutation-positive patients. One showed evidence of a significant hypoxic-ischemic event during status epilepticus. The other two demonstrated new persistent neurologic deficits postictally; they both carried heterozygous POLG variants (p.Trp748Ser or p.Gly517Val). Hippocampal sclerosis or loss of gray-white matter definition in the temporal lobe was observed in 7 of 18 patients who had MRI after age 3 years (39%). Motor seizures were recorded on video-EEG for 15 patients, of whom 12 were younger than 6 years at recording; 11 patients (73%) showed posterior onsets. Our data imply that a heterozygous X;9 translocation and rare POLG variants may modify the clinical features of Dravet syndrome. The latter may increase susceptibility for acute encephalopathy. Temporal lobe abnormalities are common in patients imaged after 3 years of age. Focal seizures seem to localize predominantly in the posterior regions in young children with Dravet syndrome.

Quantifying the contribution of video in combined video-magnetoencephalographic ictal recordings of epilepsy patients

Magnetoencephalography (MEG) measures magnetic fields generated by neuronal currents. MEG is complementary to EEG. Considerable body of evidence indicates that ictal MEG recordings can provide useful information for pre-surgical evaluation of epilepsy patients alongside the more established long-term ictal video-EEG. Ictal MEG is recorded in some epilepsy surgery centers. However, a wider adoption of ictal MEG is hampered by lack of tools for synchronized video-MEG recording similar to those of video-EEG. We have augmented MEG with a synchronized behavioral video-recording system. To estimate its additional value in ictal recordings, we retrospectively analyzed recordings of 10 epilepsy patients with and without the video. In six patients out of ten, adding the video substantially changed the resulting interpretations. In all six cases the effect was considerable: the number of detected seizures changed by more than 50%. Synchronized video and audio recording capabilities are important for effective ictal MEG recordings of epilepsy patients.