Epileptic spasms are associated with increased stereo-electroencephalography derived functional connectivity in tuberous sclerosis complex.

OBJECTIVE: Epileptic spasms (ES) are common in tuberous sclerosis complex (TSC). However, the underlying network alterations and relationship with epileptogenic tubers are poorly understood. We examined interictal functional connectivity (FC) using stereo-electroencephalography (SEEG) in patients with TSC to investigate the relationship between tubers, epileptogenicity, and ES. METHODS: We analyzed 18 patients with TSC who underwent SEEG (mean age = 11.5 years). The dominant tuber (DT) was defined as the most epileptogenic tuber using the epileptogenicity index. Epileptogenic zone (EZ) organization was quantitatively separated into focal (isolated DT) and complex (all other patterns). Using a 20-min interictal recording, FC was estimated with nonlinear regression, h2 . We calculated (1) intrazone FC within all sampled tubers and normal-appearing cortical zones, respectively; and (2) interzone FC involving connections between DT, other tubers, and normal cortex. The relationship between FC and (1) presence of ES as a current seizure type at the time of SEEG, (2) EZ organization, and (3) epileptogenicity was analyzed using a mixed generalized linear model. Spike rate and distance between zones were considered in the model as covariates. RESULTS: Six patients had ES as a current seizure type at time of SEEG. ES patients had a greater number of tubers with a fluid-attenuated inversion recovery hypointense center (p < .001), and none had TSC1 mutations. The presence of ES was independently associated with increased FC within both intrazone (p = .033) and interzone (p = .011) networks. Post hoc analyses identified that increased FC was associated with ES across tuber and nontuber networks. EZ organization and epileptogenicity biomarkers were not associated with FC. SIGNIFICANCE: Increased cortical synchrony among both tuber and nontuber networks is characteristic of patients with ES and independent of both EZ organization and tuber epileptogenicity. This further supports the prospect of FC biomarkers aiding treatment paradigms in TSC.

Functional connectivity and epileptogenicity of nodular heterotopias: A single-pulse stimulation study.

OBJECTIVE: Nodular heterotopias (NHs) are malformations of cortical development associated with drug-resistant focal epilepsy with frequent poor surgical outcome. The epileptogenic network is complex and can involve the nodule, the overlying cortex, or both. Single-pulse electrical stimulation (SPES) during stereo-electroencephalography (SEEG) allows the investigation of functional connectivity between the stimulated and responsive cortices by eliciting cortico-cortical evoked potentials (CCEPs). We used SPES to analyze the NH connectome and its relation to the epileptogenic network organization. METHODS: We retrospectively studied 12 patients with NH who underwent 1 Hz or 0.2 Hz SPES of NH during SEEG. Outbound connectivity (regions where CCEPs were elicited by NH stimulation) and inbound connectivity (regions where stimulation elicited CCEPs in the NH) were searched. SEEG channels were then classified as "heterotopic" (located within the NH), "connected" (located in normotopic cortex and showing connectivity with the NH), and "unconnected." We used the epileptogenicity index (EI) to quantify implication of channels in the seizure-onset zone and to classify seizures as heterotopic, normotopic, and normo-heterotopic. RESULTS: One hundred thirty-five outbound and 72 inbound connections were found. Three patients showed connectivity between hippocampus and NH, and seven patients showed strong internodular connectivity. A total of 39 seizures were analyzed: 23 normo-heterotopic, 12 normotopic, and 4 heterotopic. Logistic regression found that "connected" channels were significantly (p = 8.4e-05) more likely to be epileptogenic than "unconnected" channels (odds ratio 4.71, 95% confidence interval (CI) [2.17, 10.21]) and heterotopic channels were also significantly (p = .024) more epileptogenic than "unconnected" channels (odds ratio 3.29, 95% CI [1.17, 9.23]). SIGNIFICANCE: SPES reveals widespread connectivity between NH and normotopic regions. Those connected regions show higher epileptogenicity. SPES might be useful to assess NH epileptogenic network.

Neural correlates of verbal working memory in children with epilepsy with centro-temporal spikes.

BACKGROUND: Previous functional magnetic resonance imaging (fMRI) studies have identified brain systems underlying different components of working memory (WM) in healthy subjects. The aim of this study was to compare the functional integrity of these neural networks in children with self-limited childhood epilepsy with centro-temporal spikes (ECTS) as compared to healthy controls, using a verbal working memory task (WMT). METHODS: Functional MRI of WM in seventeen 6-to-13 year-old children, diagnosed with ECTS, and 17 sex- and age-matched healthy controls were conducted at 3 T. To estimate BOLD responses during the maintenance of low, medium, and high WMT loads, we used a Sternberg verbal WMT. Neuropsychological testing prior to scanning and behavioral data during scanning were also acquired. RESULTS: Behavioral performances during WMT, in particular accuracy and response time, were poorer in children with ECTS than in controls. Increased WM load was associated with increased BOLD signal in all subjects, with significant clusters detected in frontal and parietal regions, predominantly in the left hemisphere. However, under the high load condition, patients showed reduced activation in the frontal, temporal and parietal regions as compared to controls. In brain regions where WM-triggered BOLD activation differed between groups, this activation correlated with neuropsychological performances in healthy controls but not in patients with ECTS, further suggesting WM network dysfunction in the latter. CONCLUSION: Children with ECTS differ from healthy controls in how they control WM processes during tasks with increasing difficulty level, notably for high WM load where patients demonstrate both reduced BOLD activation and behavioral performances.

Surgical techniques: Stereoelectroencephalography-guided radiofrequency-thermocoagulation (SEEG-guided RF-TC).

Stereoelectroencephalography-guided radiofrequency-thermocoagulation (SEEG-guided RF-TC) consists of coupling SEEG investigation with RF-TC stereotactic lesioning directly through the recording electrodes. In this systematic review the surgical technique, indications, and outcomes are described. Maximum accuracy is reached when a frame-based procedure with a robotic assistance and a per-operative vascular X-ray imaging are performed. Monitoring of the lesioning procedure based on the impedance, a sharp modification of which indicates that the thermocoagulation has reached its maximum volume, allows the optimization of the lesion size. The first indication concerns patients in whom a SEEG is required to determine whether surgery is feasible and in whom resection is indeed possible. Even if surgery is performed owing to insufficient efficacy of SEEG-guided RF-TC, the procedure remains interesting owing to its high positive predictive value for good outcome after surgery. The second indication concerns patients in whom phase I non-invasive investigations have concluded to surgical contraindication and who may still undergo SEEG in a purely therapeutic perspective (small deep zones inaccessible to surgery and network nodes of large epileptic networks). Lastly, SEEG-guided RF-TC can be considered as a first-line treatment for periventricular nodular heterotopia (PNH). Independently of indication, the overall seizure-free rate is 23% and the responder rate is 58%. The best results are obtained for PNH (38% seizure-free and 81% responders), while the worst results have been reported for temporal lobe-epilepsy in a dedicated study. The overall complication rate is 2.5%. More evidence is needed to help determine the exact place of SEEG-guided RF-TC in the surgical management algorithm.

Epileptogenicity in tuberous sclerosis complex: A stereoelectroencephalographic study.

OBJECTIVE: In tuberous sclerosis complex (TSC)-associated drug-resistant epilepsy, the optimal invasive electroencephalographic (EEG) and operative approach remains unclear. We examined the role of stereo-EEG in TSC and used stereo-EEG data to investigate tuber and surrounding cortex epileptogenicity. METHODS: We analyzed 18 patients with TSC who underwent stereo-EEG (seven adults). One hundred ten seizures were analyzed with the epileptogenicity index (EI). In 13 patients with adequate tuber sampling, five anatomical regions of interest (ROIs) were defined: dominant tuber (tuber with highest median EI), perituber cortex, secondary tuber (tuber with second highest median EI), nearby cortex (normal-appearing cortex in the same lobe as dominant tuber), and distant cortex (in other lobes). At the seizure level, epileptogenicity of ROIs was examined by comparing the highest EI recorded within each anatomical region. At the patient level, epileptogenic zone (EZ) organization was separated into focal tuber (EZ confined to dominant tuber) and complex (all other patterns). RESULTS: The most epileptogenic ROI was the dominant tuber, with higher EI than perituber cortex, secondary tuber, nearby cortex, and distant cortex (P < .001). A focal tuber EZ organization was identified in seven patients. This group had 80% Engel IA postsurgical outcome and distinct dominant tuber characteristics: continuous interictal discharges (IEDs; 100%), fluid-attenuated inversion recovery (FLAIR) hypointense center (86%), center-to-rim EI gradient, and stimulation-induced seizures (71%). In contrast, six patients had a complex EZ organization, characterized by nearby cortex as the most epileptogenic region and 40% Engel IA outcome. At the intratuber level, the combination of FLAIR hypointense center, continuous IEDs, and stimulation-induced seizures offered 98% specificity for a focal tuber EZ organization. SIGNIFICANCE: Tubers with focal EZ organization have a striking similarity to type II focal cortical dysplasia. The presence of distinct EZ organizations has significant implications for EZ hypothesis generation, invasive EEG approach, and resection strategy.

Predictive factors and prognostic value for status epilepticus in newborns.

OBJECTIVES: To evaluate the predictive factors for status epilepticus (SE) in neonates and prognostic factors for patient outcomes in newborns suffering either isolated seizures or SE. METHODS: A retrospective single-center study from January 2010 to December 2014, included 91 newborns who had neonatal seizures. Among them, 50 newborns experienced SE and 41 newborns presented isolated seizures only. SE was defined as a single seizure lasting more than 15 min or repeated seizures without return to preictal neurological baseline for more than 15 min. Isolated seizures were defined as one single seizure lasting less than 15 min or more seizures with complete recovery of consciousness between seizures. Perinatal and electroclinical data were recorded. Outcomes were evaluated at one year follow up. RESULTS: In multivariate analysis, the factors identified as being predictive of SE were a severely abnormal initial neurological examination (OR 15.7, 95% CI (3.8-109) p = 0.00075) and hypoglycaemia (OR 6.8, 95% CI (1.5-49.2) p = 0.024), found mostly in newborns with hypoxic-ischemic encephalopathy. When studying our global cohort, SE was found to be a negative prognostic factor for outcome only in univariate analysis. In newborns with isolated seizures only, the postictal clinical examination results were the only independent prognostic factor found, normal results being associated with a more favorable evolution (OR 48.9, 95% CI (7.16-571) p = 0.0003). CONCLUSION: Two independent risk factors for SE in newborns have been identified: a severely abnormal initial neurological examination and hypoglycaemia. In newborns with isolated seizures, the only positive prognostic factor was found to be a normal postictal clinical examination.

Effective accuracy of stereoelectroencephalography: robotic 3D versus Talairach orthogonal approaches.

OBJECTIVE: Stereoelectroencephalography (SEEG) was first developed in the 1950s by Jean Talairach using 2D angiography and a frame-based, orthogonal approach through a metallic grid. Since then, various other frame-based and frameless techniques have been described. In this study the authors sought to compare the traditional orthogonal Talairach 2D angiographic approach with a frame-based 3D robotic procedure that included 3D angiographic interoperative imaging guidance. MRI was used for both procedures during surgery, but MRI preplanning was done only in the robotic 3D technique. METHODS: All study patients suffered from drug-resistant focal epilepsy and were treated at the same center by the same neurosurgical team. Fifty patients who underwent the 3D robotic procedure were compared to the same number of historical controls who had previously been successfully treated with the Talairach orthogonal procedure. The effectiveness and absolute accuracy, as well as safety, of the two procedures were compared. Moreover, in the 3D robotic group, the reliability of the preoperative MRI to avoid vascular structures was evaluated by studying the rate of trajectory modification following the coregistration of the intraoperative 3D angiographic data onto the preoperative MRI-based trajectory plans. RESULTS: Effective accuracy (96.5% vs 13.7%) and absolute accuracy (1.15 mm vs 4.00 mm) were significantly higher in the 3D robotic group than in the Talairach orthogonal group. Both procedures showed excellent safety results (no major complications). The rate of electrode modification after 3D angiography was 43.8%, and it was highest for frontal and insular locations. CONCLUSIONS: The frame-based, 3D angiographic, robotic procedure described here provided better accuracy for SEEG implantations than the traditional Talairach approach. This study also highlights the potential safety advantage of trajectory planning using intraoperative frame-based 3D angiography over preoperative MRI alone.

Stereo-electroencephalography-guided radiofrequency thermocoagulation in patients with focal epilepsy: A systematic review and meta-analysis.

OBJECTIVE: Despite the increasing number of studies reporting results of stereo-electroencephalography (SEEG)-guided radiofrequency-thermocoagulation (SEEG-guided RF-TC) in the treatment of patients with drug-resistant focal epilepsy, the exact efficacy of this approach remains unclear. The seizure-freedom rate varies greatly across studies and the factors associated with efficacy have not been formally investigated. METHODS: All prospective or retrospective studies reporting efficacy and/or safety of SEEG-guided RF-TC in patients with drug-resistant focal epilepsy were included. The primary outcome was the seizure-free rate 1 year after the procedure. Secondary outcomes were (1) the responder rate 1 year after the procedure and (2) the proportion of patients with permanent neurologic deficit 1 year after the procedure. Each outcome was assessed in all patients and in 4 groups of patients defined by the etiology of epilepsy. Each outcome was pooled using inverse variance weighting, logit transformation of proportion, and a random-effects model. RESULTS: No prospective study was identified and a total of 6 retrospective studies, reporting efficacy and safety data of 296 patients, were included. The pooled rate of permanent neurologic deficit was 2.5% (95% confidence interval [CI] 1.2%-5.3%), without heterogeneity across studies. In contrast, both the seizure-free and responder rates varied greatly across studies, and statistical heterogeneity was high. The pooled seizure-free and responder rates were 23% (95% CI 8%-50%) and 58% (95% CI 36%-77%), respectively. Both for the seizure-free and responder rates, the greatest efficacy was observed in patients with periventricular nodular heterotopia and the lowest in patients with normal magnetic resonance imaging (MRI) findings. SIGNIFICANCE: SEEG-guided RF-TC is a safe procedure with low risk of complications. In contrast, the level of evidence regarding its efficacy remains low. Better identification of factors associated with seizure outcome are needed.

SEEG-guided radiofrequency coagulation (SEEG-guided RF-TC) versus anterior temporal lobectomy (ATL) in temporal lobe epilepsy.

BACKGROUND: Stereoelectroencephalography-guided radiofrequency thermocoagulation (SEEG-guided RF-TC) is a super-selective procedure. Hippocampus has a limited volume and is widely accessible to SEEG so that SEEG-guided RF-TC could be an alternative to the anterior temporal lobectomy (ATL) in case of temporal lobe epilepsy (TLE) syndrome. OBJECTIVE: To compare seizure-free rate at 1-year follow-up between patients undergoing SEEG-guided RF-TC and patients undergoing ATL in TLE over a 15-year period. METHODS: All patients had a drug-resistant epilepsy and underwent SEEG after non-conclusive phase I investigations suspecting a TLE. Two groups were selected according to the procedure which the patients underwent (ATL or SEEG-guided RF-TC); TLE had to be confirmed by SEEG in the two groups. The primary outcome was seizure freedom at 1 year. The secondary outcome was response (at least 50% reduction of seizure frequency) at 1 year. In case of persistent seizures after SEEG-guided RF-TC, ATL was performed. RESULTS: A total of 21 patients underwent SEEG-guided RF-TC and 49 ATL. At 12 months, none of the patients of the SEEG-guide RF-TC group was seizure free, while 37 (75.5%) in the ATL group were so (p < 0.001). Ten patients (47.6%) were responders after 12 months of follow-up after SEEG-guided RF-TC; all patients in the ATL group who were seizure free were responders. CONCLUSION: SEEG-guided RF-TC is not as effective as ATL in TLE. As no memory impairment following SEEG-guided RF-TC was found, patients with dominant mesial involvement for whom hippocampectomy is not an option could benefit from the technique.

Behavioral and fMRI responses to fearful faces are altered in benign childhood epilepsy with centrotemporal spikes (BCECTS).

OBJECTIVE: We hypothesized that children with benign childhood epilepsy with centrotemporal spikes (BCECTS) might have altered social cognitive skills and underlying neural networks. METHODS: We studied 13 patients with BCECTS and 11 age-matched controls using event-related functional magnetic resonance imaging (fMRI) with an emotional discrimination task consisting of viewing happy, fearful, scrambled, and neutral faces. Behavioral performance measured during the task was correlated with clinical variables and behavioral ratings. RESULTS: In comparison with age-matched controls, children with BCECTS performing a fearful faces detection task showed significantly reduced bilateral fMRI activation in the insular cortex, caudate, and lentiform nuclei, as well as increased response time. The percentage of errors made by children with BCECTS correlated negatively with age, a finding not observed in controls. In patients, accuracy positively correlated with time since the last seizure. The above abnormalities were not observed during happy faces detection task, except for a slower response in children with BCECTS as compared to controls. SIGNIFICANCE: Our study suggests that BCECTS is associated with altered social cognition network and function, particularly for the identification of fearful faces. The age dependency of some of these findings supports the view that a delayed maturation of spiking cortical regions might underlie the cognitive dysfunction observed in BCECTS.

Stereo electroencephalography-guided radiofrequency thermocoagulation (SEEG-guided RF-TC) in drug-resistant focal epilepsy: Results from a 10-year experience.

OBJECTIVE: Stereo electroencephalography (SEEG)-guided radiofrequency thermocoagulation (SEEG-guided RF-TC) has been proposed since 2004 as a possible treatment of some focal drug-resistant epilepsy. The aim of this study is to provide extensive data about efficacy and safety of SEEG-guided RF-TC. METHODS: Over a 10-year period, 162 patients with drug-resistant focal epilepsy were eligible for SEEG-guided RF-TG during phase II invasive investigation by SEEG. All follow-up and safety data were collected prospectively. The primary outcome was seizure freedom at 2 months and at 1 year after SEEG-guided RF-TC. Secondary outcomes were the responders' rate (patient with at least 50% decrease in seizure frequency) and their long-term follow-up. RESULTS: Twenty-five percent of patients were seizure-free at 2 months and 7% at 1 year. We reported 67% of responders at 2 months and 48% at 1 year; 58% of responders maintained their status during the long-term follow-up. The seizure outcome was significantly better when the SEEG-guided RF-TC involved the occipital region (p = 0.007). When surgery followed an SEEG-guided RF-TC, the positive predictive value of being a responder 2 months after an SEEG-guided RF-TC and to be Engel's class I or II after surgery was 93%. We reported 1.1% of permanent deficit and 2.4% of transient side effects. SIGNIFICANCE: Our results, gathered in a large population over a 10-year period, confirm that SEEG-guided RF-TC is a safe technique, being efficient in many cases. More than two thirds of patients showed a short-term improvement, and almost half of them were responders at 1-year follow-up. The technique appears to be especially interesting for limited epileptic zone inaccessible to surgery and when epilepsy is related to a large unilateral network (network disruption by multiple RF-TC). Furthermore, SEEG-guided RF-TC effect is a predictor of outcome after conventional cortectomy in patients eligible for surgery.

Stereotactic Electroencephalography Is a Safe Procedure, Including for Insular Implantations.

BACKGROUND: In some cases of drug-resistant focal epilepsy, noninvasive presurgical investigation may be insufficient to identify the ictal onset zone and the eloquent cortical areas. In such situations, invasive investigations are proposed using either stereotactic electroencephalography (SEEG) or subdural grid electrodes. Meta-analysis suggests that SEEG is safer than subdural grid electrodes, but insular implantation of SEEG electrodes has been thought to carry an additional risk of intraparenchymal hemorrhagic complications. Our objectives were to determine whether an insular SEEG trajectory is a risk factor for intracranial hematoma and to report the global safety of the procedure and provide some guidelines to prevent and detect complications. METHODS: In a retrospective analysis of a surgical series of 525 consecutive procedures between 1995 and 2015, all electrodes were classified according to their insular or extrainsular trajectory. All complications were classified as major or minor according to their potential consequences regarding patient neurologic status. RESULTS: Four intraparenchymal hematomas, all related to extrainsular electrodes (4/4974; 0.08%) were reported; no hematoma was found along insular electrodes (0/1042; 0%). There were 8 major complications (1.52%): 7 intracranial hematomas (1.33%) and 1 case of meningitis. Two patients had long-term neurologic impairment (0.38%), and 1 death (not directly related to the procedure) occurred (0.19%). Eleven minor complications (2.09%) were encountered, including broken electrode (1.52%), acute pneumocephalus (0.38%), and local cutaneous infection (0.19%). CONCLUSIONS: SEEG is a safe procedure. Insular trajectories cannot be considered an additional risk of intracranial bleeding.

Stereo-electro-encephalography-Guided Radiofrequency Thermocoagulation: From In Vitro and In Vivo Data to Technical Guidelines.

BACKGROUND: Deep brain electrodes have been used for the past 10 years to produce bipolar stereo-electro-encephalography-guided radiofrequency thermocoagulation (SEEG RF-TC). However, this technique is based on empiric knowledge. The aim of this study is 3-fold: 1) provide in vivo animal data concerning the effect of bipolar RF-TC on brain and its safety; 2) assess the parameters of this procedure (current delivery and dipole selection) that produce the most efficient lesion; and 3) provide technical guidelines. METHODS: First we achieved in vivo RF-TC on rabbit brains with several conditions (power delivered and lesioning duration) and analyzed their influence on the lesion produced. Only a difference in terms of volume was found, and type of histologic lesions was similar whatever the settings were. We then performed multiple RF-TC in vitro on egg albumen, first with several parameters of radiofrequency and then with different dipole spatial selections. The end point was the size of the radiofrequency thermolesion produced. RESULTS: Using unfixed parameters of radiofrequency current delivery and increasing it until the power delivered by the generator collapsed produced significantly larger lesions (P = 0.008) than other conditions. Concerning the dipole selection, the use of contiguous contacts on electrodes led to lesions with a higher volume (P = 7.7 × 10-13) than those produced with noncontiguous ones. CONCLUSION: Besides the target selection in SEEG RF-TC, which is summarized on the basis of a literature review, we report the optimal parameters: Radiofrequency current must be increased until the power delivered collapses, and dipoles should be constituted by contiguous electrode contacts.

Functional connectivity of insular efferences.

OBJECTIVES: The aim of our study was to explore the functional connectivity between the insula and other cortical regions, in human, using cortico-cortical evoked potentials (CCEPs) EXPERIMENTAL DESIGN: We performed intra-cerebral electrical stimulation in eleven patients with refractory epilepsy investigated with depth electrodes, including 39 targeting the insula. Electrical stimulation consisted of two series of 20 pulses of 1-ms duration, 0.2-Hz frequency, and 1-mA intensity delivered at each of the 39 insular bipoles. Rates of connectivity were reported whenever a noninsular cortical region was tested by at least ten stimulating/recording electrode pairs in three or more patients RESULTS: Significant CCEPs were elicited in 193 of the 578 (33%) tested connections, with an average latency of 33 ± 5 ms. The highest connectivity rates were observed with the nearby perisylvian structures (59%), followed by the pericentral cortex (38%), the temporal neocortex (28%), the lateral parietal cortex (26%), the orbitofrontal cortex (25%), the mesial temporal structures (24%), the dorsolateral frontal cortex (15%), the temporal pole (14%), and the mesial parietal cortex (11%). No connectivity was detected in the mesial frontal cortex or cingulate gyrus. The pattern of connectivity also differed between the five insular gyri, with greater connectivity rate for the posterior short gyrus (49%), than for the middle short (29%), and two long gyri (28 and 33%) CONCLUSION: The human insula is characterized by a rich and complex connectivity that varies as a function of the insular gyrus and appears to partly differ from the efferences described in nonhuman primates.

White matter development in children with benign childhood epilepsy with centro-temporal spikes.

Benign childhood epilepsy with centro-temporal spikes (BCECTS) is a unique form of non-lesional age-dependent epilepsy with rare seizures, focal electroencepalographic abnormalities affecting the same well delineated cortical region in most patients, and frequent mild to moderate cognitive dysfunctions. In this condition, it is hypothesized that interictal electroencepalographic discharges might interfere with local brain maturation, resulting in altered cognition. Diffusion tensor imaging allows testing of this hypothesis by investigating the white matter microstructure, and has previously proved sensitive to epilepsy-related alterations of fractional anisotropy and diffusivity. However, no diffusion tensor imaging study has yet been performed with a focus on BCECTS. We investigated 25 children suffering from BCECTS and 25 age-matched control subjects using diffusion tensor imaging, 3D-T1 magnetic resonance imaging, and a battery of neuropsychological tests including Conner's scale and Wechsler Intelligence Scale for Children (fourth revision). Electroencephalography was also performed in all patients within 2 months of the magnetic resonance imaging assessment. Parametric maps of fractional anisotropy, mean-, radial-, and axial diffusivity were extracted from diffusion tensor imaging data. Patients were compared with control subjects using voxel-based statistics and family-wise error correction for multiple comparisons. Each patient was also compared to control subjects. Fractional anisotropy and diffusivity images were correlated to neuropsychological and clinical variables. Group analysis showed significantly reduced fractional anisotropy and increased diffusivity in patients compared with control subjects, predominantly over the left pre- and postcentral gyri and ipsilateral to the electroencephalographic focus. At the individual level, regions of significant differences were observed in 10 patients (40%) for anisotropy (eight reduced fractional anisotropy, one increased fractional anisotropy, one both), and 17 (56%) for diffusivity (13 increased, one reduced, three both). There were significant negative correlations between fractional anisotropy maps and duration of epilepsy in the precentral gyri, bilaterally, and in the left postcentral gyrus. Accordingly, 9 of 12 patients (75%) with duration of epilepsy>12 months showed significantly reduced fractional anisotropy versus none of the 13 patients with duration of epilepsy≤12 months. Diffusivity maps positively correlated with duration of epilepsy in the cuneus. Children with BCECTS demonstrate alterations in the microstructure of the white matter, undetectable with conventional magnetic resonance imaging, predominating over the regions displaying chronic interictal epileptiform discharges. The association observed between diffusion tensor imaging changes, duration of epilepsy and cognitive performance appears compatible with the hypothesis that interictal epileptic activity alters brain maturation, which could in turn lead to cognitive dysfunction. However, such cross-sectional association does not demonstrate causality, and other hitherto unidentified factors could represent the common cause to part or all of the observed findings.

Intrainsular functional connectivity in human.

OBJECTIVES: The anatomical organization of the insular cortex is characterized by its rich and heterogeneous cytoarchitecture and its wide network of connections. However, only limited knowledge is available regarding the intrainsular connections subserving the complex integrative role of the insular cortex. The aim of this study was to analyze the functional connectivity within- and across-insular subregions, at both gyral and functional levels. EXPERIMENTAL DESIGN: We performed intracerebral electrical stimulation in 10 patients with refractory epilepsy investigated with depth electrodes, 38 of which were inserted in the insula. Bipolar electrical stimulation, consisting of two series of 20 pulses of 1-ms duration, 0.2-Hz frequency, and 1-mA intensity, was delivered at each insular contact. For each stimulated insular anatomical region, we calculated a rate of connectivity, reflecting the proportion of other insular contacts, showing significant evoked potentials. RESULTS: Statistically significant evoked potentials were recorded in 74% of tested connections, with an average latency of 26 ± 3 ms. All insular gyri were interconnected, except the anterior and posterior short gyri. Most connections were reciprocal, showing no clear anterior to posterior directionality. No connection was observed between the right and the left insula. CONCLUSIONS: These findings point to specific features of human insula connectivity as compared to non-Human primates, and remain consistent with the complex integration role devoted to the human insula in many cognitive domains. Periodicals, Inc.

Similar semiology of epileptic and psychogenic nonepileptic seizures recorded during stereo-EEG.

We report two adolescents with refractory seizure disorders in whom both epileptic and psychogenic nonepileptic seizures (PNES) were recorded with intracerebral EEG. The ictal phenomenology of epileptic seizures (ES) and PNES, consisting of hypermotor attacks in the first patient and left-sided painful episodes in the second patient, proved remarkably similar in both cases, highlighting the difficulties which can arise with the distinction of epileptic seizures and PNES based on ictal phenomenology alone.

Hypermotor seizures in lateral and mesial parietal epilepsy.

Four patients with refractory epilepsy and hypermotor seizures (HMS) benefited from an intracerebral investigation after a presurgical evaluation and demonstrated an ictal onset zone primarily involving the posterior cortex, specifically the posterior cingulate gyrus in two patients. At seizure onset, these two patients reported a falling sensation, followed by HMSs characterized by swinging movements of the trunk with intense grasping of the bed railing. The two other patients with lateral parietal seizure onset reported blurred vision and dizziness, followed by a mixed pattern of the previously described type 1 and 2 HMSs. Three patients have been operated on, including two class I of Engel after 36 and 52months of follow-up. One patient developed a postoperative infection and continues to suffer seizures. Pathological findings disclosed a type IIa focal cortical dysplasia in all the patients. The last patient is awaiting surgery. Posterior cortex epilepsies, including those originating from the posterior cingulate cortex, can be responsible for HMSs.