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Objective: This study was undertaken to develop a standardized grading system based on expert consensus for evaluating the level of confidence in the localization of the epileptogenic zone (EZ) as reported in published studies, to harmonize and facilitate systematic reviews in the field of epilepsy surgery. Methods: We conducted a Delphi study involving 22 experts from 18 countries, who were asked to rate their level of confidence in the localization of the EZ for various theoretical clinical scenarios, using different scales. Information provided in these scenarios included one or several of the following data: magnetic resonance imaging (MRI) findings, invasive electroencephalography summary, and postoperative seizure outcome. Results: The first explorative phase showed an overall interrater agreement of.347, pointing to large heterogeneity among experts' assessments, with only 17% of the 42 proposed scenarios associated with a substantial level of agreement. A majority showed preferences for the simpler scale and single‐item scenarios. The successive Delphi voting phases resulted in a majority consensus across experts, with more than two thirds of respondents agreeing on the rating of each of the tested single‐item scenarios. High or very high levels of confidence were ascribed to patients with either an Engel class I or class IA postoperative seizure outcome, a well‐delineated EZ according to all available invasive EEG (iEEG) data, or a well‐delineated focal epileptogenic lesion on MRI. MRI signs of hippocampal sclerosis or atrophy were associated with a moderate level of confidence, whereas a low level was ascribed to other MRI findings, a poorly delineated EZ according to iEEG data, or an Engel class II–IV postoperative seizure outcome. Significance: The proposed grading system, based on an expert consensus, provides a simple framework to rate the level of confidence in the EZ reported in published studies in a structured and harmonized way, offering an opportunity to facilitate and increase the quality of systematic reviews and guidelines in the field of epilepsy surgery. [ABSTRACT FROM AUTHOR]

Epilepsy surgery in genetic drug‐resistant epilepsy is a debated subject as more histological and molecular data are available. We retrospectively collected data from focal drug‐resistant epilepsy patients that underwent stereoelectroencephalography (SEEG) invasive recordings. Patients with nonlesional brain imaging or in whom a first epilepsy surgery failed to control seizures were selected. We computed and displayed the intracranial ictal onset activity pattern on structural imaging. Patients underwent epilepsy gene panel testing, next generation sequencing—NGS. Of 113 patients, 13 underwent genetic testing, and in 6 patients, a mechanistic target of rapamycin pathway gene germline mutation (mTOR) was identified. Brain imaging was nonlesional except for one patient in whom two abnormalities suggestive of focal cortical dysplasia (FCD) were found. Patients underwent tailored brain surgery based on SEEG data, tissue analysis revealed FCD and postsurgical outcome was favorable. Our findings are similar to previous case series suggesting that epilepsy surgery can be a treatment option in patients with mTOR pathway mutation. In patients with mTOR pathway mutation, the postsurgical outcome is favorable if complete resection of the epileptogenic zone is performed. Electrophysiological seizure onset patterns in FCDs associated with mTOR pathway mutations display low‐voltage fast activity as previously described. [ABSTRACT FROM AUTHOR]

IInvestigating cognitive brain functions using non-invasive electrophysiology can be challenging due to the particularities of the task-related EEG activity, the depth of the activated brain areas, and the extent of the networks involved. Stereoelectroencephalographic (SEEG) investigations in patients with drug-resistant epilepsy offer an extraordinary opportunity to validate information derived from non-invasive recordings at macro-scales. The SEEG approach can provide brain activity with high spatial specificity during tasks that target specific cognitive processes (e.g., memory). Full validation is possible only when performing simultaneous scalp SEEG recordings, which allows recording signals in the exact same brain state. This is the approach we have taken in 12 subjects performing a visualmemory task that requires the recognition of previously viewed objects. The intracranial signals on 965 contact pairs have been compared to 391 simultaneously recorded scalp signals at a regional and whole-brain level, using multivariate pattern analysis. The results show that the task conditions are best captured by intracranial sensors, despite the limited spatial coverage of SEEG electrodes, compared to the whole-brain non-invasive recordings. Applying beamformer source reconstruction or independent component analysis does not result in an improvement of the multivariate task decoding performance using surface sensor data. By analyzing a joint scalp and SEEG dataset, we investigated whether the two types of signals carry complementary information that might improve the machine-learning classifier performance. This joint analysis revealed that the results are driven by the modality exhibiting best individual performance, namely SEEG. [ABSTRACT FROM AUTHOR]

Cognitive tasks are commonly used to identify brain networks involved in the underlying cognitive process. However, inferring the brain networks from intracranial EEG data presents several challenges related to the sparse spatial sampling of the brain and the high variability of the EEG trace due to concurrent brain processes. In this manuscript, we use a well-known facial emotion recognition task to compare three different ways of analyzing the contrasts between task conditions: permutation cluster tests, machine learning (ML) classifiers, and a searchlight implementation of multivariate pattern analysis (MVPA) for intracranial sparse data recorded from 13 patients undergoing presurgical evaluation for drug-resistant epilepsy. Using all three methods, we aim at highlighting the brain structures with significant contrast between conditions. In the absence of ground truth, we use the scientific literature to validate our results. The comparison of the three methods' results shows moderate agreement, measured by the Jaccard coefficient, between the permutation cluster tests and the machine learning [0.33 and 0.52 for the left (LH) and right (RH) hemispheres], and 0.44 and 0.37 for the LH and RH between the permutation cluster tests and MVPA. The agreement between ML and MVPA is higher: 0.65 for the LH and 0.62 for the RH. To put these results in context, we performed a brief review of the literature and we discuss how each brain structure's involvement in the facial emotion recognition task. [ABSTRACT FROM AUTHOR]

Direct electrical stimulation (DES) is considered to be the gold standard for mapping cortical function. A careful mapping of the eloquent cortex is key to successful resective or ablative surgeries, with a minimal postoperative deficit, for treatment of drug‐resistant epilepsy. There is accumulating evidence suggesting that not only local, but also remote activations play an equally important role in evoking clinical effects. By introducing a new intracranial stimulation paradigm and signal analysis methodology allowing to disambiguate EEG responses from stimulation artifacts we highlight the spatial extent of the networks associated with clinical effects. Our study includes 26 patients that underwent stereoelectroencephalographic investigations for drug‐resistant epilepsy, having 337 depth electrodes with 4,351 contacts sampling most brain structures. The routine high‐frequency electrical stimulation protocol for eloquent cortex mapping was altered in a subtle way, by alternating the polarity of the biphasic pulses in a train, causing the splitting the spectral lines of the artifactual components, exposing the underlying tissue response. By performing a frequency‐domain analysis of the EEG responses during DES we were able to capture remote activations and highlight the effect's network. By using standard intersubject averaging and a fine granularity HCP‐MMP parcellation, we were able to create local and distant connectivity maps for 614 stimulations evoking specific clinical effects. The clinical value of such maps is not only for a better understanding of the extent of the effects' networks guiding the invasive exploration, but also for understanding the spatial patterns of seizure propagation given the timeline of the seizure semiology. [ABSTRACT FROM AUTHOR]

Stereoelectroencephalography (SEEG) in children with intractable epilepsy presents particular challenges. Their thin and partially ossified cranium, specifically in the temporal area, is prone to fracture while attaching stereotactic systems to the head or stabilizing the head in robot's field of action. Postponing SEEG in this special population of patients can have serious consequences, reducing their chances of becoming seizure-free and impacting their social and cognitive development. This study demonstrates the safety and accuracy offered by a frameless personalized 3D printed stereotactic implantation system for SEEG investigations in children under 4 years of age. SEEG was carried out in a 3-year-old patient with drug-resistant focal epilepsy, based on a right temporal-perisylvian epileptogenic zone hypothesis. Fifteen intracerebral electrodes were placed using a StarFix patient-customized stereotactic fixture. The median lateral entry point localization error of the electrodes was 0.90 mm, median lateral target point localization error was 1.86 mm, median target depth error was 0.83 mm, and median target point localization error was 1.96 mm. There were no perioperative complications. SEEG data led to a tailored right temporal-insular-opercular resection, with resulting seizure freedom (Engel IA). In conclusion, patient-customized stereotactic fixtures are a safe and accurate option for SEEG exploration in young children. [ABSTRACT FROM AUTHOR]

Objective: To profile European trends in pediatric epilepsy surgery (<16 years of age) between 2008 and 2015. Methods: We collected information on volumes and types of surgery, pathology, and seizure outcome from 20 recognized epilepsy surgery reference centers in 10 European countries. Results: We analyzed retrospective aggregate data on 1859 operations. The proportion of surgeries significantly increased over time (P <.0001). Engel class I outcome was achieved in 69.3% of children, with no significant improvement between 2008 and 2015. The proportion of histopathological findings consistent with glial scars significantly increased between the ages of 7 and 16 years (P for trend =.0033), whereas that of the remaining pathologies did not vary across ages. A significant increase in unilobar extratemporal surgeries (P for trend =.0047) and a significant decrease in unilobar temporal surgeries (P for trend =.0030) were observed between 2008 and 2015. Conversely, the proportion of multilobar surgeries and unrevealing magnetic resonance imaging cases remained unchanged. Invasive investigations significantly increased, especially stereo‐electroencephalography. We found different trends comparing centers starting their activity in the 1990s to those whose programs were developed in the past decade. Multivariate analysis revealed a significant variability of the proportion of the different pathologies and surgical approaches across countries, centers, and age groups between 2008 and 2015. Significance: Between 2008 and 2015, we observed a significant increase in the volume of pediatric epilepsy surgeries, stability in the proportion of Engel class I outcomes, and a modest increment in complexity of the procedures. [ABSTRACT FROM AUTHOR]

Body awareness is the result of sensory integration in the posterior parietal cortex; however, other brain structures are part of this process. Our goal is to determine how the cingulate cortex is involved in the representation of our body. We retrospectively selected patients with drug‐resistant epilepsy, explored by stereo‐electroencephalography, that had the cingulate cortex sampled outside the epileptogenic zone. The clinical effects of high‐frequency electrical stimulation were reviewed and only those sites that elicited changes related to body perception were included. Connectivity of the cingulate cortex and other cortical structures was assessed using the h2 coefficient, following a nonlinear regression analysis of the broadband EEG signal. Poststimulation changes in connectivity were compared between two sets of stimulations eliciting or not eliciting symptoms related to body awareness (interest and control groups). We included 17 stimulations from 12 patients that reported different types of body perception changes such as sensation of being pushed toward right/left/up, one limb becoming heavier/lighter, illusory sensation of movement, sensation of pressure, sensation of floating or detachment of one hemi‐body. High‐frequency stimulation in the cingulate cortex (1 anterior, 15 middle, 1 posterior part) elicits body perception changes, associated with a decreased connectivity of the dominant posterior insula and increased coupling between other structures, located particularly in the nondominant hemisphere. [ABSTRACT FROM AUTHOR]

There are many medications that cross the blood-brain barrier affecting the central nervous system and converting the normal patterns of sleep and wakefulness. Some drugs are used to treat special sleep disorders but others can induce sleep disorders (e.g. periodic limb movements during sleep, restless leg syndrome, parasomnia, insomnia) or exacerbate them (e.g. obstructive or central sleep apnea). The most frequent classes of agents used in sleep medicine are: benzodiazepines, nonbenzodiazepines receptor agonists, melatonin and melatonin receptor agonists, antiepileptic drugs, antidepressants, atypical antipsychotics, central stimulants and dopamine agonists. [ABSTRACT FROM AUTHOR]

Objective: We aimed to (1) assess the concordance between various polymicrogyria (PMG) types and the associated epileptogenic zone (EZ), as defined by stereoelectroencephalography (SEEG), and (2) determine the postsurgical seizure outcome in PMG-related drug-resistant epilepsy.Methods: We retrospectively analyzed 58 cases: 49 had SEEG and 39 corticectomy or hemispherotomy.Results: Mean age at SEEG or surgery was 28.3 years (range, 2-50). PMG was bilateral in 9 (16%) patients and unilateral in 49, including 17 (29%) unilobar, 12 (21%) multilobar, 15 (26%) perisylvian, and only 5 (9%) hemispheric. Twenty-eight (48%) patients additionally had schizencephaly, heterotopia, or focal cortical dysplasia. The SEEG-determined EZ was fully concordant with the PMG in only 8 (16%) cases, partially concordant in 74%, and discordant in 10%. The EZ included remote cortical areas in 21 (43%) cases and was primarily localized in those in 5 (10%), all related to the mesial temporal structures. All but 1 PMG patient with corticectomy or hemispherotomy had a unilateral PMG. At last follow-up (mean, 4.6 years; range, 1-16), 28 (72%) patients remained seizure free. Shorter epilepsy duration to surgery was an independent predictor of seizure freedom.Interpretation: PMG-related drug-resistant epilepsy warrants a comprehensive presurgical evaluation, including SEEG investigations in most cases, given that the EZ may only partially overlap with the PMG or include solely remote cortical areas. Seizure freedom is feasible in a large proportion of patients. PMG extent should not deter from exploring the possibility of epilepsy surgery. Our data support the early consideration of epilepsy surgery in this patient group. Ann Neurol 2017;82:781-794. [ABSTRACT FROM AUTHOR]

Background: Based on a case report, the authors reviewed the data about involuntary emotional expression disorder (IEED). IEED includes the syndromes of pathological laughing and crying (PLC) and emotional lability (EL). PLC is a rare disorder of emotional expression characterized by relatively uncontrollable episodes of laughter and crying or both that do not have an apparent motivating stimulus.Case Presentation: Authors report the case of a 59-year-old man who presented with recurrent episodes of PLC of approximately 2 min duration, consisting of accelerated breathing, emission of guttural, snoring sounds, frowning of the eyebrows, followed by laughter accompanied by motor restlessness of all four limbs. PLC episodes preceded left carotid transient ischemic attacks (TIA's) manifested by reversible aphasia and right hemiparesis. Electroencephalography performed during PLC episodes revealed no spike-wave activity. Brain magnetic resonance imaging showed lacunar infarcts in the left lenticulo-capsulo-thalamic area and multiple round lesions in the cortical-subcortical and in the deep white matter of frontal-parietal-occipital lobes bilaterally, with T2 hyperintensity, T1 isointensity and no diffusion changes. The episodes were interpreted as transient ischemic attacks although gelastic seizures could not be excluded. The etiological investigations revealed unstable plaques on the left carotid artery bulb and the aortic arch and a degenerative mitral valve stenosis. The patient was treated first with antiplatelet therapy and antiepileptic drugs but PLC stopped only after anticoagulation was started. During follow-up the patient continued to have left carotid and vertebrobasilar TIA's being on oral anticoagulation. The patient became asymptomatic only after mitral valve replacement was performed.Conclusions: This case illustrates the difficulty distinguishing between gelastic epilepsy and TIA's in cases of PLC episodes and discuss the neuroanatomic bases and pathophysiology of this rare condition. [ABSTRACT FROM AUTHOR]

Background: The stereoelectroencephalographic (SEEG) implantation procedures still represent a challenge due to the intrinsic complexity of the method and the number of depth electrodes required. Objectives: We aim at designing and evaluating the accuracy of a custom stereotactic fixture based on the StarFix™ technology (FHC Inc., Bowdoin, ME) that significantly simplifies and optimizes the implantation of depth electrodes used in presurgical evaluation of patients with drug-resistant epilepsy. Methods: Fiducial markers that also serve as anchors for the fixture are implanted into the patient's skull prior to surgery. A 3D fixture model is designed within the surgical planning software, with the planned trajectories incorporated in its design, aligned with the patient's anatomy. The stereotactic fixture is built using 3D laser sintering technology based on the computer-generated model. Bilateral rectangular grids of guide holes orthogonal to the midsagittal plane and centered on the midcommissural point are incorporated in the fixture design, allowing a wide selection of orthogonal trajectories. Up to two additional grids can be accommodated for targeting structures where oblique trajectories are required. The frame has no adjustable parts, this feature reducing the risk of inaccurate coordinate settings while simultaneously reducing procedure time significantly. Results: We have used the fixture for the implantation of depth electrodes for presurgical evaluation of 4 patients with drug-resistant focal epilepsy, with nearly 2-fold reduction in the duration of the implantation procedure. We have obtained a high accuracy with a submillimetric mean positioning error of 0.68 mm for the anchor bolts placed at the trajectory entry point and 1.64 mm at target. Conclusions: The custom stereotactic fixture design greatly simplifies the planning procedure and significantly reduces the time in the operating room, while maintaining a high accuracy. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Since the Babylonian era up to nowadays, the large complexity of epileptic disorders made the attempt of classifying and organizing concepts one of the most challenging. The 1981 classification was a revision of the one devised by Henri Gastaut for the ILAE and published in 1970. The distinction between simple and complex partial seizures represented a significant difference. In 1989 the report of ILAE classification and terminology task force introduced the concept of epileptic syndrome. An epileptic syndrome is defined by the sum of signs and symptoms that tend to occur together, not reflecting a particular etiology and prognosis, these latter features being the hallmark not of a syndrome, but of a disease condition. Firstly, any epileptic disorder can be described as either idiopathic (primary, whose etiology is probably genetic), symptomatic (with a known or presumed cerebral pathology) or cryptogenic (with an occult cause). The epileptic diagnostic tree ramifies into four main branches in the 1989 ILAE Classification: localization-related (focal, local, or partial) epilepsies and syndromes, generalized epilepsies and syndromes, epilepsies and syndromes undetermined whether focal or generalized and special syndromes. The next important milestone in epilepsy classification was settled by ILAE in 2001, when a glossary for ictal semiology was developed and multiaxial approach of diagnosing epilepsy was proposed. The necessity of processing the new insights in epilepsy was answered by the latest ILAE Report released in february 2010, which brings awareness of and appropriately integrates the currently available data. It presents a modular approach of diagnosing epilepsy and recommends to keep a flexible vision on this topic, as every individual case requires a different prioritizing scheme. [ABSTRACT FROM AUTHOR]

Chronic inflammatory demyelinating polyradiculopathy is mainly based on clinical and electrophysiological criteria. If electrophysiological findings remain questionable for the diagnosis of CIDP and/or clinical presentation is atypical, nerve biopsy may assist the diagnosis. We present a case in which the nerve biopsy was helpful in diagnosis of CIDP and revealed the peculiar presence of tomacula. [ABSTRACT FROM AUTHOR]

Quantitative sensory testing (QST) is a potentially useful tool for measuring sensory impairment for clinical and research studies but there is still no consensus regarding the place of this evaluation in every day clinical practice. Our study included 15 patients previously diagnosed with neuropathic pain due to small fiber sensory polyneuropathy based on clinical and electrodiagnostic criteria.Variables were compared with an age matched control group of 7 healthy persons. We looked to pain severity rated on Visual Analog Scale and Pain Detect Questionnaire and we searched for correlations with sensory nerve conduction studies and parameters of quantitative sensory testing - thermotest, limits method. QST was a sensitive technique for evaluation of patients with small fiber sensory polyneuropathy. Score on Pain Detect Questionnaire has statistically significant correlation with values recorded for cooling detection threshold on QST, documenting sensory loss and A delta fibers dysfunction in the study group. [ABSTRACT FROM AUTHOR]

Diagnosis of ALS is based on clinical examination and electromyographic tests which are used to confirm the clinical suspicion and to exclude alternatives. Atypical presentations may delay the diagnostic and subject the patient to unnecessary tests and procedures. We discuss here three cases with atypical features: head dropping, highly focal weakness and amyotrophy and the last case with surgery for lumbar stenosis. [ABSTRACT FROM AUTHOR]

Purpose To investigate whether hyperventilation (HV) for 5 min increases the diagnostic yield of electroencephalography (EEG) compared to 3 min HV. Methods data were evaluated from 1084 consecutive patients, from three European centres, referred to EEG on suspicion of epilepsy. Seizures and interictal EEG abnormalities precipitated during the first 3 min and during the last 2 min of the HV period (totally 5 min) were determined. Results Eight hundred seventy-seven patients (81%) completed 5 min HV. Seizures were precipitated during the first 3 min of HV in 21 patients, and during the last 2 min in four more patients. Interictal EEG abnormalities were precipitated in the first 3 min of HV in 16 patients, and during the last 2 min in 7 more patients. Psychogenic nonepileptic seizures occurred in eight patients during the first 3 min of HV and in two more patients during the last 2 min. No adverse events occurred during the last 2 min of HV, but eight patients (1%) stopped HV during the last 2 min because they were not able to hyperventilate further. Conclusion 16% of seizures and 30% of interictal EEG abnormalities triggered by HV occurred during the last 2 min of HV, suggesting the clinical usefulness of prolonged hyperventilation for 5 min. The vast majority of patients (99%) who are able to hyperventilate for 3 min can complete 5 min HV, without additional adverse events. [ABSTRACT FROM AUTHOR]

Objectives By analyzing the responses to intracranial electrical stimulation we aim at im-proving the localization of the seizure onset zone (SOZ) and the connectivity between different areas. Methods Our center uses a set of traditional and innovative advanced analysis methods for stereo-EEG signals recorded using depth electrodes. We analyze stimulation-evoked activity in time-frequency domain to detect inter-ictal epileptogenicity biomarkers like high-frequency oscillations (HFO, f > 80 Hz) and delayed responses (DR, t > 100 ms). Results of the different quantitative EEG analyses are represented as 3-D maps superimposed with patient’s anatomy, as visible on various imaging modalities, and their evolution in time is shown as movies. Cortico-cortical evoked potentials (CCEP) based on early responses ( t = 10–110 ms) to single-pulse intracranial stimulation are used to calculate functional connectivity between cortical areas. Results Biomarker response maps and effective connectomes were calculated in a population of 24 patients undergoing presurgical evaluation for drug-resistant epilepsy. The sensitivity with respect to SOZ of HFOs was higher than the one of the DR by both response and stimulation location, whereas the specificity of the DRs was higher by the lo-cation of the stimulation. Discussion Despite variable sensitivity and specificity of the biomarkers, the positive pre-diction level of these biomarkers is less than 30%, taken separately or in combination. Conclusions Analysis of responses to intracranial electrical stimulation can contribute to the identification of the epileptogenic networks and for delineating the epileptogenic are-as. Significance We illustrate the value of using multiple advanced signal analysis techniques. [ABSTRACT FROM AUTHOR]

Objective We aim to study the connections of the posterior insula (pI) and anterior insula (aI) through cortico-cortical evoked potentials (CCEP) by single pulse electrical stimulation (SPES). Method We performed SPES stimulation protocol in a group of 8 refractory epilepsy patients presurgically explored with intracerebral depth electrodes, out of which 6 were operated on and are currently seizure-free. We selected the early responses (ER) obtained from contacts of 24 electrodes that were included in the anterior and posterior insula, when this structure was outside the seizure onset zone (SOZ). Responses were analyzed in terms of amplitude variations during wakefulness and sleep. Effective connectivity betweeen cortical was calculated based on the measured CCEPs. Results The ER amplitudes by SPES stimulation in the insula during wakefulness compared to sleep showed statistically significant ( p < 0.05 ) differences in 6 patients. There are constant connections between aI and pI. We identified connectivity of the pI with language-related brain stuctures during wakefulness, and with the temporal mesial structures during sleep, possibly influenced by the SOZ. Right pI stimulation seems to elicit ampler reponses in the rolandic operculum and parietal structures during wakefulness, and in the primary motor and premotor cortex during sleep. Anterior insula has preferential connectivity with anterior cingulate gyrus during wakefulness and with the fusiform gyrus during sleep. Discussions Connectivity of the aI versus pI, as well as right versus left insula during wakefulness and sleep is different, partially supporting previous observations. Conclusion Sleep has been shown to alter the physiological connectivity of the insula. Further investigations are in progress to confirm these results. Significance These findings describe insular connectivity and variability during sleep, with possible implications in epilepsy surgery, sleep disorders understanding and language studies. [ABSTRACT FROM AUTHOR]

We depict the case of a patient who progressively develops a motor deficit and respiratory failure, which eventually proves to be botulinus intoxication, after a series of puzzling results of various investigations leading to a different diagnosis. [ABSTRACT FROM AUTHOR]

Dementia and depression are both frequent in stroke patients. Evaluation, follow-up of the severity and treatment decisions are important in such patients. Moreover, neuropsychological testing for cognition and mood interfere and various neurological deficits could further on alter the testing. The picture is even more complicated, considering that dementia can lead to depression and vice versa. In our current pilot study we evaluated patients in days 3-5 after the onset of ischemic stroke. We found no significant correlations between cognition and depression scores in our sample, result which suggests that at very short interval after stroke, cognitive disturbance is not a predictor for depression. [ABSTRACT FROM AUTHOR]

Objectives We aim to map the function and connectivity of the cingulate gyrus (CG) using cortical direct electrical stimulation. Methods We selected patients explored by SEEG at the Emergency University Hospital Bucharest and at the Strasbourg University Hospital, that had minimum one electrode sampling the CG (anterior-ACG, middle-MCG or posterior-PCG), outside the epileptogenic zone. We systematically reviewed the functional stimulations (bipolar, 50 Hz, 0.25–3 mA). For 17 patients explored in Bucharest, cortico-cortical evoked potentials (CCEPs) elicited by single pulse electrical stimulations (SPES) were used to obtain the effective connectivity at a group level for each part of the CG. Results We included 429 bipolar stimulations from 108 patients. From 151 stimulations in the ACG, 24.5% elicited a clinical response like: emotions (19%), vestibular (13.5%), thoracic sensation (13.5%), smile (11%). There are 135 stimulations in the MCG of which 53.3% elicited clinical responses like: elementary motor (24.94%), proprioception (22.22%), elementary somatosensitive (13.2%), compulsive motor (2.77%). There were 143 stimulations in the PCG and only 18.88% were positive, for example: executive function (11.11%), vestibular (7.4%). CCEPs analysis revealed that ACG is connected with the prefrontal (frontobasal and frontopolar) regions, anterior insula, mesiotemporal regions. MCG is connected with the primary and supplementary motor areas, insulo-perisylvian region and parietal lobe. PCG is connected with the ACG, MCG, prefrontal, parietal and temporal regions. Discussion High frequency stimulations elicit clinical responses as a result of a network effect that we have mapped with CCEPs. Conclusions There is a regional organization of the cingulate gyrus for each part both in function and connectivity. Significance These findings help us understand the functional organization of the cingulate gyrus with possible implications in epilepsy surgery, depression or other mental disorders. [ABSTRACT FROM AUTHOR]

Objective To investigate default-mode network (DMN) deactivation in different types of focal epilepsy by single pulse electric stimulation (SPES). Method We analyzed 18 patients with focal epilepsy (8 frontal, 8 temporal, 2 posterior), implanted with depth electrodes. SPES was applied to each pair of adjacent contacts in seiwure onset zone (SOZ), and responses were recorded from the 10 different DMN-hubs; The responses to SPES in Gamma, Ripple (R) and Fast-Ripple (FR) bands were quantified in a 60–250 ms time-window following each stimulation pulse and compared to baseline. Time of propagation was determined based on N1 latency. These responses were compared across the three epilepsy types. Results Overall, we observed a significant deactivation of the DMN in the upper frequency ranges for all epilepsies (75% drop from baseline for gamma and 93% for R and FR). In the gamma band, the stimulation of frontal SOZs deactivated the ipsilateral posterior cingulate and precuneus significantly more than in the other epilepsy-types, with shorter general latencies of 22, 25 and 23 ms, respectively. Discussion Our results might explain why in prefrontal focal epilepsies and in generalized epilepsies, thought to have a frontal generator, the consciousness is preferentially and significantly impaired. Significance This is a promising method for quantifying the engagement of the consciousness processing areas by the epileptic focus. Detailed illustrations and tables for all 10 DMN-hubs, in all 3 high-frequency bands are provided. [ABSTRACT FROM AUTHOR]