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1.
Epilepsia Open ; 4(2): 281-292, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31168495

RESUMO

Objective: Electrical source imaging (ESI) is used increasingly to estimate the epileptogenic zone (EZ) in patients with epilepsy. Directed functional connectivity (DFC) coupled to ESI helps to better characterize epileptic networks, but studies on interictal activity have relied on high-density recordings. We investigated the accuracy of ESI and DFC for localizing the EZ, based on low-density clinical electroencephalography (EEG). Methods: We selected patients with the following: (a) focal epilepsy, (b) interictal spikes on standard EEG, (c) either a focal structural lesion concordant with the electroclinical semiology or good postoperative outcome. In 34 patients (20 temporal lobe epilepsy [TLE], 14 extra-TLE [ETLE]), we marked interictal spikes and estimated the cortical activity during each spike in 82 cortical regions using a patient-specific head model and distributed linear inverse solution. DFC between brain regions was computed using Granger-causal modeling followed by network topologic measures. The concordance with the presumed EZ at the sublobar level was computed using the epileptogenic lesion or the resected area in postoperative seizure-free patients. Results: ESI, summed outflow, and efficiency were concordant with the presumed EZ in 76% of the patients, whereas the clustering coefficient and betweenness centrality were concordant in 70% of patients. There was no significant difference between ESI and connectivity measures. In all measures, patients with TLE had a significantly higher (P < 0.05) concordance with the presumed EZ than patients with with ETLE. The brain volume accepted for concordance was significantly larger in TLE. Significance: ESI and DFC derived from low-density EEG can reliably estimate the EZ from interictal spikes. Connectivity measures were not superior to ESI for EZ localization during interictal spikes, but the current validation of the localization of connectivity measure is promising for other applications.

5.
Cereb Cortex ; 28(4): 1209-1218, 2018 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-28203797

RESUMO

As a functional homolog for left-hemispheric syntax processing in language, neuroimaging studies evidenced involvement of right prefrontal regions in musical syntax processing, of which underlying white matter connectivity remains unexplored so far. In the current experiment, we investigated the underlying pathway architecture in subjects with 3 levels of musical expertise. Employing diffusion tensor imaging tractography, departing from seeds from our previous functional magnetic resonance imaging study on music syntax processing in the same participants, we identified a pathway in the right ventral stream that connects the middle temporal lobe with the inferior frontal cortex via the extreme capsule, and corresponds to the left hemisphere ventral stream, classically attributed to syntax processing in language comprehension. Additional morphometric consistency analyses allowed dissociating tract core from more dispersed fiber portions. Musical expertise related to higher tract consistency of the right ventral stream pathway. Specifically, tract consistency in this pathway predicted the sensitivity for musical syntax violations. We conclude that enduring musical practice sculpts ventral stream architecture. Our results suggest that training-related pathway plasticity facilitates the right hemisphere ventral stream information transfer, supporting an improved sound-to-meaning mapping in music.


Assuntos
Encéfalo/diagnóstico por imagem , Imagem de Tensor de Difusão , Lateralidade Funcional/fisiologia , Imagem por Ressonância Magnética , Música , Competência Profissional , Adolescente , Adulto , Análise de Variância , Vias Auditivas , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Oxigênio/sangue , Nível de Percepção Sonora/fisiologia , Adulto Jovem
8.
Epilepsia Open ; 2(3): 322-333, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-29588961

RESUMO

Objective: We investigated the performance of automatic spike detection and subsequent electroencephalogram (EEG) source imaging to localize the epileptogenic zone (EZ) from long-term EEG recorded during video-EEG monitoring. Methods: In 32 patients, spikes were automatically detected in the EEG and clustered according to their morphology. The two spike clusters with most single events in each patient were averaged and localized in the brain at the half-rising time and peak of the spike using EEG source imaging. On the basis of the distance from the sources to the resection and the known patient outcome after surgery, the performance of the automated EEG analysis to localize the EZ was quantified. Results: In 28 out of the 32 patients, the automatically detected spike clusters corresponded with the reported interictal findings. The median distance to the resection in patients with Engel class I outcome was 6.5 and 15 mm for spike cluster 1 and 27 and 26 mm for cluster 2, at the peak and the half-rising time of the spike, respectively. Spike occurrence (cluster 1 vs. cluster 2) and spike timing (peak vs. half-rising) significantly influenced the distance to the resection (p < 0.05). For patients with Engel class II, III, and IV outcomes, the median distance increased to 36 and 36 mm for cluster 1. Localizing spike cluster 1 at the peak resulted in a sensitivity of 70% and specificity of 100%, positive prediction value (PPV) of 100%, and negative predictive value (NPV) of 53%. Including the results of spike cluster 2 led to an increased sensitivity of 79% NPV of 55% and diagnostic OR of 11.4, while the specificity dropped to 75% and the PPV to 90%. Significance: We showed that automated analysis of long-term EEG recordings results in a high sensitivity and specificity to localize the epileptogenic focus.

9.
Brain Topogr ; 30(2): 257-271, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27853892

RESUMO

Epilepsy surgery is the most efficient treatment option for patients with refractory epilepsy. Before surgery, it is of utmost importance to accurately delineate the seizure onset zone (SOZ). Non-invasive EEG is the most used neuroimaging technique to diagnose epilepsy, but it is hard to localize the SOZ from EEG due to its low spatial resolution and because epilepsy is a network disease, with several brain regions becoming active during a seizure. In this work, we propose and validate an approach based on EEG source imaging (ESI) combined with functional connectivity analysis to overcome these problems. We considered both simulations and real data of patients. Ictal epochs of 204-channel EEG and subsets down to 32 channels were analyzed. ESI was done using realistic head models and LORETA was used as inverse technique. The connectivity pattern between the reconstructed sources was calculated, and the source with the highest number of outgoing connections was selected as SOZ. We compared this algorithm with a more straightforward approach, i.e. selecting the source with the highest power after ESI as the SOZ. We found that functional connectivity analysis estimated the SOZ consistently closer to the simulated EZ/RZ than localization based on maximal power. Performance, however, decreased when 128 electrodes or less were used, especially in the realistic data. The results show the added value of functional connectivity analysis for SOZ localization, when the EEG is obtained with a high-density setup. Next to this, the method can potentially be used as objective tool in clinical settings.


Assuntos
Encéfalo/fisiopatologia , Epilepsias Parciais/fisiopatologia , Convulsões/fisiopatologia , Adulto , Algoritmos , Eletrodos , Eletroencefalografia/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neuroimagem
10.
Neuroimage Clin ; 12: 466-77, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27625987

RESUMO

Spontaneous fluctuations of neuronal activity in large-scale distributed networks are a hallmark of the resting brain. In relapsing-remitting multiple sclerosis (RRMS) several fMRI studies have suggested altered resting-state connectivity patterns. Topographical EEG analysis reveals much faster temporal fluctuations in the tens of milliseconds time range (termed "microstates"), which showed altered properties in a number of neuropsychiatric conditions. We investigated whether these microstates were altered in patients with RRMS, and if the microstates' temporal properties reflected a link to the patients' clinical features. We acquired 256-channel EEG in 53 patients (mean age 37.6 years, 45 females, mean disease duration 9.99 years, Expanded Disability Status Scale ≤ 4, mean 2.2) and 49 healthy controls (mean age 36.4 years, 33 females). We analyzed segments of a total of 5 min of EEG during resting wakefulness and determined for both groups the four predominant microstates using established clustering methods. We found significant differences in the temporal dynamics of two of the four microstates between healthy controls and patients with RRMS in terms of increased appearance and prolonged duration. Using stepwise multiple linear regression models with 8-fold cross-validation, we found evidence that these electrophysiological measures predicted a patient's total disease duration, annual relapse rate, disability score, as well as depression score, and cognitive fatigue measure. In RRMS patients, microstate analysis captured altered fluctuations of EEG topographies in the sub-second range. This measure of high temporal resolution provided potentially powerful markers of disease activity and neuropsychiatric co-morbidities in RRMS.


Assuntos
Mapeamento Encefálico , Ondas Encefálicas/fisiologia , Eletroencefalografia , Esclerose Múltipla Recidivante-Remitente/diagnóstico por imagem , Esclerose Múltipla Recidivante-Remitente/fisiopatologia , Adulto , Feminino , Humanos , Modelos Lineares , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Oxigênio/sangue , Valor Preditivo dos Testes , Escalas de Graduação Psiquiátrica
11.
Expert Rev Neurother ; 16(12): 1427-1441, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27384886

RESUMO

INTRODUCTION: Neuromodulation (NM) is a complementary therapy for patients with drug-resistant epilepsy. Vagal nerve stimulation and deep brain stimulation of the anterior thalamus are established techniques and have shown their efficacy in lowering seizure frequency, but they are invasive and rarely render patients seizure-free. Non-invasive NM techniques are therefore increasingly investigated in a clinical context. Areas covered: Current knowledge about transcranial direct-current stimulation (tDCS) and other non-invasive NM in patients with epilepsy, based on the available animal and clinical studies from PubMed search. Expert commentary: tDCS modulates neuronal membrane potentials, and consequently alters cortical excitability. Cathodal stimulation leads to cortical inhibition, which is of particular importance in epilepsy treatment. The antiepileptic efficacy is promising but still lacks systematic studies. The beneficial effect, seen in ~20%, outlasts the duration of stimulation, indicating neuronal plasticity and is therefore of great interest to obtain long-term effects.


Assuntos
Epilepsia/terapia , Estimulação Transcraniana por Corrente Contínua , Animais , Estimulação Encefálica Profunda , Humanos , Plasticidade Neuronal , Estimulação Magnética Transcraniana
12.
Swiss Med Wkly ; 146: w14310, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27322347

RESUMO

Complete seizure control is achieved in 40-50% of all epileptic patients with drug treatment, as reported in most epidemiological studies. Many effective antiepileptic drugs with a favourable profile are available in Switzerland, allowing treatment tailored to the patient's needs. Unfortunately, up to 40-50% of all patients will eventually relapse (pharmacoresistant epilepsy). These patients run a high risk of additional morbidity and mortality. Possible pharmacoresistant epilepsy should be considered early in the disease, when there is a lack of response to the first antiepileptic drug, since only 14% of those will respond to a second drug, and only 2% to a third drug if the second fails too. Epilepsy surgery is a viable option for these patients. It requires in-depth evaluation in specialized centres, and is related to complete seizure control in 50-90% of the patients, depending on the lesion type and site. Only for patients in whom surgery cannot be offered should neuromodulation treatments be considered. Today, two different approaches are approved, vagal nerve stimulation (VNS) and deep brain stimulation in the anterior thalamic nuclei (DBS-ANT). Although only a minority of patients become totally seizure-free. Both VNS and DBS-ANT represent an important adjunct in the therapeutic armamentarium. In the present review, we outline a practical approach for the different steps in therapeutic decisions and we summarise the profiles of modern antiepileptic drugs as well outcome of surgical and neuromodulatory therapies. The goal of any approach should be to obtain complete seizure control. In general, if two antiepileptic drugs are not successful, in-depth evaluation of the patient in a specialised center is strongly recommended.


Assuntos
Anticonvulsivantes/uso terapêutico , Gerenciamento Clínico , Epilepsia/tratamento farmacológico , Epilepsia/terapia , Estimulação Encefálica Profunda/métodos , Resistência a Medicamentos , Humanos , Masculino , Recidiva , Estimulação do Nervo Vago/métodos
14.
Front Behav Neurosci ; 10: 21, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26924970

RESUMO

Ecstatic epileptic seizures are a rare but compelling epileptic entity. During the first seconds of these seizures, ecstatic auras provoke feelings of well-being, intense serenity, bliss, and "enhanced self-awareness." They are associated with the impression of time dilation, and can be described as a mystic experience by some patients. The functional neuroanatomy of ecstatic seizures is still debated. During recent years several patients presenting with ecstatic auras have been reported by others and us (in total n = 52); a few of them in the setting of presurgical evaluation including electrical brain stimulation. According to the recently recognized functions of the insula, and the results of nuclear brain imaging and electrical stimulation, the ecstatic symptoms in these patients seem to localize to a functional network centered around the anterior insular cortex, where we thus propose to locate this rare ictal phenomenon. Here we summarize the role of the multiple sensory, autonomic, affective, and cognitive functions of the insular cortex, which are integrated into the creation of self-awareness, and we suggest how this system may become dysfunctional on several levels during ecstatic aura.

15.
Cortex ; 77: 54-68, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26922504

RESUMO

Spatial neglect is a neuropsychological syndrome in which patients fail to perceive and orient to stimuli located in the space contralateral to the lesioned hemisphere. It is characterized by a wide heterogeneity in clinical symptoms which can be grouped into distinct behavioral components correlating with different lesion sites. Moreover, damage to white-matter (WM) fiber tracts has been suggested to disconnect brain networks that mediate different functions associated with spatial cognition and attention. However, it remains unclear what WM pathways are associated with functionally dissociable neglect components. In this study we examined nine patients with a focal right hemisphere stroke using a series of neuropsychological tests and diffusion tensor imaging (DTI) in order to disentangle the role of specific WM pathways in neglect symptoms. First, following previous work, the behavioral test scores of patients were factorized into three independent components reflecting perceptual, exploratory, and object-centered deficits in spatial awareness. We then examined the structural neural substrates of these components by correlating indices of WM integrity (fractional anisotropy) with the severity of deficits along each profile. Several locations in the right parietal and frontal WM correlated with neuropsychological scores. Fiber tracts projecting from these locations indicated that posterior parts of the superior longitudinal fasciculus (SLF), as well as nearby callosal fibers connecting ipsilateral and contralateral parietal areas, were associated with perceptual spatial deficits, whereas more anterior parts of SLF and inferior fronto-occipital fasciculus (IFOF) were predominantly associated with object-centered deficits. In addition, connections between frontal areas and superior colliculus were found to be associated with the exploratory deficits. Our results provide novel support to the view that neglect may result from disconnection lesions in distributed brain networks, but also extend these notions by highlighting the role of dissociable circuits in different functional components of the neglect syndrome. However these preliminary findings require replication with larger samples of patients.


Assuntos
Lesões Encefálicas/fisiopatologia , Mapeamento Encefálico , Rede Nervosa/fisiopatologia , Transtornos da Percepção/fisiopatologia , Acidente Vascular Cerebral/fisiopatologia , Substância Branca/patologia , Idoso , Idoso de 80 Anos ou mais , Anisotropia , Atenção/fisiologia , Lesões Encefálicas/complicações , Imagem de Tensor de Difusão/métodos , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Masculino , Pessoa de Meia-Idade , Rede Nervosa/patologia , Testes Neuropsicológicos , Transtornos da Percepção/patologia , Acidente Vascular Cerebral/complicações , Substância Branca/fisiopatologia
18.
Mol Syndromol ; 6(2): 91-5, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26279655

RESUMO

Coffin-Lowry syndrome (CLS) is a rare neurodevelopmental condition caused by heterogeneous mutations in the RPS6KA3 gene on the X chromosome, leading to severe intellectual disability and dysmorphism in men, while women are carriers and only weakly affected. CLS is well known for stimulus-induced drop episodes; however, epilepsy is not commonly reported in this condition. We report on a CLS patient presenting with recurrent episodes of nonconvulsive status epilepticus (NCSE) with generalized epileptic activity, for which investigations did not find any other cause than the patient's genetic condition. This case underlines that the possibility of nonconvulsive epileptic seizures and status epilepticus should, therefore, be considered in those patients. The treatable diagnosis of NCSE may easily be overlooked, as symptoms can be unspecific.

20.
Neuroimage ; 109: 27-34, 2015 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-25583613

RESUMO

Dorsal and ventral pathways for syntacto-semantic speech processing in the left hemisphere are represented in the dual-stream model of auditory processing. Here we report new findings for the right dorsal and ventral temporo-frontal pathway during processing of affectively intonated speech (i.e. affective prosody) in humans, together with several left hemispheric structural connections, partly resembling those for syntacto-semantic speech processing. We investigated white matter fiber connectivity between regions responding to affective prosody in several subregions of the bilateral superior temporal cortex (secondary and higher-level auditory cortex) and of the inferior frontal cortex (anterior and posterior inferior frontal gyrus). The fiber connectivity was investigated by using probabilistic diffusion tensor based tractography. The results underscore several so far underestimated auditory pathway connections, especially for the processing of affective prosody, such as a right ventral auditory pathway. The results also suggest the existence of a dual-stream processing in the right hemisphere, and a general predominance of the dorsal pathways in both hemispheres underlying the neural processing of affective prosody in an extended temporo-frontal network.


Assuntos
Afeto/fisiologia , Encéfalo/fisiologia , Percepção da Fala/fisiologia , Substância Branca/fisiologia , Adulto , Mapeamento Encefálico , Imagem de Difusão por Ressonância Magnética , Imagem de Tensor de Difusão , Feminino , Lobo Frontal/fisiologia , Lateralidade Funcional , Humanos , Masculino , Probabilidade , Lobo Temporal/fisiologia , Adulto Jovem
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