EEG-based multivariate pattern analysis reveals the control mechanisms of emotion regulation through distancing / El análisis de patrones multivariados basado en EEG revela los mecanismos de control de la regulación de las emociones a través del distanciamiento

Background/objective: A neurocognitive model of distancing has systematically identified a set of brain regions that support the control mechanisms for emotion regulation (ER). However, the temporal dynamics of these control mechanisms during ER remains unclear. Method: To address this issue, we recorded behavioral and electroencephalogram (EEG) data to compare proactive and reactive ER modes in an adapted ER task (N = 30 adults). In different ER modes, participants were instructed to downregulate their negative emotional experiences by applying the reappraisal tactic of distancing. Results: The behavioral results showed that proactive ER, which involves preparing for the upcoming regulation, reduced the negative emotional experience more than reactive ER, which involves no preparation process, in the reappraisal-negative condition. This indicated that proactive ER was more effective than reactive ER in regulating negative emotions. Event-related potential (ERP) and multivariate pattern analysis (MVPA) results showed that ER through distancing involved two phases: First, the reappraisal cue enhanced the allocation of attention to activate the mental building blocks and constructed a new perspective in the preparation process. Second, participants who benefited from the preparation process initiated the ER earlier and adaptively re-engaged in the ER if time permitted. Conclusions: Taken together, the control mechanisms underlying the preparation process influence the timing of ER, while the control mechanisms underlying the regulation process determine the regulatory effect.(AU)

The specificity of the auditory P300 responses and its association with clinical outcomes in youth with psychosis risk syndrome / La especificidad de las respuestas auditivas P300 y su asociación con los resultados clínicos en jóvenes con síndrome de riesgo de psicosis

Background: Schizophrenia often occurs in youth, and psychosis risk syndrome (PRS) occurs before the onset of psychosis. Assessing the neuropsychological abnormalities of PRS individuals can help in early identification and active intervention of mental illness. Auditory P300 amplitude defect is an important manifestation of attention processing abnormality in PRS, but it is still unclear whether there are abnormalities in the attention processing of rhythmic compound tone stimuli in PRS individuals, and whether the P300 amplitude induced by these stimuli is specific to PRS individuals and related to their clinical outcomes. Methods: In total, 226 participants, including 122 patients with PRS, 51 patients with emotional disorders (ED), and 53 healthy controls (HC) were assessed. Baseline electroencephalography was recorded during the compound tone oddball task. The event-related potentials (ERPs) induced by rhythmic compound tone stimuli of two frequencies (20-Hz, 40-Hz) were measured. Almost all patients with PRS were followed up for 12 months and reclassified into four groups: PRS-conversion, PRS-symptomatic, PRS-emotional disorder, and PRS-complete remission. The differences in baseline ERPs were compared among the clinical outcome groups. Results: Regardless of the stimulation frequency, the average P300 amplitude were significantly higher in patients with PRS than in those with ED (p = 0.003, d = 0.48) and in HC (p = 0.002, d = 0.44) group. The average P300 amplitude of PRS-conversion group was significantly higher than that of the PRS-complete remission (p = 0.016, d = 0.72) and HC group (p = 0.001, d = 0.76), and the average P300 amplitude of PRS-symptomatic group was significantly higher than that of the HC group (p = 0.006, d = 0.48)...(AU)

Crisis epilépticas sintomáticas agudas. Descripción clinicoelectroencefalográfica etiológica y pronóstico de una serie oncopediátrica / Acute symptomatic epileptic seizures. A clinical-electroencephalographic etiological description and prognosis of an oncopediatric series

Objetivo Determinar las características clínicas, electroencefalográficas, terapéuticas y evolutivas de una serie de pacientes oncopediátricos con convulsiones sintomáticas agudas. Pacientes y métodos Efectuamos un análisis descriptivo retrospectivo y prospectivo de registros clínicos de niños oncopediátricos evaluados por neurología en el Centro Ambulatorio Integral de Pacientes Hematooncológicos durante 2017-2021. Incluimos a niños de 1 mes a 17 años con tumores intracraneales y extracraneales que presentaron convulsiones sintomáticas agudas (CSA). Definimos convulsión sintomática aguda según la clasificación de la Liga Internacional contra la Epilepsia de 2010. Clasificamos las crisis epilépticas según la clasificación de la Liga Internacional contra la Epilepsia de 2017. Excluimos a todo paciente con diagnóstico de epilepsia previa y de episodios paroxísticos no epilépticos. Resultados Analizamos 44 casos, con una mediana de 4 años (rango: 1 mes-17 años) y una media de 5,75 meses (rango: 1 mes-11 meses) y 8,33 años (2-17 años). Registramos como principales etiologías la neurotoxicidad y el contexto posquirúrgico, con cuatro pacientes asociados a disnatremias y dos a hipertensión endocraneana. Se realizaron 41 electroencefalogramas, con resultados intercríticos con anormalidades en el ritmo de base, pero sin focos ni paroxismos. No hubo registros críticos. Las convulsiones focales fueron 25 (56,8%), y las generalizadas, 19 (43,18%). El levetiracetam fue el fármaco más utilizado para el tratamiento agudo. Conclusiones Nuestra cohorte muestra que las CSA, en esta población, no evidencian diferencias considerables entre convulsiones focales motoras y generalizadas, y ocurren mayormente en un contexto neurotóxico y posquirúrgico. También se registraron disnatremias e hipertensión endocraneana asociadas a CSA. Los electroencefalogramas poscrisis fueron sin focos o paroxismos y con evolución de las crisis. (AU)

AIM To determine clinical, electroencephalographic, therapeutic and evolutive characteristics of a series of oncopediatric patients with acute symptomatic seizures. PATIENTS AND METHODS We performed a retrospective and prospective descriptive analysis of clinical records of oncopediatric children evaluated by neurology at the comprehensive outpatient Center for Hemato-Oncological Patients during 2017-2021. We included children aged one month to 17 years with intracranial and extracranial tumors who presented with acute symptomatic seizure (ASC). We defined acute symptomatic seizure according to the 2010 International League Against Epilepsy. We classified seizures according to 2017 International League Against Epilepsy classification. We excluded any patient with a diagnosis of previous epilepsy and non-epileptic paroxysmal episodes. RESULTS We analyzed 44 cases with a median of 4 years (range: 1 month-17 years) and mean of 5.75 months (range: 1 month-11 months) and 8.33 years (2-17 years). The main etiologies were neurotoxicity and post-surgical context. Four patients presented dysnatremias and two associated with endocranial hypertension. Forty-one electroencephalograms were performed with intercritical results with abnormalities in the baseline rhythm, but without foci or paroxysms. There were no critical recordings. Focal seizures were 25 (56.8%) and generalized seizures 19 (43.18%). Levetiracetam was the most commonly used drug for acute management. CONCLUSIONS Our cohort shows that ASC, in this population, do not show considerable differences between focal motor and generalized seizures and occur mostly in neurotoxic and post-surgical contexts. Dysnatremias and endocranial hypertension associated with ASC were also recorded. Postcrisis electroencephalograms were without foci or paroxysms and good seizure evolution. (AU)

Implicaciones de iniciar fármacos antiepilépticos previo a la realización de EEG en primeras crisis epilépticas / Implications of initiating antiseizure drugs prior to the performance of EEG in first epileptic seizures

Introducción: Determinar si la administración de fármacos antiepilépticos (FAE) puede alterar la probabilidad de encontrar anomalías epileptiformes en EEG realizados de forma precoz tras una primera crisis epiléptica (CE). Método: Estudio observacional retrospectivo en el que se incluyó a los pacientes atendidos en urgencias de nuestro centro por una primera CE entre julio del 2014 y noviembre del 2019. Se recogieron los datos clínicos, las características técnicas de adquisición e interpretación de los EEG efectuados durante las primeras 72 h tras la CE y los factores relacionados con la recurrencia. Resultados: Se recogieron 155 pacientes; edad media 48,6 ±22,5 años; 61,3% hombres. El 51% presentó crisis tónico-clónicas de inicio desconocido y el 12% focales con progresión a tónico-clónica bilateral. El 25,2% (39/155) recibió tratamiento con FAE antes de la realización del EEG; en 33 pacientes se administró un FAE no benzodiacepínico y en 6 una benzodiacepina. Se observaron anomalías epileptiformes en 29,7% de los pacientes. La administración previa de FAE no se asoció de forma significativa ni con la probabilidad de detectar anomalías epileptiformes (p = 0,25) ni con el riesgo de recurrencia a los 6 meses (p = 0,63). Conclusiones: La administración de un FAE previo a la realización del EEG precoz tras una primera CE no disminuye la probabilidad de detectar anomalías epileptiformes. Estos hallazgos sugieren que iniciar un FAE de forma inmediata en aquellos pacientes con alto riesgo de recurrencia precoz no implica un menor rendimiento diagnóstico de dicha prueba.(AU)

Introduction: This study aimed to determine whether the administration of antiepileptic drugs (AED) alters the likelihood of detecting epileptiform abnormalities in electroencephalographies (EEG) performed early after a first epileptic seizure. Method: We performed a retrospective, observational study including patients with a first seizure attended at our centre's emergency department between July 2014 and November 2019. We collected clinical data, as well as technical data on the acquisition and interpretation of the EEG performed within the first 72 hours after the seizure, and the factors related with seizure recurrence. Results: We recruited 155 patients with a mean (SD) age of 48.6 (22.5) years; 61.3% were men. Regarding seizure type, 51% presented tonic-clonic seizures of unknown onset and 12% presented focal to bilateral tonic-clonic seizures. Thirty-nine patients (25.2%) received AED treatment before the EEG was performed: 33 received a non-benzodiazepine AED and 6 received a benzodiazepine. Epileptiform abnormalities were observed in 29.7% of patients. Previous administration of AEDs was not significantly associated with the probability of detecting interictal epileptiform abnormalities (P=.25) or with the risk of recurrence within 6 months (P=.63). Conclusions: Administration of AEDs before an early EEG following a first seizure does not decrease the likelihood of detecting epileptiform abnormalities. These findings suggest that starting AED treatment immediately in patients with a high risk of early recurrence does not imply a reduction in the diagnostic accuracy of the test.(AU)

The role of mindfulness on theta inter-brain synchrony during cooperation feedback processing: An EEG-based hyperscanning study

Mindfulness appears to improve empathy and understanding in relationships, which are necessary for successful cooperation. However, the impact of mindfulness on cooperation has not been fully studied. This study used hyperscanning technique to examine the effect of mindfulness on the inter-brain synchrony of interacting individuals during the cooperative tasks. Forty-one dyads were randomly assigned to a mindfulness group or a non-mindfulness group. Dyads of the mindfulness group performed a short mindfulness exercise following a 15-minute mindfulness audio guidance. Dyads of the non-mindfulness group were instructed to rest quietly with their eyes closed. Then, simultaneously and continuously EEG was recorded from all dyads when they completed a computer-based cooperative game task. Reaction times (RTs) and success rates were used to indicate the behavioral performance, and phase locking value (PLV) was used to indicate the inter-brain synchrony. The results showed that (1) Greater theta inter-brain synchrony during the cooperative computer game tasks was observed in the mindfulness group than in the non-mindfulness group; (2) Greater theta inter-brain synchrony was observed in the successful cooperation conditions as compared to those in the failure cooperation conditions; (3) Greater theta inter-brain synchrony was observed at the frontal region as compared to those at the parietal-occipital region in the successful cooperation condition. The results expand the neural basis of the effects of mindfulness on cooperation feedback processing. (AU)

Dysfunction of visual novelty detection in physical but not social anhedonia in a non-clinical sample

Background/objective: Despite its obvious motivational impairment, anhedonia as a transdiagnostic psychopathological construct is accompanied by deficits in attention function. Previous studies have identified voluntary attention anomalies in anhedonia, but its involuntary attention has received less study. Method: Using a visual novelty oddball task, the current event-related potential study assessed electrophysical correlates underlying mismatch detection in anhedonia with a non-clinical sample. Well-matched healthy control (N = 28; CNT), social anhedonia (N = 27; SA), and physical anhedonia (N = 26; PA) groups were presented standard, target, and perceptually novel stimuli while their EEG was recording. Results: The PA group relative to the CNT group exhibited a reduced N2 to novel stimuli but not to target stimuli. In contrast, the SA group as compared to the other two groups showed comparable N2 responses to both target and novel stimuli. Control analyses indicated that these patterns were unaffected by depression symptoms. Conclusions: These findings suggest that anhedonia is a heterogenous construct associated with impairments in early detection of visual novelty in physical but not social anhedonia, highlighting that dysfunction in involuntary attention may play a mediating role in the development, maintenance, and consequences of anhedonia-related psychopathology. (AU)

The effect of HD-tDCS on brain oscillations and frontal synchronicity during resting-state EEG in violent offenders with a substance dependence

Violence is a major problem in our society and therefore research into the neural underpinnings of aggression has grown exponentially. Although in the past decade the biological underpinnings of aggressive behavior have been examined, research on neural oscillations in violent offenders during resting-state electroencephalography (rsEEG) remains scarce. In this study we aimed to investigate the effect of high-definition transcranial direct current stimulation (HD-tDCS) on frontal theta, alpha and beta frequency power, asymmetrical frontal activity, and frontal synchronicity in violent offenders.Fifty male violent forensic patients diagnosed with a substance dependence were included in a double-blind sham-controlled randomized study. The patients received 20 minutes of HD-tDCS two times a day on five consecutive days. Before and after the intervention, the patients underwent a rsEEG task.Results showed no effect of HD-tDCS on the power in the different frequency bands. Also, no increase in asymmetrical activity was found. However, we found increased synchronicity in frontal regions in the alpha and beta frequency bands indicating enhanced connectivity in frontal brain regions as a result of the HD-tDCS-intervention.This study has enhanced our understanding of the neural underpinnings of aggression and violence, pointing to the importance of alpha and beta frequency bands and their connectivity in frontal brain regions. Although future studies should further investigate the complex neural underpinnings of aggression in different populations and using whole-brain connectivity, it can be suggested with caution, that HD-tDCS could be an innovative method to regain frontal synchronicity in neurorehabilitation. (AU)

Transcutaneous vagal nerve stimulation to treat disorders of consciousness: Protocol for a double-blind randomized controlled trial

Background: Patients with disorders of consciousness (DoC) are a challenging population prone to misdiagnosis with limited effective treatment options. Among neuromodulation techniques, transcutaneous auricular vagal nerve stimulation (taVNS) may act through a bottom-up manner to modulate thalamo-cortical connectivity and promote patients’ recovery. In this clinical trial, we aim to (1) assess the therapeutic clinical effects of taVNS in patients with DoC; (2) investigate the neural mechanisms underlying the effects of its action; (3) assess the feasibility and safety of the procedure in this challenging population; (4) define the phenotype of clinical responders; and (5) assess the long-term efficacy of taVNS in terms of functional outcomes. Methods: We will conduct a prospective parallel randomized controlled double-blind clinical trial investigating the effects of taVNS as a treatment in DoC patients. Forty-four patients in the early period post-injury (7 to 90 days following the injury) will randomly receive 5 days of either active bilateral vagal stimulation (45 min duration with 30s alternative episodes of active/rest periods; 3mA; 200-300μs current width, 25Hz.) or sham stimulation. Behavioural (i.e., Coma Recovery Scale-Revised, CRS-R) and neurophysiological (i.e., high-density electroencephalography, hd-EEG) measures will be collected at baseline and at the end of the 5-day treatment. Analyses will seek for changes in the CRS-R and the EEG metrics (e.g., alpha band power spectrum, functional connectivity) at the group and individual (i.e., responders) levels. Discussion: These results will allow us to investigate the vagal afferent network and will contribute towards a definition of the role of taVNS for the treatment of patients with DoC. We aim to identify the neural correlates of its action and pave the way to novel targeted therapeutic strategies. (AU)

Concurrent TMS-EEG and EEG reveal neuroplastic and oscillatory changes associated with self-compassion and negative emotions

BacSelf-compassionSocial rejectionTheta burst stimulationTMS-EEGConnectivitykground/Objective: Self-compassion has a consensual relevance for overall mental health, but its mechanisms remain unknown. Using intermittent theta burst stimulation (iTBS) and concurrent transcranial magnetic stimulation-electroencephalography (TMS-EEG), this study investigated the causal relationship of the dorsolateral prefrontal cortex (DLPFC) with self-compassion and explored the changes in neuroplasticity and neural dynamics. Method: Thirty-two healthy participants received iTBS or sham stimulation over the DLPFC, before and after which they were instructed to either use self-compassionate strategies or to be rejected in the context of social rejection and to report the level of self-compassion or negative affect. TMS-evoked potentials were evaluated as novel neuroplastic techniques with N45, P60, N100, and P180. Results: iTBS uniquely decreased P180 amplitude measured with TMS-EEG whereby sham stimulation had no effect on neuroplasticity. In line with neuroplasticity changes, iTBS enhanced a widespread gamma band power and coherence, which correlated consistently with increased engagement in self-compassion. Meanwhile, iTBS demonstrated opposite effects on theta activity dependent on the social contexts whereby self-compassion decreased and social rejection enhanced it respectively. This unique effect of iTBS on theta activity was also supplemented by the enhancement of theta band coherence following iTBS. Conclusions: We found a causal relationship between DLPFC and self-compassion. We also provide evidence to indicate widespread gamma activity and connectivity to correlate with self-compassion as well as the critical role of the DLPFC in modulating theta activity and negative emotions. (AU)

Recomendaciones para el empleo de técnicas neurofisiológicas en el diagnóstico de muerte encefálica de la Sociedad de Neurofisiología Clínica de las Comunidades de Valencia y Murcia / Recommendations for the use of neurophysiological techniques in the diagnosis of brain death from the Clinical Neurophysiology Society of the Communities of Valencia and Murcia

En España, el trasplante de órganos constituye uno de los mayores retos y trabajo en equipo de los centros hospitalarios. Se estima que en 2020 España aportó a la Unión Europea el 19% de la totalidad de los donantes. El diagnóstico de apoyo confirmatorio recomienda por ley algunas técnicas complementarias en determinados casos, entre ellas las técnicas neurofisiológicas, en especial el uso del electroencefalograma y los potenciales evocados. Estos casos plantean al neurofisiólogo clínico la toma acertada de decisiones tanto clínicas como técnicas para su correcta realización e interpretación. Hasta ahora no existe a nivel nacional un consenso de realización de estas técnicas. Es una revisión bibliográfica actualizada sobre las técnicas neurofisiológicas (electroencefalograma y potenciales evocados), con análisis mediante método Delphi y juicio de expertos del grupo de trabajo de la Sociedad de Neurofisiología Clínica de las Comunidades de Valencia y Murcia. Las técnicas neurofisiológicas permiten ser un apoyo en el diagnóstico de muerte encefálica, tanto de forma confirmatoria como para acortar tiempos de observación. Para su realización se precisan unos mínimos estándares técnicos que permitan realizar de forma óptima los estudios. Especialmente hay que tener en cuenta la medicación, la situación hemodinámica, la ausencia de hipotermia y el grupo de edad. Presentamos la primera guía en castellano elaborada por la Sociedad de Neurofisiología de las Comunidades de Valencia y Murcia para la realización en nuestros hospitales de las técnicas neurofisiológicas en el diagnóstico de muerte encefálica.(AU)

In Spain organ transplantation constitutes one of the greatest challenges and teamwork of hospital centres. It is estimated that in the year 2020 Spain contributed 19% of all donors to the European Union. The confirmatory support diagnosis recommends by law some complementary techniques in certain cases, including neurophysiological techniques, especially the use of electroencephalogram and evoked potentials. These cases require the clinical neurophysiologist to make the right clinical and technical decisions for the correct performance and interpretation of the same. To date, there is no national consensus on the performance of these techniques. Updated bibliographic review on neurophysiological techniques (electroencephalogram and evoked potentials). Analysis by Delphi method and expert judgment of the working group of the Clinical Neurophysiology Society of the Communities of Valencia and Murcia. Neurophysiological techniques can be a support in the diagnosis of encephalic death, both confirmatory and to shorten observation times. In order to perform them, minimum technical standards are required to allow optimal performance of the studies, especially taking into account medication, hemodynamic situation, absence of hypothermia, and age group. We present the first guide in Spanish elaborated by the Society of Neurophysiology of the Communities of Valencia and Murcia for the performance in our hospitals of neurophysiological techniques in the diagnosis of brain death.(AU)

State of the art and new directions of Quantitative Electroencephalography use in Differential Diagnosis of ADHD / Estado de la cuestión y uso de la electroencefalografía cuantitativa en el diagnóstico diferencial del TDAH

Advances in technology in recent years have made the use of quantitative electroencephalogram more accessible to clinicians. The incorporation ofnormative databases in QEEG studies and the possibility of detecting different electroencephalographic patterns in patients with a given pathology,despite showing an apparent symptomatology homogeneity, make it an interesting source of information. The relationship of these patterns with apossible response to treatment or with prognostic estimates would justify its inclusion as a routine test in the process of the differential diagnosisof ADHD. In this paper, we present the possible benefits of the use of QEEG in the differential diagnosis of ADHD, the different electroencephalographic patterns associated with ADHD most common in the literature, and a case showcasing the use of the technique in a patient with ADHD. (AU)

El avance de la tecnología en los últimos años ha hecho que el uso del electroencefalograma cuantitativo sea más accesible a los clínicos. La incorporación de bases de datos normativas enlos estudios de QEEG y la posibilidad de detectar diferentes patrones electroencefalográficos en pacientes con una patología determinada, a pesarde mostrar una aparente homogeneidad sintomatológica, hacen que sea una fuente de información interesante. La relación de estos patrones conuna posible respuesta a tratamientos o con estimaciones pronósticas justificarían su inclusión como prueba rutinaria en el proceso de diagnósticodiferencial del TDAH. En este trabajo se presentan los posibles beneficios del uso del QEEG en el diagnóstico diferencial del TDAH, los diferentespatrones electroencefalográficos asociados al TDAH más comunes en la literatura y un caso ilustrativo del uso de la técnica en un paciente con TDAH. (AU)

Programa ADAPTATEA para mejorar la atención de niños y niñas con autismo en la realización de un electroencefalograma / The adaptatea program to improve care for children with autism undergoing an electroencephalogram

Las dificultades socio-comunicativas que presentan los/as niños/as con trastorno del espectro autista (TEA), y las barreras del entorno sanitario, pueden complicar las pruebas diagnósticas y las intervenciones sanitarias hasta el punto de no poder realizarse. Pueden darse momentos muy complicados para estos niños/as y sus familias, que son vividos con gran ansiedad generándoles gran hostilidad hacia el entorno sanitario. A su vez, los profesionales se ven desbordados e impotentes ante estas situaciones, aumentando los recursos humanos y el tiempo necesarios para atenderles. El personal de Enfermería tiene un papel fundamental en la identificación de las dificultades y barreras, tanto las que presentan los/as niños/as y sus familias, como las del propio personal sanitario implicado, pudiendo actuar como facilitadores desde el primer momento.El Servicio de Neurofisiología realiza electroencefalogramas (EEG) a pacientes con TEA, ya que la epilepsia es un problema frecuentemente asociado al mismo. Las dificultades para efectuar con éxito la prueba han llevado a la creación del programa ADAPTATEA, cuyo objetivo general es mejorar la calidad de la atención y conseguir realizar el EEG en las mejores condiciones posibles, llevando a cabo las adaptaciones sanitarias necesarias. Se basa en el empleo de pictogramas y material audiovisual cuyo objetivo es anticipar al niño o niña y familia lo que se les va a hacer, transformando la prueba en algo más cercano y cotidiano para ellos. Además, propone recomendaciones para la preparación, ejecución de la prueba, y para el mejor manejo de las conductas desadaptativas del niño/a cuando acude al hospital.(AU)

The socio-communicative difficulties presented by children with autism spectrum disorder (ASD) and the healthcare environment barriers can complicate diagnostic tests and healthcare interventions even to the point where these cannot be performed. These can lead to very difficult times for these children and their families, experienced with high anxiety and generating major hostility towards the healthcare environment. At the same time, professionals will feel overwhelmed and powerless when faced with these situations, which require an increase in human resources and time. The Nursing staff plays an essential role in the detection of these difficulties and barriers, presented both by children and their families and by the healthcare staff involved, and they can act as facilitators since the first minute.The Neurophysiology Unit performs electroencephalograms (EEG) to ASD patients, because epilepsy is a problem often associated with this disorder. The difficulties to perform this test successfully have led to the creation of the ADAPTATEA program, with the overall objective to improve the quality of care and being able to perform the EEG in the best possible conditions, by conducting the healthcare adaptations required. This is based on the use of pictograms and audiovisual materials targeted to explaining the child and his/her family what will be done and transforming the test into something closer and more common to them. Besides, it proposes recommendations for the preparation and performance of the test, and for the best management of the maladaptive behaviours of the child when attending hospital.(AU)

Estereoelectroencefalografía en la evaluación prequirúrgica de epilepsias focales refractarias: experiencia de un centro de epilepsia / Stereoelectroencephalography in the preoperative assessment of patients with refractory focal epilepsy: Experience at an epilepsy centre

Objetivo: La estereoelectroencefalografía (E-EEG) es una técnica de evaluación prequirúrgica en pacientes con epilepsia focal refractaria de difícil localización (EFRDL) que permite explorar con electrodos profundos regiones cerebrales de difícil acceso y la profundidad de la corteza. Esta técnica, en auge en centros internacionales, apenas se ha desarrollado en España. Describimos nuestra experiencia con la E-EEG en la evaluación de pacientes con EFRDL. Material y métodos: En los últimos 8 años, 71 pacientes con EFRDL fueron evaluados con E-EEG en nuestro centro. Analizamos prospectivamente los resultados obtenidos en la localización, los resultados quirúrgicos y las complicaciones asociadas a la técnica. Resultados: La mediana de edad fue de 30 años (rango 4-59 años), 27 pacientes eran mujeres (38%). La RM cerebral fue negativa en 45 pacientes (63,4%). Se implantaron 627 electrodos (mediana de 9 electrodos por paciente, rango 1-17), con un 50% de implantaciones multilobares. En 64 (90,1%) pacientes se localizó la zona epileptógena (ZE), siendo extratemporal o temporal plus en el 66% de los casos. En 55 pacientes de los 61 intervenidos el seguimiento fue superior al año: en el último año de seguimiento 32/55 pacientes (58,2%) estaban libres de crisis (Engel I) siendo los resultados favorables (Engel I-II) en el 76,4% de las intervenciones. Tres pacientes (4,2%) presentaron una hemorragia cerebral. Conclusión: La E-EEG permite localizar la ZE en pacientes en quienes anteriormente no era posible, ofreciendo unos resultados quirúrgicos superiores a otras técnicas invasivas y una tasa de complicaciones relativamente baja. (AU)

Objective: Stereoelectroencephalography (SEEG) is a technique for preoperative evaluation of patients with difficult-to-localise refractory focal epilepsy (DLRFE), enabling the study of deep cortical structures. The procedure, which is increasingly used in international epilepsy centres, has not been fully developed in Spain. We describe our experience with SEEG in the preoperative evaluation of DLRFE. Material and methods: In the last 8 years, 71 patients with DLRFE were evaluated with SEEG in our epilepsy centre. We prospectively analysed our results in terms of localisation of the epileptogenic zone (EZ), surgical outcomes, and complications associated with the procedure. Results: The median age of the sample was 30 years (range, 4-59 years); 27 patients (38%) were women. Forty-five patients (63.4%) showed no abnormalities on brain MR images. A total of 627 electrodes were implanted (median, 9 electrodes per patient; range, 1-17), and 50% of implantations were multilobar. The EZ was identified in 64 patients (90.1%), and was extratemporal or temporal plus in 66% of the cases. Follow-up was over one year in 55 of the 61 patients undergoing surgery: in the last year of follow-up, 58.2% were seizure-free (Engel Epilepsy Surgery Outcome Scale class I) and 76.4% had good outcomes (Engel I-II). Three patients (4.2%) presented brain haemorrhages. Conclusion: SEEG enables localisation of the EZ in patients in whom this was previously impossible, offering better surgical outcomes than other invasive techniques while having a relatively low rate of complications. (AU)