Noninvasive multimodal neuroimaging for Rasmussen encephalopathy surgery: simultaneous EEG-fMRI recording.

Rasmussen syndrome is characterized by continuous partial seizures with progressive neurological/cognitive impairment. Currently the only effective treatment is surgery (hemispherectomy). The objective of our study is to detect the exact epileptogenic focus through the analysis of multimodal noninvasive and innocuous functional neuroimaging. The subject is a 5-year-old female patient with Rasmussen encephalopathy. Continuous and simultaneous electroencephalography-functional magnetic resonance imaging (EEG-fMRI) was recorded. The sources of background and paroxysmal activity of EEG were computed by low resolution electromagnetic tomography (LORETA). Image analysis (SPM: statistic parametric mapping) was obtained for the areas where statistically significant differences in the fMRI BOLD response were computed, and the results from both techniques were compared. The main source of paroxysmal activity by EEG analysis was found in the anterolateral left hemisphere, with a significant increase in absolute and relative energies of slow frequency bands (theta-delta): Z > or = 3. The fMRI BOLD signal (basal vs. paroxysmal activity) was significantly different in the same region (t-test > or = 2.39). The generators of propagated paroxysmal activity were found in similar areas for both techniques. In conclusion, simultaneous EEG-fMRI recording allows the analysis of two harmless functional neuroimaging techniques separately and together in the same time period. In our case, it allowed the accurate delineation of epileptogenic foci and areas of spread with high spatiotemporal resolution, which is crucial for epilepsy surgery.

[Event-related potentials and the diagnosis of short-term verbal memory disorders in cerebrovascular disease]. / Potenciales relacionados con eventos y diagnóstico de las alteraciones de memoria verbal a corto plazo en la enfermedad cerebrovascular.

INTRODUCTION: Cerebrovascular disease can cause different memory disorders depending on the area of the brain involved. More specifically, ischemic lesions in the frontal region can be associated to short-term verbal memory disorders. PATIENTS AND METHODS: Two groups of subjects were studied, 10 of whom were patients who presented a frontal cerebral infarction and 10 healthy controls. They were administered a memory task involving word recognition. While they were performing the task the electrical activity of their brains was recorded in order to examine event-related potentials (ERP). RESULTS: The patients' performance of the task was poorer than that of the healthy control subjects. Likewise, while the latter displayed a predominantly frontal distribution of ERPs, in the patients the frontal activity diminished and was seen to be chiefly temporoparietooccipital. CONCLUSIONS: These findings allow important conclusions to be drawn about the characteristics of the memory disorder presented by these patients.

Potenciales relacionados con eventos y diagnóstico de las alteraciones de memoria verbal a corto plazo en la enfermedad cerebrovascular / Event-related potentials and the diagnosis of short-term verbal memory disorders in cerebrovascular disease

Cerebrovascular disease can cause different memory disorders depending on the area of the brain involved. More specifically, ischemic lesions in the frontal region can be associated to short-term verbal memory disorders. Two groups of subjects were studied, 10 of whom were patients who presented a frontal cerebral infarction and 10 healthy controls. They were administered a memory task involving word recognition. While they were performing the task the electrical activity of their brains was recorded in order to examine event-related potentials (ERP). The patients' performance of the task was poorer than that of the healthy control subjects. Likewise, while the latter displayed a predominantly frontal distribution of ERPs, in the patients the frontal activity diminished and was seen to be chiefly temporoparietooccipital. These findings allow important conclusions to be drawn about the characteristics of the memory disorder presented by these patients(AU)

Potenciales relacionados con eventos y diagnóstico de las alteraciones de la memoria verbal a corto plazo en la enfermedad cerebrovascular / Event-related potentials and the diagnosis of short-term verbal memory disorders in cerebrovascular disease

Introducción. La enfermedad cerebrovascular puede causar alteraciones de la memoria diferentes en función del área cerebral afectada. Las lesiones isquémicas en la región frontal pueden asociarse a alteraciones de la memoria verbal a corto plazo, específicamente. Pacientes y métodos. Se estudiaron dos grupos de sujetos, 10 de ellos pacientes que presentaban un infarto cerebral frontal, y 10 controles sanos. Se les aplicó una tarea de memoria de reconocimiento de palabras. Durante su realización se recogió la actividad eléctrica cerebral para el registro de los potenciales relacionados con eventos (PRE). Resultados. Los pacientes tuvieron una ejecución deficitaria en la tarea en comparación con los controles sanos. Igualmente, mientras éstos mostraban una distribución predominantemente frontal de los PRE, en los pacientes la activación frontal disminuía y era de preferencia temporoparietoccipital. Conclusiones. Estos resultados permiten extraer importantes conclusiones sobre las características de la alteración de la memoria presentada por los pacientes (AU)

Introduction. Cerebrovascular disease can cause different memory disorders depending on the area of the brain involved. More specifically, ischemic lesions in the frontal region can be associated to short-term verbal memory disorders. Patients and methods. Two groups of subjects were studied, 10 of whom were patients who presented a frontal cerebral infarction and 10 healthy controls. They were administered a memory task involving word recognition. While they were performing the task the electrical activity of their brains was recorded in order to examine event-related potentials (ERP). Results. The patients’ performance of the task was poorer than that of the healthy control subjects. Likewise, while the latter displayed a predominantly frontal distribution of ERPs, in the patients the frontal activity diminished and was seen to be chiefly temporoparietooccipital. Conclusions. These findings allow important conclusions to be drawn about the characteristics of the memory disorder presented by these patients (AU)

[Cognitive diagnosis of cerebrovascular disease by event related potentials: anatomical sources that generate P300]. / Diagnóstico cognitivo en la enfermedad cerebrovascular mediante potenciales relacionados con eventos: fuentes anatómicas generadoras de la P300.

INTRODUCTION: Cerebrovascular disease causes different cognitive alterations. There is a need to develop tools that are capable of diagnosing them. One of them could be event related potentials. These provide an indicator of cognitive processing in real time. PATIENTS AND METHODS: A study was conducted of 10 patients with cerebral infarction in the frontal region and 10 paired healthy controls. Evaluation of the patients was performed a week after the stroke. A continuous performance test was applied to both groups together with the recording of the electrical activity in the brain in order to obtain the P300 component. The results were submitted to the non-parametric Student's t test, and the Bayesian model averaging method (BMAM) was employed to calculate the sources generating the electrical activity recorded on the electroencephalogram. RESULTS: Patients displayed significantly poorer performances compared to the healthy controls in the attention test. The BMAM showed that the P300 component was related to the right hand temporal structures in healthy controls, whereas the left temporoparietal regions were also involved in the patients. CONCLUSIONS: These findings indicate the existence of subclinical disorders affecting sustained attention and that they can only be detected by very sensitive tools; furthermore, they also have implications for the brain circuits regulating sustained attention and the P300 component.

Diagnóstico cognitivo en la enfermedad cerebrovascular mediante potenciales relacionados con eventos: fuentes anatómicas generadoras de la P300 / Cognitive diagnosis of cerebrovascular disease by event-related potentials: anatomical sources that generate p300

Introducción. La enfermedad cerebrovascular causa alteraciones cognitivas disímiles. Es preciso desarrollar herramientas capaces de diagnosticarlas, y una de ellas podría ser los potenciales relacionados con eventos. Éstos brindan un indicador en tiempo real del procesamiento cognitivo. Pacientes y métodos. Se estudiaron 10 pacientes con infarto cerebral en la región frontal y 10 controles sanos pareados. La evaluación de los pacientes se realizó una semana después de presentar el infarto. A ambos grupos se les aplicó un test de ejecución continua asociado al registro de la actividad eléctrica cerebral para la obtención del componente P300. Los resultados obtenidos se sometieron a la prueba no paramétrica t de Student, y el electroencefalograma, al método de promediación de modelos bayesianos (MPMB) para el cálculo de las fuentes generadoras de la actividad eléctrica registrada. Resultados. Los pacientes tuvieron ejecuciones significativamente más pobres que los controles sanos en la prueba de atención. El MPMB mostró que el componente P300 se relaciona con las estructuras temporales derechas en los controles sanos, mientras que en los pacientes se suman las zonas temporoparietales izquierdas. Conclusiones. Estos resultados indican la existencia de alteraciones subclínicas de la atención sostenida, y que sólo herramientas más sensibles pueden detectarlas; además, tienen implicaciones para los circuitos cerebrales reguladores de la atención sostenida y del componente P300 (AU)

Introduction. Cerebrovascular disease causes different cognitive alterations. There is a need to develop tools that are capable of diagnosing them. One of them could be event-related potentials. These provide an indicator of cognitive processing in real time. Patients and methods. A study was conducted of 10 patients with cerebral infarction in the frontal region and 10 paired healthy controls. Evaluation of the patients was performed a week after the stroke. A continuous performance test was applied to both groups together with the recording of the electrical activity in the brain in order to obtain the P300 component. The results were submitted to the non-parametric Student’s t test, and the Bayesian model averaging method (BMAM) was employed to calculate the sources generating the electrical activity recorded on the electroencephalogram. Results. Patients displayed significantly poorer performances compared to the healthy controls in the attention test. The BMAM showed that the P300 component was related to the right-hand temporal structures in healthy controls, whereas the left temporoparietal regions were also involved in the patients. Conclusions. These findings indicate the existence of subclinical disorders affecting sustained attention and that they can only be detected by very sensitive tools; furthermore, they also have implications for the brain circuits regulating sustained attention and the P300 component (AU)