Extrahippocampal desynchronization in nonlesional temporal lobe epilepsy.

Although temporal lobe epilepsy (TLE) is traditionally associated with both hypersynchronous activity in the form of interictal epileptic discharges and hippocampal sclerosis, recent findings suggest that desynchronization also plays a central role in the dynamics of this pathology. The objective of this work is to show the imbalance existing between mesial activities in patients suffering from mesial TLE, with normal mesial structures. Foramen ovale recordings from six patients with mesial TLE and one with lateral TLE were analyzed through a cluster analysis and synchronization matrices. None of the patients present findings in the MRI presurgical evaluation. Numerical analysis was carried out in three different situations: awake and sleep interictal and also during the preictal stage. High levels of desynchronization ipsilateral to the epileptic side were present in mesial TLE patients. Low levels of desynchronization were present in the lateral TLE patient during the interictal stage and almost zero in the preictal stage. Implications of these findings in relation with seizure spreading are discussed.

Estimulación cerebral profunda para la epilepsia resistente: dianas extratalámicas / Deep brain stimulation for refractory epilepsy: extrathalamic targets

La epilepsia es un trastorno neurológico que afecta a alrededor de un 1-2% de la población. Se han desarrollado diversas estrategias terapéuticas, útiles para el control de las crisis en la mayoría de los casos. A pesar del gran desarrollo de fármacos antiepilépticos, de la posibilidad de resección de los focos epileptógenos en pacientes seleccionados y de la estimulación vagal, existe un subgrupo de pacientes con mal control de sus crisis, para los que se están llevando a cabo diversas líneas de investigación en busca de nuevas alternativas de tratamiento. La estimulación cerebral profunda del tálamo ha surgido como otra posibilidad terapéutica para pacientes que permanecen incapacitados; su utilidad es objeto de varios estudios, y aún no se ha establecido su eficacia y seguridad con suficiente evidencia científica. Existen otras dianas susceptibles de estimulación cerebral profunda como tratamiento para la epilepsia resistente. Los experimentos con modelos animales y estudios preliminares en humanos han mostrado resultados esperanzadores con estimulación cerebral profunda en el cerebelo, núcleo subtalámico, sustancia negra, hipocampo y corteza cerebral, entre otros. A continuación se muestran los estudios realizados en núcleos cerebrales extratalámicos que mostraron eficacia en la epilepsia farmacorresistente. Los estudios han mostrado distintos grados de efectividad, y es preciso realizar ensayos controlados para establecer conclusiones definitivas sobre su eficacia (AU)

Epilepsy is a neurological disorder that affects 1-2% of the population. The majority of epileptic patients achieve a good seizure control with the current available treatments. However, there is a subgroup of patients that remain severely disable despite the variety of anti-epileptic drugs, the possibility of surgery for resection of the epileptogenic foci in selected patients, and vagal nerve stimulation; various lines of research are being carried out to look for new treatment alternatives.Deep brain stimulation (DBS) of the thalamus has emerged as a therapeutic alternative for patients who remain incapacitated; the efficacy of this new therapy is subject of several studies, and its effectiveness and safety has not been established yet. There are other targets for deep brain stimulation that may be useful for drug-resistant epilepsy. Experiments with animal models and preliminary human studies have shown encouraging results with DBS on cerebellum, subthalamic nucleus, substantia nigra, hippocampus and cerebral cortex, among others. The purpose of this review is to revisit the studies that have been carried out on these brain nuclei, as targets for DBS for drug-resistant epilepsy. Studies have shown varying degrees of effectiveness, and there is a need for controlled trials to draw any definite conclusions (AU)

[Thalamic deep brain stimulation for refractory epilepsy]. / Estimulación cerebral profunda talámica para la epilepsia resistente.

Epilepsy is a neurological disorder that affects 1-2% of the population. Despite the available treatments (drug therapy, resective surgery, vagus nerve stimulation), there is a significant subgroup of patients that continues to have disabling seizures. The indications of deep brain stimulation are exponentially growing, and there is a wide experience with deep brain stimulation (DBS) for the treatment of abnormal movements. DBS for epilepsy may be a new therapy for the subgroup of patients that remain disabled despite other treatments. Experiments with animal models, and the new advances in our knowledge about the neurophysiological processes that govern the genesis of epilepsy, have led to the selection of various brain targets for stimulation. The thalamus is a fundamental relay centre in the corticothalamic and corticostriatal thalamocortical circuits, and it has been studied with this purpose. Studies on epileptic patients have shown various degrees of effectiveness; however, controlled studies do not permit definitive conclusions about the role of DBS in the treatment of epilepsy. Probably a better patient selection would lead to more decisive conclusions. Further randomised studies are needed to draw reliable conclusions and scientific evidence on the effectiveness of DBS for refractory epilepsy.

Estimulación cerebral profunda talámica para la epilepsia resistente / Thalamic deep brain stimulation for refractory epilepsy

Resumen. La epilepsia es un trastorno neurológico que afecta al 1-2% de la población. A pesar de los tratamientos disponibles (farmacoterapia, cirugía resectiva, estimulación del nervio vago...), hay un subgrupo importante de pacientes que continúa teniendo crisis incapacitantes. La estimulación cerebral profunda está experimentando un incremento exponencial de sus indicaciones y se dispone de experiencia amplia en el campo de los movimientos anormales. El tratamiento de la epilepsia mediante estimulación cerebral profunda podría ser una nueva terapia aplicable al subgrupo de pacientes resistentes a otros tratamientos. Los experimentos con modelos animales, y el avance en los conocimientos neurofisiológicos de los procesos que gobiernan la génesis de la epilepsia, han dado pie a la selección de diversas dianas cerebrales para la estimulación. El tálamo, por ser un centro fundamental de relevo en los circuitos corticotalámicos y corticoestriadotalamocorticales, ha sido objeto de estudio con esta finalidad. Los estudios realizados en pacientes epilépticos han tenido distintos grados de efectividad, si bien los estudios controlados no permiten conclusiones definitivas sobre cuál es su papel en el tratamiento de la epilepsia. Probablemente la selección de pacientes más adecuada favorezca la realización de estudios con conclusiones más determinantes. Es preciso realizar más estudios aleatorizados controlados para extraer conclusiones fidedignas y evidencia científica sobre su eficacia (AU)

Summary. Epilepsy is a neurological disorder that affects 1-2% of the population. Despite the available treatments (drug therapy, resective surgery, vagus nerve stimulation), there is a significant subgroup of patients that continues to have disabling seizures. The indications of deep brain stimulation are exponentially growing, and there is a wide experience with deep brain stimulation (DBS) for the treatment of abnormal movements. DBS for epilepsy may be a new therapy for the subgroup of patients that remain disabled despite other treatments. Experiments with animal models, and the newadvances in our knowledge about the neurophysiological processes that govern the genesis of epilepsy, have led to the selection of various brain targets for stimulation. The thalamus is a fundamental relay centre in the corticothalamic and corticostriatal thalamocortical circuits, and it has been studied with this purpose. Studies on epileptic patients have shown various degrees of effectiveness; however, controlled studies do not permit definitive conclusions about the role of DBS in the treatment of epilepsy. Probably a better patient selection would lead to more decisive conclusions. Further randomised studies are needed to draw reliable conclusions and scientific evidence on the effectiveness of DBS for refractory epilepsy (AU)

Contribución diferencial de los estudios preoperatorios al diagnóstico en la cirugía de la epilepsia temporal / Differential contribution of preoperatory studies to diagnosis in temporal lobe epilepsy surgery

Introducción. Es preciso conocer el grado de confianza de las pruebas preoperatorias en epilepsia del lóbulo temporal (ELT). Objetivo. Analizar la importancia relativa de diferentes pruebas preoperatorias –videoelectroencefalograma (vEEG), electroencefalograma (EEG), tomografía computarizada por emisión de fotón único (SPECT) y resonancia magnética (RM)–, el grado de concordancia entre ellas y desarrollar un modelo probabilístico bayesiano para el diagnóstico. Pacientes y métodos. Se ha estudiado a 73 pacientes intervenidos de ELT, con un seguimiento postoperatorio mínimo de dos años. Para analizar la capacidad localizadora, se utilizan únicamente pacientes con un grado I de Engel durante todo el tiempo de seguimiento (n = 60). Resultados. Los porcentajes de los grados I, II, III y IV de Engel a los dos años fueron del 87,7, 8,2, 3,0 y 0%, respectivamente. La concordancia preoperatoria fue < 50% para tres pruebas y del 33% para las cuatro. Se encontraron estudios de RM normales en el 33,3% de los casos. Según el índice de localización, el orden es vEEG > RM > SPECT > EEG. La probabilidad condicional de obtener un grado I de Engel por prueba es: vEEG (0,950) > EEG (0,719) > SPECT (0,717) > RM (0,683). Para más de dos pruebas, la probabilidad condicional es ≤ 0,587 (vEEG + RM). La probabilidad de obtener un grado I de Engel a priori es vEEG (0,983) > RM (0,414) > EEG (0,285) > SPECT (0,209). El modelo bayesiano resulta ser muy sólido. Conclusiones. No siempre hay un alto grado de concordancia entre las pruebas, a pesar de lo cual puede obtenerse un buen resultado funcional. La prueba más eficaz es el vEEG (AU)

Introduction. It is necessary to know the degree of concordance of preoperative studies in temporal lobe epilepsy (TLE). Aim. To analyze the relative importance of different preoperative tests (vEEG, EEG, SPECT and MRI), the degree of agreement between them, and to develop a Bayesian probability model for diagnosis. Patients and methods. We analyzed 73 patients operated by TLE, with a minimum postoperative follow-up of two years. To analyze the localization capability of different test, we used only patients with an Engel’s grade I outcome during all the follow-up time (n = 60). Results. Engel’s grades percentages at 2 years were 87.7/8.2/3.0/0.0 (I/II/III/IV, respectively). The preoperative correlation was < 50% for three tests and 33% for the four. MRI studies were found normal in 33.3% of cases. According to the localization index, the arrange was vEEG > RM > SPECT > EEG. The conditional probability of correct localization for a test was vEEG (0.950) > EEG (0.719) > SPECT (0.717) > RM (0.683). Concordance for more than two tests, was ≤ 0.587 (vEEG + MRI). The probability of obtaining a priori correct localization was vEEG (0.983) > RM (0.414) > EEG (0.285) > SPECT (0.209). The Bayesian model is highly reliable. Conclusions. Probably it is not always possible to obtain a high degree of agreement among preoperative test, despite this, it is possible to obtain a good functional result. The most effective test is the vEEG (AU)

[Differential contribution of preoperatory studies to diagnosis in temporal lobe epilepsy surgery]. / Contribución diferencial de los estudios preoperatorios al diagnostico en la cirugia de la epilepsia temporal.

INTRODUCTION: It is necessary to know the degree of concordance of preoperative studies in temporal lobe epilepsy (TLE). AIM. To analyze the relative importance of different preoperative tests (vEEG, EEG, SPECT and MRI), the degree of agreement between them, and to develop a Bayesian probability model for diagnosis. PATIENTS AND METHODS: We analyzed 73 patients operated by TLE, with a minimum postoperative follow-up of two years. To analyze the localization capability of different test, we used only patients with an Engel's grade I outcome during all the follow-up time (n = 60). RESULTS: Engel's grades percentages at 2 years were 87.7/8.2/3.0/0.0 (I/II/III/IV, respectively). The preoperative correlation was < 50% for three tests and 33% for the four. MRI studies were found normal in 33.3% of cases. According to the localization index, the arrange was vEEG > RM > SPECT > EEG. The conditional probability of correct localization for a test was vEEG (0.950) > EEG (0.719) > SPECT (0.717) > RM (0.683). Concordance for more than two tests, was = 0.587 (vEEG + MRI). The probability of obtaining a priori correct localization was vEEG (0.983) > RM (0.414) > EEG (0.285) > SPECT (0.209). The Bayesian model is highly reliable. CONCLUSIONS: Probably it is not always possible to obtain a high degree of agreement among preoperative test, despite this, it is possible to obtain a good functional result. The most effective test is the vEEG.

Bioavailability of a heme-iron concentrate product added to chocolate biscuit filling in adolescent girls living in a rural area of Mexico.

A heme-iron concentrate product derived from swine hemoglobin was used to enrich the chocolate-flavored filling of biscuits and the bioavailability of this source of heme-iron was assessed in adolescent girls. The placebo control (PC) group consisted of 35 teenagers with the highest baseline hemoglobin concentrations. The supplemented groups were randomized to receive biscuits fortified with iron sulfate (IS, n = 37) or heme-iron concentrate (HIC, n = 40). Both groups were supplemented with 10.3 mg Fe/d for 7 wk. Blood chemistry and hematology analyses were performed at baseline and at the end of the study. The baseline prevalence of anemia (hemoglobin <12 g/dl) in the entire group was 3.9% and by the end of the study it had fallen to 2.3%. The hemoglobin levels in both supplemented groups increased (P < 0.05) during the study period from 13.6 and 13.5 g/dl for HIC and IS, respectively, at baseline to 14 g/dl at the end of the study. Serum ferritin concentrations decreased by the end of the study in both the PC and IS groups (P < 0.05), but not in the heme group. In conclusion, iron bioavailability from HIC-fortified biscuits was calculated to be 23.7% higher than that observed for IS, as shown by the differences observed in serum ferritin levels during the study. The iron contained in the heme-iron concentrate was well absorbed and tolerated by the adolescents included in the study.

Morbidity associated with the use of foramen ovale electrodes.

PURPOSE: The identification of the epileptic zone in patients with mesial temporal lobe epilepsy sometimes requires intracranial recordings, for example, with foramen ovale electrodes (FOE). This paper reviews and analyzes the resulting complications in a series of patients studied with bilateral FOE for presurgical evaluation. METHODS: The clinical records of 331 consecutive FOE implantations in 329 patients were reviewed. Complications related to FOE were divided into two groups: those that were non-life-threatening or not directly attributable to FOE, or life-threatening complications and those clearly related to FOE. RESULTS: The mean length of hospital stay in the v-EEG unit with FOE was 5.8 +/- 0.2 days (range 1-19) following a bimodal distribution (peaks at 4 and 8 days). Complications were observed in 6.64% of patients, but in 4.83% of cases, complications were non-life-threatening (moderate disaesthesia, cheek bleeding, FOE expulsion). Complications were only severe in 1.81% of patients (clotting or intracranial hemorrhage). One patient died more than 20 days after FOE removal and after several episodes of status epilepticus. Patients suffering from life-threatening complications were more likely to be female (83.3%) than patients experiencing no complications or non-life-threatening complications. Patients with life-threatening complications had a more prolonged stay in the v-EEG unit during monitoring with FOE (8.2 +/- 0.7; n = 6) than the group without complications (5.7 +/- 0.2; n = 309; p < 0.01; Kruskal-Wallis test). DISCUSSION: FOE is a reasonably safe intracranial technique for v-EEG monitoring with low rates of potentially severe complications, but its indication should be carefully evaluated, especially if monitoring for more than 8 days is expected.