Valor pronóstico de la electrocorticografía en la epilepsia temporal:patrones de la relación mesial y neocortical / Prognostic value of electrocorticography in temporal lobe epilepsy: patterns of relationing mesial and neocortical activity

Introducción. La monitorización electrocorticográfica (ECoG) en la epilepsia temporal (ET) se ha realizado desde los años 40 como medio para precisar la resección quirúrgica, especialmente en la epilepsia secundaria a lesiones, para reducir su tamaño y secuelas cognitivas (memoria, nominación). Sin embargo, se ha sugerido últimamente que la ECoG carece de indicación clara y de valor pronóstico en los casos de ET no secundaria a lesiones. Con base en la relación fisiopatológica entre estructuras mesiales y neocorticales (a través de posibles vías de propagación) se sugiere una clasificación de los patrones de actividad ECoG en función del registro simultáneo en las mantas mesial y neocortical.Pacientes y métodos. Se han revisado los registros de 33 (28 sin lesión) pacientes con ET consecutivos (incluyendo la monitorización vídeo-EEG con electrodos de foramen oval), de manera independiente, por dos neurofisiólogos con experiencia (más de 200 estudios realizados). El criterio principal ha sido el de la identificación de la actividad más precoz (líder), en área mesial o neocortical, y se ha relacionado con el curso clínico poscirugía. Resultados. Se identifican, así, cinco patrones: I. Mesial puro; II. Mesial con actividad neocortical relacionada; III. Actividad mesial y neocortical independiente; IV. Predominio neocortical (aunque se identifique alguna actividad mesial independiente), y V. Origen neocortical. En los 33 se ha realizado resección a medida en dos tiempos y guiada por ECoG. Se ha obtenido una asociación significativa (test de la ji al cuadrado) entre el éxito quirúrgico y los patrones I, II y IV. El patrón V supuso un mal pronóstico. Conclusiones. La ECoG refleja el estado de afectación anatomopatológica de las estructuras mesiales y neocorticales. Un enfoque experto, si bien en un tiempo breve, permite respetar el tejido con relevancia funcional y establecer un pronóstico en función de la actividad epileptógena inicial (AU)

Changes in the colocalization of glutamate ionotropic receptor subunits in the human epileptic temporal lobe cortex.

Double-labeling immunocytochemical techniques and confocal microscopy were used to quantify possible differences in the degree of colocalization of glutamate ionotropic receptor subunits between non-spiking and spiking neocortex removed from temporal lobe epileptic patients. Spiking neocortex was characterized by laminar-specific changes in the number of cells immunoreactive for NMDAR1, GluR2/3 and GluR5/6/7 subunits, as well as the percentage of cells which colocalized various combinations of these receptors. These changes may lead to profound modifications in the functioning of excitatory synaptic circuits in spiking cortex.

[Cerebral perfusion during word repetition in epileptic patients]. / Perfusión cerebral durante la repetición de palabras en pacientes epilépticos.

OBJECTIVE: To localize the cortical regions for language in patients who are to have brain surgery. PATIENTS AND METHODS: We made a SPECT (Single Photon Emission using Computerized Tomography) study of cerebral perfusion in 14 patients with drug-resistant temporal epilepsy who were candidates for brain surgery. The patients were selected consecutively from those attending for surgical assessment. We selected the patients in whom two 99mTc-HMPAO studies could be done in the same week: one without sensory stimulation and one whilst listening and repeating a series of ordinary words in fairly frequent use. The two studies were assessed qualitatively (on a 16 colour image scale, with a background subtraction of 20% and standardized to the point of maximum uptake). Changes were considered to be significant when a greater intensity of two colours was localized and semiquantitative (with regular areas of interest, of 4 x 4 pixels, placed on the region in which the qualitative change was observed and referenced to cerebellar activity). RESULTS: We found increased perfusion in the temporo-parietal regions in 11 of the 14 patients. In most (9/14 cases) this was bilateral and in two cases on the left only. We observed a certain predominant pattern: a bilateral increase in temporal perfusion, involving the more anterior regions of the left hemisphere and also the middle and posterior regions of the right hemisphere. The maximum percentage increase in perfusion on semiquantitative assessment was 12%. CONCLUSION: Although the changes seen may correspond to activation in the cortical regions related to different cerebral functions, we consider that with the SPECT technique one may detect changes in perfusion of the regions of the brain which are involved in language processing.

Perfusión cerebral durante la repetición de palabras en pacientes epilépticos / Cerebral perfusion during word repetition in epileptic patients

Objetivo. Localizar las regiones corticales que soportan la función del lenguaje en pacientes que van a someterse a una intervención quirúrgica cerebral. Pacientes y métodos. Hemos estudiado con tomografía computarizada por emisión de fotón único (SPECT) de perfusión cerebral a 14 pacientes con epilepsia temporal farmacorresistente candidatos a tratamiento quirúrgico. Los pacientes se eligieron de forma consecutiva entre los que acudían para su valoración prequirúrgica. Se seleccionaron aquellos enfermos en los cuales pudo realizarse dos estudios con 99mTc-HMPAO en la misma semana: uno en reposo sensorial y otro durante la escucha y repetición de una serie de palabras con baja imaginabilidad y frecuencia de uso medio. Se valoraron ambos estudios de forma cualitativa (imagen en escala de 16 colores, con sustracción del 20 por ciento de fondo y normalizadas al punto de máxima captación), y se consideraron cambios significativos, cuando se localizaba un aumento de intensidad mayor de dos colores, y semicuantitativos (con áreas de interés regulares, de 4 ¥4 píxeles, colocadas sobre la región donde se apreciaba el cambio cualitativo y referenciadas a la actividad de cerebelo). Resultados. Se encontraron aumentos de la perfusión en las regiones temporoparietales, en 11 de los 14 pacientes. En la mayoría (9/14 casos) fueron bilaterales y en dos casos solamente izquierdo. Se observó un cierto patrón predominante: aumento de perfusión temporal bilateral, con implicación de las regiones más anteriores del hemisferio izquierdo, así como medias y posteriores del derecho. El porcentaje de incremento máximo de la perfusión en la valoración semicuantitativa fue del 12 por ciento. Conclusión. Aunque los cambios observados pueden corresponder a la activación de regiones corticales relacionadas con diversas funciones cerebrales, consideramos que con la técnica de SPECT son detectables cambios de perfusión en las regiones cerebrales que intervienen durante el proceso del lenguaje (AU)

[Prognostic value of electrocorticography in temporal lobe epilepsy: patterns of relationing mesial and neocortical activity]. / Valor pronóstico de la electrocorticografía en la epilepsia temporal: patrones de la relación mesial y neocortical.

INTRODUCTION: Electrocorticography (ECoG) monitoring in temporal lobe epilepsy (TLE) has been employed since the 40 s as a means to delineate surgical removal especially in lesional epilepsy, to reduce resection size and decrease cognitive sequelae (memory, naming). However in recent years, ECoG has been claimed to lack indications and prognostic value in cases of non lesional TLE. On the grounds of the pathophysiological relationship between mesial structures and neocortex (through propagation pathways) we have suggested a classification of ECoG activity patterns regarding the activities simultaneously recorded in mesial and neocortical grids. PATIENTS AND METHODS: Two experienced neurophysiologists (over 200 ECoG performed) have independently reviewed the recordings (including video EEG monitoring with foramen ovale electrodes) of 33 consecutive (28 non-lesional) TLE patients with the major criterion of a leading activity in mesial or neocortical areas, and related the results to the clinical course. RESULTS: As a result we identified five patterns: I. Pure mesial; II. Mesial with neocortial-related activity; III. Non-related mesial and neocortical activities; IV. Neocortical preponderance (although some mesial unrelated discharges may be seen), and V. Neocortical origin. In all 33, a tailored, ECpG-guided two-steps resection was performed. Surgical success significantly (c2 test) associated with patterns I, II and IV. Pattern V precluded a good outcome. CONCLUSIONS: ECoG reflects the state of pathological involvement of neocortex and mesial structures. An expertise approach, although brief in time (20-30 min), may either lead to preservation of relevant tissue (patterns I, II) and to establish a prognosis on the grounds of the initial epileptogenic activity.

[Neuropsychology of temporal partial epilepsy: a comparison of drug resistant and pharmacologically controlled patients]. / Neuropsicología de la epilepsia parcial temporal: comparación entre pacientes farmacorresistentes y pacientes controlados farmacológicamente.

INTRODUCTION: Various factors may contribute to cognitive deterioration in temporal lobe epilepsy, and there is controversy as to which has the greatest effect. PATIENTS AND METHODS: In this study, we establish a comparison between patients with temporal lobe epilepsy controlled by drugs and drug-resistant patients, with the object of discovering the effect of different factors in causing cognitive damage. RESULTS: The persons whose disorder was controlled by pharmacological means had better results in memory and intelligence tests than those with drug-resistance. The latter had alterations of declarative memory for verbal material (left) and for visio-spatial material (right) in delayed free recall tests. Also, the greater proportion of symptomatic epilepsies in the drug-resistant group affected their greater cognitive deterioration. CONCLUSIONS: Our results show that having long-standing epilepsy with great frequency of seizures and symptomatic epilepsy is correlated with cognitive alterations in memory function in temporal lobe epilepsy. Most deterioration is seen in patients with long-standing drug resistant symptomatic left mesial temporal epilepsy.

Neuropsicología de la epilepsia parcial temporal: comparación entre pacientes farmacorresistentesy pacientes controlados farmacológicamente / The neuropsychology of temporal lobe epilepsy: a comparison between drug-resistant patients and those controlled pharmacologically

Introducción. Diferentes factores pueden contribuir al deterioro cognitivo en la epilepsia parcial temporal, y entre ellos existe cierta controversia acerca de cuál es el factor que más influencia ejerce. Pacientes y métodos. En este estudio, establecemos una comparación entre enfermos con epilepsia parcial temporal controlados farmacológicamente y pacientes farmacorresistentes, con el objetivo de conocer la influencia de diferentes factores en el daño cognitivo. Resultados. Los sujetos controlados farmacológicamente presentaron mejor rendimiento en tareas de memoria e inteligencia que los sujetos farmacorresistentes. Estos últimos muestran alteraciones de la memoria declarativa de tipo episódico para material verbal (izquierdos) o para material visuoespacial (derechos) en tareas de recuerdo libre diferido. Por otro lado, el mayor porcentaje de epilepsias sintomáticas dentro del grupo farmacorresistente influyó en su mayor deterioro cognitivo. Conclusiones. Nuestros resultados indican que padecer epilepsia durante un período prolongado, con una alta frecuencia de crisis y epilepsia sintomática se correlaciona con alteraciones cognitivas sobre las funciones mnésicas en la epilepsia parcial temporal. El perfil de mayor deterioro sería el de un paciente con epilepsia sintomática temporal mesial izquierda, farmacorresistente y de larga duración (AU)

[Magnetoencephalography: a new functional diagnostic technique for the neurosciences]. / Magnetoencefalografía: una nueva técnica de diagnóstico funcional en neurociencia.

INTRODUCTION AND OBJECTIVES: We present a review on the technical, methodological and clinical advances in the functional study of the brain by means of magneto-encephalography. We look back the milestones of its historical development, through the work of the major research groups on this field and through our group's works and database (including doctoral thesis). Discussion on the neurophysiological and biomagnetism basis is provided as well as description of technical developments in superconducting detectors (SQUID, Superconducting Quantum Interference Device), signal processing, enhancement of noise-signal ratio and dipole modeling. DEVELOPMENT: The need for brain functional studies has led to newer imaging procedures (functional magnetic resonance, PET, SPECT, etc.). Their spatial and temporal resolution and invasivity are compared to that of magneto-encephalography. Current equipment, up to 306 whole-head channels, may accurately detect cortical and subcortical activity. Apart from the physiological activity, it may be applied to a number of conditions: epilepsy (ictal, interictal and presurgical); dementia, movement disorders, stroke, eloquent cortex delimitation prior to tumour or lesion resection; learning disabilities and foetal studies. CONCLUSIONS: Magnetoencephalography provides with an excellent temporal, very good spatial resolution, acquires in real-time, without references and minimal interference. It entails a great advance in the diagnostic approach in neurosciences.

Associated EMG responses to voluntary hand movement in probable Alzheimer's disease.

The goal of this work is to dilucidate the mechanism that yields the associated EMG responses in patients with probable Alzheimer's disease. Seventeen subjects fulfilling this criteria and ten normal subjects as a control group were selected. They were asked to perform an oddball task in which they had to discriminate between two kinds of stimuli and produce a response to one of them. Results show that reaction times in controls and in patients when there is no associated EMG are equal in latency. When the associated EMG response occurs in the pathological group reaction time is significantly increased. Furthermore, the associated EMG response is delayed in 55 milliseconds when compared to the voluntary movement. Although these results may reflect some controversy, we interpret this finding as a contralateral inhibitory deficit associated to the corpus callosum abnormalities that occur in the evolving course of Alzheimer's disease.

A new clinical tool for gait evaluation in Parkinson's disease.

This study was devised to check the feasibility and validity of a rating scale specifically designed to evaluate gait impairment in Parkinson's disease (RSGE). Demographic data, a brief questionnaire on general aspects influencing gait and mobility, a battery of scales (Barthel Index; Hoehn and Yahr staging; and Northwestern University Disability, Schwab and England, and Unified Parkinson's Disease Rating Scale [UPDRS]), and timed tests ("Up and Go" and "Steps x Seconds" tests) were recorded under protocol, as was the RSGE-Version 1.0 (23 items in four subscales). Fifty patients enrolled at two centers were included. Twenty-five (50%) were simultaneously (though independently) evaluated by three examiners, in order to determine the interrater reliability. The mean age of the patients was 67.6 +/- 11.16 years, with a mean 8.18 +/- 5.58 years of disease duration. Motor fluctuations were present in 48% of patients. The RSGE Cronbach's alpha was 0.94. Only the item "Dyskinesias" was not correlated with the RSGE total sum. The item "Axial rigidity" showed a fair interrater reliability (kappa = 0.30). However, most of the RSGE items (16/23, 70%) had kappa > or = 0.65. The convergent validity with the applied scales was very high (Spearman r = 0.74-0.90, p < 0.001). The highest correlation (0.90) was obtained with the UPDRS. Also, the RSGE correlation with timed tests was very satisfactory ("Up and Go" = 0.81; "Steps x Seconds" = 0.70; both, p < 0.001). Factor analysis of the RSGE disclosed four dimensions explaining 68% of the variance. The RSGE-Version 1.0 proved to be a valid instrument. The reliability of some items has to be improved, however.