Attention-deficit/hyperactivity disorder in children and adolescents: An event-related potential study of working memory.

Working memory (WM) impairments have been frequently observed as an important feature of attention-deficit/hyperactivity disorder (ADHD). Event-related potential (ERP) differences between ADHD and healthy controls (HC) would be expected during WM task performance. Especially, the so-called slow wave (SW), which is related to the retention process, might present amplitude differences in ADHD. In this ERP study participated twenty-nine ADHD children and adolescents and thirty-four HC. WM performance was assessed using the Working Memory Test Battery for Children (WMTB-C), and ERPs were analyzed with a Delayed Match-To-Sample (DMTS) task. ADHD sample showed worse behavioral performance in both WMTB-C and DMTS task, and higher SW amplitude during the retention phase of the DMTS task. Additionally, the principal component analysis indicated that the scores on the component explaining the centro-parietal SW were significantly different between ADHD subjects and HC. The observed impaired neurophysiological activity during the encoding and retention periods in ADHD, which would be the origin of the behavioral deficits in WM task performance, might be reflecting a delayed maturation of the neural processes underlying the centro-parietal SW.

MULTI-CRITERIA DECISION ANALYSIS AS A DECISION-SUPPORT TOOL FOR DRUG EVALUATION: A PILOT STUDY IN A PHARMACY AND THERAPEUTICS COMMITTEE SETTING.

OBJECTIVES: The aim of this study was to develop and to assess a specific Multi-Criteria Decision Analysis (MCDA) framework to evaluate new drugs in an hospital pharmacy and therapeutics committee (P&TC) setting. METHODS: A pilot criteria framework was developed based on the EVIDEM (Evidence and Value: Impact on DEcisionMaking) framework, together with other relevant criteria, and assessed by a group of P&TC's members. The weighting of included criteria was done using a 5-point weighting technique. Two drugs were chosen by evaluation: an orphan-drug for Gaucher disease, and a nonorphan drug for the treatment of inflammatory bowel disease. Evidence matrices were developed, and value contribution of each drug was evaluated by P&TC's members. An agreed final framework was obtained through a discussion between the P&TC's members. RESULTS: After criteria assessment, the pilot framework included eight quantitative criteria: "disease severity," "unmet needs," "comparative efficacy/effectiveness," "comparative safety/tolerability," "comparative patient-reported outcomes," "comparative cost consequences-cost of treatment," "comparative cost consequences-other medical costs," and "quality of evidence"; and one contextual criterion: "opportunity costs and affordability." The most valued criteria were: "comparative safety/tolerability," "disease severity," and "comparative efficacy/effectiveness." When assessing the drugs most valued characteristics of the MCDA were the possibility that all team may contribute to drug assessment by means of scoring the matrices and the discussion to reach a consensus in drug positioning and value decision making. CONCLUSIONS: The reflective MCDA would integrate quantitative and qualitative criteria relevant for a P&TC setting, allowing reflective discussions based on the criteria weighting score.

Neurophysiological differences between ADHD and control children and adolescents during the recognition phase of a working memory task.

Impairment of executive functions including attention and working memory (WM) have been proposed as an important feature of Attention Deficit and Hyperactivity Disorder (ADHD). During the recognition phase of a delayed match-to-sample test (DMTS) a reduced N2pc component, related to the attentional selection of the memorized item and a reduced distractor positivity (Pd), related to the processing suppression of distractors are expected in ADHD subjects. For the purpose of the study, twenty-nine ADHD subjects diagnosed with a structured interview and the DuPaul questionnaire, were included in the study. Thirty-four control subjects were recruited from public schools and matched by age (from 6 to 17 years old) and gender with the ADHD group. Reaction times (RTs), errors, and Event Related Potentials (ERPs) were obtained in a DMTS task during the recognition phase in correct trials. RTs and errors were higher in ADHD subjects compared to the control group. Specifically, errors were much higher in ADHD than in controls. The cluster mass permutation statistics showed a significant N2pc component in both groups during the recognition phase, but a significant Pd component was present only in controls. The present results suggest that in correct trials ADHD children use the same neural resources to select the memorized item from WM with similar efficacy than controls, although a lower Pd suggests a difficulty in suppressing distractors.

Frequency coupling of low and high frequencies in the EEG of ADHD children and adolescents in closed and open eyes conditions.

The present report examines the possible differences in absolute Power Spectral Density (PSD), the topography of brain rhythms, and low frequency (delta and theta) vs. beta PSD when attention deficit disorder (ADHD) children and controls are compared. These results would potentially be useful to test the validity of the developmental lag and differential developmental models for ADHD. The EEG resting state under the experimental conditions of open and closed eyes were recorded in samples of control subjects and children with ADHD (6-17 years old). The PSD from 0 to 46 Hz was calculated and ANOVAs were performed to compare the groups of subjects in the two experimental conditions. To observe differences in the co-maturation of the brain rhythms between the groups of subjects, correlations of the PSD of all frequency ranges were computed. These results showed an increase in delta power in children with ADHD compared to control subjects. The topographies of the different brain rhythms were similar in children with ADHD and controls. The maturational power-to-power frequency-coupling between low frequencies and beta rhythms was lower in children with ADHD. The increased delta PSD in ADHD and the similar brain rhythms topographies in children with ADHD and controls support the developmental lag model, whereas the decreased co-maturation of low frequencies vs. beta PSD in children with ADHD suggests a differential maturation rate for low and beta frequencies in children with ADHD compared to controls.

The neurophysiology of working memory development: from childhood to adolescence and young adulthood.

Working memory (WM) is an important cognitive function that is necessary to perform our daily activities. The present review briefly describes the most accepted models underlying WM and the neural networks involved in its processing. The review focuses on how the neurophysiological mechanisms develop with age in the periods from childhood to adolescence and young adulthood. Studies using behavioral, neuroimaging, and electrophysiological techniques showed the progress of WM throughout the development. The present review focuses on the neurophysiology of the basic processes underlying WM operations, as indicated by electroencephalogram-derived signals, in order to take advantage of the excellent time resolution of this technique. Children and adults use similar cerebral mechanisms and areas to encode, recognize, and keep the stimuli in memory and update the WM contents, although adults rely more on anterior sites. The possibility that a functional reorganization of WM brain processing occurs around the adolescent period is suggested, and would partly justify the high prevalence of the emergence of mental pathology in the adolescent period.

Event related potentials changes associated with the processing of auditory valid and invalid targets as a function of previous trial validity in a Posner's paradigm.

The present study tries to analyze the neural basis of the so-called "Inter-trial Validity-Invalidity Effects" by means of Event-Related Potentials. The N1, P2, P3a and P3b components were examined. The aim is to show the sequential effects on Event-Related Potentials by analyzing the effect of previous trial condition (n-1) in the processing of current trial target (n). Event-Related Potentials results indicate that the N1 and P2 components show higher negativity in valid trials preceded by invalid trials with respect to valid trials preceded by valid trials, elicited by the so-called "Processing Negativity". Next, the P3a and P3b components show increased positivity in invalid trials preceded by valid trials compared to invalid trials preceded by invalid trials. Present results suggest that there is a dynamic updating of attentional resources and working memory, due to the influence of previous trial condition (n-1) on the current trial processing (n). This dynamic updating would be higher after trial validity changes, and it would be compatible with the Bayesian Brain Model.

Trepanaciones históricas y prehistóricas en Venezuela

Los autores hacen el informe preliminar del primer cráneo trepanado en la época precolombina en Venezuela. Hacen referencia a las primeras operaciones craneanas publicadas en Venezuela en los siglos XVIII y XIX por insignes cirujanos precursores de la cirugía neurológica. También se citan otras intervenciones practicadas en Hispanoamérica en los siglos XVI y XVII

Authors present the preliminary report on the first trepanned skull in the pre-Columbian period in Venezuela. References are made on the first skull interventions published in Venezuela during the XVIII and XIX centuries by distinguished precursors surgeons of the neurologic surgery. Other interventions performed during the XVI and XVII centuries in Latinoamerica are also quoted

Laser como instrumento quirúrgico / Laser as surgical instrument

El laser tiene tres caracteristicas principales y únicas: la coherencia, es decir que tiene la misma longitud de onda, amplitud y fase. Las ondas son colimadas o sea que viajan en la misma dirección en forma paralela y son monocromáticas.

La última enfermedad de Isabel la Católica (1451-1504) / The last disease od Isabel Catholic (1451-1504)

La última enfermedad de la Reina Isabel la Católica, fue una afección crónica, febril, multisistémica con compromiso renal, del sistema nervioso periférico y central, de los vasos periféricos y del sistema inmunológico. La causa mas probable que explica todas las manifestaciones es vasculitis.

Tratamiento del cancer con captura de neutrones / Cancer therapy with neutrons capture

Se hace un breve resumen del método de tratamiento de algunas formas de cáncer conocido como Captura de Atomos de Boro con Neutrones. Es un método bifásico que requiere la inyección de elementos con afinidad por la célula tumoral y la exposición a un haz de neutrones epitérmicos. Los resultados en una serie de enfermos con gliomas cerebrales malignos y melanoma indican que el procedimiento es seguro y de mayor eficiencia que los métodos convencionales. La Supervivencia de los enfermos y su calidad de vida son definitivamente mejores con BNCT. Se espera que en un futuro se puedan tratar otras formas de cáncer con esta modalidad terapéutica.

Diagnostico y tratamiento de la neuropatia endemica cronica asociada con virus humano linfotropico de celulas T, tipo I (HTLV-1) / Diagnosis and treatment of chronic endemic neuropathy associated with human lymphotropic virus of T cells, type I (HTLV-1)

An abridged review of the current status of chronic endemic neuropathy associated with human lymphotropic virus type I is presented. Tropical and non trpopical spastic paraparesis are associated with HTL V -I antibodies and the virus has been isolated from the blood and spinal fluid of patients, and probably they are a similar process. The case of a 57 year old black female from St. Croix, USVI, with a six year history of progressive spastic paraparesis, sphincter disturbances and subjective sensory complaints is described. Antibodies to HTL V-I were detected by the Elisa and confirmed by Western blot. The patient was treated with Zidovudine 200 mgrs three times a day for six weeks. At the end of this period she was able to walk without assistance, dance, jump and squat. Spasticity, sensory and sphinter disturbances disappeared

Complicaciones neurologicas de la enfermedad por decompresion de los buceadores / Neurologic complications of the decompression sickness of the divers

Se revisan las complicaciones neurologicas ocasionadas por la enfermedad por decompresion de los buceadores y se presenta la experiencia personal en tres casos de lesiones del cerebro, el oido interno y la medula espinal. Teniendo en cuenta el incremento en el buceo deportivo, se hace enfasis en la importancia de difundir los conocimientos sobre el tema para prevenir las complicaciones y senalar la urgencia de administrar oxigeno y trasladar al paciente lo mas pronto posible a una camara hiperbarica para tratamiento y disminuir las complicaciones permanentes que pueden presentarse

Variaciones anatómicas aparentes de imágenes escanográficas / Apparent anatomic changes of scannographic images

La escanografía ha facilitado extraordinariamente el diagnóstico de las lesiones intracraneanas. En algunas ocasiones sin embargo la variación en el ángulo de los cortes tomográficos produce el desplazamiento aparente de lesiones localizadas y aún de las suturas del cráneo. Para establecer la situación real de las lesiones se ha utilizado su relación con las suturas, pero es preferible y recomendable la utilización de marcadores radio- opacos externos en todas las lesiones parasagitales y en los procesos de tamaño reducido abordables a través de craneotomías pequeñas

Alteraciones mentales de las lesiones expansivas endocraneanas / Mental disorders due to expansive brain lesions

Las lesiones expansivas endocraneanas, producen con frecuencia sintomas mentales que deben distinguirse de otras enfermedades psiquiatricas para tratarlas en forma adecuada. En este trabajo se informan 10 casos recientes de lesiones expansivas tratados en instituciones psiquiatricas. Los autores hacen enfasis en la importancia de la historia y del examen, para detectar el sindrome mental organico y en la conveniencia de estudiar con la escanografia cerebral los casos sospechosos, pues en todos los escanogramas se detectaron y demostraron objetivamente las lesiones. Por el contrario, solamente dos electroencefalogramas de siete estudios mostraron anormalidad focal, uno fue inespecifico y cuatro fueron normales.

Malformaciones de la union cranio-cervical / Abnormalities of the cranio-spinal junction

Las malformaciones de la union craneo-cervical, son lesiones poco frecuentes. Su importancia radica en la necesidad de distinguirlas de afecciones neurologicas actualmente clasificadas como enfermedades degenerativas. Se presentan ocho casos. Cuatro con invaginacion basilar uno de ellos con hernia cronica de las amigdalas del cerebelo y cuatro con malformacion de Arnold-Chiari los cuales se diagnosticaron y trataron quirurgicamente. El diagnostico clinico se sospecha en presencia de alteraciones motoras de las cuatro extremidades de caracter progresivo y alteraciones de la sensibilidad principalmente parestesias. En caso de invaginacion basilar, las radiografias simples muestran elevacion de la apofisis odontoides por encima de la linea palato-occipital. En la Malformacion de Arnold-Chiari la mielografia cervical generalmente evidencia la hernia de las amigdalas del cerebelo. El tratamiento en los casos sintomaticos y progresivos consiste en la decompresion quirurgica de la zona afectada.

Neurinoma del glosofaringeo / Neurinoma of the glossopharingeal nerve

Los autores presentan un caso de Neurinoma del glosofaringeo, noveno informado en la literatura. El paciente un hombre de 42 anos presento disfonia por dos anos, dos meses y medio antes de su ingreso aparecio hipertension endocraneana y ataxia. Habia ademas compromiso de pares craneanos en el lado izquierdo y Babinski del mismo lado. La escanografia confirmo el diagnostico y el paciente fue intervenido haciendose una reseccion completa del tumor. Dos anos despues de intervenido el paciente se encuentra en buenas condiciones pero persiste la sordera izquierda y la voz bitonal.

Tratamiento de la neurocisticercosis con praziquantel / Treatment of cysticercosis of the CNS with praziquantel

La Neurocisticercosis multiquistica racemosa basal es una afeccion maligna con alta mortalidad hasta ahora por falta de tratamiento especifico. La enfermedad ha disminuido notablemente en Bogota por las medidas sanitarias, pero aun persiste en algunas zonas del pais. La aparicion de un nuevo cestocida util contra las formas embrionarias y las tenias constituye una esperanza para los enfermos con estas parasitosis. En este articulo se presenta un caso quirurgicamente en el cual la evolucion progresiva y el deterioro clinico fue detenida con la administracion de Praziquantel, con recuperacion del paciente.

Discopatias cervicales / Cervical disk lesions

Las discopatias cervicales son causa frecuente de cervico-braquialgia. En este estudio se presenta la experiencia obtenida con 50 pacientes hospitalizados por esta causa. Veinte mejoraron con tratamiento conservador y treinta fueron intervenidos con la operacion de Cloward. Se presentan las indicaciones para la cirugia y las complicaciones observadas. En los ultimos diez casos se ha utilizado injertos de banco esterilizados con oxido de etileno con buenos resultados.

Hematomas subdurales cronicos / Chronic subdural hematomas

Los autores presentan las manifestaciones clinicas, los hallazgos escanograficos y los resultados del tratamiento quirurgico en 90 pacientes con hematomas subdurales cronicos supratentoriales atendidos entre 1973 y 1980. La mayor proporcion ocurrio despues de los 50 anos en hombres quienes habian sufrido traumatismos leves o moderados entre uno y dos meses antes del comienzo de cefalea, trastornos motores, cambios mentales, principalmente. Dos pacientes tuvieron el cuadro de un accidente cerebrovascular y dos presentaron solamente cefalea con examen neurologico normal. La escanografia en 45 casos mostro 51% isodensos entre ellos 4 bilaterales, 42% hipodensos y 6.6 hiperdensos. Se presentaron diez recurrencias de ellas dos pacientes murieron en el post-operatorio.

Abordaje labio-mandibulo-faringeo para acceso al clivus, foramen magno, atlas y axis / Lip-maxilo-pharingeal approach to clivus, foramen magnun, atlas and axis

The technique to reach the area of the clivus, anterior part of the foramen magno, anterior arch of the Atlas and bodies of the Axis and C3 is presented. Surgical microscope and CO2 Laser facilitates the operation. The surgical procedure is described and the first case of a patient with a recurrent clivus chordoma operated on with this approach is presented.