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Mechanisms of Magnetic Stimulation of Central Nervous System Neurons  [PDF]
Tamar Pashut,Shuki Wolfus,Alex Friedman,Michal Lavidor,Izhar Bar-Gad,Yosef Yeshurun,Alon Korngreen
PLOS Computational Biology , 2011, DOI: 10.1371/journal.pcbi.1002022
Abstract: Transcranial magnetic stimulation (TMS) is a stimulation method in which a magnetic coil generates a magnetic field in an area of interest in the brain. This magnetic field induces an electric field that modulates neuronal activity. The spatial distribution of the induced electric field is determined by the geometry and location of the coil relative to the brain. Although TMS has been used for several decades, the biophysical basis underlying the stimulation of neurons in the central nervous system (CNS) is still unknown. To address this problem we developed a numerical scheme enabling us to combine realistic magnetic stimulation (MS) with compartmental modeling of neurons with arbitrary morphology. The induced electric field for each location in space was combined with standard compartmental modeling software to calculate the membrane current generated by the electromagnetic field for each segment of the neuron. In agreement with previous studies, the simulations suggested that peripheral axons were excited by the spatial gradients of the induced electric field. In both peripheral and central neurons, MS amplitude required for action potential generation was inversely proportional to the square of the diameter of the stimulated compartment. Due to the importance of the fiber's diameter, magnetic stimulation of CNS neurons depolarized the soma followed by initiation of an action potential in the initial segment of the axon. Passive dendrites affect this process primarily as current sinks, not sources. The simulations predict that neurons with low current threshold are more susceptible to magnetic stimulation. Moreover, they suggest that MS does not directly trigger dendritic regenerative mechanisms. These insights into the mechanism of MS may be relevant for the design of multi-intensity TMS protocols, may facilitate the construction of magnetic stimulators, and may aid the interpretation of results of TMS of the CNS.
La estimulación eléctrica del sistema nervioso central con finalidad analgésica
López-López,J. A.;
Revista de la Sociedad Espa?ola del Dolor , 2006,
Abstract: different procedures using electricity for pain control (mainly neuropathic) are described in this review. history of the so-called utility of electricity for pain control, describing the early attempts at the xviii century and their evolution. spinal cord stimulation: how does it works, patient?s selection, implant techniques, how to do the different procedures and complications and their management are described. brain stimulation: the same scheme as above, concerning both deep brain stimulation and motor cortex stimulation.
Qué hay de nuevo en? trasplantes del sistema nervioso central Central nervous system transplantation
Humberto Uribe
Iatreia , 1993,
Abstract: En forma somera se describen algunos aspectos históricos de los trasplantes del sistema nervioso central y se discuten desarrollos recientes en este campo, entre ellos sus posibles mecanismos de acción y los aspectos Inmunológicos; se alude a las objeciones de índole moral y se hace énfasis en que se trata de procedimientos aún experimentales. Some historical aspects of central nervous system transplantation are briefly described and recent developments in this field are discussed, namely: the possible mechanisms of action of the transplanted tissue and some immunological aspects; moral objections are considered; the fact that these are still experimental procedures is emphasized.
Characterization of Patients with Central Nervous System Infections Caracterización de pacientes con infecciones del sistema nervioso central  [cached]
Benigno Figueiras Ramos,ángel Julio Romero Cabrera,Raúl López Fernández,Sandra Borroto Lecuona
MediSur , 2011,
Abstract: Background: Central nervous system infections tend to present specific characteristics according to their clinical form and the causative agents that produce them. Objective: To characterize patients with central nervous system infections. Methods: Descriptive case series study conducted at the General University Hospital "Dr. Gustavo Aldereguía Lima’’, in Cienfuegos. Patients with central nervous system infections were analyzed from January 2002 to December 31st, 2006. Variables such as age, sex, duration of stay at hospital, date of their stay, clinical manifestations, tests used for diagnosis, predisposing conditions, most common germs and final outcome. Results: The average age of patients was 35.65 years old. Females were predominant. Average stay time was 5 days. Out of the total, 22 patients died (6.9%), mainly due to bacterial meningoencephalitis being lymphocyte meningoencephalitis the most frequent. The most affected age group was that from 20 to 29 years old. From July to October there was a higher incidence of lymphocytic meningitis. From January to December bacterial meningoencephalitis was predominant. The most frequent symptoms and signs were headache (92.1%), fever (82.7%), meningism (67.6%) and vomiting (37.7%). The clinical method and the study of the cerebrospinal fluid were the most widely used methods for diagnosis. The predisposing factors were pneumonia, sinusitis and alcoholism. S. pneumoniae was the most frequently isolated microorganism while E. Coli caused the highest mortality rate. Conclusions: symptoms like fading consciousness (OR = 41.735), purpuric lessions (OR = 6.641) or bacterial meningoencephalitis (OR = 22.958) were independently associated with the risk of dying. Fundamento: las infecciones del sistema nervioso central se manifiestan con características propias según la forma clínica que adopten y los agentes causales que las producen. Objetivo: caracterizar a pacientes con infecciones del sistema nervioso central. Métodos: estudio descriptivo de serie de casos realizado en el Hospital “Dr. Gustavo Aldereguía Lima” de Cienfuegos a pacientes con infecciones del sistema nervioso central, desde enero del 2002 al 31 de diciembre del 2006. Se analizaron variables como: edad, sexo, estadía, fecha, manifestaciones clínicas, exámenes utilizados para el diagnóstico, condiciones predisponentes, gérmenes más frecuentes y evolución final. Resultados: la media de edad fue 35,65 a os con predominio discreto del sexo femenino y la estadía de 5 días; ocurrieron 22 fallecimientos (6,9 % de letalidad), fundamentalmente por meningoenc
Infecciones del sistema nervioso central en urgencias Infections of the central nervous system in emergency department
I. Gastón,J. Muruzábal,P. Quesada,E. Maraví
Anales del Sistema Sanitario de Navarra , 2008,
Abstract: Las infecciones del sistema nervioso central son enfermedades frecuentes en la atención urgente, pudiendo ser de origen bacteriano, parasitario o vírico. Los síntomas iniciales pueden ser inespecíficos, lo que puede dificultar y retrasar su diagnóstico, por lo que es de suma importancia toda la información que pueda obtenerse a través de la anamnesis y exploración física y con frecuencia exploraciones complementarias. En los últimos cien a os, con la introducción de fármacos antibióticos ha disminuido de forma importante la mortalidad secundaria a meningoencefalitis, pero a pesar de ello siguen provocando alta morbi-mortalidad. Otros fenómenos, como las campa as de vacunación, movimientos migratorios, infección por el virus de la inmunodeficiencia humana y otros estados de inmunosupresión, han dado lugar a importantes cambios epidemiológicos como son la práctica desaparición de algunas infecciones o la aparición de otras previamente casi inexistentes. La lista de infecciones potenciales de sistema nervioso central es extensa por lo que en este artículo de revisión expondremos desde el punto de vista clínico, diagnóstico y terapéutico las más frecuentes en nuestro medio y algunas que, aunque poco frecuentes, pueden requerir atención urgente por su gravedad. Infections of the central nervous system are frequent diseases in emergency care. They can have a bacterial, parasitic or viral origin. Initial symptoms can be non-specific, which can complicate and delay diagnosis, hence the extreme importance of all the information that can be obtained through anamnesis and physical exploration, with frequent complementary explorations. In the last hundred years, with the introduction of antibiotic drugs, there has been a significant fall in mortality secondary to meningoencephalitis, but in spite of that they continue to provoke high morbidity and mortality. Other phenomena, such as vaccination campaigns, migratory movements, infection by HIV and other states of immunosuppression, have given rise to important epidemiological changes such as the virtual disappearance of some infections or the appearance of others that rarely existed previously. The list of potential infections of the central nervous system is extensive, which is why in this review we set out, from the clinical, diagnostic and therapeutic point of view, those that are most frequent in our environment and some that, although very infrequent, might require emergency attention due to their severity.
Ecografía de las malformaciones congénitas del sistema nervioso central Echography of congenital malformations of the central nervous system  [cached]
Carlos Andrés Toirac Romani,Acelia Salmon Cruzata,Mirelvis Musle Acosta,Yamilé Rosales Fargié
MEDISAN , 2010,
Abstract: Se realizó un estudio descriptivo y prospectivo de 173 embarazadas atendidas en el Departamento Provincial de Genética Clínica de Santiago de Cuba, desde enero del 2000 hasta diciembre del 2004, para identificar las malformaciones congénitas del sistema nervioso central detectadas mediante la ecografía. La malformación más frecuente fue la hidrocefalia, seguida de los defectos de fusión de la columna vertebral, asociados con la hidrocefalia y la ausencia de cavidad craneana. Hubo predominio de la alfafetoproteína alterada y del líquido amniótico elevado. A descriptive and prospective study was conducted in 173 pregnant women attended at the Provincial Department of Clinical Genetics of Santiago de Cuba, from January, 2000 to December, 2004, to identify congenital malformations of the central nervous system detected by means of echography. The most frequent malformation was the hydrocephaly, followed by the fusion defects of the spine, associated with the hydrocephaly and the absence of cranial cavity. There was a prevalence of altered alpha fetoprotein and of elevated amniotic fluid.
Supervivencia de la población infantil con tumores del sistema nervioso central Survival of the children population with tumors of the central nervous system  [cached]
Julio S Brossard Alejo,Pedro Nú?ez Ferrer,Ernesto Rodríguez Herrera,Luis M Agustín Antomarchi
MEDISAN , 2011,
Abstract: Se efectuó un estudio descriptivo, longitudinal y retrospectivo de todos los pacientes con tumores del sistema nervioso central, ingresados en el Hospital Infantil Sur de Santiago de Cuba, desde 1987 hasta el 2006, a fin de analizar la supervivencia de esta población infantil, cuya media fue de 45-49 meses ± 5,84. Se halló que la edad, los aspectos tisulares, la localización anatómica, el grado de resección, así como los tratamientos aplicados (radioterapia y quimioterapia), constituyeron factores determinantes para mejorar el pronóstico de vida de los integrantes de la casuística. A descriptive, longitudinal and retrospective study of all the patients with tumors of the central nervous system, admitted to the Southern Children Hospital in Santiago de Cuba, from 1987 to 2006, in order to analyze the survival of this population whose mean was 45-49 months ± 5,84. It was found that age, tissue aspects, anatomical site, and resection degree, as well as the applied treatments (radiotherapy and chemotherapy), constituted decisive factors to improve the life prognosis of the case material.
Tumores del sistema nervioso central en el primer a o de vida Tumors of the central nervous system in the first year of life  [cached]
Julio S Brossard Alejo,Ernesto Rodríguez Herrera,Ricardo Hodelín Tablada,Lázaro I Romero García
MEDISAN , 2010,
Abstract: Se efectuó un estudio descriptivo, longitudinal y retrospectivo de los 8 pacientes con tumores del sistema nervioso central en el primer a o de vida, diagnosticados en el Hospital Infantil Sur de Santiago de Cuba desde 1987 hasta 2008, de los cuales 5 (62,5 %) habían fallecido cuando se elaboró el presente artículo. Los tratamientos indicados en este caso son la resección de la masa tumoral, lo más radical que permitan su tama o y localización, así como la quimioterapia según el tipo hístico. A descriptive, longitudinal and retrospective study of 8 patients with tumors of the central nervous system in the first year of life was carried out. They were diagnosed in the Southern Children Hospital of Santiago de Cuba from 1987 to 2008, 5 of them (62,5%) had died when the present article was made. The treatments indicated in this case are the resection of the tumor mass, the most radical surgery depending on its size and localization, as well as the chemotherapy according to the tissular type.
Tendencias del tratamiento radiante en los tumores del sistema nervioso central Trends of the radiant treatment in the central nervous system tumors
José Alert Silva,José Jiménez Medina
Revista Cubana de Medicina , 2004,
Abstract: Se sabe que el tratamiento de los tumores del sistema nervioso central (SNC) está basado en el empleo de la cirugía y la radioterapia (RT) y que la quimioterapia (QMT) se emplea cada vez más, así como los otros medicamentos. Se hizo una revisión bibliográfica para actualizar los conocimientos sobre las tendencias actuales y perspectivas de la RT aplicada a los tumores del SNC, entre las cuales se hallan: a) combinaciones de RT y QMT; b) radiosensibilizadores incorporados al tratamiento radiante; c) inhibidores de la angiogénesis asociados a la RT; d) la escalada o incremento de las dosis de RT, gracias al desarrollo de nuevas tecnologías como la radioterapia conformacional en tercera dimensión, la radioterapia de intensidad modulada, la cirugía y otros; otro campo de investigación es el constituido por los cambios en el ritmo o fraccionamiento de la RT: hiperfraccionada, acelerada, combinaciones de ambas, etc., lo que permitirá principalmente incrementar el escalado de las dosis. It is known that the treatment of the central nervous system (CNS) tumors is based on the use of surgery and radiotherapy (RT) and that chemotherapy (QMT) is used even more, as well as the other drugs. A bibliographic review was made to update the knowledge on the current trends and perspectives of RT applied to CNS tumors. The following were found among them: a) combinations of RT and CMT; b) radiosensibilizers incorporated to the radiant treatment; c) angiogenesis inhibitors associated with RT; d) the scale-up or increase of the RT doses thanks to the development of new technologies, such as 3 D conformal radiotherapy, intensity- modulated radiotherapy, surgery and others. Another field of research is that of the changes in the rhythm or fractioning of the RT: hyperfractionated, accelerated, combinations of both, etc., which will allow mainly to increase the dosage scale-up.
Primary central nervous system lymphomas in immunocompetent patients Linfomas primarios del sistema nervioso central en pacientes immunocompetentes  [cached]
T. Alécio-Mattei,J. Alécio-Mattei,P.H. Aguiar,R. Ramina
Neurocirugía , 2006,
Abstract: Objectives. Primary central nervous system lymphoma (PCNSL) is a rare pathology and is most often seen in immunodeficient patients. This article presents our casuistic of PCNSL in immunocompetent patients and make a literature review on this issue with focus on recent advances, investigations, and controversies in diagnosis and management of this pathology. Matherial and methods. Nine patients operated in the last years in our clinics are analysed in relation to sex, age, time of symptoms, procedures and adjuvant treatment. Posteriorly the results are compared with those in the preview literature. Results. The age ranged from 44-68 years (middle of 66 years); 62,5% of the patients were female. The mean time of symptoms, when the diagnostic was made, was 3.2 months (range 1-6 months). The most common symptoms were hemiparesis (present in 75% of the patients) headache (37.5%) seizures (25%) and ataxia (25%). The most common localization was the parietal, frontal and temporal lobe surface with 25% of the patients for each localization. Five patients (50%) were treated with stereotactic biopsy, three with surgery (37.5%) and one (12.5%) with both of them. Five patients (62,5%) were submitted to pos-operative radiotherapy as adjuvant treatment. In relation to the hystology, the most common cell type was Difuse B Cells. Conclusions. This study demonstrated that complete surgical ressection followed by radiotherapy have shown good results. In opposition to the literature, the authors regard chemotherapy as a secondary line treatment and recommend its use only in some selected cases. Objetivos. En este trabajo presentamos nuestra casuística de linfomas cerebrales primarios en pacientes immunocompetentes comparandolo con los datos previos de la literatura, con especial enfoque en los recientes avaces, investigaciones, y controversias acerca del diagnóstico y manejo terapéutico de estas patologías. Material y método. Nueve pacientes operados el a o pasado en nuestra clínica con diagnóstico de PCNLS son analizados en relación al sexo, edad, tiempo de sintomatología, procedimientos y tratamiento. Posteriormente, los resultados son comparados con los de la literatura. Resultados. La edad varió entre 44-68 a os (media de 60,6 a os); 62,5% de los pacientes fueron del sexo femenino; el tiempo medio de duración de los síntomas antes del diagnóstico de la enfermedad varió de 1-6 meses, con un rango medio de 3,2 meses. Los síntomas clínicos más frecuentes fueron : hemiparesia (75%), cefalea (37,5), crisis convulsivas (25%) y ataxia (25%). Las localizaciones predominaron e
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