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1.
Cir. plást. ibero-latinoam ; 45(2): 159-168, abr.-jun. 2019. ilus
Artigo em Espanhol | IBECS | ID: ibc-184223

RESUMO

Introducción y objetivo. La trigonocefalia, originada por la sinostosis prematura de la sutura metópica, en sus formas más graves presenta mayor restricción del crecimiento lateral de los huesos frontales y temporales, afectando a los rebordes supraorbitarios, limitando el crecimiento y condicionando un hipoteleorbitisimo aparente. Los principales problemas de las técnicas quirúrgicas empleadas para su tratamiento son: falta de corrección del defecto, vaciamiento temporal, daño de suturas no afectadas al hacer transposiciones que producen defectos de crecimiento (sinostosis secundarias), sobrecorrección del hipoteleorbitisimo y defectos óseos. El objetivo de este trabajo es presentar nuestra experiencia en una serie de casos tratados de forma temprana con modificaciones propias a las técnicas abiertas propuestas por Dhellemmes en Francia. Material y método. Entre 2010 y 2018 operamos 7 pacientes con trigonocefalia no sindrómica severa, con una media de 7 meses de edad. Todos fueron estudiados con tomografía computerizada de cráneo con reconstrucción ósea en tres dimensiones (TCC-3D) preoperatoria, postoperatoria inmediata y al año de evolución, electroencefalograma, valoración del neurodesarrollo y por Pediatría y Oftalmología. Resecamos la sutura metópica estenosada y efectuamos craneotomías frontales en forma de alas de escarabajo respetando la sutura coronal. Remodelamos la barra frontoorbitaria con injerto óseo para corregir la angulación y la fijamos con un injerto de hueso. Finalmente practicamos osteotomías radiadas en parietal para modificar la restricción del crecimiento de la bóveda. Resultados. Los resultados funcionales y estéticos fueron excelentes, sin defectos de osificación ni vacío de la fosa temporal, ni morbimortalidad, con cicatriz oculta por el cabello. El desarrollo neurocognitivo de los niños tuvo una mejoría notable de la irritabilidad y de la actividad e interacción con los padres. Conclusiones. En trigonocefalia, la cirugía temprana logra la corrección total del defecto en un solo tiempo quirúrgico, obteniendo una remodelación ósea y un crecimiento armónico del cráneo al respetar el crecimiento del sistema suturario. Las modificaciones a la técnica que proponemos evitan el defecto de vaciamiento temporal y permiten no utilizar material de osteosíntesis


Background and objective. The premature synostosis of the metopic suture in the most severe forms occurs with a restriction of the lateral growth of frontal and temporal bones, affecting the supraorbital rims, which limits its growth and leads to hypoteleorbitism. The triangular shape of the forehead is accentuated by the compensatory growth of the other structures of the skull. The main problem of the handling techniques are: temporal emptying, lack of defect correction, damage of unaffected sutures while making transpositions that will later produce defects in growth and cranial molding. Our aim is to show our surgical experience operated with the variations of the open technique that was conceived by Dhellemmes in France. Methods. Between 2010 and 2018 we operated 7 patients with trigonocephaly; patients' average age was 7 months. They were studied with presurgical and post operatory CBT-3D, electroencephalograms, neurodevelopmental assessment and by Pediatry and Ophthalmology. Stenosed metopic suture was resected and frontal craniotomies shaped like beetle wings were performed out without drying the coronal suture, securing them to the fronto-orbital bar with a discreet progress of the side edges. The medial osteotomy of the orbital toolbar was used to reshape it and correct its angulation fixing it with a bone graft and radiated parietal osteotomy to modify the restriction of frontoparietal growth. Results. Functional and aesthetic results were excellent, without ossification defects or vacuum the temporal fossa, morbidity or mortality, with the scar hidden by hair. Children's neuropsychological development had a noticeable improvement in irritability, activity and interaction with their rents. Conclusions. In trigonocephaly, early surgery achieves total defect correction in a single procedure and a bone remodeling and harmonic skull growth by respecting the sutures system. Our modifications to the technique avoid the temporary emptying defect and don't use osteosynthesis material


Assuntos
Humanos , Masculino , Feminino , Recém-Nascido , Lactente , Pré-Escolar , Craniossinostoses/cirurgia , Craniotomia/métodos , Craniossinostoses/diagnóstico por imagem , Sinostose/cirurgia , Osteogênese , Remoção de Cabelo , Procedimentos de Cirurgia Plástica/métodos , Osteotomia/métodos , Diagnóstico Diferencial
2.
Childs Nerv Syst ; 25(5): 551-7, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19148652

RESUMO

OBJECTIVE: To evaluate clinical evolution of pediatric patients diagnosed with glioblastoma multiforme (GBM) at Hospital Infantil de México Federico Gómez. METHODS: Cases of patients treated from January to May, 2007, were included in this study. Variables analyzed were: age, diagnosis, size of tumor, histopathological description, degree of resection, time of stay in hospital, complications and outcome using Pearson's chi-squared test and logistic regression. CONCLUSION: Sixteen patients were identified. Mean age of presentation was 8.8. An increased frequency of complications was observed in younger patients and longer survival rates in patients with greater resections; main mode of presentation was directly related to intracranial hypertension; size of tumor was not related to evolution or outcome. Modern histological classifications especially designed for children are deemed necessary to accurately diagnose GBM.


Assuntos
Neoplasias Encefálicas/complicações , Neoplasias Encefálicas/diagnóstico , Glioblastoma/complicações , Glioblastoma/diagnóstico , Hipertensão Intracraniana/etiologia , Fatores Etários , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/fisiopatologia , Distribuição de Qui-Quadrado , Criança , Feminino , Glioblastoma/patologia , Glioblastoma/fisiopatologia , Hospitais Pediátricos , Humanos , Hipertensão Intracraniana/fisiopatologia , Modelos Logísticos , Masculino , México , Análise Multivariada , Prognóstico , Fatores de Risco , Taxa de Sobrevida
3.
Salud ment ; 30(5): 47-54, Sep.-Oct. 2007.
Artigo em Espanhol | LILACS | ID: biblio-986041

RESUMO

resumen está disponible en el texto completo


Summary: Action of GABA agonists and antagonists on memory. The θ rhythm. Muscimol may directly alter memory. Recently, a modified matching to position (MTP) paradigm was employed aimed at influencing the type of associations a rat may use to solve the task. The main behavioral manipulation was the application of a differential outcomes procedure (DOP). DOP implies correlating each event to be remembered with a different reward condition. This procedure will result in the development of specific reward expectations which will in turn increase and guide choice behavior. Such different reward expectations will not be present when the reward assignation used is either common or random (non-differential outcomes procedure, NOP). Intraventricular infusion of muscimol or CSF in rats carrying out a delayed MTP using either a MOP or an NOP protocol will affect both groups of rats, but the nature of the deficit will differ depending on the reinforcement contingencies. Rats trained in DOP will show general non-mnemonic damage independent of delay, i.e., performance will be affected at all delay intervals employed. On the contrary, rats trained in NOP will show delay-dependent damage. This appears to demonstrate that muscimol may also have untoward memory effects, which further indicates that activation of GABA receptors will affect a set of memory associations and functions. Difficulties experienced in the past regarding LTP induction at the level of the CA3-CA1 synapse using time-based spike presentation protocols have been disconcerting given the preeminence of these synapses as a model system for the study of synaptic plasticity. Results previously discussed in experiments using picrotoxin as a GABA inhibitor have suggested that such difficulties arise from the requirement that, for LTP to be induced, CA1 dendrites must be persistently and totally activated. Doublets used in this case represent a minimal burst, or level of post-synaptic stimulation for LTP induction that subsumes greater depolarizations. In vitro, synaptically induced bursts would correspond to regenerative electrical events in apical dendrites of pyramidal neurons. The same requirements for dendritic activation would be satisfied in vivo during the θ rhythm, which is present during active exploration. Therefore, GABA might serve as an engram modulator through the activation of the hippocampal θ rhythm. Effect of μ-opioid receptors on hippocampal memory activity. Hippocampal μ-opioid receptors (MOR) have been involved in the formation of memory associated with the abuse of opioid drugs. When chronically activated, and during programmed drug abstinence, MORs acutely modulate hippocampal synaptic plasticity At the level of neuronal networks, MORs increase excitability of area CA1 by means of a disinhibition of pyramidal cells. The specific inhibitory interneuronal subtypes which become affected by activation of MORs are not known. Nevertheless, not all subtypes are inhibited and some subtypes preferentially express these receptors. In one study, the effect of activation of MORs on inhibitory patterns and propagation of excitatory activity in CA1 of rat hippocampus was investigated through cortical images created using voltage-sensitive dyes. MOR activation increased excitatory activity originated by the increased stimulating input to stratum oriens (i.e., Schäffer collateral and commissural [SCC] fibers, as well as the retrograde pathway), to stratum radiatum (i.e., SCC fibers) and to stratum lacunosum-moleculare (i.e., the perforant pathway and the thalamus). Increased excitatory activity was additionally facilitated by propagation through the neural network of area CA1. This was observed as a proportionally greater increment of amplitudes of excitatory activity in sites distant from the originally evoked activity. Such facilitation was noted in excitatory activity propagating from three sites of stimulation. The increment and facilitation were prevented with GABAA receptor antagonists (bicuculline, 30 μM), but not with GABAB receptor antagonists (CGP, 10 μM). Besides, MOR activation inhibited inhibitory post-synaptic potentials (IPSPs) in every layer of area CA1. These findings suggest that MOR-originated suppression of GABA release to GABAA receptors increases every type of input to pyramidal CA1 neurons and facilitates propagation of excitatory activity through the neural network of area CA1. Cannabis indica and memory. Cannabinoids (derived from Cannabis indica, or marihuana) disturb memory processes in mammalians. In spite of the fact that the neuronal cannabinoid CB1 receptor was identified several years ago, the neuronal network mechanisms mediating these effects are still controversial. Tritium-labeled GABA-releasing experiments have been used to test for the localization of this receptor at a cellular and subcellular level in the human hippocampus. CB1 expression detected with this technique is limited to hippocampal interneurons, most of which, it could be determined, are cholecystokinin-containing basket neurons. The CB1-positive neuronal somata show immune staining of their cytoplasm, but not of their somatodendritic plasma membrane. CB1-immunoreactive axonic terminals densely cover the entire hippocampus and form symmetrical synapses, characteristic of GABAergic neuronal boutons. It could thus be observed that WIN 55,212-2, a CB1-receptor agonist, considerably reduces the release of tritium-labeled GABA, and that this effect is preventable using the receptor antagonist, SR 141716A. This single pattern of expression and pre-synaptic modulation of GABA release suggests the existence of a preserved role of CB1 receptors in the control of inhibitory hippocampal networks responsible for the generation and maintenance of fast and slow oscillation patterns. Therefore, a probable mechanism whereby cannabinoids could affect associational processes in memory might be a disturbance of synchrony of rhythmical events in distinct neuronal populations. GABA effects against aging. Certain components which stimulate GABAergic neurotransmission might prevent the hippocampal and striatal degeneration which typically appears with old age and causes memory deterioration. On using a 4-vessel occlusion model in animals to study the effect of ischemia on expression of GABAA receptor subunits, which are vulnerable in region CA1 and resistant in region CA3 of Amnion's horn, an increment in expression of GABAA2, GABA B2, GABA G2 units and a decrement in expression of GABA A1 and GABA A3 subunits in region CA3 were obtained. On the contrary, there was no change in region CA1 or the dentate gyrus under the same conditions. These data speak in favor of the stimulation of type 2 receptor GABAergic subunits which might protect certain hippocampal areas against a harmful neurodegenerative effect, for example, of memory activities during old age.

4.
Salud ment ; 30(4): 7-15, jul.-ago. 2007.
Artigo em Espanhol | LILACS | ID: biblio-986025

RESUMO

resumen está disponible en el texto completo


Summary: Introduction. The entire hippocampus is derived from the telencephalon. Embryologically, it is made up of the most archaic cortices. Through special phylogenetic and ontogenetic telencephalization processes, it will arrive at its particular mesial basal position. This structure has three components: a) Retrocommisural hippocampus, or hippocampus proper (RH). b) Supracommisural hippocampus (SH). c) Precommisural hippocampus (PH). The RH is situated in the most medial part of the 5th temporal gyrus (5 TG). The outer/upper face of the RH is to be found in the temporal recess of the lateral ventricle. It is called pes hippocampi or albeus. Inwards, it is limited by the choroid fissure, outwards and downwards by the parenchyma of the 5th TG, forwards, by the amygdala of the striatal body and, backwards, by the isthmus. The fornix is a continuation of efferent pathways from CA3, CA1 and the subiculum. By means of a circular course, it ascends over the thalamus and, descending in front of Monro's foramina and traversing the hypothalamus, reaches the mammillary bodies. It consists of fimbria, posterior pillars and a body and anterior pillars. The latter pass behind the anterior white commisure (AWC), and make up the anterior portion of Monro's foramina. The SH originates in the RH. At the level of the splenium of the corpus callosum (CC), the fornix produces two striae, medial and lateral, and the dentate gyrus turns from fasciola cineria into induceum griseum. These structures are to be found in both hemispheres and, traveling over the CC, will reach the preoptic and hypothalamic septal areas, as well as the PH. The PH is a small fiber contingent which stems from the fornix at the level and in front of the AWC. Memory. General aspects. There is general agreement that the main role of the hippocampus is that of creating new memories relative to experienced events (episodic or autobiographic memory). Some researchers, however, prefer to think of the hippocampus as part of a major medial temporal lobe memory system responsible for declarative memory. This memory would include, besides episodic memory, memory of events. Another very important hippocampal function would relate to storage of semantic (conceptual) memories. Engrams. Memory and synaptic plasticity. Engrams are hypothetical means whereby memory traces are stored as physical or chemical changes in the brain in response to external stimuli. The existence of engrams has been proposed by diverse scientific theories which try to explain the persistence of memory and how some memories are stored in the brain. The term engram was coined by Sermon and explored by Pavlov Lashley tried to locate the engram and failed in finding a sole biological locus for the same which made him think that memories were not localized in any particular part of the brain, but distributed throughout the cerebral cortex. Afterwards, in 1949, Hebb, a student of Lashley's, published his empiricist theories in The Organization of Behavior. Hebb referred to Lorente de Nó's reverberating circuits to propose a mechanism for maintaining activity in the cerebral cortex after the external stimulus had ceased: the so called central autonomous process. This led him to consider the cellular assembly, a complex reverberating circuit which could be assembled by experience. Changes in synaptic resistance with experience were eventually named Hebb's, or the Hebbian, synapse. Hebbian theory describes a basic mechanism for synaptic plasticity by means of which an increment in synaptic efficacy stems from repetitive and persistent stimulation of the post-synaptic cell. This theory receives the name of Hebb's rule. The fact that memory is persistent stresses the relevance of understanding those factors which maintain synaptic strength and prevent undesired synaptic changes. There is evidence that recurrent inhibitory connections in region CA1 of Ammon's horn of the hippocampus might contribute in this sense by modulating the ability to induce long-term potentiation (LTP) or long-term depression (LTD) of synaptic activity, given by a sequence of high-or low-frequency stimulations, respectively. The hippocampus seems to be able to select the most relevant from the least relevant aspects of a definite experience in order to transform them into long-term memory. According to the concept of Emotional Tagging, for example, through the activation of the amygdala by emotionally suggestive events, the experience will be tagged as important and synaptic plasticity promoted in other cerebral regions, such as the hippocampus. Recently, it has been shown that activation of the amygdala transforms transient plasticity into long-term plasticity. This finding directly relates to the afore mentioned hypothesis of emotional tagging, since activation of this organ could trigger neuromodulatory systems, further reduce the activation threshold of the synaptic marker and facilitate transformation of early into late memory at the level of the hippocampus via direct amygdalar action on the latter organ. γ-aminobutyric acid. γ-aminobutyric acid (GABA), together with its different receptor subunits, functions as an inhibitor neurotrans-mitter in hippocampus and memory activities. GABA and memory. LTP has been a widely studied mechanism of synaptic plasticity and, as we have mentioned, it is intimately related to diverse memory and learning processes in mammals. It has been observed in pyramidal cells of area CA1 of the hippocampus of young C57BL/6 mice that the pairing of pre-synaptic stimulation with just one post-synaptic action potential will be sufficient to induce LTP, whereas in the adult animal this stimulation must be paired with several post-synaptic action potentials to achieve such induction. This change might result from a modification during maturation of GABAergic inhibitory processes. A bath of muscimol, a GABAA agonist, given to sections of hippocampal area CA1 will increase the range of frequencies inducing LTD, while in the presence of picrotoxin, a GABAA antagonist, LTD will be induced only at very low stimulation frequencies. The resulting recurrent inhibition appears to stem from GABAergic input to pyramidal neurons of CA1. In this way, post-synaptic spike activity could increase GABAergic feedback inhibition, and thus favor LTD. However, in experiments in which the pairing of stimulating action potentials is set apart in time, LTD, LTP or no plasticity may be observed. An explanation for these results could be that, in the presence of picrotoxin, and therefore GABA inhibition, the first action potential may have a greater tendency to "back propagate", so that only one spike would be enough to cause LTP instead of LTD, and affect memory processes differently.

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