Abordaje quirúrgico temprano de la trigonocefalia / Early quirurgic management of trigonocephaly

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

Expression of microRNAs in tumors of the central nervous system in pediatric patients in México.

PURPOSE: MicroRNAs were identified as molecules that participate in gene regulation; alterations in their expression characterize central nervous system (CNS). Information in pediatrics is scarce, so the objective of this work was to determine and then compare the patterns of expression of microRNAs in astrocytomas, ependymomas, and medulloblastomas, as well as in non-neoplastic brain. METHODS: Low-density arrays were utilized to evaluate 756 microRNAs in three samples of each type of tumor and non-neoplastic brain. The relative expression was calculated in order to identify the three microRNAs whose expression was modified notably. This was verified using RT-qPCR in more number of tumor samples. RESULTS: The microRNAs selected for testing were miR-100-5p, miR-195-5p, and miR-770-5p. A higher expression of miR-100-5p was observed in the astrocytomas and ependymomas compared to the medulloblastomas: on average 3.8 times (p < 0.05). MiR-770-5p was expressed less in medulloblastomas compared to astrocytomas four times (p = 0.0162). MiR-195-5p had a low expression in medulloblastomas compared to non-neoplastic cerebellum (p = 0.049). In all three tumor types, expression of miR-770-5p was lower than in non-neoplastic brain (p < 0.001). CONCLUSIONS: These microRNAs may represent potential markers in these tumors.

Brachmann-Cornelia de Lange syndrome with a papilloma of the choroid plexus: analyses of molecular genetic characteristics of the patient and the tumor. A single-case study.

PURPOSE: A 10-month-old girl with a Brachmann-Cornelia de Lange syndrome and a choroid plexus papilloma of the brain was studied at the Hospital Infantil de México Federico Gómez (HIMFG) in Mexico City. METHODS AND RESULTS: Presumptive papilloma of the third ventricle was evidenced on CT and MR images and removed. Pathological analysis confirmed its origin. A posterior radiosurgery was required due to a tumor relapse. Karyotypes (GTG bands) of the patient and her parents undertaken at HIMFG were normal. Array comparative genomic hybridization (array CGH) analyses of blood DNA of the patient and her parents carried out at BlueGnome's Laboratory in Cambridge, UK, set in evidence amplification of genes SPNS2, GGT6, SMTNL2, PELP1, MYBBP1A, and ALOX15 in chromosome 17p of the patient. Since MYBBP1A is a proto-oncogene and ALOX15 participates in the development of cancer and metastases of tumors, further fluorescent in situ hybridization (FISH) analyses of these two genes were implemented at HIMFG. Amplification of the two genes was found in the tumor of the case under study but not in an unrelated papilloma of the choroid plexus. DISCUSSION: Further analyses of the association of choroid plexus papillomas with disorders of psycho-neural development and its relationship to molecular genetic modifications at chromosome 17p are now under way at HIMFG.

Reductions in the expression of miR-124-3p, miR-128-1, and miR-221-3p in pediatric astrocytomas are related to high-grade supratentorial, and recurrent tumors in Mexican children.

PURPOSE: Astrocytomas are the most frequent type of tumor of the central nervous system in children. Hence, it is important to describe markers that may improve our understanding of their behavior. Mature microRNAs (miRNAs) may be such biological markers. They are small molecules of RNA that regulate gene expression post-transcriptionally. Due to their importance in cancer, the objective of the present study was to determine the profile of expression of precursor and mature forms of miR-124-3p, miR-128-1, and miR-221-3p using RT-qPCR in pediatric samples. METHODS: A total of 57 astrocytomas embedded in paraffin were selected. As controls, the study included 13 samples of normal brain tissue. RESULTS: Three of eight miRNAs were selected after a preliminary screening. All the miRNAs showed higher levels of expression in normal brain tissue. The expression of miR-124-3p and miR-128-1 decreased in astrocytomas than in normal brain tissue in all grades (p < 0.05 in both cases), and this reduction was most evident in GIV (407- and 1,469-fold, respectively); however, the expression of the precursor forms pre-miR-128-1 and pre-miR-221 was higher in GIV (3.5-fold) than in GI. The levels of miR-128-1 were higher in infratentorial tumors than in supratentorial cases (p = 0.006). Finally, the expression of miR-221-3p was higher in non-recurrent tumors and live patients (p = 0.0185 and p = 0.0004, respectively). CONCLUSIONS: The low expression of these miRNAs may constitute a potential marker of astrocytomas that correlates with localization, possibly due to alterations in the maturation processes of these miRNAs that produced low mature forms in patients with recurrent pediatric astrocytomas.

Glioblastoma multiforme in children: experience at Hospital Infantil de Mexico Federico Gomez.

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.

Neurotransmisores del sistema límbico. Hipocampo. GABA y memoria. Segunda parte

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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.

Neurotransmisores del sistema límbico. Hipocampo, GABA y memoria. Primera parte

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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.

Tumores intracraneanos del niño / Pediatric intracranial tumors

Introducción. Los tumores intracraneanos (TIC) pediátricos son las neoplasias sólidas más frecuentes en niños. Se presenta la experiencia del Hospital Infantil de México Federico Gómez (HIMFG) de los últimos 36 años. Material y métodos. Se utilizaron los siguientes archivos del HIMFG: Clínico, de los Departamentos de Neurocirugía y de Patología. Los resultados se compararon con los datos del Hospital for Sick Children de Toronto y del Instituto Nacional de Pediatría de México, D. F. Resultados. En el HIMFG, 55% de los pacientes eran del sexo masculino. Predominaron desde lactantes mayores hasta escolares, con más de 50%. Los tumores fueron: 397 supratentoriales y 413 infratentoriales. Los más frecuentes fueron: astrocitomas (32%), meduloblastomas (19%), craneofaringiomas (11%) y ependimomas (10%); en el quinto lugar quedaron los germinomas (4%). Los gliomas mixtos, los meningiomas, los tumores neuroectodérmicos primitivos y los ependimoblastomas representaron de 1 a 3%. Conclusiones. En el HIMFG, los 4 tipos más frecuentes de tumor fueron: astrocitomas, meduloblastomas, craneofaringiomas y ependimomas. El trabajo de campo del HIMFG ha tenido un desarrollo exponencial desde la mitad de los años setenta. Actualmente, el volumen de pacientes manejado por el HIMFG es semejante a, o rebasa discretamente, al de otras instituciones.

Introduction. Pediatric intracranial tumors (PIC) make up the most frequent solid neoplastic pathology in children. We present an analysis of the experience of Hospital Infantil de Mexico Federico Gomez (HIMFG), in Mexico City, over the course of 36 years in this regard. Material and methods. Cases from the archives of the Department of Clinical Records, Department of Neurosurgery and Department of Pathology at HIMFG were used for this analysis. Results were compared to data published by the Hospital for Sick Children of Toronto (HSCT) and by Instituto Nacional de Pediatria (INP) in Mexico City. Results. Of 810 cases reviewed at HIMFG, 55% belonged to the male gender. By age, older-infant and grade-school-children cases predominated (> 50%). Of those, 397 cases were supratentorial and 413 infratentorial. Most frequent tumors were: astrocytomas (23%), medulloblastomas , craniopharyngiomas (11%) and ependymomas (10%). Fifth place was occupied by germinomas (4%). Mixed gliomas, meningiomas, primitive neuroectodermal tumors and ependymoblastomas were the last (1 to 3%). Conclusions. At HIMFG, the most frequent tumour types were: astrocytomas, medulloblastomas, craniopharyngiomas and ependymomas. Since the 70s, on the number of patients presenting with intracranial tumors at HIMFG has grown exponentially, and the amount carried out till now at this hospital parallels, or slightly exceeds, that carried out at similar institutions in Mexico and abroad.

Surgery of tumors of the cerebellum and prefrontal cortex, and sensory memory and motor planning disturbances in children.

OBJECT: This study addressed the integration of sensory short-term memory (SSTM) and motor planning (MP) in the lateral cerebellar region, where the dentate nucleus is localized, and in the prefrontal cortex (PF). METHODS: Boucher and Lewis's test of SSTM and MP was administered pre- and postsurgically to 8 patients of either sex, between 5 and 19 years of age, with tumors of the cerebellum, PF (area 9 medial) or the parieto-occipital region, and on one occasion to 8 corresponding controls. RESULTS: Whereas lesions of the midline portions of the cerebellum and of the parietal-occipital region did not appear to cause any cognitive defects, patients with lesions affecting either the lateral cerebellar region or PF exhibited statistically significant deficits of SSTM and MP. CONCLUSIONS: The lateral cerebellum seems to act in concert with PF to integrate different cognitive activities related to holding objects in SSTM and planning motor strategies in reference to them.