Callosotomía: técnicas, resultados y complicaciones: revisión de la literatura / Callosotomy: techniques, results and complications: literature review

Background: Patients with intractable seizures who are not candidates for focal resective surgery are indicated for a palliative surgical procedure, the callosotomy. This procedure is based on the hypothesis that the corpus callosum is an important pathway for interhemispheric spread of epileptic activity and, for drug resistant epilepsy. It presents relatively low permanent morbidity and an efficacy in the control of seizures. Based on literature, the corpus callosotomy improves the quality of life of patients that has the indication to perform this procedure because it allows reducing the frequency of seizures, whether tonic or atonic, tonic-clonic, absence or frontal lobe complex partial seizures. Aim: The aim of this literature review is discuss the technical details, modalities, risks, complications, results as well de prognosis of callosotomy based on critical literature review and the authors experience. Casuistry and Methods: It was performed bibliographical consultation, using the databases MEDLINE, LILACS, SciELO, utilizing language as selection criteria, choosing preferably recent articles in Portuguese, Spanish or English, with publication year higher than 2000. Conclusion: According to author’s experience and references, callosotomy is a safe procedure when indicated to selected cases and the success rate is proportional to the extent of callosal resection. A greater resection can reduce the seizure frequency, however the morbidity may also be larger. There is no important study comparing VNS versus Callosotomy versus VNS plus callososotomy, what would be for future necessary for an important source of data about this topic.

Introducción: Los pacientes con convulsiones intratables que no son candidatos para la cirugía de resección focal están indicados para un procedimiento quirúrgico paliativo, la callosotomía. Este procedimiento se basa en la hipótesis de que el cuerpo calloso es una importante vía para la propagación interhemisférica de la actividad epiléptica y, para la epilepsia resistente a fármacos. Presenta relativamente baja morbilidad permanente y una eficacia en el control de las convulsiones. Sobre la base de la literatura, la callostomía mejora la calidad de vida de los pacientes que tiene la indicación para realizar este procedimiento, ya que permite reducir la frecuencia de las crisis, ya sean tónica o átona, tónico-clónicas, ausencia o lóbulo frontal crisis parciales complejas. Objetivo: El objetivo de esta revisión de la literatura es discutir los detalles técnicos, modalidades, riesgos, complicaciones, resultados y de pronóstico de callosotomía basado en la revisión crítica de la literatura y la experiencia de los autores. Casuística y Métodos: Se realizó la consulta bibliográfica, utilizando la base de datos MEDLINE, LILACS, SciELO, que utiliza el lenguaje como criterios de selección, la elección de los artículos recientes preferiblemente en portugués, español o Inglés, con el año de publicación superior a 2000. Conclusión: De acuerdo con la experiencia y las referencias del autor, callosotomía es un procedimiento seguro cuando indicado para casos seleccionados y la tasa de éxito es proporcional a la extensión de la resección del cuerpo calloso. A mayor resección puede reducir la frecuencia de las crisis, sin embargo, la morbilidad puede ser también mayor. No hay ningún estudio que compara la estimulación del nervio vago frente a frente callosotomía VNS más callososotomy, lo que sería la futura necesaria para una importante fuente de datos sobre este tema.

Changes caused by hidrocephalus, induced by kaolin, in the corpus callosum of adult dogs / Alterações causadas pela hidrocefalia, induzida por caulim, no corpo caloso de cães adultos

PURPOSE: To analyze the ventricular enlargement and myelination of the corpus callosum in adult dogs after four and eight weeks of kaolin-induction of hydrocephalus. METHODS: 36 dogs were randomly divided into 3 groups: 1 - without hydrocephalus, 2 - kaolin-induction of hydrocephalus until the fourth week, and 3 - kaolin-induction of hydrocephalus until the eighth week. Ventricular ratios and volumes were calculated using magnetic resonance images, and myelination of the corpus callosum were histologically evaluated using solocromo-cianin stain. RESULTS: Radiological hydrocephalus was observed in 93.75 percent and overall mortality was 38.4 percent. Ventricular volumes and ratios were higher in groups 2 and 3 compared to group 1 and similar when measures in the fourth and eighth weeks were compared in the group 3. Indices of luminescence in the knee and in the splenium of the corpus callosum were higher in group 2 than in group 1 indicating that there was loss of myelin in group 2, and similar in groups 1 and 3, showing a tendency to remyelination after 8 weeks. CONCLUSION: The corpus callosum of dogs with kaolin-induced hydrocephalus responds with demyelination of the knee and splenium by the fourth week with a tendency to remyelination by the eighth week.

OBJETIVO: Analisar a dilatação ventricular e a mielinização do corpo caloso em cães adultos após quatro e oito semanas da indução de hidrocefalia por caulin. MÉTODOS: 36 cães foram aleatoriamente divididos em 3 grupos: 1- sem hidrocefalia, 2- quatro semanas de hidrocefalia induzida por caulin, 3- oito semanas de hidrocefalia induzida por caulin. As razões e volumes ventriculares foram calculados utilizando imagens de ressonância magnética, e, a mielinização do corpo caloso por estudo histológico (coloração com solocromo- cianina). RESULTADOS: Hidrocefalia foi observada radiologicamente em 93,75 por cento e a mortalidade global foi de 38,4 por cento. Os volumes e as razões ventriculares foram maiores nos grupos 2 e 3 em relação ao grupo 1 e semelhantes nas quarta e oitava semanas no grupo 3. Índices de luminescência no joelho e no esplênio do corpo caloso foram maiores no grupo 2 em relação ao grupo 1, indicando que houve perda de mielina no grupo 2, e semelhantes nos grupos 1 e 3, mostrando uma tendência à remielinização em torno de 8 semanas. CONCLUSÃO: O corpo caloso de cães com hidrocefalia induzida por caulin responde com desmielinização no joelho e esplênio em torno de quatro semanas com tendência à remielinização em torno da oitava semana.

O corpo caloso: dimorfismo sexual / The corpus callosum: sexual dimorphism

A sotura realiza uma revisäo da literatura, estudando o dimorfismo sexual no corpo caloso humano

Anomalous patterns of callosal connections develop in visual cortex of monocularly enucleated hamsters

In this study we analyzed the effect of neonatal monocular enucleation on the pattern of callosal connections in striate cortex of the golden hamster. Callosal connections were revealed in the hemisphere ipsilateral to the remaining eye following multiple injections of either the enzyme horseradish peroxidase or the fluorescent tracer Fluoro-Gold into the contralateral hemisphere. The most salient anomaly induced by the removal of one eye at birth is the appearance of a dense band of callosal connections that runs anteroposteriorly in medial portions of striate cortex. No obvious changes in the laminar distribution of callosal connections were observed. Comparison of our present results with those obtained by Olavarria et al (1987) in monocularly enucleated rats reveals that neonatal enucleation induces remarkably similar anomalies in the callosal patterns of rats and hamsters. This similarity suggests that the role the eyes play in the development of the visual callosal pathway is similar among rodent species. Moreover, the finding of an anomalous callosal band in striate cortex one-eyed hamsters supports the notion that disruption of visual input does not arrest callosal development, but rather leads to the development of entirely new features in the callosal pattern

Consecuencias funcionales de la vía transcallosa / Functional consequences of the transcallosal approach

Desde su descripción inicial, el abordaje transcalloso ha demostrado su utilidad y la ausencia apaente de secuelas a largo plazo. Apesar de ello, los estudios sobre la función del cuerpo calloso han demostrado que esta estructura participa activamente en la transferencia interhemisférica de información sensorial y cognitiva. Ante esto es necesario conocer si la vía transcallosa daña al cuerpo calloso lo suficiente como para perjudicar el desarrollo de una vida independiente. Los estudios neurpsicológicos demuestran que la utilización de la vía transcallosa genera signos de desconexión cerebral. Estos no son percibidos por los pacientes y no tienen repercusíon clínica. Para que ellos ocurra es necesario que la callosotomía sea pequeña y se utilicen técnicas microqurúrgicas. De análisis bibliográficos surge claramente que la vía trascallosa no genera trastornos funciolnales que perjudiquen una vida independiente