Is structural connectivity different in child and adolescent relatives of patients with bipolar disorder? A narrative review according to studies with DTI.

INTRODUCTION: Bipolar disorder (BD) has been associated with a decrease in white matter integrity. Diffusion tensor imaging (DTI) studies have enabled these changes to be elucidated with higher quality. Due to BD's high heritability, some studies have been conducted in relatives of BD patients looking at white matter integrity, and have found that structural connectivity may also be affected. This alteration has been proposed as a potential BD biomarker of vulnerability. However, there are few studies in children and adolescents. OBJECTIVE: To conduct a review of the literature on changes in white matter integrity determined by DTI in high-risk children and adolescents. RESULTS: Brain structural connectivity in the paediatric population is described in studies using DTI. Changes in the myelination process from its evolution within normal neurodevelopment to the findings in fractional anisotropy (FA) in BD patients and their high-risk relatives are also described. CONCLUSIONS: Studies show that both BD patients and their at-risk relatives present a decrease in FA in specific brain regions. Studies in children and adolescents with a high risk of BD, indicate a reduced FA in axonal tracts involved in emotional and cognitive functions. Decreased FA can be considered as a vulnerability biomarker for BD.

¿Es diferente la conectividad estructural en niños y adolescentes familiares de pacientes con trastorno bipolar? Una revisión narrativa según estudios con DTI

Introducción: El trastorno afectivo bipolar (TAB) se ha asociado con una disminución de la integridad de la sustancia blanca. Los estudios con imágenes con tensor de difusión (DTI) han permitido elucidar con una mayor calidad estos cambios. Debido a la gran heredabilidad del TAB, se han realizado estudios en familiares de pacientes con TAB acerca de la integridad de la sustancia blanca, y se ha encontrado que la conectividad estructural también puede estar afectada. Dicha alteración se ha propuesto como un potencial biomarcador de vulnerabilidad a este trastorno. Sin embargo, los estudios en niños y adolescentes son pocos. Objetivo: Revisar la literatura sobre los cambios en la integridad de la sustancia blanca determinados mediante DTI en niños y adolescentes con alto riesgo. Resultados: Se describe la conectividad estructural cerebral en la población pediátrica en estudios que utilizaron DTI. Se describen los cambios en el proceso de mielinización desde su evolución dentro del neurodesarrollo normal hasta los hallazgos en la anisotropía fraccional (AF) en pacientes con TAB y los familiares en alto riesgo. Conclusiones: Los estudios demuestran que tanto pacientes con TAB como sus familiares en riesgo presentan disminución de la AF en regiones cerebrales específicas. Los estudios en niños y adolescentes con riesgo familiar de TAB señalan una AF reducida en tractos axonales implicados en funciones emocionales y cognitivas. La disminución de la AF puede considerarse como un biomarcador de vulnerabilidad al TAB.

Introduction: Bipolar disorder (BD) has been associated with a decrease in white matter integrity. Diffusion tensor imaging (DTI) studies have enabled these changes to be elucidated with higher quality. Due to BD's high heritability, some studies have been conducted in relatives of BD patients looking at white matter integrity, and have found that structural connectivity may also be affected. This alteration has been proposed as a potential BD biomarker of vulnerability. However, there are few studies in children and adolescents. Objective: To conduct a review of the literature on changes in white matter integrity determined by DTI in high-risk children and adolescents. Results: Brain structural connectivity in the paediatric population is described in studies using DTI. Changes in the myelination process from its evolution within normal neurodevelopment to the findings in fractional anisotropy (FA) in BD patients and their high-risk relatives are also described. Conclusions: Studies show that both BD patients and their at-risk relatives present a decrease in FA in specific brain regions. Studies in children and adolescents with a high risk of BD, indicate a reduced FA in axonal tracts involved in emotional and cognitive functions. Decreased FA can be considered as a vulnerability biomarker for BD.

Is Structural Connectivity Different in Child and Adolescent Relatives of Patients with Bipolar Disorder? A Narrative Review According to Studies with DTI. / ¿Es diferente la conectividad estructural en niños y adolescentes familiares de pacientes con trastorno bipolar? Una revisión narrativa según estudios con DTI.

INTRODUCTION: Bipolar disorder (BD) has been associated with a decrease in white matter integrity. Diffusion tensor imaging (DTI) studies have enabled these changes to be elucidated with higher quality. Due to BD's high heritability, some studies have been conducted in relatives of BD patients looking at white matter integrity, and have found that structural connectivity may also be affected. This alteration has been proposed as a potential BD biomarker of vulnerability. However, there are few studies in children and adolescents. OBJECTIVE: To conduct a review of the literature on changes in white matter integrity determined by DTI in high-risk children and adolescents. RESULTS: Brain structural connectivity in the paediatric population is described in studies using DTI. Changes in the myelination process from its evolution within normal neurodevelopment to the findings in fractional anisotropy (FA) in BD patients and their high-risk relatives are also described. CONCLUSIONS: Studies show that both BD patients and their at-risk relatives present a decrease in FA in specific brain regions. Studies in children and adolescents with a high risk of BD, indicate a reduced FA in axonal tracts involved in emotional and cognitive functions. Decreased FA can be considered as a vulnerability biomarker for BD.

Tractografía de la vía dento-rubro-talámica en mutismo cerebeloso postoperatorio en niños con tumores de fosa posterior / Analysis of diffusion tensor imaging tractography of the dentate-rubro-thalamic pathway in postoperative cerebellar mutism in children with posterior fossa tumors

Introduction: Cerebellar mutism syndrome refers to the muteness (lack of speech) that follows lesions of the cerebellum. It’s characterized by a late onset, limited duration, and in some cases long-term language sequelae. Its pathogenesis it s not clear yet, but it has been attributed a role to a damage of the dentate nucleus and of the dento-rubro-thalamic tract. Objectives: Identify potential risk factors (clinical or anatomical) to predict the onset of cerebellar mutism after posterior fossa surgery Compare, using MRI analysis and DTI tractography, the integrity of the dento-rubro-thalamic tract in patients with and without cerebellar mutism. Methods: Prospective follow up study of patients operated of posterior fossa tumors between November 2012 and 2013. We performed a study with DTI of the dento rubro thalamic tract in pacients with and without postoperative mutism. Results: 53 patients under the diagnosis of posterior fossa tumor underwent surgical resection. 5 pacients presented postoperative mutism (9,4 percent). There was a significant association between postoperative medulloblastoma diagnosis and postoperative mutism. Tumor volume was not significant. The volume of left and right dento rubro thalamic tract were significantly lower in patients with cerebellar mutism. The fractional anisotropy of the right superior cerebellar peduncle was also lower in patients with postoperative mutism. Conclusions: The postoperative cerebellar mutism is a relevant complication after a posterior fossa surgery. Our study supports the role of dento rubro thalamic tract damage in the pathogenesis of this syndrome. Special care must be taken during surgery to prevent damage to this tract.

Introducción: El síndrome mutismo cerebeloso consiste en falta del habla posterior a lesiones del cerebelo. Se caracteriza por inicio tardío, duración limitada, y ocasionalmente secuelas lingüísticas. Su patogenia no está clara, pero se ha atribuido un rol a daños en el núcleo dentado y en la vía dento-rubro-talámica. Objetivos: Identificar posibles factores de riesgo (clínicos o anatómicos) asociados a la aparición de mutismo cerebeloso después de una cirugía de fosa posterior. Comparar, mediante un análisis de resonancia magnética (IRM) y tractografía por tensor de difusión (DTI), la integridad de la vía dento-rubro-talámica en pacientes con y sin mutismo cerebeloso. Métodos: Estudio prospectivo de pacientes operados por tumores de fosa posterior entre noviembre de 2012 y 2013. Se analizó con DTI la vía dento-rubro-talámica en pacientes con y sin mutismo postoperatorio. Se comparó la volumetría del tracto en ambas cohortes. Resultados: Cincuenta y tres pacientes con diagnóstico de tumor de fosa posterior fueron sometidos a cirugía de exéresis. Cinco pacientes presentaron mutismo postoperatorio (9,4 por ciento). Hubo una asociación significativa entre el diagnóstico de meduloblastoma y mutismo postoperatorio. El volumen tumoral no fue significativo. El volumen de la vía dento-rubro-talámica fue significativamente menor en pacientes con mutismo, en forma bilateral, así como la anisotropía fraccional del pedúnculo cerebeloso derecho. Conclusiones: El mutismo cerebeloso es una complicación relevante después de una cirugía de fosa posterior. Nuestro estudio apoya el papel del daño de la vía dento-rubro-talámica en la patogénesis de este síndrome. Se debe tener especial cuidado durante la cirugía para prevenir daños al núcleo dentado.