El papel de la tractografía en la localización del núcleo ventralis intermedius del tálamo y el haz dentatorrubrotalámico en el tratamiento del temblor / The role of tractography in the localization of the Vim nucleus of the thalamus and the dentato-rubro-thalamic tract for the treatment of tremor

Introducción: La diana habitual empleada para el tratamiento quirúrgico del temblor es el núcleo ventralis intermedius (Vim) del tálamo. Su localización es compleja, ya que no se puede visualizar con métodos de imagen convencionales, por lo que para el procedimiento quirúrgico se toman clásicamente medidas indirectas y se correlacionan con la clínica y neurofisiología intraoperatorias. Sin embargo, procedimientos ablativos actuales como la talamotomía por gamma-knife o por ultrasonidos (MRgFUS) hacen que sea preciso buscar otras alternativas para su localización. El objetivo del presente trabajo es comparar la localización indirecta del Vim mediante técnica esterotáctica con la realizada directamente por tractografía para el tratamiento del temblor.DiscusiónLa definición citoarquitectónica más empleada del Vim es la del atlas de Schaltenbrand-Wahren. Existe un límite claro entre el tálamo motor y el sensitivo; las neuronas del Vim responden a movimientos pasivos articulares y su actividad es sincrónica con el temblor periférico. Las coordenadas estereotácticas del Vim más frecuentemente utilizadas se basan en mediciones indirectas respecto a la línea intercomisural y el III ventrículo, las cuales dependen de variaciones interindividuales. Estudios recientes han propuesto el haz dentatorrubrotalámico como una diana óptima para el control del temblor, postulando que se asocia a una mejoría clínica; sin embargo, esto no ha sido corroborado por otros autores.ConclusionesLa visualización de la vía cerebelorrubrotalámica por tractografía puede ayudar a definir la localización del Vim. Esta técnica tiene limitaciones inherentes y sería necesaria una estandarización del método para lograr resultados más precisos. La posible mayor utilidad de la diana por tractografía, directa, sobre la indirecta queda por demostrar a largo plazo en pacientes con temblor. (AU)

Introduction: The ventralis intermedius (Vim) nucleus of the thalamus is the usual surgical target for tremor. However, locating the structure may be difficult as it is not visible with conventional imaging methods; therefore, surgical procedures typically use indirect calculations correlated with clinical and intraoperative neurophysiological findings. Current ablative surgical procedures such as Gamma-Knife thalamotomy and magnetic resonance-guided focused ultrasound require new alternatives for locating the Vim nucleus. In this review, we compare Vim nucleus location for the treatment of tremor using stereotactic procedures versus direct location by means of tractography.DiscussionThe most widely used cytoarchitectonic definition of the Vim nucleus is that established by Schaltenbrand and Wahren. There is a well-defined limit between the motor and the sensory thalamus; Vim neurons respond to passive joint movements and are synchronous with peripheral tremor. The most frequently used stereotactic coordinates for the Vim nucleus are based on indirect calculations referencing the mid-commissural line and third ventricle, which vary between patients. Recent studies suggest that the dentato-rubro-thalamic tract is an optimal target for controlling tremor, citing a clinical improvement; however, this has not yet been corroborated.ConclusionsVisualisation of the cerebello-rubro-thalamic pathway by tractography may help in locating the Vim nucleus. The technique has several limitations, and the method requires standardisation to obtain more precise results. The utility of direct targeting by tractography over indirect targeting for patients with tremor remains to be demonstrated in the long-term. (AU)

The role of tractography in the localization of the Vim nucleus of the thalamus and the dentato-rubro-thalamic tract for the treatment of tremor. / El papel de la tractografía en la localización del núcleo ventralis intermedius del tálamo y el haz dentatorrubrotalámico en el tratamiento del temblor.

INTRODUCTION: The ventralis intermedius (Vim) nucleus of the thalamus is the usual surgical target for tremor. However, locating the structure may be difficult as it is not visible with conventional imaging methods; therefore, surgical procedures typically use indirect calculations correlated with clinical and intraoperative neurophysiological findings. Current ablative surgical procedures such as Gamma-Knife thalamotomy and magnetic resonance-guided focused ultrasound require new alternatives for locating the Vim nucleus. In this review, we compare Vim nucleus location for the treatment of tremor using stereotactic procedures versus direct location by means of tractography. DISCUSSION: The most widely used cytoarchitectonic definition of the Vim nucleus is that established by Schaltenbrand and Wahren. There is a well-defined limit between the motor and the sensory thalamus; Vim neurons respond to passive joint movements and are synchronous with peripheral tremor. The most frequently used stereotactic coordinates for the Vim nucleus are based on indirect calculations referencing the mid-commissural line and third ventricle, which vary between patients. Recent studies suggest that the dentato-rubro-thalamic tract is an optimal target for controlling tremor, citing a clinical improvement; however, this has not yet been corroborated. CONCLUSIONS: Visualisation of the cerebello-rubro-thalamic pathway by tractography may help in locating the Vim nucleus. The technique has several limitations, and the method requires standardisation to obtain more precise results. The utility of direct targeting by tractography over indirect targeting for patients with tremor remains to be demonstrated in the long-term.

The role of tractography in the localisation of the Vim nucleus of the thalamus and the dentatorubrothalamic tract for the treatment of tremor.

INTRODUCTION: The ventralis intermedius (VIM) nucleus of the thalamus is the usual surgical target for tremor. However, locating the structure may be difficult as it is not visible with conventional imaging methods; therefore, surgical procedures typically use indirect calculations correlated with clinical and intraoperative neurophysiological findings. Current ablative surgical procedures such as Gamma-Knife thalamotomy and magnetic resonance-guided focused ultrasound require new alternatives for locating the VIM nucleus. In this review, we compare VIM nucleus location for the treatment of tremor using stereotactic procedures versus direct location by means of tractography. DISCUSSION: The most widely used cytoarchitectonic definition of the VIM nucleus is that established by Schaltenbrand and Wahren. There is a well-defined limit between the motor and the sensory thalamus; VIM neurons respond to passive joint movements and are synchronous with peripheral tremor. The most frequently used stereotactic coordinates for the VIM nucleus are based on indirect calculations referencing the mid-commissural line and third ventricle, which vary between patients. Recent studies suggest that the dentato-rubro-thalamic tract is an optimal target for controlling tremor, citing a clinical improvement; however, this has not yet been corroborated. CONCLUSIONS: Visualisation of the cerebello-rubro-thalamic pathway by tractography may help in locating the VIM nucleus. The technique has several limitations, and the method requires standardisation to obtain more precise results. The utility of direct targeting by tractography over indirect targeting for patients with tremor remains to be demonstrated in the long-term.

Resonancia magnética intraoperatoria de 3 teslas: Nuestra experiencia en patología tumoral / Intraoperative 3 tesla magnetic resonance imaging: our experience in tumors

Objetivo. Describir nuestra experiencia con la resonancia magnética intraoperatoria (RMio) de 3 teslas en procedimientos neuroquirúrgicos en patología tumoral y evaluar los criterios que condicionaron la ampliación quirúrgica. Material y métodos. Estudio retrospectivo en el que se incluyeron todas las RMio consecutivas realizadas por patología neurooncológica en los primeros 13 meses tras su instalación. Se registraron las posibles complicaciones inmediatas, la presencia de restos tumorales y la modificación de la actitud quirúrgica por los resultados de la RMio. Se midió el tiempo quirúrgico en todos los casos. Resultados. El mayor porcentaje de lesiones resecadas correspondió a glioblastomas recidivados, seguido de glioblastomas primarios y metástasis. Se evidenció una resección completa en un 28% y restos tumorales en un 72%. La RMio permitió a los neurocirujanos mejorar la extensión de la resección en un 85%. La media del tiempo quirúrgico fue de 390±122 minutos. Conclusión. La RMio con equipos de alto campo (3 teslas) es una técnica novedosa y válida, que permite estudiar la resección tumoral de forma precisa y evaluar si se puede continuar la resección sin dañar zonas elocuentes. Aunque su empleo conlleva una prolongación del tiempo quirúrgico, este mejora con la curva de aprendizaje del personal

Objective. To report our experience in the use of 3 tesla intraoperative magnetic resonance imaging (MRI) in neurosurgical procedures for tumors, and to evaluate the criteria for increasing the extension of resection. Material and methods. This retrospective study included all consecutive intraoperative MRI studies done for neuro-oncologic disease in the first 13 months after the implementation of the technique. We registered possible immediate complications, the presence of tumor remnants, and whether the results of the intraoperative MRI study changed the surgical management. We recorded the duration of surgery in all cases. Results. The most common tumor was recurrent glioblastoma, followed by primary glioblastoma and metastases. Complete resection was achieved in 28%, and tumor remnants remained in 72%. Intraoperative MRI enabled neurosurgeons to improve the extent of the resection in 85% of cases. The mean duration of surgery was 390±122minutes. Conclusion. Intraoperative MRI using a strong magnetic field (3 teslas) is a valid new technique that enables precise study of the tumor resection to determine whether the resection can be extended without damaging eloquent zones. Although the use of MRI increases the duration of surgery, the time required decreases as the team becomes more familiar with the technique

Intraoperative 3 tesla magnetic resonance imaging: our experience in tumors. / Resonancia magnética intraoperatoria de 3 teslas: Nuestra experiencia en patología tumoral.

OBJECTIVE: To report our experience in the use of 3 tesla intraoperative magnetic resonance imaging (MRI) in neurosurgical procedures for tumors, and to evaluate the criteria for increasing the extension of resection. MATERIAL AND METHODS: This retrospective study included all consecutive intraoperative MRI studies done for neuro-oncologic disease in the first 13 months after the implementation of the technique. We registered possible immediate complications, the presence of tumor remnants, and whether the results of the intraoperative MRI study changed the surgical management. We recorded the duration of surgery in all cases. RESULTS: The most common tumor was recurrent glioblastoma, followed by primary glioblastoma and metastases. Complete resection was achieved in 28%, and tumor remnants remained in 72%. Intraoperative MRI enabled neurosurgeons to improve the extent of the resection in 85% of cases. The mean duration of surgery was 390±122minutes. CONCLUSION: Intraoperative MRI using a strong magnetic field (3 teslas) is a valid new technique that enables precise study of the tumor resection to determine whether the resection can be extended without damaging eloquent zones. Although the use of MRI increases the duration of surgery, the time required decreases as the team becomes more familiar with the technique.