Reducing VNS stimulation parameters: Is it safe?

Introduction Vagal nerve stimulation (VNS) is an adjuvant therapy used in the treatment of patients with refractory epilepsy who are not candidates for resective surgery or who have limited results after surgical procedures. Currently, there is enough evidence to support its use in patients with various types of epilepsy. Therefore, the present study was conducted to explore the possibility of optimizing therapy by reducing the consumption of the system's battery. Methods The prospective and double-blind analysis consisted in the evaluation of 6 patients submitted to VNS implantation for 3 months, followed by adjustment of the stimulation settings and continuity of follow-up for another month. The standard protocol was replaced by another with a frequency value of 20 Hz instead of 30 Hz to increase battery life. The safety of this procedure was evaluated through the assessment of two main variables: seizures and side effects. Results The stimulation at 20 Hz showed 68% reduction in the incidence of seizures (p»0.054) as well as low incidence of side effects. Conclusion The present study suggests that the reduction of the stimulation frequency from 30 to 20 Hz is a safe procedure, and it does not compromise the effectiveness of therapy.

Anatomical study of jugular foramen in the neck / Estudo anatômico do forame jugular no pescoço

Abstract Introduction The anatomical complexity of the jugular foramen makes surgical procedures in this region delicate and difficult. Due to the advances in surgical techniques, approaches to the jugular foramen became more frequent, requiring improvement of the knowledge of this region anatomy. Objective To study the anatomy of the jugular foramen, internal jugular vein and glossopharyngeal, vagus and accessory nerves, and to identify the anatomical relationships among these structures in the jugular foramen region and lateral-pharyngeal space. Methods A total of 60 sides of 30 non-embalmed cadavers were examined few hours after death. The diameters of the jugular foramen and its anatomical relationships were analyzed. Results The diameters of the jugular foramen and internal jugular vein were greater on the right side in most studied specimens. The inferior petrosal sinus ended in the internal jugular vein up to 40 mm below the jugular foramen; in 5% of cases. The glossopharyngeal nerve exhibited an intimate anatomical relationship with the styloglossus muscle after exiting the skull, and the vagal nerve had a similar relationship with the hypoglossal nerve. The accessory nerve passed around the internal jugular vein via its anterior wall in 71.7% of cadavers. Conclusion Anatomical variations were found in the dimensions of the jugular foramen and the internal jugular vein, which were larger in size on the right side of most studied bodies; variations also occurred in the trajectory and anatomical relationships of the nerves. The petrosal sinus can join the internal jugular vein below the foramen.

Resumo Introdução A complexidade anatômica do forame jugular torna a realização de procedimentos cirúrgicos nessa região delicada e difícil. Devido aos avanços obtidos nas técnicas cirúrgicas, as abordagens do forame jugular têm sido feitas com maior frequência, o que requer uma melhoria correspondente no conhecimento de sua anatomia. Objetivo Estudar a anatomia do forame jugular, da veia jugular interna e dos nervos glossofaríngeo, vago e acessório, assim como as relações anatômicas entre estas estruturas na região do forame jugular e no espaço parafaríngeo. Método Foram examinados 60 lados de 30 cadáveres frescos algumas horas após a morte. Os diâmetros e suas relações anatômicas foram analisados. Resultados Os diâmetros do forame jugular e da veia jugular interna foram maiores no lado direito na maioria dos espécimes estudados. O seio petroso inferior terminava na veia jugular interna até 40 mm abaixo do forame jugular, em 5% dos casos. O nervo glossofaríngeo exibiu uma relação íntima anatômica com o músculo estiloglosso após a sua saída do crânio e o nervo vago exibiu uma relação semelhante com o nervo hipoglosso. O nervo acessório passou em torno da veia jugular interna via sua parede anterior em 71,7% dos cadáveres. Conclusão Foram encontradas variações anatômicas nas dimensões do forame jugular e da veia jugular interna, que apresentaram tamanhos maiores à direita na maioria dos espécimes estudados; variações também ocorreram na trajetória e nas relações anatômicas dos nervos. O seio petroso pode se unir à veia jugular interna abaixo do forame.

Apparent origin of glossopharyngeal, vagus and accessory nerves: an aspect to consider in human neuroanatomy teaching / El origen aparente de los nervios glosofaríngeo, vago y accesorio: un aspecto para considerar en la enseñanza de neuroanatomía humana

In various neuroanatomy texts and articles related to this area of knowledge, there is a conceptual vacuum associated with the precise sites where the roots of the cranial nerves emerge. The objective of the study was to establish the exact location of the apparent origin of the glossopharyngeal, vagus and accessory cranial nerves in the medulla oblongata of the human being 120 human brainstems, previously fixed in formalin solution at 10 % were assessed, the location where such nerve roots emerge was identified by direct examination and once the piamater was removed at both right and left sides as it has been stated in the literature. It was found that in 100 % of the studied brainstems their nerve roots emerge on average at about 2.63 mm behind the retro-olivary groove, different to what has been stated in the literature. Glossopharyngeal, vagus and accessory human nerves do not emerge directly from the retroolivary groove, as commonly reported; instead, they emerge behind the said groove, specifically in the retro-olivary groove area, where they form a continuous line of nerve roots.

En diversos textos de neuroanatomía y artículos relacionados con esta área del conocimiento, se evidencia un vacío conceptual asociado con los sitios precisos por donde emergen los pares craneales. El objetivo de este estudio fue stablecer la ubicación exacta del origen aparente de los nervios craneales glosofaríngeo, vago y accesorio en el bulbo raquídeo de 120 tallos cerebrales humanos, previamente fijados en solución de formalina al 10 %. Fueron evaluados, el lugar donde surgen tales raíces nerviosas se identificó mediante examen directo y una vez que se retiró la piamadre tanto en el lado derecho como en el izquierdo como se ha dicho en la literatura. Se encontró que en el 100 % de los troncos cerebrales estudiados, sus raíces nerviosas emergen en promedio a unos 2,63 mm detrás del surco retroolivar, diferente a lo que se ha dicho en la literatura. Los nervios humanos glosofaríngeos, vago y accesorio no emergen directamente de la ranura retroolivar, como se informa comúnmente, sino que emergen detrás de dicha ranura, específicamente en el área de surco retroolivar, donde forman una línea continua de raíces nerviosas.

The recurrent laryngeal cardiac nerve in fetuses / El nervio laríngeo recurrente cardiaco en fetos

The recurrent laryngeal nerve has been reported to supply cardiac branches to the cardiac plexus. A review of anatomical literature on the existing term used to describe these branches revealed that varying interpretations and descriptions exist among various authors. Therefore, this study aimed to investigate the origin and incidence of branches from the recurrent laryngeal nerves to the cardiac plexus and their connections with sympathetic cardiac nerves. The sample comprised 40 cadaveric fetuses (n=80) (gestational ages: 16-30 weeks). The recurrent laryngeal cardiac nerve was described as the cardiac branch that originated directly from the recurrent laryngeal nerve and reached the superficial or deep parts of the cardiac plexus. This study found the recurrent laryngeal cardiac nerve in 76% of the cases contributing direct and indirect branches in 75% and 25% of the cases, respectively. This study recorded only two (2%) of these branches contributing to the superficial cardiac plexus while the rest (74%) of these branches contributed to the deep cardiac plexuses. The remaining 24% had no contributions from the recurrent laryngeal nerve to either the superficial or deep part of the cardiac plexus. The most common point of origin for the recurrent laryngeal cardiac nerve was at the lower distal part in 59% of the specimens. In the remaining 41% of branches, this nerve originated from the point of curvature, upper proximal part and both the point of curvature and lower distal part in 26%, 10% and 5% of the specimens.

El nervio laríngeo recurrente suministra las ramas cardiacas para el plexo cardíaco. Una revisión de la literatura anatómica nos muestra que existen diferentes interpretaciones y descripciones de estas ramas por parte de los distintos autores consultados. En consecuencia este estudio tuvo como objetivo investigar el origen, además de la incidencia de las ramas de los nervios laríngeos recurrentes al plexo cardíaco y sus conexiones con los nervios cardiacos simpáticos. La muestra incluyó 40 fetos (n=80) (edades gestacionales: 16-30 semanas). El nervio laríngeo recurrente cardiaco fue descrito como la rama cardíaca que se originó directamente del nervio laríngeo recurrente, que llega a las partes superficiales o profundas del plexo cardíaco. En este estudio observamos que el nervio laríngeo recurrente cardiaco en el 76% de los casos contribuye a las ramas directas e indirectas, en el 75% y el 25% de los casos, respectivamente. Se observó en este estudio que solamente dos (2%) de estas ramas contribuían en la formación del plexo cardíaco superficial, mientras que el resto (74%) de estas ramas contribuía a los plexos cardíacos profundos. El 24% restante no tenía contribuciones del nervio laríngeo recurrente ya sea para la parte superficial o profunda del plexo cardíaco. El punto de origen más común del nervio laríngeo recurrente cardiaco se observó en la parte distal inferior en un 59% de las muestras. En el 41% restante de las ramas este nervio se originó desde el punto de curvatura, la parte proximal superior y tanto en el punto de curvatura inferior como la parte distal en 26%, 10% y 5% de los especímenes.

The brainstem localization of gastric preganglionic parasympathetic neurons in the Agouti (Dasyprocta leporina) / Localización del tronco encefálico de las neuronas parasimpáticas preganglionares gástricas en el agutí (Dasyprocta leporina)

This study was designed to determine qualitatively, the source of gastric vagal nerve fibres in the Agouti. A total of 18 male and female adult agoutis were used for the present investigation. Following anaesthesia, laparotomy was performed and the stomach exteriorized. Multiple intramuscular injections of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) were then made into different areas of the stomach in the experimental animals. The control animals were divided into four groups of two animals each. The first group had intraperitoneal injection of the tracer, the second had intramuscular injection of normal saline, the third group had injection of tracer into the hepatic portal vein and the last group had injection of the tracer into the gastric walls followed immediately by bilateral vagotomy. Following a survival period offive to seven days, the animals were sacrificed by transcardial perfusion, first with normal saline followed by fixative and finally with 20% buffered sucrose. Following perfusion, the brainstem was extracted from the brain, immersed in 20% buffered sucrose and kept refrigerated overnight for cryoprotection. The brainstems were subsequently sectioned serially, processed for WGA-HRP neurohistochemistry and then analysed under light and dark-field illuminations. The analysis of the sections taken from the experimental animals revealed bilateral presence of WGA-HRP labelled neurons in the dorsal motor nucleus of the vagus nerve (DMNV) and the nucleus ambiguus (nA) of the medulla oblongata. No labelled neurons were seen in any of the sections taken from the control animals. The implications of the findings are discussed.

Este estudio fue diseñado para determinar cualitativamente el origen de las fibras gástricas del nervio vago en el agutí. Un total de 18 agutíes adultos masculinos y femeninos fueron utilizados para la presente investigación. Después de la anestesia, se realizó una laparotomía y se sacó el estómago al exterior. Luego se hicieron múltiples inyecciones intramusculares de aglutinina de germen de trigo con peroxidasa de rábano (WGA-HRP) en diferentes áreas del estómago de los animales experimentales. Los animales del control fueron divididos en cuatro grupos de dos animales cada uno. Al primer grupo se le puso una inyección intraperitoneal del marcador; al segundo se le administró una inyección intramuscular de solución salina normal; al tercer grupo se le inyectó el marcador en la vena porta hepática; y al último grupo se le puso la inyección del marcador en las paredes gástricas, seguida inmediatamente por una vagotomía bilateral. Tras un periodo de supervivencia de cinco a siete días, los animales fueron sacrificados por perfusión transcardíaca, primero con solución salina normal, seguida de fijador, y finalmente con sacarosa tamponada al 20%. Después de la perfusión, el tronco encefálico fue extraído del cerebro, inmerso en sacarosa tamponada al 20%, y mantenido en refrigeración durante la noche para su crioprotección. Los tronos encefálicos fueron luego seccionados en serie, procesados para para el análisis neuro-histoquímico mediante aglutinina de germen de trigo con peroxidasa de rábano, y analizados entonces bajo iluminaciones de campo de luz y campo oscuro. El análisis de las secciones tomadas de animales experimentales reveló la presencia bilateral de neuronas etiquetadas WGA-HRP en el núcleo motor dorsal del nervio vago (DMNV) y en el núcleo ambiguo (nA) de la médula oblonga. No se observaron neuronas etiquetadas en ninguna de las secciones tomadas de los animales de control. Se discuten las implicaciones de los hallazgos.

The organization of the brainstem nuclei associated with the vagus nerve in the agouti (Dasyprocta Leporina): a neurohistological study / Organización de los núcleos del tronco del encéfalo asociados con el nervio vago en el agutí (Dasyprocta Leporina): un estudio neurohistológico

A total of six adult animals were used for the study. Following anaesthesia via intraperitoneal injection of a mixture ofketamin and bombazine in ratio 2:1, thoracotomy was performed to exteriorize the heart for intracardial perfusion. The perfusion canular was inserted into the left ventricle and animal perfused sequentially with normal saline and 10% formal saline. Following perfusion, craniotomy was performed to remove the entire brain along with the upper segments ofthe spinal cord. The brain specimen was then dehydrated, cleared and infiltrated with paraffin wax. The specimen was then cut in 15 micron thick serial sections. The sections were then processed for neurohistological analyses using a Nikon microscope to which was attached Nikon camera. Analyses ofthe sections revealed bilateral representation ofthe dorsal motor nucleus ofthe vagus nerve in the medulla oblongata. The nucleus ambiguus, nucleus ofthe tractus solitarius, hypoglossal nucleus and the area postrema were also identified in the medulla oblongata. The implications ofour findings are discussed in the text ofthe article.

Un total de seis animales adultos fueron usados para el estudio. Tras de una anestesia mediante una inyección intraperitoneal de una mezcla de ketamina y bombazina en proporción 2:1, se practicó una toracotomía para extraer el corazón y realizar una perfusión intracardíaca. La cánula de perfusión fue insertada en el ventrículo izquierdo y el animal fue perfundido de forma secuencial con solución salina normal, y 10% de solución salina formal. A continuación de la perfusión, se realizó una craneotomía a fin de extraer todo el cerebro junto con los segmentos superiores de la espina dorsal. La muestra del cerebro fue entonces deshidratada, aclarada, e infiltrada con cera de parafina. La muestra fue entonces cortada en secciones seriadas de 15 micrones de espesor. Las secciones fueron entonces procesadas a fin de someterlas a análisis neurohistológico, usando un microscopio Nikon al cual se le conecta una cámara Nikon. Los análisis de las secciones revelaron una representación bilateral del núcleo motor dorsal del nervio vago en la médula oblonga (bulbo raquídeo). También se identificaron el núcleo ambiguo, el núcleo del tracto solitario, el núcleo hipoglosal, y el área postrema, en la médula oblonga. En el texto del artículo, se discuten las implicaciones de nuestros resultados.

Comportamento dos nervos glossofaríngeo e vago, na região retrofaríngea de ovinos: origem aparente no crânio, trajeto, ramificação e distribuição / Behavior of the glossopharyngeal and vagus nerves in the retropharyngeal region of sheep: apparent origin in cranium, course, branching and distribution

In 60 hemiheads of sheep of the Santa Ines breed the apparent origin in the skull of itinerary, ramification and distribution of the glossopharingeal nerve (Gf) and the vagus nerve (Vg) in the retropharyngeal region (Rr) were studied. By fixation and dissection of the specimens it was seen that the glossopharyngeal nerve and the vagus nerve arise from the jugular foramen in 100 percent of the cases. The right and the left glossopharingeal nerve (Glde) are frequently (86.6 percent) located more medially to the tympanic bulla, pass caudally to the stylohyoid bone, bypass the margin of the caudal stylopharyngeal muscle, the tonsilla, of the pharyngeal and the lingual mucous membrane. These branches are distributed, respectively, in the carotid sinus, pharyngeal musculature, soft palate, stylopharyngeal muscle, palatine tonsil, pharyngeal mucosa and the caudal third of the tongue (100 percent). The right and the left vagus nerve run caudally in association with the accessory nerves (Ac) up to the atlas (70 percent) and go then medially to the occipital artery, dorsally to the common carotid and the sympathetic trunk in the cervical region (80 percent). The vague nerves have pharyngeal (86.6 percent) and cranial laryngeal (100 percent) branches.

Em 60 hemicabeças de ovinos da raça Santa Inês foram estudadas a origem aparente no crânio, trajeto, ramificação e distribuição do nervo glossofaríngeo (Gf) e do nervo vago (Vg), na região retrofaríngea (Rr). Mediante fixação e dissecação das peças, foi observado que os nervos glossofaríngeos e vagos originam-se no forame jugular em 100 por cento dos casos. Os nervos glossofaríngeos direito e esquerdo (Gfde) são localizados, com maior freqüência (86,6 por cento), medialmente à bula timpânica, passam caudalmente ao osso estiloióide, contornam a margem caudal do músculo estilofaríngeo caudal, tonsilar, da mucosa faríngea e lingual. Estes ramos distribuemse, respectivamente, no seio carotídeo, musculatura faríngea, palato mole, músculo estilofaríngeo caudal, tonsila palatina, mucosa faríngea e terço caudal da língua (100 por cento). Os nervos vagos direito e esquerdo (Vgde) correm caudalmente em associação com os nervos acessórios (Ac) até o atlas (70 por cento), após o que passam medialmente à artéria occipital, dorsalmente à carótida comum e ao tronco simpático, na região cervical (80 por cento). Os ramos dos nervos vagos são os faríngeos (86,66 por cento) e os laríngeos craniais (100 por cento).

Evidence of collateralization of vagal efferents innervating subdiaphragmatic segments of the gastrointestinal tract in the rat using the double labelling fluorescent dyes technique

Collateralization of the abdominal vagal trunks was investigated in the rat using double labelling fluorescence dye technique. A total of 20 adult male and female rats were used for the study. The anterior and posterior walls of the corpus and fundus of the stomach were injected with 0.1 microliter (microliter) of 5 aqueous solution of diamidino yellow (Dy) in eight rats. The same quantity and percentage of fast blue (Fb) was injected into the walls of the duodenum and proximal jejunum in the same eight rats that were injected with Dy. The anterior and posterior walls of the stomach of four rats were injected with 0.1 microliter of 5 Dy only while four other rats had injections of 0.1 microliter of Fb only into the duodenum and proximal jejunum. Two control rats had stomach injections with normal saline, and two rats had saline injections into the intestine. Each rat was perfused with a preservative 14 days after injection and serial sections taken for examination with a fluorescence microscope. The results of the experiment revealed that in the eight rats injected simultaneously with Dy and Fb, some neurons of the dorsal motor nucleus of the vagus nerve (DMX) were labelled with Dy only, some with Fb only and some were doubly labelled with Dy and Fb. No double-labelled neurons were seen in the rat injected with one dye only and no labellings at all were seen in the controls. The pattern of labelling obtained in the study is suggestive of collateralization of axons of the abdominal vagal trunks

Parálisis cordal y alcoholismo / Vocal cord paralysis and alcoholism

La parálisis recurrencial por alcoholismo es un hallazgo muy raro, si bien la literatura mundial menciona algunos casos. La inercia de las cuerdas vocales es debido a una neuropatía por probable déficit de vitamina B1 (tiamina). El siguiente trabajo relata una interesante manifestación clínica en un paciente alcohólico quien presentó disfonía, diagnosticándose paresia recurrencial izquierda cuya etiología, luego de descartar las causas más frecuentes y considerando que evolucionó favorablemente con vitamina B1, resultó ser una neuritis recurrencial alcohólica.

Nervio vago dorsal terminal y ganglios celiacos / Terminal dorsal vagus nerve and celiac ganglia

Prosiguiendo una línea de investigación, mediante disección anatómica del nervio vago en su porción abdominal, se analizan los resultados obtenidos en 30 cadáveres adultos, comunicando en esta ocasión conclusiones de la disección específica del nervio vago dorsal terminal y los ganglios semilunares. Se deja constancia en el estudio de estas estructuras, las características de: situación topográfica, relaciones, variaciones de forma de los ganglios semilunares. Haciéndose mención además de la relación y dimensiones del ramo celíaco proveniente del vago dorsal

Relación anatómica entre la superficie de la pared gástrica e inervación selectiva vagal / Relation between the gastric wall surface and vagal selective innervation

En el Departamento de Anatomía Normal de la Facultad de Medicina, de la Universidad de Chile, se realiza un trabajo de disección en 25 estómagos humanos adultos sin patología demostrada. La observación permite concluir que la porción vertical gástrica (superficie: 165,6 cm*) recibe 6 a 7 ramos nerviosos vagales. A su vez, la porción horizontal (superficie de 43,6 cm*) recibe 8 ramos vagales. El número de estos ramos nerviosos tiene relación inversa con respecto a la superficie de cada porción gástrica

Distribución parietal de los nervios vagos en curvatura menor del estomago / Parietal distribution of the vagus nerves in the low curvature of the stomache

Fueron estudiados 25 especímenes gástricos humanos disecando en detalle los ramos gástricos del nervio vago, en especial aquellos que llegan a la curvatura menor. Fue precisada la longitud promedio de esta curvatura gástrica. Se observó el número de ramos nervioso que llegan a la porción vertical y horizontal de la curvatura menor y se concluye que existe una relación inversa entre este número con la longitud de las porciones gástricas