Imaging secondary neuronal degeneration.

OBJECTIVE: Distal nerve degeneration refers to the process of disintegration of a neuron or neuronal circuit as a consequence of distal damage. The end result of multiple etiologies, this finding is becoming common due to the increasing number of imaging tests done. This paper aims to define the different types of distal nerve damage, review the anatomy and function of the most commonly affected tracts, and illustrate distal nerve damage through diagrams and representative cases from routine practice. CONCLUSION: Knowing the distant response that can be expected according to the topography of a neuronal lesion is crucial to avoid diagnostic errors. Axonal degeneration and transsynaptic degeneration can be both antegrade and retrograde. Studies of cerebral metabolism, perfusion sequences, and diffusion sequences are showing increasingly earlier changes related to the same process; radiologists need to be aware of these changes.

Smartphone as a tool for evaluating oblique muscle dysfunction / Uso do smartphone como ferramenta para avaliar disfunções de músculos oblíquos

ABSTRACT Purpose: The aim of this study was to describe a simple, accessible, and reliable method using a smartphone for evaluating oblique muscle dysfunctions. Methods: The photograph rotation tool in the iPhone PHOTO app was used by 75 examiners to evaluate 22 photographs from only 9 patients, captured in infra- and supra-dextroversion, and infra- and supra-levoversion, as not all the patients were photographed in the 4 positions mentioned. Each patient received a score for the superior and inferior oblique muscle functions, ranging from -4 (hypofunction) to 4 (hyperfunction) or 0 (normal function), using preediting and postediting photographs. These values were compared with the scores previously given by trained personnel in strabismus screening. The difference in score between the two groups was expressed in natural (whole and non-negative) numbers. The mean and pattern deviation were then calculated. Results: The scores of most of the edited photos showed a lower mean than those of the unedited ones, except for a patient with left superior oblique hyperfunction. The patients with no oblique dysfunction and those with right superior oblique hyperfunction demonstrated (after editing the photograph) scores with greater similarity with their initial scores (p<0.05 and p<0.01, respectively). Similar results were found in the patients with oblique hypofunctions and right inferior oblique hyperfunction (p<0.01). Conclusion: The proposed method for assessing muscular function in vertical strabismus is reproducible, accessible, simple, and reliable, and provides better consistency to the admeasurement.

RESUMO Objetivo: Descrição de um método simples, acessível e confiável para a medida das disfunções dos músculos oblíquos, utilizando-se smartphone. Métodos: Foi utilizado o recurso de rotação de fotografias do aplicativo FOTOS do iPhone®; 75 examinadores avaliaram 22 fotos de 9 pacientes, obtidas em infra e supra dextroversão, infra e supra levoversão (nem todos os pacientes foram fotografados nas 4 posições citadas). Conferiu-se aos pacientes uma pontuação para a função do músculo oblíquo superior e músculo oblíquo inferior, que variou de -4 (negativo para hipofunção) a +4 (positivo para hiperfunção), ou 0 (normofuncionantes), antes e depois da edição das fotografias. Esses valores foram comparados à avaliação prévia atribuída pelos assistentes do estrabismo. Computou-se a diferença da pontuação entre eles em números naturais (inteiros e não negativos); foram calculadas média e desvio padrão dessas medidas. Resultado: A medida da maioria das fotos editadas apresentou média inferior as não editadas, à exceção de um paciente com hiperfunção de oblíquo superior esquerdo. Pacientes sem disfunção de oblíquos demonstraram, após edição das fotos, maior similaridade com o valor inicialmente determinado (p<0,05), assim como os pacientes com oblíquo superior direito hiperfuncionantes (p<0,01). Os mesmos resultados são encontrados nos pacientes com hipofunção dos oblíquos e hiperfunção de oblíquo inferior direito (p<0,01). Conclusão: O método utilizado para medida das funções musculares nos estrabismos verticais é reprodutível, acessível, simples, confiável, e confere maior uniformidade à aferição.

Carretera perdida: imagen de la degeneración neuronal secundaria / Imaging secondary neuronal degeneration

Objetivo: La degeneración neuronal distal (DND) define el proceso de desintegración de una neurona o un circuito neuronal como consecuencia de una noxa localizada a distancia. Es un hallazgo frecuente debido al creciente número de realización de pruebas de imagen y a que refleja un desenlace común a múltiples etiologías. El objetivo de este artículo es definir los distintos tipos de daño neuronal a distancia, revisar la anatomía y función de los tractos más frecuentemente afectados e ilustrar la DND con esquemas y casos representativos de la práctica habitual. Conclusión: El conocimiento de la respuesta a distancia esperable según la topografía de una lesión neuronal es crucial para evitar errores diagnósticos. La degeneración axonal y transináptica puede ser tanto anterógrada como retrógrada. Los estudios de metabolismo cerebral, las secuencias de perfusión y de difusión muestran cambios cada vez más precoces del mismo proceso con los que debemos estar familiarizados.(AU

Objective: Distal nerve degeneration refers to the process of disintegration of a neuron or neuronal circuit as a consequence of distal damage. The end result of multiple etiologies, this finding is becoming common due to the increasing number of imaging tests done. This paper aims to define the different types of distal nerve damage, review the anatomy and function of the most commonly affected tracts, and illustrate distal nerve damage through diagrams and representative cases from routine practice. Conclusion: Knowing the distant response that can be expected according to the topography of a neuronal lesion is crucial to avoid diagnostic errors. Axonal degeneration and transsynaptic degeneration can be both antegrade and retrograde. Studies of cerebral metabolism, perfusion sequences, and diffusion sequences are showing increasingly earlier changes related to the same process; radiologists need to be aware of these changes.(AU)

SIXTO OBRADOR SENEC PRIZE 2019: Utility of diffusion tensor imaging as a prognostic tool in moderate to severe traumatic brain injury. Part II: Longitudinal analysis of DTI metrics and its association with patient's outcome. / PREMIO SIXTO OBRADOR SENEC 2019: El uso de la secuencia Tensor de difusión como herramienta pronóstica en los pacientes con traumatismo craneoencefálico grave y moderado. Parte II: Análisis longitudinal de las características del Tensor de difusión y su relación con la evolución de los pacientes.

BACKGROUND AND OBJECTIVES: Traumatic axonal injury is the main cause of the cognitive and neuropsychological situation of patients after head trauma (TBI). Additionally, there are some evidences about the dynamic evolution of traumatic axonal injury. Although the diffusion tensor MRI (DTI) sequence is considered a useful technique for modifying the extent of the traumatic axonal injury, few studies have evaluated the longitudinal changes in the characteristics of the DTI and its relation to evolution of patients. MATERIALS AND METHODS: We performed a prospective observational study in 118 patients with moderate to severe TBI. The study included clinical outcome assessment based on the Glasgow Outcome Scale Extended and serial DTI studies in the early subacute setting (<60 days) and 6 and 12 months after injury. Fractional anisotropy, axial and radial diffusivities were measured in the 3 portions of corpus callosum (genu, body, splenium) at each time point and compared to normalized values from an age-matched control group. Longitudinal fractional anisotropy analysis and its correlation with patient improvement was also done by non-parametric testing and ordinal regression analysis. RESULTS: Although dynamic changes in DTI characteristics have been detected in the 3 portions of corpus callosum, patients continue to show lower fractional anisotropy and axial diffusivities values and higher radial diffusivities values compared to controls at the end of the period of study. We have also found differences in the pattern of DTI metrics change between subgroups of patients according with their favorable outcome CONCLUSIONS: The temporal profile of the change in DTI characteristics seems to provide important information about the clinical recovery of patients after TBI.

Sixto Obrador SENEC prize 2019: Utility of diffusion tensor imaging as a prognostic tool in moderate to severe traumatic brain injury. Part I. Analysis of DTI metrics performed during the early subacute stage. / Premio Sixto Obrador SENEC 2019: el uso de la secuencia tensor de difusión como herramienta pronóstica en los pacientes con traumatismo craneoencefálico grave y moderado. Parte I. Análisis de las características del tensor de difusión realizado durante la fase subaguda precoz.

BACKGROUND AND OBJECTIVES: Traumatic axonal injury (TAI) contributes significantly to mortality and morbidity after traumatic brain injury (TBI). Its identification is still a diagnostic challenge because of the limitations of conventional imaging techniques to characterized it. Diffusion tensor imaging (DTI) can indirectly identify areas of damaged white matter integrity by detecting water molecule diffusion alterations. Our main objective is to characterize the TAI using DTI at the early subacute stage in our series of moderate to severe TBI patients and to evaluate if there is a relationship between the information provided by the DTI and patient's outcome. MATERIALS AND METHODS: We have obtained DTI data from 217 patients with moderate to severe TBI acquired at a median of 19 days after TBI, and patient DTI metrics were compared with data obtained from 58 age-matched healthy controls. Region of interest method was applied to obtain mean fractional anisotropy (FA) value in 28 white matter fiber bundles susceptible to TAI. RESULTS: Our main results were that when we compared patients with controls, patients, regardless of TBI severity, showed significantly reduced mean FA in almost all region of interest measured. We found statistically significant correlation between FA metrics and some clinical characteristics. Additionally, the FA values of the three portions of Corpus callosum, Cingulum and cerebral peduncles measured at the early subacute stage were highly associated with outcome assessed at hospital discharge and at 6 and 12 months after TBI. CONCLUSIONS: We conclude that DTI is a useful tool to characterize TAI and the detection of FA reduction in the subacute stage after TBI is associated with long-term unfavorable outcome.

Volumetría de fascículos cerebrales en población sana / Brain fascicles volumetry in healthy population

Objetivo Desde la aparición de la tractografía, al tratarse de una técnica no invasiva y que usa la ampliamente conocida resonancia magnética (RM), el estudio de la sustancia blanca se ha facilitado. A partir de eso, se han logrado grandes descubrimientos en cuanto a fascículos cerebrales involucrados en funciones cognitivas. Sin embargo, su evaluación sigue siendo subjetiva y depende de la experiencia y entrenamiento del evaluador, razón por la cual se ha limitado su aplicabilidad en la práctica clínica. En ese sentido, es conveniente parametrizar volúmenes cerebrales de sustancia blanca en población sana a través de una herramienta electrónica que se pueda reproducir y así poderlo aplicar en enfermos. Materiales y métodos Se reportan 10 sujetos sanos desde el punto de vista neurológico. Para cada sujeto, se adquirieron imágenes ponderadas por difusión y los resultados se visualizaron mediante FiberNavigator (http://scilus.github.io/fibernavigator). Finalmente, esa misma herramienta fue utilizada para purificar los fascículos objeto de estudio y realizar el conteo de las fibras. Resultados Se obtuvieron valores de volumetría del fascículo longitudinal superior (FLS), fascículo longitudinal inferior (FLI), fascículo frontoccipital inferior (FFI), fascículo uncinado (FU) y fascículo del cíngulo (FC), identificando que no existen diferencias estadísticamente significativas entre el número de fibras que componen los fascículos cerebrales. Discusión Los resultados alcanzados de la anatomía y la direccionalidad de fibras de los fascículos cerebrales de este estudio coinciden con el resto de la evidencia publicada hasta el momento, sin encontrar diferencias en cuanto a su organización y recorrido. Conclusión Aunque esos resultados no sirven como valores de referencia para ser aplicados en pacientes con patología neurológica, brindamos información inexistente hasta el momento, con ese equipo en específico y la reproducción entre los distintos usuarios y el software.

Objective Since the appearance of tractography, as it is a non-invasive technique and uses the widely known magnetic resonance (MR), the study of white matter has been facilitated. After this, great discoveries have been made regarding the brain fascicles involved in cognitive functions. However, its evaluation continues to be subjective and depends on the evaluator's experience and training. That the reason why its applicability has been limited in clinical practice. Because of this, it is convenient to parametrize cerebral volumes of white matter in healthy population through an electronic, reproducible tool that could be applied in patients. Materials and Methods Ten neurologically healthy subjects are reported, for each subject we acquired images weighted by diffusion and the results were visualized by means of FiberNavigator (http://scilus.github.io/fibernavigator). Finally, this same tool was used to purify the fascicles under study and perform the fiber count. Results Volumetric values of the upper longitudinal fasciculus, inferior longitudinal fasciculus, inferior frontoccipital fasciculus, uncinated fasciculus and cingulate fasciculus were obtained, identifying that there are not statistically significant differences in the number of fibers that make up the cerebral fascicles. Discussion The results achieved of the anatomical and fiber directionality of the cerebral fascicles of this study, coincide with the rest of the evidence published up to now, without finding differences regarding its organization and route. Conclusion Although these results do not serve as reference values to be applied in patients with neurological pathology, do we provide nonexistent information so far, with this specific equipment and the reproducibility between the different users and the software.

Clinical features and corneal optical anisotropies in a rabbit model of limbal stem cell deficiency / Fenótipos clínicos e anisotropias ópticas da córnea em coelhos com deficiência de células tronco limbais

ABSTRACT Purposes: To investigate the intra-laboratory reproducibility of clinical features and to evaluate corneal optical anisotropies in a rabbit model of limbal stem cell deficiency. Methods: Limbal injury was induced in the right eye of 23 adult New Zealand White rabbits using a highly aggressive protocol that combined 360 degrees limbal peritomy, keratolimbectomy, alkaline chemical burn, and mechanical removal of the epithelium. Clinical evaluation of the injured eyes was performed for 28 days and included corneal impression cytology. Corneas with a severe clinical outcome set typical of limbal stem cell deficiency were then collected, subjected to a histopathological examination, and examined for optical anisotropies. Corneas from healthy rabbit eyes were used as controls. Differences in optical path due to stromal collagen birefringence, as well as linear dichroism related to the expression and spatial orientation of glycosaminoglycan chains from proteoglycans, were measured from cross-sections under a quantitative polarized light microscope. Results: One eye showed signs of hypopyon and was excluded. Signs of ocular inflammation were observed in all eyes studied (n=22). Corneal impression cytology did not detect goblet cells. Twelve of the 22 corneas presented a clinical outcome set typical of limbal stem cell deficiency, which is characterized by the presence of epithelial defects, inflammatory cells, moderate-to-severe opacity, and neovascularization. Microscopic studies under polarized light revealed that relative to controls, limbal stem cell deficiency caused a 24.4% increase in corneal optical path differences. Further, corneas with limbal stem cell deficiency were less dichroic than controls. Conclusions: These results suggest that rabbit models of limbal stem cell deficiency must be rigorously screened for use in preclinical studies to ensure experimental homogeneity because protocols used to create limbal stem cell deficiency could be not associated with good intra-laboratory reproducibility of clinical features. Limbal stem cell deficiency, as induced herein, altered the optical anisotropic properties of the corneal stroma. Such alterations are indicative of changes in collagen packing and the spatial orientation of glycosaminoglycan chains from proteoglycans. Knowledge of these changes is important to potentiate strategies aimed at restoring the morphofunctional integrity of the corneal stroma affected by limbal stem cell deficiency.

RESUMO Objetivos: Investigar a reprodutibilidade intra-la­boratorial dos fenótipos clínicos e avaliar anisotropias ópticas em córneas de coelhos com deficiência de células tronco limbais. Métodos: Lesões ao limbo foram feitas no olho direito de 23 coelhos adultos da Nova Zelândia Branco, usando um protocolo altamente agressivo, que envolveu peritomia limbal em 360 graus, ceratolimbectomia, cauterização por álcali, e remoção mecânica de epitélio remanescente. Os olhos foram clinicamente avaliados por 28 dias, inclusive por citologia de impressão corneal. As córneas que manifestaram um conjunto de alterações típicas de deficiência de células tronco limbais foram coletadas e submetidas à estudos em histopatologia e em anisotropias ópticas. Córneas saudáveis foram usadas como controles. Diferenças de caminho óptico de birrefringência relacionada à organização do colágeno estromal, e dicroísmo linear relacionado à expressão e à orientação das cadeias de glicosaminoglicanos dos proteoglicanos estromais, foram quantificados por microscopia de luz polarizada. Resultados: Um olho apresentou hipópio e foi excluído do estudo. Todos os olhos estudados (n=22) apresentaram sinais de inflamação ocular. A citologia de impressão não detectou células caliciformes na superfície corneal. Doze de 22 córneas manifestaram alterações clínicas típicas de deficiência de células tronco limbais, caracterizado por defeitos epiteliais, infiltrados inflamatórios, opacidade de moderada à severa, e neovascularização. Estudos por microscopia de luz polarizada mostraram que a deficiência de células tronco limbais aumentou a diferenças de caminho óptico corneal em 24,4% (versus controles). As cór­neas com deficiência de células tronco limbais foram menos dicroicas do que as córneas controle. Conclusões: Coelhos com deficiência de células tronco limbais, para aplicações em estudos pré-clínicos, devem ser rigorosamente selecionados para assegurar homogeneidade experimental, pois há evidências de que protocolos utilizados para indução de deficiência de células tronco limbais não estão associados com boa reprodutibilidade intra-laboratorial de fenótipos clínicos. A deficiência de células tronco limbais, como induzida aqui, alterou as propriedades ópticas anisotrópicas do estroma corneal. Tais alterações são indicativas de mudanças no empacotamento de colágeno e na orientação das cadeias de glicosaminoglicanos dos proteoglicanos. Conhecimentos nessas alterações são importantes para potencializar estratégias que visam a restabelecer a integridade morfofuncional do estromal corneal acometido pela deficiência de células tronco limbais.

Fragmentation targeted at preferred discontinuities: A new concept in endolithotripsy with Holmium laser:YAG. / Fragmentación dirigida a discontinuidades preferentes: un nuevo concepto en endolitotricia con láser Holmium:YAG.

INTRODUCTION: There are currently 3holmium laser, YAG (Ho:YAG) endolithotripsy procedures that are considered basic (fragmentation, pulverisation, "pop-corn" technique). We present the technique of fragmentation targeted at preferred discontinuities (FTPD), a new concept of endolithotripsy by Ho:YAG laser. MATERIAL AND METHODS: The FTPD technique is based on the selective application of energy (targeting a specific preselected point) to an area that is visually prone to the formation of a fracture line or preferred discontinuity (conditioned by the anisotropy of the urolithiasis). The ideal energy regimen (setting) is a high range of working energy (2-3J) with a very low frequency range (5-8Hz) and short pulse width. Between January 2015 to February 2017, the FTPD technique was used in 37 procedures (7 NLP, 16 RIRS, 12 URS, 2 cystolithotomies), with a Ho:YAG laser (Lumenis Pulse 120H®, Tel-Aviv, Israel). Maximum power used: 24W (3J/8Hz) with fibres of 365µ and 273µ (URS, RIRS), and 32W (4J/8Hz) with fibres of 550µ (NLP, cystolithotomy). RESULTS: Strategic improvement was achieved in all cases using the TFPD technique to continue the endolithotripsy or remove fragments. No complications were recorded after the use of this method. CONCLUSIONS: FTPD can be considered a complementary option in combination with the basic methods of fragmentation and pulverisation. In our experience, it constitutes significant progress in optimising the performance of Ho:YAG laser endolithotripsy.

Neuralgia del trigémino: estudio funcional mediante tensor de difusión de alta densidad como herramienta diagnóstica / Trigeminal Neuralgia: functional study using high density diffusion tensor imaging as a diagnostic tool

Objetivo: El objetivo del presente artículo es demostrar la alteración de la fracción de anisotropía (FA) en la neuralgia esencial del trigémino (NET). Materiales y métodos: Se evaluaron 10 pacientes con diagnóstico de neuralgia esencial del trigémino mediante secuencias de tensor de difusión de alta densidad e imágenes anatómicas 3D en un resonador de alto campo 3 Tesla. En todos los casos se localizaron los nervios. Las imágenes obtenidas se posprocesaron para realizar la tractografía y medir la FA en 20 nervios. Resultados: Se correlacionaron los hallazgos patológicos entre la medición de la FA y la clínica de los pacientes. De los 10 casos, 6 presentaron compresión neurovascular de lado con neuralgia y un valor de FA descendido con respecto al contralateral en rango normal; mientras que 2 mostraron compresión neurovascular bilateral, pero solo descenso del valor de FA del lado afectado clínicamente. En los otros 2 pacientes no se determinó compresión neurovascular, aunque en el lado con manifestación clínica neurálgica la FA se encontraba descendida. Conclusión: La realización de la difusión anisotrópica de alta densidad y la medición de la FA pueden ser una herramienta en la evaluación de la neuralgia esencial del trigémino, ya que es un método reproducible y seguro que permite estudiar la función del nervio.

Objective: The objective of this article is to demonstrate the alteration of the anisotropy factor (FA) in essential trigeminal neuralgia. Materials and methods: Ten patients with essential trigeminal neuralgia were studied with sequences of high density diffusion tensor and anatomic 3D images with a high-field 3 Tesla resonator. The nerves were located in all cases studied. The obtained images were post-processed to perform tractography and FA was measured in 20 nerves. Results: There was correlation of pathological findings between measuring FA and clinical presentation of the patients. Six of the ten patients studied with neurovascular compression at the neuralgia side had decreased FA values compared to contralateral normal range. Two of the ten patients showed bilateral neurovascular compression, but only abnormal values of FA were found at the clinically affected side. In the remaining two patients no neurovascular compression was determined; however the FA was lower at the clinical manifestation neuralgic side. Conclusión: The performing of high density anisotropic diffusion and the measurement of the FA may be useful in the evaluation of Trigeminal neuralgia, since it is a safe and reproducible method that allows the study of nerve function.

Neuralgia del trigémino: estudio funcional mediante tensor de difusión de alta densidad como herramienta diagnóstica

Objetivo: El objetivo del presente artículo es demostrar la alteración de la fracción de anisotropía (FA) en la neuralgia esencial del trigémino (NET). Materiales y métodos: Se evaluaron 10 pacientes con diagnóstico de neuralgia esencial del trigémino mediante secuencias de tensor de difusión de alta densidad e imágenes anatómicas 3D en un resonador de alto campo 3 Tesla. En todos los casos se localizaron los nervios. Las imágenes obtenidas se posprocesaron para realizar la tractografía y medir la FA en 20 nervios. Resultados: Se correlacionaron los hallazgos patológicos entre la medición de la FA y la clínica de los pacientes. De los 10 casos, 6 presentaron compresión neurovascular de lado con neuralgia y un valor de FA descendido con respecto al contralateral en rango normal; mientras que 2 mostraron compresión neurovascular bilateral, pero solo descenso del valor de FA del lado afectado clínicamente. En los otros 2 pacientes no se determinó compresión neurovascular, aunque en el lado con manifestación clínica neurálgica la FA se encontraba descendida. Conclusión: La realización de la difusión anisotrópica de alta densidad y la medición de la FA pueden ser una herramienta en la evaluación de la neuralgia esencial del trigémino, ya que es un método reproducible y seguro que permite estudiar la función del nervio.(AU)

Objective: The objective of this article is to demonstrate the alteration of the anisotropy factor (FA) in essential trigeminal neuralgia. Materials and methods: Ten patients with essential trigeminal neuralgia were studied with sequences of high density diffusion tensor and anatomic 3D images with a high-field 3 Tesla resonator. The nerves were located in all cases studied. The obtained images were post-processed to perform tractography and FA was measured in 20 nerves. Results: There was correlation of pathological findings between measuring FA and clinical presentation of the patients. Six of the ten patients studied with neurovascular compression at the neuralgia side had decreased FA values compared to contralateral normal range. Two of the ten patients showed bilateral neurovascular compression, but only abnormal values of FA were found at the clinically affected side. In the remaining two patients no neurovascular compression was determined; however the FA was lower at the clinical manifestation neuralgic side. Conclusión: The performing of high density anisotropic diffusion and the measurement of the FA may be useful in the evaluation of Trigeminal neuralgia, since it is a safe and reproducible method that allows the study of nerve function.(AU)

Surgical results of strabismus correction in patients with myelomeningocele / Resultados cirúrgicos da correção do estrabismo em pacientes com mielomeningocele

Purpose: Myelomeningocele is one of the most common birth defects. It is associated with severe neurological deficiencies, and ocular changes, such as strabismus, are very common. The purpose of this study was to describe indications for strabismus surgery in patients with myelomeningocele and to evaluate the results achieved with surgical correction. Methods: We retrospectively reviewed records of all patients with myelomeningocele who underwent surgery for strabismus correction in a 5-year period in an institution for disabled children. Results: The main indications for strabismus surgery were esotropia and A-pattern anisotropia. Excellent surgical results were achieved in 60.9% of patients, satisfactory in 12.2%, and unsatisfactory in 26.9%. Conclusion: Patients with myelomeningocele and strabismus had a high incidence of esotropia and A-pattern anisotropia. Strabismus surgery in these patients had an elevated percentage of excellent and satisfactory results, not only for the ocular deviation, but also for improvement of head posture. .

Objetivo: A mielomeningocele é um dos mais frequentes defeitos do nascimento e está associada a disfunções neurológicas severas. Alterações oculares como estrabismo são muito comuns nesses pacientes. O objetivo deste estudo foi descrever as principais indicações de cirurgia de estrabismo em pacientes com mielomeningocele e avaliar os resultados atingidos com a correção cirúrgica. Métodos: Foi realizado estudo restrospectivo com revisão de prontuários de todos os pacientes com mielomeningocele submetidos à cirurgia para correção de estrabismo em um período de 5 anos em uma instituição de assistência a crianças deficientes. Resultados: As principais indicações para cirurgia de estrabismo foram esotropia e anisotropia com padrão em A. Resultados cirúrgicos excelentes foram alcançados em 60,9% dos pacientes, satisfatórios em 12,2% e insatisfatórios em 26,9%. Conclusão: Pacientes com mielomeningocele e estrabismo têm uma alta incidência de esotropia e anisotropia com padrão em A. A cirurgia de estrabismo nesta população teve uma elevada porcentagem de resultados excelentes e satisfatórios, não somente em relação ao desvio ocular, mas também na melhora na posição viciosa de cabeça .

Correspondência histológica de parâmetros de imagens de tensores de difusão / Correspondence of histological parameters from diffusion tensor images

INTRODUÇÃO: Imagens por tensores de difusão (diffusion tensor imaging - DTI) do cérebro são parte fundamental de exames de ressonância magnética (RM) na rotina clínica. Entretanto, não há informação científica suficiente para inferir a base histológica de parâmetros de imagens de DTI. Um dos achados frequentes nos exames de RM são as áreas de alteração de sinal na substância branca (AASSB). Neste estudo, analisamos imagens de RM post-mortem, em particular as AASSB, e seus correlatos histológicos e imuno-histoquímicos. OBJETIVOS: Descrever os parâmetros quantitativos de imagens de DTI imagens obtidas in cranio post-mortem, comparar com parâmetros de relaxometria e transferência de magnetização e avaliar seus correlatos histológicos nas AASSB e AHAN, utilizando técnicas de correspondência espacial ponto-a-ponto. MÉTODOS: Analisamos áreas distribuídas na substância branca de encéfalos de quatro sujeitos submetidos ao exame de RM post-mortem, aproximadamente 12,87 horas (±2,59). A RM foi realizada em sistema com campo de 3,0 T, sendo utilizadas imagens FLAIR; T2 multi-eco, DTI, Densidade de Prótons para cálculo da taxa de transferência de magnetização (magnetization transfer ratio - MTR). Foram delimitadas regiões de interesse (ROI) em 20 áreas contendo AASSB e 20 áreas homólogas aparentemente normais (AHAN). Para cada área, foram obtidos valores de anisotropia fracional (FA), coeficiente de difusão aparente (ADC), MTR e tempo T2. Os encéfalos foram seccionados em fatias de 0,4mm e fotografados em alta resolução. Estas imagens foram co-registradas tridimensionalmente com as imagens de RM, utilizando técnica semi-automatizada para correlação ponto-a-ponto. Os fragmentos analisados foram corados por hematoxilina-eosina (HE), Kluverx Barrera (KB), galocianina (GALL), anti-neurofilamento (anti-NF), antiproteína básica de mielina (anti-MBP) e anti-proteína ácida fibrilar glial (anti- GFAP). RESULTADOS: Os valores de FA foram 0,40 ±0,12 nas...

BACKGROUND: Diffusion tensor imaging (DTI) is part of magnetic resonance imaging (MRI) acquisition methods available in clinical exams. However, there are not enough scientific basis to infer the histological substract of DTI parameters. White matter hyperintensities (WMH) are frequent findings in clinical MRI routine. In the last years, scientific evidences show that these injuries are not just age-related benign changes, but they could be associated to pathological processes. In this study we analyzed post-mortem MRI DTI data, specifically investigating WMH, their histological and immunohistochemical correlates. OBJECTIVES : At present study, we aimed to analyze quantifiable DTI parameters - Fractional Anisotropy (FA) and Apparent Diffusion Coefficient (ADC) - relaxometry (RT2) and magnetization transfer ratio (MTR) in WMH compared and normal appearing white matter (NAWM) from images obtained postmortem and in situ, and assess their histological substracts at WMH and NAWM using a point-topoint correlation platform. METHODS : We analyzed 20 regions of interest (ROI) encompassing WMH and NAWM selected from four subjects using in situ post-mortem MRI data acquired in 3.0T MR system. The subjects were scanned with a post-mortem interval of approximately 12h54m (±2h36m). The MRI analysis included 3D T1, FLAIR; multi-echo T2, DTI, and proton density to calculate the rate of magnetization transfer (magnetization transfer ratio - MTR). In each ROI we obtained measures of FA, ADC, RT2 and MTR. Brain specimens were posteriorly fixed in celloidin, sectioned into 0.4mm slices and photographed in high resolution. These images were co-registered with three-dimensional MR images using semi-automated technique for correlation using a point-to-point method established in our group. WMH and NAWM ROIs from MRI were submitted to quantitative histological analysis based on optical density color-deconvolution technique. Histological section were stained in...

Propagación de onda en un tejido cardiaco 3D usando dos modelos auriculares / Wave propagation in a 3D cardiac tissue using two atrial models

Objetivo: evaluar el grado de predictibilidad entre dos modelos de electrofisiología celular para aurícula humana, analizando las propiedades, a nivel tisular, de la duración del potencial de acción (APD) y velocidad de conducción (CV) en un tejido en tres dimensiones incorporando el direccionamiento de fibras para toda la anatomía auricular. Métodos: se implementaron los modelos celulares de Courtemanche-Ramírez-Nattel y Nygren; además se desarrolló un modelo geométrico detallado y realista de una aurícula humana, partiendo del modelo burdo de Harrild-Henriquez al que se le incorporó el direccionamiento de fibras en toda la anatomía auricular. Resultados: las constantes de difusión implementadas permitieron obtener en ambos modelos velocidades de conducción muy similares a las velocidades de conducción reales; además, en las regiones de alta conductividad el direccionamiento de fibras longitudinal permitió obtener velocidades de conducción más altas que en otras zonas de la aurícula. Conclusiones: la curva del potencial de acción muestra un APD90 (AP al 90% de la repolarización) de 320 ms en NYG y 235 ms en CRN. En condiciones donde las propiedades de la membrana no han cambiado en la aurícula normal, se ha observado que en ambos modelos se generan subidas de potencial de acción rápidas que se aprecian en la forma del potencial, asociados con una baja velocidad de propagación en la dirección transversal y una subida lenta del potencial de acción, que se relaciona también con una alta velocidad de propagación en el sentido longitudinal.

Objective: to evaluate the degree of predictability between two models of human atrial cellular electrophysiology, analyzing at tissue level the properties of the action potential duration (APD) and conduction velocity (CV) in a three-dimensional tissue incorporating direction of fibers for the entire atrial anatomy. Methods: we implemented the cellular models of Courtemanche-Ramirez-Nattel and Nygren, also developed a detailed and realistic geometric model of a human atrium, starting from the clumsy model of Harrild-Henriquez to which we incorporated the direction of fibers throughout the entire atrial anatomy. Results: The diffusion constants implemented allowed to obtain in both models conduction velocities very similar to the real conduction velocities; moreover, in the high conductivity regions the longitudinal fiber direction allowed to obtain conduction velocities higher than in other areas of the atrium. Conclusions: the action potential curve shows a APD90 (AP at 90% of repolarization) of 320 ms in NYG and 235 ms in CRN. Under conditions where the membrane properties have not changed in the normal atrium, we observed that in both models increases of fast action potential are generated, which can be seen as the potential associated with a low propagation velocity in the transversal direction and a slow rise of the action potential, which is also related to a high propagation velocity in the longitudinal direction.

Cambios cerebrales en la morfometría en pacientes con VIH / Cerebral changes in them morphometrics of hiv patients

La atrofia cerebral es un hallazgo común en pacientes con infección por el virus de la inmunodeficiencia humana, especialmente en pacientes con demencia; lo que demuestra compromiso neocortical en estadios tardíos de la enfermedad y compromiso de los ganglios basales en las fases tempranas o asintomáticas. Objetivo: Evaluar los cambios en el volumen cerebral total, el volumen del núcleo caudado, el volumen del núcleo accumbens y la anisotropía fraccional de los tractos de sustancia blanca en pacientes con VIH sin síntomas neurodegenerativos, en relación con sujetos sanos. Métodos: Para la segmentación y cuantificación del tejido cerebral se extrajo el cerebro y el cráneo; se normalizó de acuerdo con el volumen cerebral total, y a partir de este se segmentaron los volúmenes del núcleo caudado y del núcleo accumbens. Se utilizó el método de tractografía espacial estadística para la cuantificación y búsqueda de diferencias en el coeficiente de anisotropía fraccional. Resultados: El porcentaje de volumen de sustancia blanca respecto al volumen cerebral fue menor en los pacientes con VIH (42,83 ± 2,65%), comparado con los sujetos sanos (43,56 ± 1,60%). El porcentaje de volumen del núcleo de accumbens izquierdo en los pacientes con VIH fue del 0,0254 ± 0,0073 % del cerebro, y en los individuos sanos, del 0,0351 ± 0,0067% del cerebro; (p < 0,05). Conclusión: No fue evidente ni significativa la disminución del volumen del parénquima cerebral de la sustancia gris, a excepción del núcleo accumbens izquierdo. En relación con el volumen de la sustancia blanca, se hallaron cambios globales y no regionales en dichos tractos…

Cerebral atrophy is a common finding in patients infected with the Human Immuno-deficiency Virus (HIV), particularly in patients with dementia. This disease shows neocortical compromise in late stages as well as compromise in the basal ganglia in early or asyntomatic phases. Objective: Evaluate changes in total brain volume, caudate nucleus volume, nucleus accumbens volume, and fractional anisotropy of white matter tracts in HIV pa tients without neurodegenerative symptoms, in comparison with healthy subjects. Methods: For segmentation and quantification purposes of the brain tissue, the brain and skull were extracted and the tissue was normalized according to total brain volume. From the tissue thus obtained, the caudate nucleus and nucleus accumbens volumes were segmented. The method of statistic spatial tractography was used for quantification and search of differences in the fractional anisotropy coefficient. Results: The percentage of white mat ter volume with respect to brain volume was smaller in HIV patients (42.83±2.65 %) when compared with healthy subjects (43.56±1.60 %). The percentage of left nucleus accumbensvolume in HIV patients was 0.0254±0.0073 % of the brain and 0.0351±0.0067 % in healthy subjects; (p<0.05). Conclusions: It was not evident A decrease in the volume of the gray matter parenchyma was not evident or significant, except in the left nucleus accumbens. Global but not regional changes were found in white matter tracts…

[Cerebral Changes in the Morphometrics of HIV Patients]. / Cambios cerebrales en la morfometría en pacientes con VIH.

UNLABELLED: Cerebral atrophy is a common finding in patients infected with the Human Immunodeficiency Virus (HIV), particularly in patients with dementia. This disease shows neocortical compromise in late stages as well as compromise in the basal ganglia in early or asyntomatic phases. OBJECTIVE: Evaluate changes in total brain volume, caudate nucleus volume, nucleus accumbens volume, and fractional anisotropy of white matter tracts in HIV patients without neurodegenerative symptoms, in comparison with healthy subjects. METHODS: For segmentation and quantification purposes of the brain tissue, the brain and skull were extracted and the tissue was normalized according to total brain volume. From the tissue thus obtained, the caudate nucleus and nucleus accumbens volumes were segmented. The method of statistic spatial tractography was used for quantification and search of differences in the fractional anisotropy coefficient. RESULTS: The percentage of white matter volume with respect to brain volume was smaller in HIV patients (42.83±2.65 %) when compared with healthy subjects (43.56±1.60 %). The percentage of left nucleus accumbens volume in HIV patients was 0.0254±0.0073 % of the brain and 0.0351±0.0067 % in healthy subjects; (p<0.05). CONCLUSIONS: It was not evident A decrease in the volume of the gray matter parenchyma was not evident or significant, except in the left nucleus accumbens. Global but not regional changes were found in white matter tracts.

The brain subcortical white matter and aging: a quantitative fractional anisotropy analysis / Substância branca cerebral e envelhecimento: análise com anisotropia fracionada quantitativa

Abstract ? To study the integrity of hemispheric subcortical white matter by comparing normal young and elderly subjects using quantitative fractional anisotropy (DTI-FA). Methods: Subjects of two different age groups (young=12, elderly=12) were included. MR - GE Signa Horizon - 1.5T scans were performed. Cases with Fazekas scores ?3 were assessed on FLAIR sequence. Standard parameters for DTI-FA were used. ROIs were placed at various sites of the subcortical white matter, and the genu and splenium of the midline corpus callosum. Analysis was performed using Functool. Statistics for anterior and posterior white matter, as well as the genu and splenium were compared between the groups. The study was approved by the Ethics Committee of IPUB-UFRJ and informed consent obtained. Results: DTI-FA showed lower anisotropy values in the anterior region (subcortical white matter and genu), but not in the posterior region (subcortical white matter and splenium), in elderly normal subjects compared to young subjects. Conclusion: The results may represent loss of integrity of anterior (frontal) white matter fibers in the elderly subjects. These fibers constitute important intra- and inter-hemispheric tracts, components of neural networks that provide cognitive, behavioral, motor and sensory integration. The loss of integrity of the anterior segments of the studied fiber systems with ageing, represents a disconnection process that may underlie clinical manifestations found in elderly subjects such as executive dysfunction.

Resumo ? Estudar a integridade da substância branca hemisférica subcortical, comparando sujeitos normais jovens e idosos, com anisotropia fracionada quantitativa (DTI-FA). Métodos: Foram incluídos sujeitos de dois grupos etários (jovem=12, idoso=12). Obtidas imagens de MR - GE Signa Horizon - 1.5T. Escore de Fazekas ?3 avaliado na sequência em FLAIR. Utilizados parâmetros padrão para DTI-FA. ROIs colocados em locais variados da substância branca subcortical, e no joelho e esplênio do corpo caloso na linha média. Análise com Functool. Estatística para comparar a substância branca anterior e posterior entre os grupos. Aprovado pela Comissão de Ética do IPUB-UFRJ, consentimento informado obtido. Resultados: DTI-FA mostrou redução dos valores de anisotropia na região anterior (substância branca subcortical e joelho), porém não na região posterior (substância branca subcortical e esplênio), nos sujeitos normais idosos em comparação aos jovens. Conclusão: Os resultados podem ser considerados como representando perda da integridade das fibras da substância branca anterior (frontal) no sujeitos do grupo idoso. Tais fibras constituem os importantes feixes intra- e inter-hemisféricos, componentes de redes neurais relacionadas com integração cognitiva, comportamental, motora e sensorial. A perda da integridade com o envelhecimento dos segmentos anteriores dos sistemas de fibras estudados representa um processo de desconexão que pode estar subjacente a manifestações clínicas, como a disfunção executiva, eventualmente encontradas em sujeitos idosos.

Binswanger's disease and quantitative fractional anisotropy / Doença de Binswanger e anisotropia fracionada quantitativa

OBJECTIVE: To study the integrity of the white matter in Binswanger's disease (BD) patients with quantitative fractional anisotropy (DTI-FA). METHOD: Controls (12) and patients with BD (12) were included. Scans performed with MR (GE Signa Horizon/1.5T). Fazekas's score=6 with white matter hyperintensities extension >75 percent assessed on FLAIR scans. Standard parameters for DTI-FA were used. ROIs placed in symmetrical regions on two axial planes, data pooled in anterior (frontal) and posterior (temporo-parieto-occipital) regions. Analysis with Functool. Statistics for anterior and posterior regions comparison. RESULTS: DTI-FA showed reduction of anisotropy, reflecting axonal damage and demyelination of fibers, more prominent in anterior in relation to posterior region, in BD patients in comparison to controls. CONCLUSION: Loss of integrity of fiber tracts reflects interruption of neural networks that subserve cognitive, behavioral, and motor integration. The more severely affected frontal region is related to executive dysfunction, a characteristic feature of Binswanger's disease.

OBJETIVO: Estudar a integridade da substância branca em pacientes com doença de Binswanger (DB) com anisotropia fracionada quantitativa (DTI-FA). MÉTODO: Incluídos controles (12) e pacientes com DB (12). Obtidas imagens de RM (GE Signa Horizon/1,5T). Escore=6 de Fazekas com hiperintensidades da substância branca com extensão >75 por cento avaliados em imagens em FLAIR. Utilizados parâmetros padrão para DTI-FA. ROIs colocados em regiões simétricas de dois planos axiais, dados das regiões anterior (frontal) e posterior (têmporo-parieto-occipital) reunidos. Análise com Functool. Estatística para comparar regiões anteriores e posteriores. RESULTADOS: DTI-FA mostrou redução da anisotropia, refletindo lesão axonal e desmielinazação de fibras, com predomínio na região anterior em relação à posterior, nos pacientes com DB em comparação aos controles. CONCLUSÃO: Perda da integridade de feixes de fibras reflete interrupção de redes neurais subjacentes à integração cognitiva, comportamental e motora. A região frontal, mais gravemente atingida, está relacionada à disfunção executiva, aspecto característico da doença de Binswanger.

Tractografía y tensor de difusión en el estudio por resonancia magnética del nervio mediano: reporte de un caso / Tractography and diffusion tensor imaging in the study of the median nerve by magnetic resonance imaging: a case report

Introduction: Magnetic resonance imaging (MRI) is an essential tool for the study of central nervous system disorders. Several studies consider the application of diffusion tensor imaging (DTI) and tractography in the study of peripheral nerves. Methodology: We performed tractography and DTI in two female patients, one with a confirmed carpal tunnel syndrome and the other in good health conditions. Values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were recorded. Results: The average FA valué of the fiber was 0.461 (case) and 0.632 (control). No differences were reported between the average valúes of the ADC of the fiber. Discussion: We were able to represent the tract of the median nerve by using a software fortractography reconstruction. The morphology and valúes of quantitative analysis of DTI depend directly on the reconstruction algorithm used, mainly on the minimum FA value of the fiber to be reconstructed. The value of the FA, obtained by zone, was the most constant variable, being lower for the case.

Introducción: La resonancia magnética es una herramienta indispensable en el estudio de enfermedades del sistema nervioso central. Varios estudios consideran la aplicación del tensor de difusión (DTI) y tractografía en el estudio de nervios periféricos. Metodología: Se realizó tractografía y DTI en dos mujeres, una con síndrome del túnel carpiano confirmado y otra sin patología. Se consignaron valores de fracción de anisotropía (FA) y coeficiente de difusión aparente (ADC). Resultados: El valor promedio de FA de la fibra fue 0,461 (caso) y 0,632 (control). No hubo diferencias entre valores promedios de ADC de fibras. Discusión: Se logró representar el tracto del nervio mediano utilizando software de reconstrucción de tractografía. La morfología y valores del análisis cuantitativo del DTI dependen directamente del algoritmo de reconstrucción utilizado, especialmente del umbral mínimo de FA de la fibra a reconstruir. El valor más constante es FA, obtenido por zona, siendo menor en el caso.

Diffusion tensor MR imaging evaluation of the corpus callosum of patients with multiple sclerosis / Avaliação do corpo caloso em pacientes com esclerose múltipla através de imagens de RM por tensor de difusão

OBJECTIVE: To evaluate the fractional anisotropy (FA) values of the normal-appearing white matter of the corpus callosum (CC) in patients with relapsing-remitting multiple sclerosis (MS). METHOD: Fifty-seven patients with diagnosis of relapsing-remitting MS and 47 age- and gender-matched controls were studied. A conventional MR imaging protocol and a DTI sequence were performed. One neuroradiologist placed the regions of interest (ROIs) in the FA maps in five different portions of the normal-apearing CC (rostrum, genu, anterior and posterior portion of the body and splenium) in all cases. The statistical analysis was performed with the Mann-Whitney U test and p<0.05 was considered statistically significant. RESULTS: The FA values were lower in the MS patients compared with the controls (p<0.05) in the following CC regions: rostrum (0.720 vs 0.819), anterior body (0.698 vs 0.752), posterior body (0.711 vs 0.759) and splenium (0.720 vs 0.880). CONCLUSION: In this series, there was a robust decrease in the FA in all regions of the normal-appearing CC, being significant in the rostrum, body and splenium. This finding suggests that there is a subtle and diffuse abnormality in the CC, which could be probably related to myelin content loss, axonal damage and gliosis.

OBJETIVO: Avaliar os valores da anisotropia fracionada (FA) da substância branca aparentemente normal do corpo caloso (CC) em pacientes com esclerose múltipla (EM) remitente recorrente. MÉTODO: 57 pacientes com diagnóstico de EM remitente recorrente e 47 controles pareados por sexo e idade foram estudados. O protocolo convencional de RM e imagens de tensor de difusão foram adquiridas. Um neurorradiologista posicionou as regiões de interesse nos mapas de FA em seis porções do CC aparentemente normal (rostro, joelho, anterior e posterior porções do corpo e esplênio) em todos os casos. A análise estatística foi realizada com o teste Mann-Whitney U e p<0,05 foi considerado estatisticamente significativo. RESULTADOS: Os valores de FA foram menores nos pacientes com EM comparados com os controles (p<0,05) nas seguintes porções do CC: rostro (0,720 vs 0,819), corpo anterior (0,698 vs 0,752), corpo posterior (0,711 vs 0,759) e esplênio (0,720 vs 0,880). CONCLUSÃO: Na presente série houve redução robusta na FA em todas as regiões aparentemente normais do CC, sendo significativa no rostro, corpo e esplênio. Este achado sugere que há alteração difusa no corpo caloso de pacientes com EM, provavelmente relacionada a perda da mielina, lesão axonal e gliose.

A substância branca cerebral: localização dos principais feixes com anisotropia fracionada direcional / The cerebral white matter: localization of the main tracts with directional fractional anisotropy

A substância branca compreende cerca de metade do volume cerebral. É formada por numerosos feixes que apresentam direções diversas, interligando áreas corticais entre si e com estruturas subcorticais. Os estudos anatômicos que revelaram esses feixes tiveram sua origem na antiguidade. Foram utilizados métodos clássicos de dissecção e, mais recentemente, complementados com técnicas laboratoriais. Desse modo, foram identificados os principais feixes e as regiões que interconectam. Técnicas de neuroimagem modernas, introduzidas nas duas últimas décadas e ainda em plena evolução, vem trazendo contribuições que permitem aprofundar o conhecimento sobre o assunto, pela visualização in vivo do cérebro e de seus componentes. O mapeamento da substância branca obtido com imagens com tensor de difusão é uma das técnicas que têm permitido observá-la com mais detalhe, inclusive de modo quantitativo. Os princípios básicos dessas técnicas vêm relatados de modo sumário. A codificação em cores representa um aprimoramento dessa técnica que possibilita visualizar a direção dos feixes de fibras. Permite obter mapas direcionais e identificar os feixes que percorrem a substância branca. É apresentada uma descrição dos principais feixes cerebrais acompanhada por imagens ilustrativas. Esses recursos técnicos permitem fazer estudos mais detalhados dos feixes da substância branca cerebral, em condições normais e patológicas, e contribuem de modo importante para entender melhor a função cerebral e obter correlações anátomo-clínicas mais detalhadas.

The white matter represents about half of the cerebral volume. It is composed of numerous tracts that present varied directions, interconnecting cortical areas among them and with the subcortical structures. The anatomic studies that revealed these tracts stem from ancient times. Classic dissection methods were used, and more recently they were complemented with laboratory techniques. In this way, the main tracts and the regions they interconnect were identified.Modern neuroimaging techniques, introduced in the last two decades and still in plain evolution, are adding contributions that permit to deepen the knowledge on this issue, by visualizing in vivo the brain and its components. The mapping of the white matter obtained with diffusion tensor imaging is one of these techniques that allow making more detailed observations, inclusive quantitative ones. The basic principles of these techniques are described in a brief manner. The color-coding represents a refinement of this technique that permits to visualize the direction of the tracts of fibers. This permits to obtain directional maps, and to identify the tracts that traverse the white matter. A description of the main cerebral tracts accompanied by illustrative images is presented. These technical resources make possible to perform more detailed studies of the cerebral white matter, in normal and pathological conditions, and contribute in an important way to understand better the cerebral function, and to obtain more detailed anatomical-clinical correlations.