Cefalea pospunción dural. Ultraestructura de las lesiones durales y agujas espinales usadas en las punciones lumbares / Post dural puncture cephalea. UItra-structure of the dural lesions and spinal needles used in lumbar punctures

Con el microscopio electrónico de barrido, se examinó la morfología de las lesiones durales y aracnoideas en muestras de saco dura-aracnoideo extraídos de cuerpos humanos recién fallecidos. Después de hacer punciones con agujas Quincke y Whitacre 22-G y 25-G, no se encontraron diferencias estadísticamente significativas entre las áreas de las lesiones durales y aracnoideas. La lesión tenía una morfología diferente con cada aguja. La aguja Whitacre producía una lesión de bordes rotos con gran destrucción de fibras durales, mientras que la aguja "biselada" Quincke causaba una lesión con forma de "U" o "V", como la tapa de una lata, con bordes de corte limpio. La alineación paralela o perpendicular entre el bisel de la punta de la aguja Quincke y el eje del axis no modificaba el área de las lesiones durales y aracnoideas. Se analizó cómo se puede producir cada tipo de lesión y se interpretaron los otros factores que podrían participar. Con la misma técnica se estudiaron agujas espinales nuevas obteniéndose, en cierto porcentaje de éstas, una imagen tridimensional a gran aumento de la fragmentación de puntas, defectos del pulido y existencia de rebabas. Se analizó cómo se pueden alterar las puntas de las agujas al chocar contra el hueso y de qué manera los defectos de estas constituyen otro aspecto de la compleja suma de variables que predisponen a la aparición de una cefalea pospunción dural.

The morphology of dural and arachnoid lesions was electronically scanned, from samples of dura-arachnoid sacs taken from recently deceased human beings. After punctures with Quincke y Whitacre 22-G y 25-G needles, no statistically significant differences were found between the areas of the dural and arachnoid lesions. The lesion had a different morphology with each needle. The Whitacre needle produced a lesion of broken edges with great destruction of the dural fibers, whereas the Quincke "beveled" needle caused a "U" or "V" shaped lesion, like the lid of a can, with clean-cut edges. The parallel or perpendicular alignment between the bevel of the Quincke needle tip and the axis of the axis did not modify the area of the dural and arachnoid lesions. A study was made of how each type of lesion could have come about and of other possible participating factors. The same technique was used to study new spinal needles and, in a certain percentage, a three dimensional image was obtained, showing a great increase in the fragmentation of the tips, burnish defects and the existence of burrs. We also analyzed how hitting against the bone could affect the tips of the needles and how their defects could be another factor in the complex sum of variables that predispose the patient to suffer post dural puncture cephalea.

Com o microscópio eletrônico de varredura, examinou-se a morfologia das lesoes durais e da aracnóide em amostras de saco dural-aracnóideo extraídos de corpos humanos de recem-falecidos. As diferencas entre as áreas das lesoes durais e da aracnóide pós-puncao com agulhas Quincke e Whitacre 22-G e 25-G nao foram estatisticamente significativas, e a morfologia da lesao causada com cada agulha foi diferente. A agulha Whitacre provocou lesao de bordas rompidas com grande destruicao de fibras durais, enquanto a agulha "biselada" Quincke causou lesao com forma de "U" ou "V", como a tampa de uma lata, com bordas de corte limpo. O alinhamento paralelo ou perpendicular do bisel da ponta da agulha Quincke com o eixo do áxis nao modificou a área das lesóes durais e da aracnóide. Foram analisadas as causas de cada tipo de lesao e interpretados outros fatores envolvidos. Utilizando a mesma técnica, avaliaram-se imagens tridimensionais de algumas agulhas espinhais novas tiradas com grande aumento: fragmentacao das pontas, defeitos de polimento e presenca de rebarbas. Avaliou-se também como se modificam as pontas das agulhas ao atingirem o osso e a influência dos defeitos das pontas na complexa soma de variáveis que predispoem o aparecimento de cefaléia pós-puncao dural.

El saco dural humano. Morfología de la dura-aracnoides espinal. Origen del espacio subdural espinal / The human dural sac. Morphology of the spinal dura-arachnoid membrane. Origin of the spinal subdural space

Esta revisión resume los hallazgos encontrados en el saco dural de cadáveres de recién fallecidos estudiados con diferentes técnicas histológicas. El saco dural espinal está formado por tres estructuras concéntricas: la duramadre, que ocupa el 85-90 por ciento de su espesor, del lado externo; el compartimiento subdural, integrado por células neuroteliales, y la lámina aracnoidea, que ocupa el 5 al 8 por ciento interno. La duramadre, que consta de aproximadamente 80 láminas durales concéntricas, es una estructura permeable y fibrosa, por lo cual posee resistencia mecánica. El compartimiento subdural es una estructura concéntrica, celular, de resistencia mecánica muy baja, donde se pueden producir fisuras concéntricas por rotura de las células neuroteliales dando origen a un espacio subdural adquirido. La lámina aracnoidea es una estructura celular con mayor resistencia mecánica que el compartimiento subdural. Sus células están firmemente unidas por uniones especializadas de membrana y forman una barrera semipermeable que regula el pasaje de sustancias a través del espesor del saco dural.

histological study of the dura mater using light and electron microscope

The present study has been undertaken to investigate the ultrastructure of the dura mater so as to correlate its structure with its mechanical function. This study aimed also to contribute further to the understanding of the functional morphology of the barrier formed by the mesothelial lining of the arachnoid mater to find a satisfactory explanation of the mechanism of bulk outflow of cerebrospinal fluid from the subarachnoid space into the dural sinuses. The clinical implication of this study in lumbar puncture procedure is also discussed. Six young adult sheep, eight rats, and four monkeys were used in this study. Specimens of 7 human lumbar dura and arachnoid were obtained during surgical treatment of disc herniation. Dura and arachnoid specimens were prepared for light and electron microscopy. Human Lumbar dura mater is divided into three parts: outer, middle and inner. In the outer part of the dura, collagen appears to be running in a longitudimal direction. Few elastic fibers and nerve fibers are also present. In the middle part, the collagen fibers are arranged in various directions with few elastic fibers in between. The inner part is less dense with collagen running mainly in a longitudinal direction. Numerous fibroblasts are present. The outer arachnoid is lined by a single layer of mesothelial cells. Below this are dark cells. The inner spinal human arachnoid is composed of groups of clear cells As regards spinal dura and arachnoid in the sheep, collagen fibers appear, in the outer dura, to be running in a longitudinal direction. In the middle dura, collagen is arranged in various directions. The inner dura is composed of collagen fibers running longitudinally and obliquely. Dark and light cells are present in the arachnoid. The collagen in the rat's dura is running mainly in a longitudinal direction in the outer part of the dura and in various directions in the inner part. The dural-arachnoid interface is readily identified by the presence of electron-dense granular material. At places, the arachnoid cells approximate that dense band thus diminishing the subdural space. The arachnoid is composed of fibrous connective tissue with numerous trabeculae. The arachnoid dark cells are characterized by dark nuclei with abundant heterochromatin. The dura of the monkey is composed of dense fibrous connective tissue consisting of collagen bundles and fibroblasts. The inner dura is highly cellular containing elongated fibroblasts. The collagen is loosely arranged in the inner dura. The subdural space is observed at the dural arachnoid interface in places however, this space was obliterated by the close approximation of the dural and arachnoid walls. The arachnoid is composed of two types of cells, clear and dark. The dura is composed of dense flbroblastic connective tissue and the collagen fibers are its major structural component. They have the strongest mechanical properties. Thus, the orientation of collagen fibers may explain the mechanical properties observed in different tissues. It has been previously indicated that the collagen fibers are arranged in a longitudinal and this explains the strong mechanical properties of the dura when subjected to stretching and deforming forces during movements and postural changes. Hopefully, increased understanding may open the way for new approaches in the evaluation of dural lesions produced by different needle bevels and the relationship of dural lesions to the production of postural headache

Estudo morfológico das granulaçöes aracnóides humanas com referência a sua classificaçäo / Morphological study of human arachnoid granulations regarding their classification

O estudo das granulaçöes aracnóides humanas por esteromicroscópio e microscópio óptico revelou que em um mesmo indivíduo estäo presentes granulaçöes morfologicamente distintas, que classificamos em simples e lobuladas. As granulaçöes simples eram pequenas e completamente envoltas por cápsula fibrosa que delimitava, em torno das granulaçöes, espaço subdural contínuo desdce o pedículo até o ápice. As granulaçöes lobuladas eram maiores que as simples; em seu ápice a cápsula era delgada e ocorria interrupçäo do espaço subdural, devido à fusäo do tecido fibroso da cápsula com a periferia da granulaçäo. As granulaçöes simples estavam possivelmente em fase inicial de desenvolvimento, enquanto as granulaçöes lobuladas estariam em fase mais avançada, com estrutura morfológica ideal para absorçäo do LCR