Morfología de la lámina aracnoidea espinal humana. Barrera que limita la permeabilidad del saco duralStructure of the arachnoid layer of the human spinal meninges: a barrier that regulates dural sac permeability
Section snippets
Introducción
Durante años se ha mantenido que, tras la administración de un fármaco en el espacio epidural, se produce un paso hacia el espacio subaracnoideo, en parte, a través de las vellosidades aracnoideas localizadas en los manguitos durales1., 2., 3., 4. y, en parte, por difusión a través del espesor del saco dural.
La hipótesis del paso de moléculas a través de las vellosidades aracnoideas se basaba probablemente en la idea inversa: el tránsito de sustancias desde el líquido cefalorraquídeo (LCR)
Material y método
Para la realización de este trabajo se ha contado con la aprobación del Comité de Ética de Investigaciones Clínicas (CEIC) del hospital, así como con el consentimiento informado de los pacientes intervenidos quirúrgicamente, para la obtención de muestras de tejidos. Se extrajeron muestras de membrana aracnoidea en dos pacientes, aprovechando el momento de la apertura de la aracnoides y la necesidad de extirparla parcialmente, para permitir una mejor visión y manipulación quirúrgica de la lesión
Resultados
Los resultados obtenidos fueron similares en todas las muestras. Del total de muestras se estudiaron once muestras y tres fueron descartadas por artefactos derivados de su procesamiento.
Bajo el microscopio electrónico, esta lámina tenía un espesor de 35-40 μm y estaba constituida por cuatro porciones bien diferenciadas: desde externo hacia interno encontramos una primera porción ocupada por células alargadas, ramificadas y oscuras, próxima al espacio subdural adquirido, que se corresponden con
Discusión
La lámina aracnoidea, entre sus componentes, tiene una capa de células fuertemente unidas entre sí, que puede justificar su efecto barrera, y que hemos denominado capa barrera de la aracnoides. Esta capa (tercera porción) representa por sí sola, aproximadamente el 20% del espesor de la lámina aracnoidea. En la primera porción más externa, se han encontrado células neuroteliales que se rompen durante las maniobras de apertura dural, para dar origen al espacio subdural adquirido. Internamente
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2017, World NeurosurgeryCitation Excerpt :Ability to dissect within the narrowest working zone interface, coupled with micromovements of hands without heating or vibration and feasibility to work in close contact with nerves or any other critical structure, makes it better than all other dissecting tools. Laboratory training enables a surgeon to dissect within the narrow range of 18–55 μm and thereby preserve an arachnoid layer of 35- to 40-μm thickness at the interface in extra-axial lesions.18 The aim of arachnoid preservation is pursued from the beginning of the meningioma resection, which is the objective evidence confirming the preservation of normal brain tissue (see Figure 4A and Video 2).
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2017, NeuromodulationCitation Excerpt :It is comprised of concentric dural laminas containing fibers distributed randomly in all directions (139–142). The arachnoid lamina has a thickness of 50–60 microns (µm) (143). Its barrier effect is due to arachnoid cells strongly bonded by specific membrane junctions.
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2011, European Journal of Pain SupplementsCitation Excerpt :It has cellular and fibrillar components (Fig. 4B). The cellular component is made up by an inner arachnoid lamina, with a thickness of 35–40 μm with different cells (Reina et al., 2010a). From outside to inside there are 10–14 layers of neurothelial cells that form the subdural compartment, then collagen fibers with different directions that take up to 40–50% of total width and another inner layer of arachnoid cells that play the role of barrier.
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2010, European Journal of Pain SupplementsCitation Excerpt :The cellular component of nerve root cuffs is a transition tissue between the cells of the dural cuff and the tissue of the peripheral nerves that originate from nerve roots at the intervertebral foramen (Figs. 5c and 6a–c). Within the dural cuff, these cells form the laminar arachnoid (Reina et al., 2007b, 2008b, 2010), the trabecular arachnoid (Reina et al., 2008c) and the pia mater (Reina et al., 2004, 2008a), around the medulla, nerve roots and the cerebrospinal fluid (CSF). In peripheral nerves, these cells form the concentric laminae of the perineurium, surrounding each fascicle (Reina et al., 2002, 2003).