ABSTRACT
La hipotensión de líquido cefalorraquídeo y la tracción de estructuras encefálicas sensibles al dolor ha sido una de las hipótesis más reiterada para justificar la cefalea pospunción dural. En este trabajo se recogen resultados obtenidos de diferentes estudios realizados por nuestro grupo, que se completan con nuevas aportaciones. Se estudió con técnicas con microscopia óptica y electrónica la morfología de los componentes del saco dural espinal humano, las lesiones que se producían con agujas de punción lumbar de diferente diámetro y diseño de punta, y tras la disección de un encéfalo, se señalan detalles del trayecto aparente de los pares craneales que pueden ser traccionados cuando un paciente con hipotensión de líquido cefalorraquídeo está en posición erecta. Los resultados aportan detalles morfológicos que contribuyen al conocimiento de la fisiopatología de la cefalea pospunción dural (AU)
Hypotension caused by cerebrospinal fluid leakage and traction over certain brain structures has been blamed as the main reason for post-dural puncture headache (PDPH) In this paper we review different papers published by our group in which we show old and new data. We light and electron optic microscopy to study the morphology of the human dural sac plus the damage caused by different types of needles with different diameters. We dissected different brain specimens to show the path of the cranial nerves focusing on those that can be affected by traction during orthostatic position. These results show several morphology details that can contribute to the physiopathology of post-dural puncture headache (AU)
Subject(s)
Humans , Spinal Puncture/adverse effects , Post-Dural Puncture Headache/physiopathology , Needles/adverse effects , Cranial Nerve Injuries/etiology , Microscopy, ElectronABSTRACT
OBJECTIVES: Drugs injected into the epidural space are known to penetrate the subarachnoid space by simple diffusion through the dural sac. We aimed to study the cellular ultrastructure of the arachnoid membrane and the type of intercellular junctions responsible for creating the barrier that regulates the passage of drugs through the dural sac in humans. MATERIAL AND METHODS: Fourteen tissue samples of arachnoid membrane were taken from 2 patients during procedures that required opening the lumbar dural sac. The samples were treated with glutaraldehyde, osmium tetroxide, ferrocyanide and acetone, and then embedded in resin. Ultrathin sections were stained with lead citrate for examination by transmission electron microscopy. RESULTS: The arachnoid membrane was 35 to 40 microm thick. The outer surface contained neurothelial cells (dural border cells) along the subdural compartment, while the internal portion was made up of a plane 5 to 8 microm thick with 4 to 5 arachnoid cells overlapping to form a barrier layer. The intercellular spaces on this plane were 0.02 to 0.03 microm wide; the arachnoid cells were bridged by specialized junctions (desmosomes and other tight junctions). CONCLUSIONS: Structural features of the arachnoid cells provide a barrier within the human dural sac. They occupy only the internal portion of the arachnoid membrane. Specialized intercellular junctions explain the selective permeability of this membrane.
Subject(s)
Arachnoid/ultrastructure , Spinal Cord/ultrastructure , Arachnoid/metabolism , Humans , Microscopy, Electron, Transmission , Permeability , Spinal Cord/metabolismABSTRACT
OBJETIVOS: Se ha demostrado que las moléculas inyectadas en el espacio epidural pasan desde éste al espacio subaracnoideo por difusión simple a través de la pared del saco dural. Nuestro objetivo fue estudiar la ultraestructura de células de la lámina aracnoidea y tipo de uniones especializadas responsables del efecto barrera que gobierna el tránsito de moléculas a través del saco dural humano. MATERIAL Y MÉTODO: Se estudiaron catorce muestras de la lámina aracnoidea obtenidas de dos pacientes durante intervenciones con apertura del saco dural lumbar. Las muestras se trataron con glutaraldehido, tetróxido de osmio, ferrocianuro, acetona, e incluyeron en resina. Los cortes ultrafinos se contrastaron con citrato de plomo, para poder ser observados con un microscopio electrónico de transmisión. RESULTADOS: La lámina aracnoidea posee un espesor de 35-40 μm. En su porción externa se hallan células neuroteliales del compartimento subdural, mientras que su porción interna está formada por un plano celular de 5-8 μm de espesor, constituido por la superposición de 4-5 células aracnoideas que forman la capa barrera. El espacio intercelular de este plano fue de 0,02-0,03 μm. Entre las células aracnoideas se encontraron uniones especializadas de membrana de tipo desmosomas y uniones estrechas. CONCLUSIONES: Las células aracnoideas poseen características estructurales que aseguran la función barrera del saco dural humano y no ocupan todo el espesor de la lámina aracnoidea, sólo su porción interna. La presencia de uniones especializadas de membrana entre sus células justifica la permeabilidad selectiva de esta lámina(AU)
OBJETIVES: Drugs injected into the epidural space are known to penetrate the subarachnoid space by simple diffusion through the dural sac. We aimed to study the cellular ultrastructure of the arachnoid membrane and the type of intercellular junctions responsible for creating the barrier that regulates the passage of drugs through the dural sac in humans. MATERIAL AND METHODS: Fourteen tissue samples of arachnoid membrane were taken from 2 patients during procedures that required opening the lumbar dural sac. The samples were treated with glutaraldehyde, osmium tetroxide, ferrocyanide and acetone, and then embedded in resin. Ultrathin sections were stained with lead citrate for examination by transmission electron microscopy. RESULTS: The arachnoid membrane was 35 to 40 μm thick. The outer surface contained neurothelial cells (dural border cells) along the subdural compartment, while the internal portion was made up of a plane 5 to 8 μm thick with 4 to 5 arachnoid cells overlapping to form a barrier layer. The intercellular spaces on this plane were 0.02 to 0.03 μm wide; the arachnoid cells were bridged by specialized junctions (desmosomes and other tight junctions). CONCLUSIONS: Structural features of the arachnoid cells provide a barrier within the human dural sac. They occupy only the internal portion of the arachnoid membrane. Specialized intercellular junctions explain the selective permeability of this membrane(AU)
