Biomedical subjects

M A Reina

Publications and source records attributed to M A Reina.

14 recordsLinked to original sources

PubMed1999

[Electron microscopic analysis of particles from surgical gloves and their possible introduction into the epidural space during epidural anesthesia].

OBJECTIVE: Many publications have linked surgical glove powder to inflammatory reactions of the peritoneum, pleura, pericardium and meninges. Accidental contamination may also increase the likelihood of complications after spinal and epidural anesthesia. We aimed to analyze the morphological characteristics of microscopic particles adhering to surgical gloves and to analyze how likely such particles are to enter the epidural space during catheterization. MATERIAL AND METHOD: One hundred epidural catheters were studied in two groups (A and B) of 50. Group A catheters contained stylettes and the distal ends were open (Vygon). Group B catheters contained no stylettes and had closed distal ends and three side openings (Becton Dickinson). Continuous epidural anesthesia was simulated with half the catheters in each group (25) by touching the distal end of each line with the gloves and later inserting the catheter through a Tuohy needle. All catheters--those used in the simulation as well as the untouched ones--were then examined under a scanning electron microscope. The particles on the internal and external surfaces of the gloves had previously been identified under a microscope and analyzed by X-ray diffraction. RESULTS: Gloves: external glove surfaces carried particles measuring between 3 and 4 mu; their morphology was consistent with calcium carbonate. On internal surfaces we found larger particles, between 11 and 14 mu in diameter, shaped differently and of smooth appearance. Analysis of the latter showed them to contain traces of magnesium and to have characteristics consistent with organic molecules. The particles of one surface were never observed on the other. Catheters: the non-manipulated catheters in both groups contained no free particles matching those described above, whereas the outside surfaces of the catheters in contact with gloves contained particles consistent with those of external glove surfaces. The number of particles per square millimeter of surface was 2,598 (95% CI 2,200 to 2,900) in group A catheters and 2,340 (95% CI 2,000 to 2,600) in the group B catheters (p = NS). The differences in the number of particles adhering to catheters touched by gloves and those that had not been manipulated were statistically significant (p < 0.001). CONCLUSIONS: Particles adhering to gloves can be drawn into the epidural space during continuous epidural anesthesia. All unnecessary manipulation should therefore be avoided, and the portion of the catheter to be inserted into the epidural space should not be touched in order to prevent possible nonspecific meningeal inflammatory responses.

Anesthesia, Epidural↗

PubMed1999

[Hypothesis concerning the anatomical basis of cauda equina syndrome and transient nerve root irritation after spinal anesthesia].

OBJECTIVE: Cauda equine syndrome is a rare neurological complication associated with subarachnoid anesthesia, and particularly with the use of 5% hyperbaric lidocaine and small gauge catheters. Our aim was to study a possible anatomical factor that might impede adequate dilution of local anesthetic and explain the development of cauda equine syndrome and transitory radicular irritation. MATERIAL AND METHOD: The spinal dura matters and their contents from two male human cadavers were examined after organs had been extracted for transplantation. Both men had recently died at ages 56 and 65 years of age. Samples were fixed in a glutaraldehyde phosphate buffer and dehydrated in acetone, which was then removed by critical point elimination. The samples were then metallized with gold and observed under a scanning electron microscope. RESULTS: We found that one portion of the arachnoids was more compact and another was lax. The compact portion had a laminar structure formed by the fusion of fibers and cell components lining the inner surface of the dural mater. The lax portion was comprised of a weblike network of filaments and few cells bodies. This portion extended from the compact inner arachnoid lamina to the cell plane of the pia mater, where it dispersed, sending out compact arachnoid projections that wrapped around structures in the subarachnoid space. We termed these wrappings "arachnoid sheaths".

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PubMed1999

[Thickness variation of the dural sac].

OBJECTIVE: To measure carefully the thickness of the dural sac and evaluate possible variation in recently removed human specimens that had not yet undergone postmortem change. The thickness of the dural membrane is of interest because of its function as a barrier during diffusion processes and during closure of spinal lesions. MATERIAL AND METHODS: After receiving the consent of our hospital's ethics committee and the family of the deceased, and immediately after extraction of organs for transplantation, we removed the dural sac and nerves contained therein from the cadaver of 56-year-old patient diagnosed of brain death. The membrane was dissected and 240 measurements of thickness were made over the entire surface of the sample. A micrometer was used, controlled through a surgical microscope. To analyze variations in thickness, the specimen was divided into 48 zones. RESULTS: The dural sac open on its anterior side was treated as a rectangular membrane measuring 130 x 54 mm. Mean thickness of the sample was 0.322 mm. Mean thickness of anterior zones was 0.353 mm, with no significant differences among them. Posterior zones measured a mean 0.295 mm with significant differences among them (p < 0.001). Up to the second lumbar root, anterior and posterior zone thicknesses presented no significant differences. However, after the space between the second and third lumbar roots, the posterior side was significantly thinner. Where the first, second and third lumbar roots emerged, we measured thicknesses of 0.315, 0.361 and 0.322 mm, with no significant differences among anterior, posterior and side zones on any level. At the fourth lumbar root and in the spaces of the dura mater between the emergence of the first and second, the second and third, the third and fourth and fourth and fifth lumbar roots, we observed significant differences. The measurements were 0.298 mm (p < 0.01); 0.348 mm (p < 0.01); 0.337 mm (p < 0.001), 0.306 mm (p < 0.01); 0.289 mm (p < 0.001), respectively. CONCLUSION: Possible inter- or intra-individual variation in dural sac thickness is an unpredictable variable affecting the management of dural lesions. The data we report on thickness allow for future objective assessment of the maximum sizes recommended for the lateral orifices of bevelled, pencil-point needles in order to avoid straddling the membrane when subarachnoid anesthesia is given. The data also contributes to the study of substance diffusion through this membrane.

Dura Mater↗

PubMed1998

[New results in the visualization of the spinal dura mater with scanning electron microscopy].

UNLABELLED: Although there are various published descriptions of the dura mater spinalis [4, 7, 9, 11, 16], some points relating to the texture of the collagen fibres in the dura have still not been adequately explained. In this study the orientation of the collagen fibril bundles was revealed with the aid of scanning electron microscopy, and our observations have yielded new insights into the three-dimensional structure of the human dura mater spinalis. MATERIALS AND METHODS: The preparations used were taken from the bodies of four persons who had died of acute cardiac infarct at the ages of 70-78 years. The histories of these patients gave no indications of earlier neurological, endocrine or septic illnesses. The tissue examined was taken 8-12 h after death in all cases; it was immediately fixed in glutaraldehyde and then processed for scanning electron microscopy in the usual way. RESULTS: In the outermost (epidural) layer of the dura mater spinalis the collagen fibres are bunched together in bands that run in all directions. Elastic fibres 2 mm thick are woven into this three-dimensional network of collagen systems. On the inside (the arachnoid side) thin collagen fibres are fused into layers in such a way that the innermost layer resting on the arachnoid has a smooth, shiny appearance comparable to that of a serosa. It is attached to the actual dura with a supporting band of connective tissue. Rests of the subdural neuroepithelium could contribute to the smooth appearance of the superficial aspect. CONCLUSIONS: The outermost layer of the dura is made up mainly of collagen fibres, which run in all three directions--longitudinal, horizontal and transverse--both singly and in groups. These findings are at odds with "classic" descriptions, according to which the fibres in the dura mater spinalis all have a parallel course with a longitudinal orientation in tangential sections.

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PubMed1998

[Anatomical description of a natural perforation present in the human lumbar pia mater].

OBJECTIVE: The pia mater has always been considered more permeable than other meningeal membranes. Natural pia mater perforations found in some animals at-test to this membrane's permeability. Such perforations, however, have never been demonstrated in human tissue. Our objective was to study human pia mater from the dorsal lumbar region, looking for perforations that facilitate the diffusion of substances to the spinal cord following subarachnoid administration. MATERIAL AND METHOD: The specimens were removed from four human cadavers aged 70, 72, 77 and 78 years between 8 and 12 hours after death. The specimens were fixed in a phosphate glutaraldehyde buffer solution, followed by desiccation in acetone and critical point elimination of acetone, treatment with carbon and metallization with gold. RESULTS: The pia mater was composed of a smooth surfaced, thin layer of cells and underlying connective tissue formed mainly of collagen fibers and fundamental amorphous matter. The collagen fibers were oriented in various directions. Throughout the surface of the pia mater, natural circular, elliptical and ovoid perforations were distributed irregularly. Size varied. Most measured over 10 to 15 micrometers in diameter or less than 5 to 8 micrometers. Inside the openings, fibers similar to collagen fibers could be seen at the point where they would normally be found beneath the cell layer. CONCLUSION: The total thickness of the pia mater varies in different zones of the spine, as a result of variations in the thickness of the cell layer and in the underlying extracellular layer. The existence of natural fenestrations in all the analyzed specimens of human dorsal lumbar pia mater accounts for the high permeability of this membrane, which permits substances administered in spinal fluid to reach the spinal cord. These natural fenestrations are areas where the cell surface in absent, with underlying collagen fibers usually visible. The pia mater is generally believed to be composed of a complete cell layer that forms a barrier between the central nervous system and the subarachnoid space; however, the presence of fenestrations would indicate that such a barrier does not exist, the base membrane being placed under the connective fibers, the only intact structure prior to medullary glial cells.

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PubMed1998

[Does the subdural space exist?].

A potential space between the dura mater and the arachnoides is thought to exist, occupied by a serous fluid and called the subdural space. Recent studies may change this classical concept, however. The dura-arachnoid complex from the epidural to the arachnoid space is formed by morphologically distinct layers: the dura mater, the subdural compartment and the arachnoid mater, which are made up of different cell types. The dura mater consists of greater and lesser laminae formed mainly of collagen fibers aligned differently. The subdural compartment is formed by a number of so-called "neurothelial cells", which are in close contact with the inner dural layers. These cells are flat and have long interlaced branches. The arachnoides are made of cells grouped in three different layers. The outer layer is the "barrier arachnoid layer". Located just inside the anterior cell plane, this layer is made of less flattened cells that form an epithelial-type tissue, with complex cell-cell junctures surrounded by collagen fibers. The middle layer is the reticular arachnoid, composed of irregularly interlaced cells alternating with collagen fibers and intercellular gaps of varying sizes. The innermost layer, the trabecular arachnoid, is in direct contact with the subarachnoid space. The cells of this layer form strands that contribute to the weblike pattern found in the subarachnoid space. Recently, special techniques for fixing and preparing samples, preserving in situ the anatomical relations between the arachnoides and the dura mater, have allowed us to examine the normal configuration of the subdural space. All samples examined revealed the presence of a cellular plane between the dura mater and the arachnoides, with no evidence of the classically described space. The zone of least resistance in the dura-arachnoid complex was the subdural compartment, which could be torn mainly along intercellular spaces, though cell rupture was also observed, affecting the cytoplasmic membranes of adjacent cells. The subdural space is opened by tearing the subdural compartment between neurothelial cells alongside the collagen fibers of the dura mater. Such a tear can be caused mechanically by injecting air or contrast media, which exert pressure on a laminar structure that tends to separate because it is weaker than neighboring ones.

Animals↗

PubMed1997

[Electron microscopy of the lesions produced in the human dura mater by Quincke beveled and Whitacre needles].

INTRODUCTION: Comparisons of Quincke needles and non traumatic "pencil point" needles in recent years have reported lower rates of post dural puncture headache using the later type. Our new understanding of the morphology of the human dura mater motivated us to study dural lesions caused by the Whitacre 25 G and Quincke 26 G needles, using scanning electron microscopy with the aim of determining whether there is an anatomic basis for the different outcomes. METHOD: The dura mater from three fresh cadavers of individuals aged 65, 70 and 72 years were punctured 40 times at an angle of 90 degrees each time. The Whitacre 25 G needle was used for 20 punctures and the Quincke 26 G needle was used for the other 20. Half the punctures were performed with the bevel in the parallel alignment and the other half with the bevel perpendicular to the spinal column. Fifteen min after causing the punctures, specimens were fixed in solutions of glutaraldehyde phosphate buffer and dehydrated in acetone. After critical point removal of the acetone, after the specimens were treated with carbon and metallized with gold. The lesions were examined externally and internally and expressed as the ratio of area of lesion to diameter of the needle that had caused them. RESULTS: Whitacre needle: each lesion consisted in the superimposition of multiple damaged layers that started to close individually. After 15 min the outermost layers were 90% closed and the innermost ones had closed entirely. Layers in the arachnoid surface of the dura mater had closed from 86 to 88%, while deeper layers in the thick part had closed 97 to 98%. Quincke needle: lesions were V-shaped or half-moon shaped, much like the opening formed by a can opener, on both the external and internal surfaces. Alignment of the bevel of the needle parallel to the spinal column did not lead to a different shape of puncture. After 15 min the lesions had closed 94 to 95% on the epidural surface and 95 to 96% on the arachnoid side, a difference attributable to the retraction of the arachnoid layers over the spinal column. CONCLUSION: Non traumatic beveled dural needles, termed "pencil point needles", only partially separate dural fibers, and lesions caused by these needles develop in a more complex way. The Quincke 26G needle produced a puncture that is morphologically different from that caused by the Whitacre 25G needle, although lesions produced by both types close more than 94% after 15 min. We believe the size of the lesion caused by these needles does not explain the difference in post dural puncture headache due to loss of spinal fluid.

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PubMed1997

[Microscopic characteristics of epidural filter pores].

OBJECTIVE: The increased use of the epidural route for administering opioids to treat chronic pain and the need to reduce complications as much as possible, has led some authors to recommend using micro filters to reduce catheter contamination. This study was motivated by the lack of technical information documenting epidural filters used routinely, as well as by the scarcity of literature describing their characteristics. Our aim was to investigate the true nature of the membrane pores, their characteristics and dimensions. MATERIAL AND METHOD: Samples from 30 epidural filters labelled "Porosity: 0.2 microns" from three different manufacturers were studied. Filters from Vygon, Braun and Abbot were labelled A, B and C, respectively. The samples were placed in six groups of five filters each, and 15 random studies were made of each sample. Three of the six groups were used to study prefiltration surfaces and the others to study postfiltration surfaces. Each sample was metalized with gold and its center was then studied by scanning electron microscope. Given that the pores were anfractuous, they were measured by taking the diameter of the largest circle fitting inside that could predict the size of the smallest spherical non elastic body that might be retained. The samples for measuring thickness were cryofractured for determining the number of filtration planes in the 15 filters. RESULTS: Prefiltration surface: Pore diameters were 0.70 (0.66 to 0.74), 0.45 (0.41 to 0.49), and 2.077 (2.01 to 2.15) microns on the filtration surfaces of manufacturers A, B and C, respectively. The differences were significant (p < 0.01) and the pore shapes were also different. Postfiltration surface: The function pores of filters from manufacturers A and B measured 0.26 (0.25 to 0.28) and 0.26 (0.24 to 0.28) microns, and the differences were not significant. The pores of filters from company C were significantly larger (p < 0.01), measuring 0.46 (0.43 to 0.49) microns. There were significant differences (p < 0.001) in pore size on the pre- and postfiltration surfaces from all three manufacturers. Gauge: The five A, B and C filters averaged 130, 118 and 165 microns thick, respectively, with an average number of 140, 220 and 210 filtration planes, respectively. CONCLUSION: The pores of filters for epidural use labelled "0.2 microns" actually had much larger pores on their prefiltration surfaces and throughout the membrane thickness. On the postfiltration surface, however, the diameters of pores on filters manufactured by Vygon and Braun approached 0.2 microns. Pores on filters manufactured by Abbot, however, were approximately 0.46 microns. We believe that in the future manufacturers should include more information in the documentation accompanying their filters.

Analgesia, Epidural↗

PubMed1996

[Analysis of the external and internal surface of human dura mater with scanning electron microscopy].

INTRODUCTION: In recent years several studies have raised questions about the anatomy of the human dura mater. Our objective has therefore been to examine its tridimensional structure with the aid of the scanning electron microscope. METHOD: Samples were taken from 4 human cadavers (70, 72, 77 and 78 years old) between 8 and 12 hours after death. After fixing in glutaraldehyde phosphate buffer, dehydration in acetone and elimination of the acetone at the critical point, treatment with carbon and metallization with gold, the external and internal surfaces were examined. RESULTS: The external, or epidural, surface of the dura mater is made up of thin collagen fibers joined in bands running in different directions. The outer surface and lower layers of the dura contain elastic, interwoven fibers surpassing 2 microns in diameter. The inner surface, which is smooth and glossy, is formed of thin ribbons of arachnoids that are fused and tightly attached to the structure of the dura mater. CONCLUSION: The outer surface of the dura mater consists mainly of collagen fibers which alone or in groups run in different directions: longitudinally, horizontally or obliquely, depending on the are studied. These findings contradict the classical descriptions of the dura mater as having parallel, longitudinally placed collagen fibers in the tangential plane.

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PubMed1996

[Structural analysis of the thickness of human dura mater with scanning electron microscopy].

INTRODUCTION: The only references to the thickness of the human dura mater, reporting its size at various levels, are now 50 years old. Our aim was to study its tridimensional structure with the aid of the scanning electron microscope. METHOD: The samples, which were taken 8-12 h after death from 4 human cadavers between 70 and 78 years old, were examined on 2 orthogonal planes (radial longitudinal and transversal). RESULTS: The architectural structure of the external membrane of the meninges was unusual. The dura mater is made up of elastic collagen fibers organized in successive parallel planes on the surface of the medulla. Each plane constitutes a unit which we will call a sub-laminae. The sub-laminae are found in groups of 8 to 12 that form larger units called laminae, which are between 4 and 5 microns thick. The full thickness of the dura mater at the level of the third lumbar vertebrate contains from 78 to 82 laminae which together measure 270 microns. CONCLUSION: The dura mater is made up of a large number of sublaminae that are concentrically parallel to the surface of the medulla. The fibers in general run in all directions and are oriented differently in each sub-lamina. The orientation of fibers that can be seen on the outer or epidural surface corresponds only to the fibers of the outermost lamina, which has a thickness of 78 to 82 microns. A needle that pierces the dura mater passes through some 700 to 800 sublaminae, each with its own particular distribution of fibers.

Aged↗

PubMed1996

[Iatrogenic spinal epidermoid tumors. A late complication of spinal puncture].

INTRODUCTION. Epidermoid tumors in the spinal canal are rare. Whether congenitally or iatrogenically caused, they form as the result of epidermal cells implanted within the spinal channel. Such implantation can occur during a variety of procedures and events such as bullet wounds, surgery, myelography or punctures for diagnosis, anesthesia or treatment. Although this complication is not discussed in books or journals on anesthesiology, we have found it mentioned in over 100 published cases reporting iatrogenically caused spinal epidermoid tumors. ETIOPATHOGENESIS. Iatrogenic epidermoid tumors of the spine derive from the implantation of epidermal tissue transported inside the spinal canal during lumbar punctures without guidance or with inadequate guidance. There is ample evidence that such tumors are iatrogenic. All cases occur in patients with a history of lumbar puncture. They are rarely associated with congenital anomalies. They are extramedullary. They tend to develop near sites of earlier lumbar puncture, usually near the conus medullaris and the cauda equina. Iatrogenic epidermoid tumors of the spine have been reproduced experimentally in two studies in which autologous skin fragments were implanted in the spinal canal. CLINICAL SIGNS. These tumors are well tolerated by patients for extended periods of time, ranging from 2 to 10 years. At the cauda equinus, tumors can grow slowly for long periods without signs of nerve compression. Symptoms are directly related to tumor size and site. All patients with tumors at the cauda equinus report severe pain radiating toward the roots of compressed nerves. Nuclear magnetic resonance makes it possible to detect the tumor without administration of intrathecal contrast. At present gadolinium-DTPA improves the image so that these tumors can be distinguished from other types. The prognosis for epidermoid tumors of the spine is good, as they are histologically benign. Treatment is always surgical. CONCLUSION. Although the causal relation between epidermoid spinal tumors and lumbar puncture is well documented, anesthesiologists are not sufficiently aware of this possible complication. Between 1977 and 1995, 28 new cases were published. We believe that a deeper understanding of such rare complications will show us how to prevent them while providing appropriate use of epidural and subarachnoid anesthesia.

Epidermal Cyst↗

PubMed1995

[Skin fragments carried by spinal needles in cadavers].

Epidural or intradural puncture with inappropriately stiffened or improperly placed needles can carry cells or fragments of epithelial tissue into the epidural or intradural space. These skin fragments feed by imbibition, possibly leading to the development of epidermoid cysts. We aimed to study the ability of today's needles to transport cells or epithelial fragments. We studied 120 needles in 6 groups of 20, as follows: group 1, Touhy G-16; group 2, Touhy G-17; group 3, Quincke G-22; group 4, Quincke G-26; group 5, Sprotte G-22, and group 6, Sprotte G-24. These needles were used to make intradural and epidural insertions, as indicated, with stiffeners fully in place. Insertions were made into 3 cadavers, epidermal cells or skin fragments were then isolated from the solutions used to wash the needles, and the samples were studied under an optical microscope. We identified groups of cells or epidermal tissues in 45% of the Touhy G-16 samples and in 30% of the Touhy G-17 samples. Squamous epithelial cells were found in 15% of the Quincke G-22 samples and in 30% of the Sprotte G-22 samples. There was a significant difference between the amount of tissue transported by the Touhy needles in comparison with the Quincke (p < 0.01) and Sprotte (p < 0.05) needles. Needles from some manufacturers transport epithelial fragments during lumbar puncture. We believe that better quality control during manufacture of epidural and intradural needles can help to eradicate the rare neurological complications derived from the removal of epithelial cells and their subsequent deposit inside the spinal channel.

Cadaver↗

PubMedDate not supplied

New perspectives in the microscopic structure of human dura mater in the dorsolumbar region.

BACKGROUND AND OBJECTIVES: The object of this study was to describe the three-dimensional structure of the dura mater by use of scanning electron microscopy. METHODS: Microscopic dissection of the dura mater from four fresh cadavers (aged 70, 75, 76, and 80 years) 8-12 hours after death were investigated in three different planes (longitudinal, tangential, and transverse). RESULTS: The external surface of the dura mater, facing the epidural space, consisted of a network of randomly oriented fine collagen fibers. The thicker elastic fibers (2 microns in diameter) were observed on the surface of the dura. In the inner part of the dura mater, there were very fine lamellae of collagen fibers, which were bundled into thicker (4-5 microns) layers. The dura mater consisted of 78-82 layers, each layer including 8-12 very fine lamellae. CONCLUSIONS: The fibers of the dura mater do not run in a longitudinal direction and are not arranged in a parallel fashion. Cytoarchitecturally the dura mater is a laminated structure built up from well-defined layers oriented concentrically around the medulla spinalis.

Aged↗

PubMedDate not supplied

An in vitro study of dural lesions produced by 25-gauge Quincke and Whitacre needles evaluated by scanning electron microscopy.

BACKGROUND AND OBJECTIVES: A study using scanning electron microscopy showed that although the laminas forming the dura mater are concentric and parallel to the surface of the medulla, the fiber layers' orientations are different in each sub-lamina, dispelling the conventional knowledge that all the fibers of the dura are arranged in a parallel direction. Thus, this study evaluated the dural lesions produced by Whitacre and Quincke spinal needles in the external and internal surface of the dura mater of the lower spine area in an attempt to gain more insight into the pathophysiology of postdural puncture headaches (PDPH). METHODS: The T11-L4 dural membranes from 5 fresh (immediately after extraction of organs for transplantation), male patients declared brain dead, ages 23, 46, 48, 55, and 60 years, were excised by anterior laminectomy. Morphologic orientation of the membrane and normal pH were maintained with an apparatus designed for this purpose. One hundred punctures (20 on each sample) at 90-degree angles were done with a new needle each time, 50 with 25-gauge Whitacre and 50 with 25-gauge Quincke needles. Half of the punctures with the Quincke needles were done with the bevel in parallel direction to the axis of the spinal cord, and the rest with the bevel perpendicular to it. Fixation in solutions of 2.5% glutaraldehyde phosphate buffer, followed by dehydration with acetone, was done 15 minutes after the punctures. After acetone was removed at ideal conditions of temperature and pressure, the specimens were then metallized with carbon followed by gold and inspected under a scanning electron microscope. RESULTS: Twenty-five of the Whitacre and 23 of the Quincke punctures were found for evaluation. There were no differences in the cross-sectional area of the punctures produced by the Whitacre or Quincke needles on the dura. The area of the dural lesions produced by 25-gauge Quincke needles, 15 minutes after they have been withdrawn, was 0.023 mm2 (confidence interval [CI] 95%, 0.015 to 0.027) in the external aspect (epidural surface) and 0.034 mm2 (CI 95%, 0.018 to 0.051) in the internal aspect (arachnoid surface) of the dural sac. The area of the lesions produced by the 25-gauge Whitacre needles was 0.026 mm2 (CI 95%, 0.019 to 0.032) and 0.030 mm2 (CI 95%, 0.025 to 0.036) in the external and internal surfaces of the dural sac, respectively. There were no significant differences in the cross-sectional areas of the punctures produced by the 25-gauge Whitacre or 25-gauge Quincke needles. Moreover, with Quincke needles the dural lesions closed in an 88.3% (CI 95%, 86.3 to 92.4) and 82.7% (CI 95%, 74.1 to 90.9) of their original sizes in the epidural and arachnoid surfaces, respectively. With Whitacre needles, the closure occurred in an 86.8% (CI 95%, 83.8 to 90.3) and 84.8% (CI 95% 81.7 to 87.3) in the dural and arachnoid surfaces, respectively. However, there were differences in the morphology of the lesions. The Whitacre needles produced coarse lesions with significant destruction in the dura's fibers while the Quincke needles produced a 'U'-shaped lesion (flap) that mimics the opened lid of a tin can, regardless of the tip's direction. CONCLUSIONS: The needles produced lesions in the dura with different morphology and characteristics. Lesions with the Quincke needles resulted in a clean-cut opening in the dural membrane while the Whitacre needle produced a more traumatic opening with tearing and severe disruption of the collagen fibers. Thus, we hypothesized that the lower incidence of PDPH seen with the Whitacre needles may be explained, in part, by the inflammatory reaction produced by the tearing of the collagen fibers after dural penetration. This inflammatory reaction may result in a significant edema which may act as a plug limiting the leakage of cerebrospinal fluid.

Adult↗