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J A de Andrés

Publications and source records attributed to J A de Andrés.

17 recordsLinked to original sources
PubMed2000

[Morphology of peripheral nerves, their sheaths, and their vascularization].

This review aims to update our understanding of peripheral nerves, including the nature and function of their sheaths and, finally, their vascularization. The peripheral nervous system is made up of nerves whose function is to gather stimuli from the periphery as well as to transport the motor, secretory or vegetative responses that are triggered to the periphery. The connective tissue surrounding peripheral nerves all along their extension is made up of endoneurial, perineurial and epineurial. The endoneurium surrounds individual axons, which are grouped in fasciculi, each of which is surrounded by the perineurium and finally, the group of fasciculi that comprise all the axons present in this nerve are surrounded by the epineurium. Axons form an intraneural plexus such that they occupy positions in the various fasciculi along the trajectory of the plexus. The number and size of fasciculi vary along the trajectory of a nerve as a result of the plexus positioning of the axons. Peripheral nerves are richly vascularized throughout their length, with multiple anastomoses forming the intraneural vascular network, which is made up mainly of arterioles, capillaries, postcapillary venules and venules. Regarding the blood-nerve barrier and the existence of capillary permeability: endoneural capillaries have junctions that are stronger than those of the endothelial cells of vessels in the epineurium and perineurium. Two distinct lymph channels networks are present in the peripheral nerve stems and are separated by the perineural barrier. The nervi-nervorum are special nerves of a sympathetic and sensory nature that arise from the nerve itself and the perivascular plexuses.

Axons↗
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".

Aged↗
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

[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↗
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↗
PubMedDate not supplied

[Continuous intradural anesthesia in geriatric patients undergoing orthopedic and traumatologic surgery].

OBJECTIVES: The aim of the study was to prospectively evaluate the results of continuous intradural anesthesia with 18G Tuohy needle and 20G catheter in geriatric patients. MATERIAL AND METHODS: We studied 70 patients with a mean age of 75.9 +/- 10.8 years who were subjected to orthopedic or traumatologic surgery of the lower extremities with a duration of 104.6 +/- 53.6 min. RESULTS: Success index was 95.7%. The initial dose of 1% tetracaine was 10.36 +/- 3.96 mg, the second dose in 29 patients was 7.2 +/- 2.7 mg, the third in 7 cases was 7.40 +/- 2.47 mg, and the total dose was 14.56 +/- 5.6 mg. The metameric level was between T8 and T11 in 80.32% of patients. Peroperative complications were limited to paresthesia in 5 cases (7.14%) during insertion of the catheter, difficulties in catheter placement in one case (1.42%), and accidental catheter extraction during withdrawal of the needle in 2 cases (2.85%). Ten patients (14.28%) presented arterial hypotension (pressure decrease greater than 30% of baseline systolic arterial pressure). During the postoperative phase there were 3 cases of slight headache after dural puncture (4.28%) that recovered with conservative treatment, and one case of lumbalgia at the puncture zone (1.42%). CONCLUSIONS: Continuous intradural anesthesia with the material used in this study is technically easy. It allows to accurately reach the desired metameric level, avoiding massive sympathetic blockade, and providing a steady hemodynamic condition. All these effects are essential for anesthesia in geriatric patients.

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PubMedDate not supplied

[Bilateral axillary brachial plexus block guided by multiple nerve stimulation and ultrasound in a multiple trauma patient].

We present the case of a woman with multiple wounds and injuries after attempted suicide by jumping from a high place. She had multiple craniofacial injuries and fractures of both forearms requiring emergency osteosynthesis. The neurosurgeons requested that a level of consciousness be maintained for frequent assessment; therefore it was decided to provide a bilateral axillary brachial plexus block. The procedure was carried out with the aid of a nerve stimulator to locate a triple response in the left arm (radial, medial and musculocutaneous nerves) and with both ultrasound and double nerve stimulation in the right arm (medial and radial nerves). Surgery proceeded without adverse events. The location of nerves or nerve roots with both ultrasound and stimulators was highly useful in this patient in need of bilateral brachial plexus blockade. This combination, and ultrasound in particular, might be the technique of choice because it offers an image in real time and assessment of the least amount of anesthetic that seems to be needed for achieving a block.

Adult↗
PubMedDate not supplied

[Comparative study of detection methods in epidural anesthesia: Episensor and loss of resistance].

The aim of the present study is to evaluate an electronic detector of negative pressure (Episensor, Palex, Spain) designed for the identification of epidural space. Ninety patients were randomly assigned to two groups: group 1 (n = 47) received epidural anesthesia as perioperative analgesic technique with Episensor method and group 2 (n = 43) received epidural anesthesia with the classic method of loss of resistance with gas mandrin. The following parameters were studied: a) demographic features, b) characteristics of epidural anesthesia, and c) complications occurring during space detection. There were no statistical differences in the analysis of demographic variables neither in the quality of the epidural anesthesia achieved in both groups. With respect to complications, group I presented the highest number of complications although only the lack of detection of epidural space achieved statistical significance (8.5%, p less than 0.05); the incidence was lower than that reported in the literature as physiologically possible in the lumbar epidural segment. We conclude that progressive knowledge of Episensor may decrease the initial incidence of complications with a success rate similar to that of classic techniques of identification of epidural space.

Adult↗
PubMedDate not supplied

[Importance of the needle in regional anesthesia].

The safety of regional anesthesia lies on a set of factors, namely, selection of the adequate technique, skill and proper training from the part of anesthesiologists and use of right equipment. The needle, as a prolongation of the hand of the anesthesiologist, must provide references in technique either by itself or joined to an objective method of nerve localization; this will result in a high percentage of success without iatrogenesis. We have reviewed 1,132 cases of regional anesthesia and grouped them into: intradural anesthesia, epidural anesthesia, and plexus anesthesia. We have evaluated the equipment used according to the success and iatrogenesis directly produced by the needle. Results were analyzed by Fisher's exact test and were statistically significant in the three groups, a fact that would indicate some specificity of the characteristics of the needle in each group of techniques. It would seem reasonable to adopt those techniques appearing to be the most efficacious after analysis in order to increase percentage of success and achieve the greatest safety in the clinical practice of anesthesiologists.

Anesthesia, Conduction↗
PubMedDate not supplied

[Continuous block of the brachial plexus with nerve stimulation. Intra and postoperative control in orthopedic surgery of the arm].

A perivascular axillary plexus block was performed to 87 patients scheduled for orthopedic surgery of hand or arm using an electric nerve stimulator. A catheter was inserted for the postoperative pain control. The success rate was of 90.8% (79 cases); 65 patients (74.7%) presented a complete motor block. Complications were: arterial puncture (3), difficulty in inserting catheter (3), injection out of the sheath (1), pain at the electric stimulation (3). No allergic reactions nor neurologic complications were founded during a year of posterior control.

Adolescent↗