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.     

The polarization microscopy characteristics of collagen in dura mater transplants

In order to establish the polarizing microscopical characteristics of collagen in preserved dura mater transplants and in controls, a study was performed. Attempt was made for an intrpretation of velocity of collagen rehydratation by means of data of total anisotropy. The results show a faster rehydratation of collagen fibrils in control (unpreserved) dura mater. Changes in the velocity of rehydratation of collagen fibrils in lyophilized dura mater were connected with structural changes during lyophilization. The most appropriate period of time for rehydratation of lyophilized dura mater transplant was determined from the results of the polarizing microscopical study.     

Role of endothelin in mediating neurogenic plasma extravasation in rat dura mater

In addition to their potent vasoconstrictor properties, the endothelins (endothelin-1 and -3) may possess neurotransmitter/neuromediator and neuroendocrine actions. The aim of the present study was to evaluate the role of endothelins (ET) in mediating neurogenic inflammation of cephalic tissues in the rat. For this purpose, bosentan, a specific non-peptide mixed antagonist of ET receptors, was tested in rat models of neurogenic and non-neurogenic plasma extravasation in the dura mater and extracranial tissues (eyelid, conjunctiva, lip, tongue). Bosentan was effective for preventing neurogenic inflammation in the dura mater induced by unilateral electrical stimulation of the trigeminal ganglion or intravenous injection of capsaicin, whereas it was ineffective in extracranial tissues or after injection of substance P (non-neurogenic inflammation). The effect of nerve fiber stimulation on ET plasma concentrations in superior sagittal sinus was measured using selective radioimmunoassays for ET-1 and -3. Endothelin-3 concentration significantly increased after intravenous injection of capsaicin, whereas ET-1 levels remained unchanged. Competition binding assays on microsomal membranes from the trigeminal ganglion revealed a single class of binding sites with equal affinity for ET-1 and ET-3, suggesting a homogenous population of ETB receptors. The role of ETB receptors in mediating inflammation was evidenced by the lack of efficacy of a selective ETA receptor antagonist, in contrast to the full efficacy of a selective ETB receptor antagonist, for preventing neurogenic inflammation induced by unilateral stimulation of the trigeminal ganglion. The role of ETB receptors was finally confirmed by the observation that exogenous administration of the ETB receptor agonist sarafotoxin S6c also induced plasma protein extravasation in the dura mater. This extravasation was not a direct effect of ETB receptor stimulation, because it was inhibited by spantide, a selective tachykinin receptor antagonist. These data strongly suggest that ET, acting through ETB receptors, may play an important role in mediating neurogenic inflammation in the meninges of rats. Since the profile of activity of bosentan is similar to that of the 5-HT1D/B agonists, sumatriptan and ergot alkaloids, one may speculate that ET receptor antagonists might be potentially effective in the treatment of acute migraine attacks.     

Development of a dural substitute for preventing prion diseases induced by grafting of freeze-dried human dura mater

To provide a substitute for the dura mater a new bioabsorbable composite sheet was developed. This composite was composed of two L-lactic acid-epsilon-caprolactone (50:50) copolymer films and a poly (glycolic acid) nonwoven fabric. They displayed good mechanical properties and were completely absorbed 24 weeks after implantation in the back of rats. Histological evaluation of the composite sheet was undertaken by implanting it in 31 rabbits with dural defects and examining the sites of implantation 2 weeks to 26 months later. Any infection, cerebrospinal fluid leakage, evidence of convulsive disorders, significant adhesion to underlying cortex, and calcification was not noticed in any cases. In addition, the regenerated duralike tissue had a high pressure-resistant strength 2 weeks after implantation.     

Human dura mater as a wrapping material for hydroxyapatite implantation in the anophthalmic socket

Homologous sclera and autologous fascia lata have been accepted as common wrapping materials for hydroxyapatite implantation; however, various problems have been observed, such as the risk of transmittable diseases such as AIDS or hepatitis. This report details the use of cadaver dura mater to wrap hydroxyapatite implants. For 73 eyes of 73 patients with hydroxyapatite implantation, cadaver dura mater was used to wrap the hydroxyapatite after enucleation or secondary implantation. Of the 73 patients, 20 had conjunctival erosion; however, all of the patients but 1 healed spontaneously within an average of 22 days. Only 1 of the 73 patients progressed to implant exposure requiring a dermis graft. The authors suggest that cadaver dura mater is a suitable wrapping material for hydroxyapatite implantation.     

The demonstration of the vessels of the microcirculatory bed of the dura mater by using ATPase

In order to reveal the microcirculatory bed vessels, a histochemical method is suggested, lead technique for determination of ATFase localization being taken as its base. Owing to this method, it is possible to reveal constantly and rather fully microvessels long time after death and differentiate various links of the microcirculatory bed in the connective tissue membranes.     

Cranial sutures require tissue interactions with dura mater to resist osseous obliteration in vitro

A chemically defined serum-free medium, which supports the development of bones and fibrous tissues of rat calvaria from nonmineralized mesenchymal precursor tissues, was employed to investigate tissue interactions between the dura matter and overlying tissues. Fetal calvarial rudiments from stages prior to bone and suture morphogenesis (fetal days 19 and 20) and neonatal calvarial rudiments with formed sutures (day 1) were cultured with and without associated dura mater. Removal of calvaria for in vitro culture allowed the examination of suture morphogenesis in the absence of tensional forces exerted on the sutures via fiber tracts in the dura mater originating in the cranial base. Ossification of frontal and parietal bones proceeded in a fashion comparable to development in vivo, but the cranial (coronal) sutures--primary sites for subsequent skull growth--were obliterated by osseous tissue union in the absence of dura mater. Bony fusion did not occur when rudiments were cocultured with dura mater on the opposite sides of 0.45 microns polycarbonate transwell filters, suggesting that the influence of dura mater on sutural obliteration was mediated by soluble factors rather than cell-cell or cell-matrix interactions. These results indicate that cell signaling mechanisms rather than biomechanical tensional forces are required for morphogenesis of the calvaria.     

Juvenile amyotrophy of the distal upper extremity: pathologic findings of the dura mater and surgical management

OBJECTIVE: To evaluate the potential superiority of either oral or intraperitoneal treatment of catheter tunnel infections (TI), using clindamycin as a first-line antibiotic and ultrasound as a diagnostic tool. DESIGN: This was a prospective, randomized study in continuous ambulatory peritoneal dialysis patients. From August 1993 until August 1995, 16 clinically- and ultrasound-proven episodes of TI were randomly assigned to either an oral or an intraperitoneal (IP) treatment (100 patients, 1414 patient-months). Main criteria for TI diagnosis were purulent drainage from the exit site and/or a positive ultrasound (pericatheter fluid collection of at least 2 mm, 7.5 MHz transducer). Initially, clindamycin (20 mg/kg body weight) was given via the oral (three times per day) or intraperitoneal route (four times per day). In the case of incompatibility or resistance to clindamycin, either oxacillin or ciprofloxacin were used orally or IP. RESULTS: Based on ultrasound criteria, the mean time until a > or = 50% reduction of pericatheter abscess diameter was 26 days (median) (range: 8-28 days) in the oral, and 15 days (8-27 days) in the IP group (p < or = 0.05). Showing no significant difference of pericatheter fluid at study entry with 4 mm (median) (range: 2-6 mm) in the oral group and 4 mm (2-4 mm) in the IP group, the IP treatment resulted in a decrease to 0 mm (0-2 mm) after 28 days (p < 0.05), while the diameter was still 2 mm (0-10 mm) (NS) in the oral group. Disappearance of exit-site infection was also somewhat earlier in the intraperitoneal group (51 vs 15 days, NS). Catheter removal had to be done once in the IP group and twice in the oral group within 6 months after study entry. CONCLUSIONS: The results give evidence for greater efficacy of the IP application of clindamycin as a first-line antibiotic compared to the oral route for the treatment of tunnel infections.     

Effect of adrenomimetics and sympatholytics on the adrenergic neural fibers and mast cells of the dura mater

The effect of noradrenaline, dophamine and rausedyle on the adrenergic nervous apparatus and on the labrocytes of the dura mater in white rats was studied by means of Falk's and Glenner's methods and under light electron microscopy. The adrenergic nerve fibres and labrocytes are stated to respond to the injection of adrenomimetic and sympathomimetic drugs with increase or decrease of deposited monoamines on the background of corresponding clinical and vessel phenomena. The data obtained makes it possible to consider the adrenergic nerve fibres and labrocytes to be a single adrenergic apparatus of the dura mater.     

The plica mediana dorsalis of the dura mater and its relation to lumbar peridurography (canalography)

Lewit and Sereghy (1975) have expressed some doubts about the existence of the dorsal plica mediana and its relation to the median translucency regularly seen on peridurographic pictures made in the PA projection. The present paper reports the demonstration of the dorsal plica mediana in fresh anatomical preparations under conditions lowering the intradural pressure, and the relation of the plica to the peridurographical median translucency, shown on the basis of the injection into the lumbar peridural space of a gelatine solution containing India ink.     

Transneuronal labeling of CNS neurons involved in the innervation of the adrenal gland

In the light of the observation obtained with the application of the viral-tract tracing method, the CNS connection of the adrenal gland, with focusing on the central nervous connection of the adrenal cortex is reviewed.     

Ultrastructure of the cellular patches of the arachnoid membrane of the human brain (concerning the origin of the arachnoid-endothelial cleavages of the cerebral dura mater). Electron microscopic study

The ultrastructure of cellular spots was studied--growths of the external arachnoidendothelial layer of the arachnoid membrane of the human cerebral hemispheres. The peculiarities of their ultrastructure depending on the stage of their development were revealed. "Young", cellular spots were formed by accumulations of osmiophobic round-shaped cells that are lined from the outside by osmiophilic cells like the whole of the arachnoid membrane surface. "Mature" cellular spots contain great number of oxmiophobic (viable) cells located in a immediate proximity of the subdural space, and they form the main source of viable arachnoidenodthelial cells found in the subdural fluid. The author believes that these cells penetrate together with the subdural fluid flow into the dura mater where, under specific conditions, they may become a source of arachnoidendothelial chippings.     

The innervation of human epidermis

Using immunohistochemical procedures numerous nerve fibers have been found in all cell layers of human epidermis. These nerves originate from nerve trunks in the dermis, enter the epidermis, then divide distally to eventually end in small enlargements, near the surface of the skin and in deeper areas. Some endings may be external to stratum granulosum cells. Epidermal nerves appear to have a three-dimensional territorial distribution in relationship to the skin's surface. The presence of epidermal nerve fibers was confirmed by electron microscope studies. The nerves are presumed to be sensory in nature. The existence of epidermal nerve fibers will necessitate changes in present theory of structure and function of peripheral sensation.     

Autonomic and peptidergic innervation of the human larynx

Asymmetry in the face and dentition is a naturally occurring phenomenon. In most cases facial asymmetry can only be detected by comparing homologous parts of the face. The etiology of asymmetry includes: a) Genetic or congenital malformations e.g. hemifacial microsomia and unilateral clefts of the lip and palate; b) Environmental factors, e.g. habits and trauma; c) Functional deviations, e.g. mandibular shifts as a result of tooth interferences. Dental asymmetries and a variety of functional deviations can be treated orthodontically. On the other hand, significant structural facial asymmetries are not easily amenable to orthodontic treatment. These problems may require orthopedic correction during the growth period and/or surgical management at a later point. Patient complaints and desires need to be addressed since they may vary from unrealistic expectations to a lack of concern even in the presence of large deviations. With mild dental, skeletal and soft tissue deviations the advisability of treatment should be carefully considered.