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Clinical experience with expanded polytetrafluoroethylene sheet used as an artificial dura mater.

Dural repair using chemically treated cadaveric dura mater often results in atrophic and fragile change of the substitute as well as adhesion between the dura mater and brain surface at reoperation. Creutz-feldt-Jakob disease has occurred after repair using cadaveric dura mater. Expanded polytetrafluoroethylene (EPTFE) surgical sheet was used for dural repair in 34 patients. Suturing of EPTFE was easy and the incidence of cerebrospinal fluid accumulation in the epidural space was the same as when cadaveric dura mater was used. Six patients underwent reoperation, 1-15 months after the first operation. At reoperation the EPTFE sheet showed no change except for becoming transparent, and the strength was well preserved. A very thin layer of granulation tissue was formed between the EPTFE sheet and brain surface, but the EPTFE sheet was easily detached from the brain surface without adhesion even 15 months after the first operation. Our results suggest that the EPTFE sheet can be used safely and effectively as an artificial dura mater.

Brain Diseases↗

Dura mater for soft-tissue augmentation. Evaluation in a rabbit model.

Irradiated human dura mater, a commercially available preparation of dura mater (Tutoplast), and irradiated rabbit dura mater were implanted in subcutaneous pockets in the pinna and forehead of New Zealand white rabbits and evaluated for their usefulness in soft-tissue augmentation at 3 months and 6 months. Postoperatively, no evidence of erythema, purulence, hematoma or seroma formation, wound dehiscence, graft extrusion, or flap necrosis was noted. Irradiated human dura mater was well tolerated by the host and elicited a mild cellular inflammatory response. The graft was well preserved, infiltrated by fibrous connective tissue, and fixed in place in the pinna sites. Forehead grafts were surrounded by a capsule of host tissue and were intact. Dura mater seems to be useful for soft-tissue augmentation. Tutoplast may give good results clinically. Because this represents a short-term evaluation, long-term clinical results are needed to define the potential of dura mater grafts.

Animals↗

Direct innervation of sensory fibers from the dorsal root ganglion of the cervical dura mater of rats.

STUDY DESIGN: Sensory innervation in the cervical dura mater of rats was investigated immunohistochemically in whole tissues and transverse sections of the decalcified vertebral column. OBJECTIVE: To investigate the origin and distribution of sensory innervation in the cervical dura mater. SUMMARY OF BACKGROUND DATA: It has been generally accepted that irritation of the cervical structures is one of the major causes of pain in the neck and the upper extremities. Sensory fibers in the cervical dura mater are possible mediators of pain. However, there is little information about sensory innervation in the cervical dura mater, including the epiradicular sheath. METHODS: Ten Wistar rats were used for wholemount immunohistochemical observations of the cervical dura mater. The vertebral columns of five rats were processed for immunohistochemistry after decalcification. In all specimens, sensory fibers were demonstrated by the peptide immunohistochemistry, and sensory innervation was examined. RESULTS: The cervical dura mater was arbitrarily divided into three areas: ventral, dorsal, dorsal root ganglion. A large number of fibers were in the dorsal root ganglion area and were distributed in the corresponding segments. Some calcitonin gene-related peptide immunoreactive fibers in the dorsal root ganglion were directly innervated from dorsal root ganglion area neurons and did not form nerve bundles, similar to the sinuvertebral nerve. Several immunoreactive fibers were seen in the ventral area; fibers were rarely observed in the dorsal area. CONCLUSIONS: A large number of sensory fibers are segmentally distributed in the cervical dura mater, and some of them are directly traced from dorsal root ganglion neurons.

Animals↗

Studies in cranial suture biology: regional dura mater determines overlying suture biology.

The influence of dura mater on adjacent cranial sutures is significant. By better understanding the mechanisms of normal suture fusion and the role of the dura mater, it may be possible to delineate the events responsible for the premature suture fusion seen in craniosynostosis. In the Sprague-Dawley rat, the posterior frontal suture normally fuses between 12 and 20 days of postnatal life and has proved to be an excellent model to describe normal suture fusion. The purpose of this study was to document the critical role that the dura mater-suture complex may play on cranial suture biology. Forty Sprague-Dawley rats at 8 days of age were divided into two groups of 20 animals each. The control group (group A) had surgical disruption of the dura mater-calvarial interface. This was accomplished by elevating a strip of cranium inclusive of the posterior frontal and sagittal sutures and replacement of the cranial strip back to its anatomic position, all with the dura mater left intact. The experimental group (group B) had the same calvarial elevation (strip craniectomy), but the sutural anatomy/alignment was rotated 180 degrees. This rotation placed the posterior frontal suture into the sagittal suture's anatomic position and the sagittal suture into the posterior frontal suture's anatomic position. All of these procedures were accomplished by leaving the underlying dura mater intact. Animals were killed at 20, 30, 40, and 50 days (12, 22, 32, and 42 days postoperatively), and tissue sections were examined with hematoxylin and eosin staining. Group A (control) showed normal but delayed suture activity. The posterior frontal suture fused, and the sagittal suture remained patent. Fusion was delayed, not beginning before 20 days (12 days postoperative) and showing complete fusion between 30 and 40 days. Group B (180-degree calvarial rotation) demonstrated that the suture in the posterior frontal anatomic position (actual sagittal suture) fused between 20 and 40 days, whereas the suture in the sagittal anatomic position (actual posterior-frontal suture) remained patent throughout the study. This study demonstrates that the location of the dura mater-suture complex is important in determining either suture patency or closure in this model. Normal closure of the suture overlying the posterior frontal dura mater demonstrates that the dura mater itself, or forces derived in specific cranial locations, determines the overlying suture biology.

Animals↗

Evidence of remodeling in dura mater cardiac valves.

Subcellular changes in 12 dura mater cardiac valves (in the mitral or aortic position) surgically removed after 23 to 108 months of implantation owing to calcification, rupture, or endocarditis show signs of a remodeling process. Significant morphologic changes in the connective tissue fiber matrices and cell populations were noted in the recovered valvular leaflets. Macrophages were found within electronlucent (cleared-out) areas, and they seemed to play an essential role in the remodeling process by ingesting and digesting selected connective tissue components. Fibroblasts found within these "rebuilding" areas in the dura mater tissue possessed small cytoplasmic vesicles (65 nm in diameter) being extruded from the cell. Evidence of early collagen formation was also found in association with both peripheral filaments and peripheral condensations, as well as within the connective tissue matrices surrounding the cellular elements, where electron dense amorphous material was observed. In conclusion, the long-term durability of dura mater bioprosthetic cardiac valves may be directly related to (1) glycerin stabilization and preservation of the collagen fibers, (2) the viability of the fibroblasts and macrophages within the implanted valves, and (3) the unique morphology and fine structure of the double-layered dura mater encephali. We hypothesize that the fibroblasts or myofibroblast-like cells found within the implanted leaflets, no matter what their origin, are capable of giving form and organization to the early developing connective tissue.

Adolescent↗

[Sinuses of the dura mater in dogs].

Sinuses of the dura mater were studied in 50 preparations of the venous system in mongrel dogs--10 moist, 40 corrosive prepared from plastics AKP-7 and AKP-15. Sinuses of the fornix--superior, sagittal, straight, transversal, occipital sinusal gutter, and sinuses of the basis--cavernous, intracavernous, petrous-basal, occipital and marginal were detected and their connections were described. Emissary and diploid veins and extracranial venous plexus are demonstrated to mediate a close connection between the sinuses of the dura mater. Common features in the sinusal structure of the human dura mater and those of the animals studied are noted; comparative-anatomical differences which should be taken into account when planning the experiment are presented.

Animals↗

Structural changes in implanted cardiac valvular bioprostheses constructed of glycerol-treated human dura mater.

Histological, scanning and transmission electron microscope studies were made of normal human dura mater and cardiac valvular bioprostheses made of glycerol-treated human dura mater recovered after having been implanted in the aortic position (8 patients) or the mitral position (1 patient) for periods up to 4 years. Human dura mater has two layers: an inner or meningeal layer and an outer or endosteal layer. The surface of the inner layer is smoother than that of the outer layer. Both layers are composed mainly of large, wavy collagen fibrils (which are thought to correspond to type I collagen) and are relatively poor in elastic fibers and proteoglycans. Small calcific deposits were found in normal dura from older patients. Changes occurring in dura mater bioprostheses within 2 days after implantation consisted mainly of small surface thrombi. Calcific nodules, degenerated collagen and evidence of penetration of erythrocytes and plasma proteins into the cusps were observed in bioprostheses that had failed after being in place for 1-4 years. The calcific deposits and the degenerated collagen appeared structurally similar to those in glutaraldehyde-treated porcine aortic valvular bioprostheses. However, collagen fibrils in the latter were smaller than those in dura mater. Platelet aggregates on the cuspal surfaces were much less numerous in dura mater bioprostheses than in porcine aortic valvular bioprostheses. It is postulated that this difference is a function of the size of the collagen fibrils in the bioprostheses and that this accounts for the very low incidence of clinically evident thromboembolism in patients with implanted dura mater valves.

Adolescent↗

No effects of cervical spine motion on cranial dura mater strain.

OBJECTIVE: The aim of this study was to analyze the effects of cervical spine motion on cranial dura mater length variations in anatomical specimens using high-resolution linear displacement transducers. We hypothesized that transducer resolution was sufficient to measure dura mater length changes if they occurred during cervical spine motion. DESIGN: Cranial dura mater strain was measured using differential variable reluctance transducers during cervical spine motion in 11 formaldehyde-fixed whole-body anatomical specimens (mean age: 82 years). BACKGROUND: Several theories hypothesize that functional maneuvers carried out on the spine have an effect on intra-cranial structures due to the supposed continuity of spinal and cranial dura mater. The displacements of the spinal dura mater are supposed to be transmitted to the cranial dura mater. METHODS: Eleven anatomical specimens were used. Each specimen (positioned supine) was provided with three openings in the skull (frontal and parietal regions), leaving the dura mater intact. A differential variable reluctance transducer was inserted in frontal or sagittal orientation in the dura mater exposed in each opening. Strain was recorded during cyclic motions of cervical spine flexion-extension, lateral bending and axial rotation. RESULTS: Average length changes ranged from 0.01 to 0.13% (SD 0.01-0.21%) of initial length for all motions and locations studied, which in all cases was less than the accuracy of the transducers. CONCLUSION: It can thus be concluded that cervical spine motion does not induce significant strain of the cerebral dura mater. RELEVANCE: The present study does not support theories that are based on the transmission of strains from spinal to cranial dura mater.

Aged↗

Correction of coronal suture synostosis using suture and dura mater allografts in rabbits with familial craniosynostosis.

OBJECTIVE: Resynostosis following surgical correction of craniosynostosis is a common clinical correlate. Recent studies suggest that the dura mater is necessary to maintain suture patency. It has also been hypothesized that dura mater from synostotic individuals may provide aberrant biochemical signals to the osteogenic fronts of the calvaria, which result in premature suture fusion and subsequent resynostosis following surgery. This study was designed to test this hypothesis by surgically manipulating the coronal suture and dura mater in rabbits with familial craniosynostosis to prevent postsurgical resynostosis. DESIGN: Craniofacial growth and histomorphometric data were collected from 129 rabbits: 72 normal controls and 57 rabbits with bilateral coronal suture synostosis (15 unoperated on controls; 13 surgical controls; 9 dura mater transplant only; 10 suture transplant only; and 10 suture and dura mater transplant). At 10 days of age, all rabbits had radiopaque amalgam markers placed on either side of the coronal, frontonasal, and anterior lambdoidal sutures. At 25 days of age, 42 synostosed rabbits had a 3 to 5-mm wide coronal suturectomy. Coronal sutures and/or underlying dura mater allografts were harvested from same-aged, wild-type, isohistogenic control rabbits and transplanted onto the dura mater of synostosed host rabbits. Serial radiographs were taken at 10, 25, 42, and 84 days of age, and the suturectomy sites were harvested at 84 days of age in 44 rabbits and serially sectioned for histomorphometric examination. RESULTS: Results revealed that cranial vault growth was significantly (p < .05) improved following surgical release of the fused coronal suture compared with synostosed rabbits who were not operated on but was still significantly different (p < .05) from that of normal control rabbits. By 84 days of age, significant (p < .05) differences were noted in calvarial suture marker separation, cranial vault shape indices, and cranial base angles between rabbits with and without dura mater allografts, probably as a result of resynostosis of the suturectomy site or suture-only allografts. Qualitative histological examination revealed that at 84 days of age rabbits with suture and dura allografts had patent coronal sutures, suture-only allografts had fused coronal sutures with extensive endosteal hyperostosis, dura mater-only allografts had some new bone in the suturectomy site that resembled rudimentary osteogenic fronts, and suturectomy controls had extensive endosteal bone formation and resynostosis of the suturectomy site. Significantly (p < .05) more bone was found in the suturectomy sites of rabbits without dura mater allografts compared with rabbits with dura mater allografts. CONCLUSIONS: Results support the initial hypothesis that normal dura mater allografts will maintain suture or suturectomy site patency and allow unrestricted craniofacial growth. However, it is still unclear whether the dura mater from normal rabbits was providing biochemical signals to the transplanted sutures or suturectomy sites or simply acting as a barrier to prevent abnormal biochemical signals from the dura mater of synostosed rabbits from reaching the calvaria. The clinical and therapeutic implications of these procedures are discussed.

Analysis of Variance↗

Late results of replacement of cardiac valves by dura-mater allografts.

Homologous dura-mater valve was employed in a series of 2.338 patients in the period between January 1971 and January 1979. A restricted group of the first 272 patients were followed-up from six to eight years. This study showed gratifying results following mitral and tricuspid valves replacement and not as satisfactory results after aortic replacement. The postoperative complications were, for mitral valve: fungal endocarditis (0.68%), bacterial endocarditis (2.56%) thromboembolism (1.36%) valve dysfunction (12.9%) and reoperation was performed in 5.12% of the cases. For aortic valve replacement there was fungal endocarditis in 1.36% of cases, bacterial endocarditis in 5.68%, valve dysfunction in 29.54% and the incidence of reoperation was 23.28%. No anticoagulants were employed in this series.

Aortic Valve↗

Six years clinical experience with dura mater cardiac valves.

Homologous dura mater bioprostheses have been used for over 6 years in 217 patients who hae undergone cardiac valve replacement at Chulalongkorn Hospital and Medical School, Bangkok. The mitral valves were replaced in 151 patients (69.6%), aortic valve replacements were performed in 29 patients (13.7%), and multiple valve replacement were performed in 37 patients (16.7%). This study will be confined mainly to the isolated mitral and aortic valve replacements. The early deaths in the mitral replacement series was 10.5%, and 13.8% in the aortic valve replacement. Myocardial (pump) failure was the cause of early death in the majority of cases. The late mortality was 7.3% in the mitral position and 12.0% in the aortic position. The mean improvement of NYHA class was from 3.76 to 1.13 in the mitral series, and from 3.64 to 1.32 in the aortic group. The actuarial survival rates at 6 years after operation were 87% and 84% respectively and compare favorably with several prostheses currently in use. There was no case of thromboembolism even though no anticoagulants were used.

Actuarial Analysis↗

Local mechanical anisotropy in human cranial dura mater allografts.

Human cranial dura mater (CDM) allograft's success as a repair biomaterial is partly due to its high mechanical strength, which facilitates its ability to form water-tight barriers and resist high in-vivo mechanical loads. Previous studies on CDM allograft mechanical behavior used large test specimens and concluded that the allograft was mechanically isotropic. However, we have quantified CDM microstructure using small angle light scattering (SALS) and found regions of well-aligned fibers displaying structural symmetry between the right and left halves (Jimenez et al., 1998). The high degree of fiber alignment in these regions suggests that they are mechanically anisotropic. However, identification of these regions using SALS requires irreversible tissue dehydration, which may affect mechanical properties. Instead, we utilized CDM structural symmetry to estimate the fiber architecture of one half of the CDM using computer graphics to flip the SALS fiber architecture map of the corresponding half about the plane of symmetry. Test specimens (20 mm x 4 mm) were selected parallel and perpendicular to the preferred fiber directions and subjected to uniaxial mechanical failure testing. CDM allografts were found to be locally anisotropic, having an ultimate tensile strength (UTS) parallel to the fibers of 12.76 +/- 1.65 MPa, and perpendicular to the fibers of 5.21 +/- 1.01 MPa (mean +/- sem). These results indicate that uniaxial mechanical tests on large samples used in previous studies tended to mask the local anisotropic nature of the smaller constituent sections. The testing methods established in this study can be used in the evaluation of new CDM processing methods and post-implant allograft mechanical integrity.

Aged↗

Homologous dura mater cardiac valves. Structural aspects of eight implanted valves.

We studied eight homologous dura mater valves removed 1 to 35 months after implantation. Five dura mater valves were placed in the mitral position and three in the aortic position. Two of the valves were obtained after deaths not related to the valve itself and six after reoperations due to immediate or late incompetence. In 2 cases the dura mater valves were entirely normal, both macroscopically and microscopically. In 2 other cases the leaflets were caught by stitches related to the struts, a technical error that caused laceration of the leaflets. Not withstanding this fact, the dura mater was normal on histologic examination. In 3 cases, and probably in 1 other, one or two leaflets were detached partially from the suture line, probably because of a technical error in the manufacture of the valve. These studies demonstrated satisfactory evolution of the homologous dura mater valves until 35 months after implantation. No signs of rejection or degeneration of the dura mater were observed in the present series.

Adolescent↗

Neuropeptide Y- and substance P-like immunoreactive nerve fibers in the rat dura mater encephali.

Density and pattern of nerve fibers with neuropeptide Y-like immunoreactivity (NPY-LI) and substance P-like immunoreactivity (SP-LI) in the rat dura mater encephali were investigated by light and electron microscopy using whole-mount preparations. NPY-LI fibers are observed throughout the encephalic dura mater. A remarkable net of NPY-LI nerve fibers is located in the walls of the sagittal and transverse sinuses. Beyond that NPY-LI network, distinct NPY-LI nerve fibers or plexus occur in the rostral falx, parietal dura mater of the olfactory bulb, supratentorial dura mater, parietal dura mater of the cerebellum, tentorium cerebelli and the ventral dura mater. Electron microscopic studies reveal that NPY-LI is exclusively located in unmyelinated axons of small and large nerve fiber bundles, with or without a perineural sheath. Immunopositive C-fibers are predominantly associated with the vascular bed. SP-LI nerve fibers have a moderate and more uniform distribution in the encephalic dura mater. A distinct plexus of SP-LI fibers follows the branches of the middle meningeal artery and the adjacent dura mater. SP-LI fibers are most prominent in the parietal dura mater of the cerebellum. Fine beaded SP-LI fibers, arising from larger SP-LI fiber bundles, are observed in close association to the capillary bed. SP-LI axons are all unmyelinated. They are found in larger nerve fiber bundles with a perineural sheath or in Schwann cells lacking any perineural sheath. The function of NPY-LI and SP-LI nerve fibers in the rat dura mater is discussed in relation to their topography, density and termination.

Animals↗

Usefulness of dura mater in providing DNA samples for identifying cadavers.

We examined the usefulness of the dura mater in identifying human remains. Dura mater was collected from 50 cadavers, including drowned, charred, and mummified remains. The STR genotype using the AmpFlSTR Identifiler Kit could be typed at 15 STR and amelogenin loci in 30 samples of 33 cases. Furthermore, the ABO genotype and amelogenin using gel-based methods could be typed in 44 samples of 50 cases. In cases with successful typing of STR, ABO-DNA, and amelogenin, the longest time after death was from 12 to 26 days in a drowned body. The minimum quantity of dura mater required for DNA extraction was about 2.5 mg, dried and fixed by ethanol, in a cadaver 15 h after death. The state of the DNA from the dura mater from the calvaria may be better than that from the basis cranii interna. We found that DNA from dura mater is one of the most useful samples for forensic identification.

ABO Blood-Group System↗

[The strength and elasticity of the dura mater].

The strength and extensibility of human dura mater cold-preserved at--30 degrees--50 degrees and stored for up to 2 years were investigated. A total of 38 preserved and 5 fresh specimens were tested. The test-trials were made by using standard tensile-testing machines; The strength of preserved dura mater specimens was found to vary from 0.4 to 2 kg/mm2 and of the fresh ones--from 0.4 to 1.1 kg/mm2. The extensibility of the speciments equalled 10--30 per cent without any marked difference between the fresh and preserved ones. The duration of storage of the preserved dura mater does not affect adversely its strength.

Adult↗

ABO and Rh phenotyping by absorption-elution technique using cerebral dura maters.

Phenotyping of ABO and Rh blood groups was performed by the absorption-elution technique using cerebral dura maters. For the ABO system, the cerebral dura maters extracted from nine autopsied cadavers including two burnt bodies, two putrefied corpses, and one half-mummified and one skeletal structure were tested with commercially available Wako antisera (animal polyclonal antibodies). At the same time, blood, fingernails or bones were sampled. In all the cases, the phenotypes could be typed correctly and more clearly with the use of 2 x 2 x 0.3 mm dura maters (0.6 mm thick dura maters were sliced to 0.3 mm thickness) than the phenotyping using 2 x 2 mm fingernails or 2 x 2 x 1 mm bones. For the Rh system, the cerebral dura maters extracted from eight autopsied cadavers within 2 days after death including two burnt bodies were tested with commercially available Ortho Bioclone anti-C, anti-c, anti-E and anti-e sera (human monoclonal antibodies), and Ortho anti-D serum (human polyclonal antibody). The eluate of anti-D antibody was needed to perform the indirect anti-globulin test (Ortho Coombs serum). At the same time, blood was sampled. In all the cases, the Rh blood groups of cerebral dura maters were in agreement with those of blood.

ABO Blood-Group System↗

Primary lymphoblastic B-cell lymphoma of the cranial dura mater: a case report and review of the literature.

Primary lymphomas of the cranial dura mater are rare. Mucosa-associated lymphoid tissue extranodal marginal zone lymphomas are the most common subtype of non-Hodgkin's lymphomas that present as primary cranial dura tumors. A 33 year-old male presented with a 3-month history of a growing lump in the right frontal area. Neuroimaging studies demonstrated an extra-axial, broad-based mass with a dural tail in the right frontal bone convexity. Biopsy led to the diagnosis of localized dural precursor B-cell lymphoblastic lymphoma. The patient was treated with a combination of chemotherapy and radiotherapy, achieving durable disease-free survival. This is the first report of precursor B-cell lymphoblastic lymphoma of dura mater. A review of the literature on primary lymphomas of cranial dura mater is presented. Primary lymphomas of the cranial dura mater are rare. Mucosa-associated lymphoid tissue extranodal marginal zone lymphomas are the most common subtype of non-Hodgkin's lymphomas that present as primary cranial dura tumors. A 33 year-old male presented with a 3-month history of a growing lump in the right frontal area. Neuroimaging studies demonstrated an extra-axial, broad-based mass with a dural tail in the right frontal bone convexity. Biopsy led to the diagnosis of localized dural precursor B-cell lymphoblastic lymphoma. The patient was treated with a combination of chemotherapy and radiotherapy, achieving durable disease-free survival. This is the first report of precursor B-cell lymphoblastic lymphoma of dura mater. A review of the literature on primary lymphomas of cranial dura mater is presented.

Adult↗