Changes in end-plate vascularity after Nd: YAG laser application to the guinea pig intervertebral disc

The authors previously have reported the effects of neodymiumyttrium-aluminum-garnet (Nd: YAG) laser on the cartilage end-plates (CEPs) in an animal model. However, there is no experimental study in the literature which specifically addresses the effects of the laser on CEP vascularity. The aim of our study is to investigate the vascular response of the CEP to Nd: YAG laser. In this study, sixteen guinea pigs were used. Experimental intervertebral disc (IVD) degeneration was induced in 12 animals by a ventral disc incision to study the effects of Nd: YAG laser on the CEP of the degenerated IVD from the aspects of pathology and radiology. At 2 months after the experimental annular lesion, the CEP vascular channel counts had increased significantly (p = 0.00) in the cranial CEP to 104%, and to 99% in the caudal CEP. In the early period after laser irradiation the vessel counts from both CEPs decreased due to the extensive damage of Nd: YAG laser on disc tissue (p = 0.00). Accordingly, the value of CEP index and MR signal intensity of the CEPs (cranial and caudal) had decreased one month after laser application. Thereafter, both the CEP vascular channel counts and the MR signal intensity remained relatively constant throughout the course of the experiment, but the value of CEP index had increased to 68% of the normal IVD. From the results of present study, it is evident that laser application had a significant negative influence on the CEP vascularization of the degenerated IVD.

Evolution of disc degeneration in lumbar spine: a comparative histological study between herniated and postmortem retrieved disc specimens

This is a prospective comparative histological study on blood supply between lumbar herniated discs and postmortem retrieved ones. The aim of this study is to observe the evolution of disc degeneration in relation to its blood supply changes. Disc vascularization is present early in life, but the nucleus pulposus becomes avascular after adolescence. Vascularization of the annulus fibrosus (AF) probably also occurs late in life in association with degenerative changes and in response to trauma. Capillary neoformation and hypervascularity in degenerated discs have also been mentioned, based on animal cases. In the present study, intervertebral lumbar disc specimens were surgically removed from 84 patients with an average age of 41 years (range 24-60 years) operated on for disc herniation. In addition, control autopsy specimens were selected from 24 cadavera with an age of 39 years (range 24th gestation week to 80 years). The material was fixed in neutral buffered formalin, and 4-microm-thick sections were stained with hematoxylin-eosin and reticulin. In addition, with use of an immunohistochemical avidin-biotin complex technique, paraffin sections were stained for Ulex europaeus agglutinin receptors (UEA-1) after binding UEA-1 to the tissue. In surgical specimens, small blood vessels were identified in 45% of the disc cases. They were of the capillary-type vessels and were intermingled with proliferating endothelial cells, fibroblasts, and few mononuclear cells. All of them were located along the edges of the surgically retrieved fibrocartilage fragments. Sometimes thin bands of fibrin were attached to them and extravasated erythrocytes were occasionally seen. In autopsy specimens, blood vessels were identified in 78% of the retrieved discs. In contrast to the edge neovascularity observed in surgical specimens, capillaries were observed at the outer layer of AF surrounded by dense hyalinized and inactive-appearing collagen. From these results it is concluded that the blood vessels in extruded tissue from every type of herniation are newly formed, possibly through metaplasia of undifferentiated mesenchymal cells. It is also possible that they are derived from blood vessels that have invaded the AF as a result of disc degeneration. The finding of detection of progressive disc degeneration in both groups after 20-25 years seems to be of special interest because disc degeneration is a process that may not be directly correlated to disc herniation in these age groups.

Sensory and sympathetic innervation of the vertebral endplate in patients with degenerative disc disease

We obtained intervertebral discs with cartilage endplates and underlying cancellous bone at operation from patients with degenerative disc disease and then used immunohistochemical techniques to localise the nerves and nerve endings in the specimens. We used antibodies for the ubiquitous neuronal protein gene product 9.5 (PGP 9.5). Immunoreactivity to neuropeptide Y was used to identify autonomic nerves and calcitonin gene-related peptide (CGRP) and substance P to identify sensory nerves. Blood vessels were identified by immunoreactivity with platelet-endothelial cell-adhesion molecule (CD31; PECAM). In a control group with no known history of chronic back pain, nerve fibres immunoreactive to PGP 9.5 and neuropeptide Y were most closely related to blood vessels, with occasional substance P and CGRP immunoreactivity. In patients with severe back pain and markedly reduced disc height, proliferation of blood vessels and accompanying nerve fibres was observed in the endplate region and underlying vertebral bodies. Many of these nerves were immunoreactive to substance P or CGRP, and in addition, substance P- and CGRP-immunoreactive nociceptors were seen unrelated to blood vessels. Quantification by image analysis showed a marked increase in CGRP-containing sensory nerve fibres compared with normal control subjects. We speculate that a chemotactic response to products of disc breakdown is responsible for the proliferation of vascularity and CGRP-containing sensory nerves found in the endplate region and vertebral body adjacent to degenerate discs. The neuropeptides substance P and CGRP have potent vasodilatory as well as pain-transmitting effects. The increase in sensory nerve endings suggests increase in blood flow, perhaps as an attempt to augment the nutrition of the degenerate disc. The increase in the density of sensory nerves, and the presence of endplate cartilage defects, strongly suggest that the endplates and vertebral bodies are sources of pain; this may explain the severe pain on movement experienced by some patients with degenerative disc disease.

Platelet-derived growth factor and vascular endothelial growth factor expression in disc herniation tissue: and immunohistochemical study

Angiogenesis is essential in tissue growth and regeneration. There are several factors that are able to stimulate vascular endothelial cell growth, including platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF). Disc herniation tissue (DHT) contains vascular ingrowth, which promotes granulation tissue formation. In this study we observed 50 disc herniations for PDGF and VEGF immunoreactivity. PDGF immunopositivity was detected in 38 samples (78%). In 28 samples (56%) there were PDGF immunopositive capillaries, PDGF immunopositive disc cells were detected in 19 samples (38%) and PDGF immunopositive fibroblasts in 6 DHT samples (12%). VEGF immunopositive capillaries were identified in 44 DHT samples (88%). For neither growth factor was immunopositivity dependent on preoperative radicular pain duration. In extrusions (n = 25) VEGF immunopositive capillaries were detected in 23 samples (92%) and PDGF immunopositivity in 21 samples (84%). PDGF immunopositivity was more commonly associated with capillaries than with nuclei of disc cells. In sequesters (n = 20) VEGF immunopositive capillaries were identified in all samples and PDGF immunopositivity in 16 (80%). As in extrusions, PDGF immunoreaction was more prevalent in capillaries than in disc cells. Patient age did not relate to VEGF expression. In all age groups it was higher than 80%. Thus capillaries in disc herniation tissue are evidently newly formed and our results demonstrate that PDGF and VEGF participate in the neovascularization process. The presence of PDGF in fibroblasts and in disc cells suggests that this growth factor regulates the function of these cells, possibly the proliferation of the cells and the production of extracellular matrix components.

The prolapsed intervertebral disc. The high-intensity zone with discography correlation

STUDY DESIGN

The study compared the presence of the high-intensity zone on magnetic resonance imaging with the results of awake discography.

OBJECTIVES

To see if there was a correlation between the results of awake discography and the presence of a high-intensity zone on magnetic resonance imaging.

SUMMARY OF BACKGROUND DATA

The evaluation of discogenic pain has proved to be somewhat elusive. Recent studies have indicated the high-intensity zone as being highly sensitive in the diagnosis of the painful discogenic segment. The present study was designed to investigate whether the presence of a high-intensity zone is associated with a concordant pain response on awake discography.

METHODS

Magnetic resonance images were obtained in 29 patients with low back pain with and without radiculopathy. Consecutive patients were considered for surgical intervention after falling to respond to conservative treatment. The presence of a high-intensity zone was specifically looked for within the posterior anulus. Each patient subsequently underwent awake discography with computed tomography. Computed tomography was classified according to the Dallas Discogram Scale and the presence of a concordant pain response. Chi-square analysis was used to calculate the presence of a high-intensity zone versus disc disruption and the correlation of high-intensity zone and concordant pain response.

RESULTS

There was no statistically significant correlation between the presence of a high-intensity zone and a concordant pain response at any level. The high-intensity zone was, however, never seen in a morphologically normal disc.

CONCLUSIONS

Although the high-intensity zone is present within the posterior anulus of some abnormal discs, it is not necessarily associated with a concordant pain response.

Prevalence, morphology, and topography of blood vessels in herniated disc tissue. A comparative immunocytochemical study

STUDY DESIGN

Ninety disc herniations removed during surgery were studied by immunocytochemistry, using two different endothelial cell markers, to study the prevalence, morphology, and topography of blood vessels in disc herniations.

OBJECTIVES

To increase the specific localization of even very small blood vessels present in disc herniations by using specific antibodies to endothelial cells; to study blood vessels comparatively with two different endothelial cell antibodies, comparing their prevalence; and to study blood vessel morphology and topographic relationships of blood vessels to other tissue elements, particularly disc cells.

SUMMARY OF BACKGROUND DATA

In many previous macroscopic studies and in studies using conventional histologic methodology, blood vessels have been observed in degenerated and injured intervertebral discs. In a smaller patient sample, the authors previously observed blood vessels in approximately 80% of disc herniations by immunocytochemistry, the blood vessels co-localizing with macrophage cells. Many of these blood vessels are the product of very active neovascularization after disc tissue injury. The presence of such blood vessels has not, however, been studied in greater detail or in larger patient samples. Immunocytochemistry offers superior visualization and more specific localization and was thus used in the present study.

METHODS

Thin frozen sections from 90 disc herniations were immunostained in parallel with von Willebrand factor and Ulex europaeus antibodies, both of which localize endothelial cells specifically. Indirect immunocytochemistry by avidin-biotin-peroxidase complex or alkaline phosphatase-antialkaline phosphatase were used for immunolocalization. Blood vessels were classified as being: +, abundant: (+), very few; or +, totally absent.

RESULTS

The prevalence of blood vessels in disc herniations was found in 82 of 90 (91%) disc herniations with von Willebrand factor antibody and in 75 of 90 (83%) disc herniations with Ulex europaeus antibody. In 59 disc herniations (66%), blood vessels were observed with both antibodies in parallel, whereas they were observed with neither antibody in only six of 90 disc herniations. Furthermore, the ratio of abundant to very few blood vessels was 73:9 with von Willebrand factor antibody and 63:12 with Ulex europaeus antibody, further supporting the abundance of blood vessels in disc herniations. Blood vessels were most prevalent in sequestrated discs, but they were also observed in six of eight protrusions. Dense blood vessel networks were observed to penetrate the disc tissue, and blood vessels were also present in areas of inflammatory cell infiltration. Topographically, blood vessels were, on several occasions and with both antibodies, seen to pass close by or to surround disc cells.

CONCLUSIONS

By immunocytochemistry with endothelial cell markers, blood vessels can be observed to be numerous, and their prevalence in herniated discs is very high, presumably as a result of a very intense neovascularization process after the disc injury. A close apposition to disc cells may suggest attempts to increase the nutrition of these cells and will influence the metabolism of the cells.

Degenerative disk vascularization on MRI: correlation with clinical and histopathologic findings

OBJECTIVE

This prospective study was designed to determine the MRI features, clinical significance, and correlation to histopathologic findings of secondary vascularized degenerative intervertebral disks.

MATERIALS AND METHODS

Fifty-three patients with localized painful spine syndrome were investigated prospectively by contrast-enhanced MRI. Pain was not predominantly radiating and there was no clinical evidence of spinal infection. In all patients sagittal SE T1-weighted, fast SE T2-weighted or turbo-STIR, and T1-weighted frequency-selective fat-suppressed images were obtained.

RESULTS

We identified 37 vascularized disks in 26 patients. In 18 patients the changes had occurred spontaneously, in 6, the affected disk had been operated on previously, and 2 patients had spondylolisthesis. In 15 patients, vascularization was accompanied by medullary edema adjacent to the vertebral endplates. In one of the vascularized disks, herniation was also found. In seven patients, ventral diskectomy was performed. Histopathologic findings confirmed disk vascularization in six of seven cases.

CONCLUSIONS

Degenerative, band-like disk vascularization is a feature which is associated with local pain. It was demonstrated by contrast-enhanced MRI. Degenerative disk vascularization is an important differential diagnosis to bacterial spondylodiskitis. It can be a cause of pain in patients with postdiskectomy syndrome.

Morphologic differences of the vascular buds in the vertebral endplate: scanning electron microscopic study

STUDY DESIGN

Vascular buds in rabbit vertebral endplates were examined by scanning electron microscopy of corrosion casts.

OBJECTIVES

To examine morphologic differences between vascular buds in two regions of the vertebral endplate (inner anular and nucleus pulposar).

SUMMARY OF BACKGROUND DATA

Vascular buds are specific structures present at the vertebral endplate that are important as nourishing channels. There is a significant difference in permeability between the lateral portion (inner anular) and the central portion (nucleus pulposar) of the endplate, the latter usually being permeable and the former being impermeable. Morphologic differences between vascular buds in the two regions have not been investigated previously.

METHODS

Eight 20-week-old rabbits were used. Vascular buds in rabbit vertebral endplates were examined by scanning electron microscopy of corrosion casts.

RESULTS

The vascular buds in the region of the inner anulus form simple loops, but those in the area near the nucleus pulposus exhibit swollen and complex coil-like loops. Although they differ structurally, the average number of vascular buds per area does not vary between the two regions.

CONCLUSIONS

We suggest that the morphologic difference between the vascular buds in the two regions (inner anular and nucleus pulposar) plays a principal role in permeability at the endplate.

A posterolateral microsurgical approach to extreme-lateral lumbar disc herniation

Extreme-lateral lumbar disc herniations present a surgical challenge because the conventional posterior approach requires bone resection for complete visualization of the pathology. The authors have identified constant anatomical landmarks in cadaveric dissections that facilitate access to the intervertebral foramen when combined with a posterolateral approach, as described by Watkins, for lumbar spinal fusion. The authors describe a technique that allows rapid localization and safe excision of these extreme-lateral lumbar disc herniations without the need for bone resection.

Herniated intervertebral disc-associated periradicular fibrosis and vascular abnormalities occur without inflammatory cell infiltration

STUDY DESIGN

Prospective histologic comparison of perineural tissues from patients requiring decompression surgery for herniated intervertebral disc with those from cadaveric controls.

OBJECTIVES

To examine the significance of herniated intervertebral-disc-associated perineural vascular and fibrotic abnormalities with respect to back pain symptom generation.

SUMMARY OF BACKGROUND DATA

Previous cadaveric studies have demonstrated perineural vascular congestion, dilatation, and thrombosis and perineural and intraneural fibrosis occurring in association with herniated intervertebral disc. It was suggested that these neural abnormalities were the result of ischemia, due to venous outflow obstruction, and also represented a possible cause of ongoing back pain symptoms. Criticisms of such a conclusion arose, however, because the possibility could not be excluded that these abnormalities were the result of postmortem artifact.

METHODS

Histologic and immunohistochemical comparison of discal and peridiscal tissues removed from 11 patients with radiographically proven herniated intervertebral disc requiring decompressive surgery and from 6 fresh cadavers without history of back pain in life.

RESULTS

Histology and immunohistochemistry of perineural and extraneural tissues from patients revealed vascular congestion, neovascularization, and endothelial abnormalities including luminal platelet adhesion, in association with reductions in von Willebrand factor levels, together with perivascular and perineural fibrosis. Elevated fibrogenic cytokine concentrations were also detected in patients' tissues. These changes occurred without evidence of inflammation and were absent in cadaveric control tissues.

CONCLUSIONS

The vascular abnormalities detected in patients may represent an important etiopathologic factor predisposing to intraneural and perineural fibrosis, and hence to chronic pain symptoms, after disc herniation. It seems important to preserve the perineural microcirculation following disc herniation.

[An experimental study on the relationship between disc nutrition and disc degeneration]

Micro-angiography, scanning electron microscopy and hydrogen washout technique were used to investigate the disc nutrition condition and the nutritional pathway of endplate in bipedal rats with agting. Compared with the controls, the nutrition condition of bipedal rats underwent deterioration and the number of vascular distribution under the endplate decreased significantly, but no increase in thickness of endplate caused by microfractures of subchondral bone and callus formed during the healing process was observed. The abnormal stress may bring about vertebral body intra-osseous circulation disorder and then consequent decrease of vascular channels which related to the disturbance of disc nutrition. This strongly suggested that nutrition conditions of nucleus pulposus were not deteriorated by impaired diffusion capacity, but by decrease of vasculature that contacts with endplate.

Basic fibroblast growth factor immunoreactivity in blood vessels and cells of disc herniations

STUDY DESIGN

Basic fibroblast growth factor immunoreactivity was studied in disc herniation tissue.

OBJECTIVES

The first objective was to analyze in which tissue components, if any, fibroblast growth factor is expressed in the disc herniation. The second objective was to compare such expression with that in fresh cadaver disc tissue.

SUMMARY OF BACKGROUND DATA

Disc herniation tissue contains vascular ingrowth, which promotes the formation of granulation tissue. Fibroblast growth factor is a potent inducer of angiogenesis and also regulates extracellular proteolysis.

METHODS

Twenty-seven disc herniation tissue and five macroscopically normal fresh cadaver discs were treated with an identical immunohistochemical protocol. Serial frozen sections were stained with a polyclonal basic fibroblast growth factor antibody and a polyclonal antibody to von Willebrand factor, which localizes endothelial cells. The immunostaining data were compared with relevant clinical data.

RESULTS

Histologically, 74% of the samples contained anulus fibrosus and 59% nucleus pulposus. Basic fibroblast growth factor immunoreactivity was detected in 81% of the samples. There were immunopositive small blood vessels and scattered immunopositive disc cells (67%). Not all observed blood vessels were basic fibroblast growth factor immunopositive. In control discs, no immunoreactivity was observed.

CONCLUSIONS

The observed presence of fibroblast growth factor in small blood vessels suggests an active angiogenesis as a result of disc injury. Cellular expression of fibroblast growth factor may be linked to proteolytic activity in disc extracellular matrix.

Ingrowth of blood vessels in disc degeneration. Angiographic and histological studies of cadaveric spines

Angiograms were made of twenty-two cadaveric lumbar spines to determine the presence of any new blood vessels between adjacent lumbar vertebrae and corresponding discs. The annulus and adjacent longitudinal ligaments were also analyzed histologically. A total of 105 intervertebral spaces were studied. It was found that the normal anastomosing arteries in the posterior longitudinal ligament were significantly obliterated with advancing degeneration of the disc (p < 0.001), whereas several tiny tortuous arteries--often running between the osteophytic spurs--were seen in the anterolateral aspects of the intervertebral spaces connecting the adjacent vertebrae. Histological examination of the anterolateral part of the annulus showed that the vascularity of the annulus increased significantly with degeneration of the disc (p < 0.001), and most of the arteries had a vertical orientation. Regression analysis showed that vascular changes occurred before degeneration of the disc at every lumbar level, suggesting that disturbances in the nutritional supply may precede degeneration. The correlation coefficient was 0.77 (95 per cent confidence limit, 0.52 to 0.90) for the increase in annular vascularity with an increase in the age of the individual at the time of death and 0.86 (95 per cent confidence limit, 0.69 to 0.94) for the increase in degeneration of the disc with an increase in age.

Does plate fixation prevent disc degeneration after a lateral anulus tear?

STUDY DESIGN

The sheep model was used to investigate the development of disc degeneration after outer anular tearing.

OBJECTIVES

The authors determined whether plate fixation promotes healing of peripheral anular tears and thereby minimizes disc degeneration.

SUMMARY OF BACKGROUND DATA

A limited outer anular tear (similar to the rim lesion) in the sheep lumbar disc causes progressive and irreversible degeneration within 6 months. Incomplete healing of the tear may result from continued movement in the vicinity of the lesion.

METHODS

In 15 sheep, a cut 4 x 10 mm was made in the lateral anulus of two nonadjacent lumbar discs, and a metal plate was fixed across one. Three sheep were killed immediately, and the remainder were killed after 6 months for histologic examination.

RESULTS

There were no significant differences in propagation of the cut through the inner anulus, extent of healing, or extent of nuclear degeneration, between plated and nonplated motion segments after 6 months. Vascularization of the cartilage endplate was significantly increased on the operated side (P < 0.01), but remained unchanged on the nonoperated side.

CONCLUSIONS

Disc degeneration was not prevented by this method of plate fixation, despite similar but limited healing of the outer anulus tear in both plated and nonplated levels.

Substance P in intervertebral discs. Binding sites on vascular endothelium of the human annulus fibrosus

The annulus fibrosus of the human intervertebral disc is sparsely innervated, some of the fibers containing substance P. We could demonstrate, by autoradiography, binding sites for substance P localized on the endothelium of small blood vessels in the annulus fibrosus of human intervertebral discs removed during anterior fusion for back pain. In binding inhibition studies, binding of 125I-Bolton Hunter-substance P was inhibited by unlabeled substance P and the related tachykinins neurokinin A and neurokinin B with a rank order of potency substance P > NKA > NKB. Specific binding was reduced > 75 percent by 5'-guanylylimidodiphosphate, indicating G-protein coupling. These features are characteristic of an NK1 receptor through which vascular effects, i.e., vasodilation, plasma extravasation and angiogenesis of substance P, are mediated. The presence of NK1 receptors on blood vessels in the annulus fibrosus may indicate a role for substance P in tissue repair although acute proinflammatory effects may contribute to discogenic pain.

Neural elements in the normal and experimentally injured porcine intervertebral disk

There is increasing evidence that-back pain may originate from degenerated or damaged disks, even in the absence of disk herniation. For a study of the pattern of innervation in injured disks, the anterior part of the annulus fibrosus of a lumbar disk in 11 domestic pigs was incised with a scalpel through a retroperitoneal approach. The animals were killed 2 weeks, 1, 2, 3, and 5 months postoperatively, and the whole anterior annulus of each injured disk and corresponding tissue from intact animals were excised. Cryostat sections 20 microns thick were cut from the surface downward, fixed, and stained with different antisera. Antisera to neurofilament triplet protein (R39), protein gene product (PGP) 9.5 and synaptophysin were used as general neural markers. Antiserum to substance P (SP) and calcitonin gene-related peptide (CGRP) were used to localize nerves mainly of the sensory type, and C flanking peptide of neuropeptide Y (CPON) to visualize nerve fibers of the sympathetic type. It was observed that in the intact porcine disk, the outer and middle parts of the anterior annulus were innervated to a depth of 7 mm from the annular surface, but the innermost annular layers showed no immunoreactivity to any of the neural antibodies. Disk injury did not cause any major changes in the nerve topography of the wound area, even though there were granulation tissue and neovascularization in this area.

Microsurgical anatomy of the lower cervical spine and cord

The authors dissected the cervical spine and its surrounding structures from 40 adult cadavers under a surgical microscope. The anterior part of the spine and spinal cord was examined after vertebrectomy. The posterior longitudinal ligament (PLL) consists of two layers; the anterior one is termed the deep layer, and the posterior one is termed the superficial layer. These two layers adhered together loosely. In the lateral portion of the spinal canal, the superficial layer joined the periradicular sheath at the level of the intervertebral disc spaces and joined the dura mater at the level of the vertebral bodies. After the removal of the deep layer, the anterior internal vertebral venous plexus was seen on top of the lateral part of the superficial layer. The venous plexus was embedded between the double-layered PLLs, was not located in the epidural space, and was not seen in the medial part of the PLL. The PLL without venous channels on top of it was about 10 mm in width at the levels of the intervertebral disc and about 5 mm at the levels of the vertebral body. The anterior root exit zone (AREZ) was an elliptical shape; the transverse length of the AREZ was about 2 mm, and the longitudinal length was 10 to 15 mm. The average number of anterior rootlets on the AREZ was 17 to 25 and tended to decrease in the lower cervical spinal cord. The posterior structures were examined after en bloc laminectomy.(ABSTRACT TRUNCATED AT 250 WORDS)

The histology of lumbar intervertebral disc herniation. The significance of small blood vessels in the extruded tissue

Six hundred surgical cases of lumbar intervertebral disc herniation were evaluated histologically for the presence of blood vessels. These patients ranged in age from 12 to 77 years. Blood vessels were observed in 57 of 101 cases of complete prolapse type of herniated disc (56.4%), 12 of 32 cases of incomplete prolapse type of herniated disc (37.5%), and 53 of 467 cases of protrusion type of intervertebral disc herniation (11.3%). The presence of blood vessels in intervertebral discs was also investigated in postmortem specimens. Blood vessels were observed in 293 of 616 intervertebral discs (T10-L5), in individuals older than 40 years of age from 100 postmortem spines. The specimen age range was 16-89 years. Most of the blood vessels seen in the extruded tissue, exposed to the epidural space in cases of complete and incomplete prolapse type of herniation, are thought to have been newly formed after herniation occurred. As invasion of the intervertebral disc by blood vessels was found to occur with the advance of age, it is possible that such blood vessels become extruded with the intervertebral disc tissue. The intervertebral disc may herniate posteriorly in three basic patterns. The first pattern is "protrusion type of herniated disc." In protrusion hernia type there is abnormal posterior bulging of the anulus fibrosus. The disc pathology is predominantly nucleus pulposus, and the peripheral layer of the anulus fibrosus remains attached to the vertebral body bony rim, however.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of lymph and blood vessels in the human intervertebral disc by histochemical and immunohistochemical methods

Twenty-four intervertebral discs from the lumbar region of postmortem human subjects were investigated by immunohistochemical and histochemical methods to evaluate the pattern of blood and lymph vessels of the discus intervertebralis and surrounding tissue at different ages. Antibodies against the basement membrane component laminin, and the lectin Ulex europaeus agglutinin as a marker for L-fucose in endothelial cells, were used to make the blood vessels visible. The 5'-nucleotidase activity in lymph endothelium served as a marker for lymphatic vessels. The dorsolateral parts of the connective tissue adjacent to the discus intervertebralis were well vascularized in all age groups examined. Vessels in the outer anulus fibrosus were detected in young individuals up to 20 years of age. Vascular canals, i.e. blood vessels in the cartilage end plate, were seen up to 7 years of age. Lymph capillaries are first described here penetrating the disc and peridiscal tissue and accompanying most of the small blood vessels into the areas specified.

Lymph and blood supply of the human intervertebral disc. Cadaver study of correlations to discitis

Immunohistochemical (antibodies against laminin) and histochemical methods (Ulex europaeus lectin, 5'-nucleotidase activity) were used to describe the vascular pattern of human intervertebral discs and the surrounding tissue at different ages. Blood and lymph vessels were found in the connective tissue outside the annulus in all age groups. In the annulus blood vessels and lymphatics were detected up to 20 years of age, in the cartilage end-plate blood vessels appeared up to 7 years of age (cartilage canals). In the nucleus pulposus neither blood nor lymph vessels could be seen at any age. The occurrence of blood and lymph vessels in growing intervertebral discs help us to understand childhood discitis without simultaneous affection of the vertebral body.

Changes in endplate vascularity after an outer anulus tear in the sheep

In 31 2-year-old sheep, a 5-mm deep cut was made parallel to the end plates in the left anterolateral anulus fibrosus of 3 randomly selected lumbar intervertebral discs. At 2 months, the area of the end plate occupied by blood vessels on the left (operated) side had increased significantly (P less than 0.05) in the cranial end plate to 9.94%, and to 9.39% in the caudal end plate, compared with nonoperated values of 5.17% (cranial) and 5.87% (caudal). One year after operation, these elevated values had diminished significantly (P less than 0.05) to 7.92% (cranial) and 7.13% (caudal), and continued to decline progressively to 7.48% (cranial) and 6.88% (caudal) by 2 years. In contrast, no significant differences were found on the right (nonoperated) side of the discs. Thus, there was an early proliferation of vascular channels in the end plate in the vicinity of the experimental anular lesion, but not on the nonoperated side of the same disc. Thereafter, the end plate vascularity progressively diminished toward a normal level.

Human intervertebral disc acid glycosaminoglycans

Alcian blue critical electrolyte concentration (CEC) staining of intervertebral discs (annulus and nucleus of cervical, thoracic and lumbar discs) distinguished 3 groups where CEC staining correlated with age (less than 3 months; from 3 months to 5 years; over 10 years). The CEC increased markedly (implying increased sulphation of the glycosaminoglycans) in the period of maturation (fetal life to 10 years) and then remained constant throughout adult life. This is at variance with accepted views which attribute such changes to degenerative changes in old age. The major part of the CEC increase occurred after the disappearance of blood vessels from the disc, which is almost complete by 4 years. Our results are compatible with the hypothesis that keratan sulphate replaces chondroitin sulphate, functionally, in conditions of oxygen lack.