Yasuo Kokubo

Herniation of cervical intervertebral disc: immunohistochemical examination and measurement of nitric oxide production.

Study Design. Surgically obtained cervical herniated intervertebral discs were examined histologically and immunohistochemically. The production of nitric oxide (NO) in the local tissue was examined using the electron spin resonance (ESR) method. Objectives. To investigate the local histologic and immunohistochemical changes in cervical disc herniation, including NO production, and to compare such changes with those in autopsy cases. Summary of Background Data. Very little is known about the histopathologic processes of cervical disc herniation. In addition, no information is available on the level of in vivo NO production in cervical disc herniation. Methods. Thirty-six herniated cervical discs obtained from 31 patients were immunohistochemically examined for localization of blood vessels, matrix metalloproteinase (MMP)-3, and inducible NO synthetase (iNOS). We also compared the production of NO, measured by the ESR method, in eight specimens with that of five control discs obtained from fresh cadavers. Results. The presence of herniated discs correlated with the degeneration of cartilaginous endplate and torn anulus fibrosus. Formation of new blood vessels around the herniated discs was detected, using von Willebrand factor antibody, in seven uncontained hernias and 20 contained hernias. Immunohistochemical studies showed the presence of cells positive for MMP-3 (chondrocytes), iNOS (chondrocytes and granulation tissue) in cervical disc hernias. ESR analysis showed a significantly higher NO production in herniated cervical discs than in disc samples of fresh cadavers. Conclusions. Herniated cervical intervertebral disc is characterized by the presence of an inflammatory process associated with neovascularization and increased expression of MMP-3. Production of NO was markedly high in both contained- and uncontained-type hernias.

Effect of mechanical compression on the lumbar nerve root: localization and changes of intraradicular inflammatory cytokines, nitric oxide, and cyclooxygenase.

Study Design. Investigation of intraradicular inflammation induced by mechanical compression. Objective. To investigate the mechanism of nerve root pain, this study used a lumbar nerve root compression model. Summary of Background Data. The manifestation of pain at sites of inflammation has a close relationship with the release of mediators from macrophages. However, the mediators involved in inflammation of nerve roots as a result of mechanical compression remain almost unknown. Methods. In this study, the seventh lumbar nerve root of dogs was compressed with a clip for 3 weeks to observe the changes caused by compression. Immunohistochemistry was performed using the avidin-biotin-peroxidase complex method to observe the changes of T cells (CD45) and macrophages (Mac-1) after compression. Antibodies against as interleukin-1 (IL-1), tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (i-NOS), and cyclooxygenase (COX)-1 and 2 were used to examine the localization and changes of these mediators caused by nerve root compression. Results. In control animals, resident T cells were detected, but there were no macrophages. IL-1β and COX-2 were positive in the Schwann cells and vascular endothelial cells, while COX-1 was detected in the vascular endothelial cells. However, no cells showed TNF-α or i-NOS positively. After nerve root compression, numerous T cells and macrophages appeared among the demyelinized nerve fibers. The macrophages were positive for IL-1β, TNF-α, i-NOS, and COX-2. Conclusion. Inflammatory cytokines, NO, and COX-2 may be deeply involved in radiculitis caused by mechanical compression, and these mediators seem to be important in the manifestation of root pain.

Thoracic ossification of the human ligamentum flavum: histopathological and immunohistochemical findings around the ossified lesion

OBJECT The object of this study was to histopathologically and immunohistochemically characterize ossification of the ligamentum flavum (OLF) in samples of the thoracic spine harvested en bloc during surgery and to enhance the understanding of the ossifying process, particularly calcification and ossification. METHODS Samples of OLF plaque were obtained en bloc from 43 patients who underwent posterior decompression. The histopathological findings were correlated with radiological subtypes using computed tomography. The expression of type I and type II collagens, vascular endothelial growth factor (VEGF), transforming growth factor (TGF)beta, and bone morphogenetic protein (BMP)-2 was investigated. RESULTS Surgical decompression using the posterior floating and en bloc resection technique resulted in neurological improvement in 40 of 43 patients. Progression of the OLF lesion longitudinally and medially was associated with significant degeneration of elastic fibers, fiber bundle derangement, decrements in fiber diameter, and fragmentation. Calcification and ossification paralleled the degeneration of the elastic fibers, extended more medially, and fused in the central area. Expression of BMP-2, TGFbeta, and VEGF was significant in chondrocytes in the calcified cartilage and fibrocartilage layers, especially around the calcified front. CONCLUSIONS Histopathologically, the progress of calcification and ossification was closely associated with the degeneration of elastic fibers and with significant expression of BMP-2, TGFbeta, and VEGF in the ossification front.

Effect of lumbar nerve root compression on primary sensory neurons and their central branches: changes in the nociceptive neuropeptides substance P and somatostatin.

Study Design. This study examined the effect of lumbar nerve root compression on nociceptive neuropeptides in the axonal flow using an in vivo model. Objectives. The aim was to investigate changes in axonal flow after nerve root compression by using immunohistochemical techniques to detect substance P (SP) and somatostatin (SOM), which is thought to be involved in temperature and pain sensation. Summary of Background Data. Disturbance of intraradicular blood flow and nerve fiber deformation caused by mechanical compression are thought to be involved in the pathophysiology of diseases characterized by radicular symptoms, such as lumbar disc herniation and lumbar canal stenosis. However, little research has been conducted into the changes of axonal flow associated with nerve root compression. Methods. In dogs, the lumbar nerve roots were compressed using four types of clips with different pressures. Changes of SP and SOM levels in the spinal dorsal horn, dorsal root, and dorsal root ganglions were examined immunohistochemically after compression for 24 hours or 1 week. Results. After compression for 24 hours, axonal flow in the dorsal root was impaired, accumulation of SP and SOM was observed distal to the site of compression, and there was a decrease in the number of dorsal root ganglion cells showing positively for these neurotransmitters. Compression for 1 week resulted in a decrease in the number of SP- and SOM-positive fibers in the spinal dorsal horn. Conclusion. Change of axonal flow resulting from direct nerve compression could affect the metabolism of neurotransmitters that flow inside the axons and may be a primary cause of the decline in nerve function.

Ganglion cyst of the posterior longitudinal ligament causing lumbar radiculopathy: case report

We describe a man aged 26 years who presented with a neurological syndrome, which was found on lumbar radioculopathy to be due to a ganglion cyst originating from the posterior longitudinal ligament. Based on MRI findings, a cystic lesion was suspected, a round lesion at L4 level with no connection to the adjacent facet or to the dura matter. During surgery, a liquid-containing cystic lesion was found to originate from the posterior longitudinal ligament at L4 level. The resected cyst was diagnosed histologically as a ganglion cyst. A complete cure was established after surgery and no recurrence was noted at a follow-up 1.7 years postoperatively. A ganglion cyst of the posterior longitudinal ligament should be considered in the differential diagnosis of a cyst in the lumbar region causing neurological complications.

Ultrastructural analysis on lumbar disc herniation using surgical specimens: role of neovascularization and macrophages in hernias.

Study Design. The mechanisms responsible for the spontaneous regression of lumbar disc herniation (LDH) were studied by examining herniated tissue collected at operation from patients with LDH. Objective. The aim of the present study was to investigate the role of neovascularization and macrophages in hernias when spontaneous regression of LDH occurred. Summary of Background Data. Spontaneous regression of LDHs has already been demonstrated by diagnostic imaging with tools such as magnetic resonance imaging. However, there have been few studies on the mechanisms of spontaneous regression based on pathologic examination of herniated tissue. In particular, there has been no detailed work on the role of macrophages, which are thought to be closely associated with spontaneous regression. Methods. The magnetic resonance imaging and operative findings of 73 patients who underwent surgery were investigated, and specimens collected during surgery were examined by light and transmission electron microscopy. Results. Capillaries that invade the hernia and macrophages derived from monocytes migrating out of these capillaries are considered to be important factors in the regression of the herniated disc. Macrophages contain lysosomes filled with collagen-degrading enzymes that break down substances after phagocytosis, whereas primary lysosomes are secreted by these cells and break down intercellular substances such as collagen. Both of these mechanisms are closely involved in the regression of herniation. Conclusion. The inflammatory response that occurs around hernia tissue in the epidural space is believed to play an important role in herniated disc resorption, although it may also have a harmful effect on the adjacent nerve root. Therefore, control of the inflammatory reac-tion is an important challenge when treating patients with disc herniation.

Ossification of the posterior longitudinal ligament of the cervical spine: histopathological findings around the calcification and ossification front

OBJECT The authors studied the histological and immunohistochemical features of ossified posterior longitudinal ligament (PLL) of the cervical spine, especially in the calcification and ossification front. METHODS Samples of en bloc ossified PLL plaque obtained in 31 patients were stained with H & E and immunohistochemically prepared for collagens (types I and II), vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-beta, and bone morphogenetic protein (BMP)-2, and by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling method for apoptosis. RESULTS Enchondral ossification was evident between the ligamentous enthesis and deep layer of the ligament, with irregularly disorganized arrangement of elastic fibers in association with advancement of the degenerative process. In the ossification front, many hypertrophic metaplastic chondrocytes were noted in the ossifying plaque immediately contiguous to the ligament fibers, together with a considerable degree of neovascularization. Both TGFbeta and BMP-2 were highly expressed in metaplastic hypertrophic chondrocytes in the ossification front, and BMP-2 was also expressed in fibroblastic cells near the ossified PLL plaque. Expression of type I collagen was significant in the matrix of the ossified PLL lesion, whereas that of type II was marked in metaplastic chondrocytes in the ossification front. Apoptotic hypertrophic chondrocytes were observed mainly in the fibrocartilaginous area near the calcification front. CONCLUSIONS The enchondral ossification process in the ossified PLL was closely associated with degenerative changes of elastic fibers and cartilaginous cartilage formation, together with the appearance of metaplastic hypertrophic cartilage cells and neovascularization. The authors also found that VEGF-positive metaplastic chondrocytes in the ossification front and different expression patterns of collagens probably play some role in the extension of the ossified PLL from the ossification front.

Synapse involvement of the dorsal horn in experimental lumbar nerve root compression: a light and electron microscopic study.

Study Design. This study was aimed at investigating changes in the dorsal horn of the lumbar cord induced by mechanical compression using an in vivo model. Objective. To determine the effect of axonal flow disturbance in the dorsal horns induced by nerve root compression. Summary of Background Data. Few studies have looked at changes of synapses within the dorsal horn caused by disturbance of axonal flow and the axon reaction as a result of mechanical compression of the dorsal root. Methods. In mongrel dogs, the 7th lumbar nerve root was compressed for 1 week, or 3 weeks using a clip. After intravenous injection of Evans blue albumin, they were observed under a fluorescence microscope for the purpose of clarifying the function of the blood-spinal cord barrier. Morphologic changes of the synapses in the dorsal horns secondary to the nerve fiber degeneration were examined by light and electron microscope. Changes on immuno-staining for substance P, calcitonin gene-related peptide, and somatostatin in the dorsal horn were also examined. Results. Light microscope observation conducted 1 week after compression of the nerve roots revealed Wallerian degeneration of the myelinated nerve in the dorsal horn, and fluorescence microscope observation of these areas demonstrated edema formation resulting from damage of the blood-spinal cord barrier. Three weeks after the compression, electron microscope observation revealed shrinkage of the axon terminals, ubiquitous presence of high electron density degeneration and presence of synapses whose contact with synapses was disrupted. Immuno-histochemical studies showed a marked decrease of substance P, calcitonin gene-related peptide, and somatostatin staining in substance gelatinosa with Wallerian degeneration after compression of nerve root. Conclusion. It is important to recognize that compressive disturbance of the nerve roots caused Wallerian degeneration not only at the site of compression of nerve roots but also at the synapses of spinal cord dorsal horns.

Ligamentum flavum hematoma in the thoracic spine.

We report a case of a hematoma of ligamentum flavum at T11-12 in a 66-year-old man who presented with progressive weakness of the right foot and numbness of both legs. Past history was negative and no precipitating episode of lower back sprain or trauma. The resected T11 and T12 laminas showed old hematoma with degenerative changes in the ligamentum flavum. Hematoma occurring in the thoracic spine has never been reported previously.

Chronic expanding hematoma of the thigh

Hematomas following surgery or trauma usually resolve without complications. In some instances, for reasons that are not completely understood, hematoma formation is followed by slow expansion of the mass. The large fluid collection is surrounded by a pseudocapsule and fibrous tissue, and present months or years after the original insult, as chronic expanding hematoma. In this case study, we present a rare case of chronic expanding hematoma in an 84-year-old woman. The patient noted a painful swelling in the posteromedial aspect of the lower thigh, and recalled a bump to the left knee 64 years earlier. The lesion was successfully resected, with a preoperative presumptive diagnosis of organized hematoma, although the clinical findings were suggestive of malignancy. We describe the radiological findings, discuss the differential diagnosis.