Herniated and Spondylotic Intervertebral Discs of the Human Cervical Spine: Histological and Immunohistochemical Observations

Abstract

We investigated the histological and immunohistochemical changes within and around the cervical intervertebral discs in symptomatic myeloradiculopathy and myelopathy patients. A total of 163 cervical intervertebral discs, 100 herniated discs and 63 spondylotic discs, were harvested en bloc during anterior decompressive surgeries and histological examination was performed, focusing on nucleus pulposus, annulus fibrosus, cartilaginous endplate, and ligamentous enthesis. There was a close relationship between MRI grade and histological degenerative changes. Histological features of the herniated intervertebral discs were the presence of granulation tissue, newly-developed blood vessels and infiltration of CD68-positive cells, which surrounded the herniated tissue in the outer layer of the annulus fibrosus. Marked vascular invasion was detected in 67% of herniated discs and 54% of spondylotic discs. Immunohistochemically, chondrocytes positive for matrix metalloproteinase (MMP)-3, tumor necrosis factor (TNF)-a, basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) were detected in both herniated and spondylotic discs. Our results indicate that the neoangiogenesis process is associated with overexpression of bFGF and VEGF, and suggest that intervertebral disc degradation is enhanced by macrophage infiltration, which is regulated by MMP-3 and TNF-a. The expression of these proteins may be enhanced by the tear of annulus fibrosus.

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

“…Interestingly, we found a number of small blood vessels in the degenerated PLL, particularly in its deep layer, near the ligamentous enthesis and ossification front. In our previous studies, we made a similar finding of small blood vessel invasion in vivo within the torn PLL in patients with symptomatic herniated intervertebral discs 18 and in human tissue in cases of degenerated ligamentum flavum. 32 Degeneration of the elastic fiber within the fibrocartilage tissue could be associated, at least in part, with neovascularization.…”

“…Histopathological samples of the PLL and ligamentous enthesis obtained in 10 age-matched patients (average age 61.2 years, range 32-75 years) with spondylosis served as positive controls. 18 The surgical technique of anterior decompression and resection of the ossified PLL has been described in our previous reports. 1,18 Briefly, a left-sided anterolateral approach was used to expose the affected vertebral level(s).…”

“…18 The surgical technique of anterior decompression and resection of the ossified PLL has been described in our previous reports. 1,18 Briefly, a left-sided anterolateral approach was used to expose the affected vertebral level(s). We performed a 2.0-cm-wide transverse vertebral resection at the level of vertebrotomy.…”

“…On the other hand, using a spinal hyperostotic mouse model (twy/twy), 2,3,8,21,28,29 our group observed the appearance of mesenchymal metaplastic chondrocytes and osteoblast-like cells in the ossification front, followed by initiation of the ossification process and development of OPLL. Based on these studies of calcification of the spinal ligaments 32 and herniated intervertebral discs, 18 we examined human ossified PLL samples in vivo to gain greater insight into this pathological process.…”

Morphological changes in disc herniation in the lower cervical spine: an ultrastructural study

“…Kokubo et al described structural changes such as vessel in-growth and macrophage infiltration into the outer layers of the AF in herniated discs and Risbud et al [28] report evidence for progenitor cells in cervical discs. In herniations, fragmented hyaline cartilage was observed [29]. Others were able to show at the light microscopic level, small cysts and fissures that, due to shear stress, form clefts in the posterior portion of the cervical disc [30].…”