Herniation of cervical intervertebral disc - Immunohistochemical examination and measurement of nitric oxide production

Study Design. Surgically obtained cervical herniated intervertebral discs w ere examined histologically and immunohistochemically. The production of ni tric oxide (NO) in the local tissue was examined using the electron spin re sonance (ESR) method. Objectives. To investigate the local histologic and immunohistochemical cha nges in cervical disc herniation, including NO production, and to compare s uch 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 avail able 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 m etalloproteinase (MMP)-3, and inducible NO synthetase (iNOS), We also compa red the production of NO, measured by the ESR method, in eight specimens wi th that of five control discs obtained from fresh cadavers. Results. The presence of herniated discs correlated with the degeneration o f cartilaginous endplate and torn anulus fibrosus. Formation of new blood v essels around the herniated: discs was detected, using von Willebrand facto r antibody, in seven uncontained hernias and 20 contained hernias. Immunohi stochemical studies showed the presence of cells positive for MMP-3 (chondr ocytes), iNOS (chondrocytes and granulation tissue) in cervical disc hernia s. ESR analysis showed a significantly higher NO production in herniated ce rvical 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.