Nerve Ingrowth into Intervertebral Disc in Internal Disc Disruption / 대한척추외과학회지

ABSTRACT

STUDY DESIGN: The ingrowth of the nociceptive nerve ending into intervertebral disc was examined using immunohistochemistry and quantified using western blotting. OBJECTIVES: To determine if the nociceptive nerve innervates into the intervertebral discs of internal disc disruption (IDD). SUMMARY AND LITERATURE REVIEW Nociceptive nerve ending and vessel ingrowth into intervertebral disc is associated with IDD and HNP. Substance P is a neurotransmitter that is found in the nociceptive nerve endings. Immunohistochemistry has confirmed the presence, and western blot has isolated the target. The localization of novel nociceptive innervation, and a quantitative comparison was made according to the original pathology is of interest. MATERIALS AND METHODS: 10 specimens of intervertebral disc were collected from IDD during total disc replacement surgery , and another 10 specimens of intervertebral disc from HNP were collected during discectomy. The control samples of intervertebral disc were obtained from 3 adolescent patients with idiopathic scoliosis, and 2 patients with a lumbar bursting fracture. Standard immunohistochemical techniques were used to test for the nociceptive neurotransmitter (substance P), which is a protein expressed during axonogenesis (growth-associated protein 43, GAP43), and a general nerve marker (protein gene produce 9.5, PGP9.5). The expression of substance P protein was quantified using western blot for its polyclonal antibody. RESULTS: In IDD (n=10), substance P was expressed in 6 cases of outer annulus fibrosus (AF), 5 cases of inner AF, and 3 cases of nucleus pulposus (NP). In HNP (n=10), substance P was expressed in 4 cases of outer AF, 3 cases of inner AF, and 2 cases of NP. In the control group, only 2 cases expressed substance P in outer AF. GAP43 was only positive in outer AF as follows IDD 3 cases, HNP 1 case, and control 1 case. None of the specimens showed localized PGP 9.5. Substance P was localized significantly in larger quantities in IDD than in the control group (p=0.002). In HNP, the expression level was larger than the control and lower than the IDD group but this was not statistically significant (p=0.158, p=0.108). CONCLUSIONS: Innervation of nociceptive nerve endings was identified at the degenerative intervertebral disc of IDD, which may contribute to back pain.