Objective evaluation of pain in various spinal diseases: neuropeptide immunoreactivity in the cerebrospinal fluid

A quantitative analysis was performed of substance P-like immunoreactivity (SPLI) and of beta-endorphin-like immunoreactivity (beta-ENDLI), in the cerebrospinal fluid (CSF) in various diseases. The results reported to date have not been consistent. The purpose of this study was to investigate whether or not the concentration of SPLI or that of beta-ENDLI in CSF demonstrated any potential for assessing the degree of subjective pain in various spinal diseases. SPLI in CSF was measured by radioimmunoassay in 158 patients with a spinal disease; involving 57 patients with a lumbar disc herniation (LDH), 38 with lumbar canal stenosis (LCS), 46 with cervical myelopathy (CM) and 17 with cervical radiculopathy (CR), and also in 20 healthy controls. beta-ENDLI in CSF was measured in 25 of these same patients; involving 12 with LDH, seven with LCS and six with CM, and also five of the same controls. The concentration of serum SPLI was also measured in 50 of these 158. The severity of pain was self-evaluated by each patient using a linear visual analogue scale (VAS). Their Japanese Orthopaedic Association (JOA) score was also calculated objectively using the clinical findings. Correlations were investigated among the concentrations of SPLI and beta-ENDLI in the CSF and the VAS and JOA clinical assessments of these patients. The concentration of SPLI in CSF was significantly higher in various spinal diseases than in control (P < 0.05), and was correlated with the severity on the VAS and with the JOA score. However, beta-ENDLI was not correlated with either the VAS or the JOA score. We conclude that the measurement of the SPLI concentration in CSF has the potential for assessing objectively the severity of pain associated with various spinal diseases.