Plasma neuropeptides in patients undergoing lumbar discectomy

Study Design. A prospective analysis of patients with lumbar disc herniation (LDH). Objectives. To determine the role of neuropeptides as a biochemical signature of pain states in patients with LDH. Summary of Background Data. Increases in the plasma level of neuropeptides have been reported in patients suffering from a variety of painful conditions. However, there is no such report on patients with LDH. Methods. From a total of 27 patients with a single-level LDH, blood samples were collected before and 3 weeks after lumbar discectomy. Plasma levels of alpha calcitonin gene-related peptide (CGRP), galanin, neuropeptide Y, and substance P were determined by using enzyme-linked immunosorbent assay. The association or correlation between preoperative concentration of plasma neuropeptides and gender, patients' age, and VAS were analyzed statistically. Also, the concentration of plasma neuropeptides was compared before and after lumbar discectomy. Results. Preoperative plasma levels of CGRP were correlated significantly with the extent of sciatica as determined by VAS. In addition, plasma levels of CGRP and galanin significantly decreased after lumbar discectomy in line with the disappearance of pain symptoms. Conclusions. These findings indicate the role of plasma CGRP and possibly galanin as a systemic neurochemical signature of pain states in patients with LDH.