A study was performed to analyze whether local denervation of the medial branch of the dorsal ramus of the lumbar spinal nerve occurs in a patient with postoperative failed-back surgery syndrome/postdiscotomy syndrome (FBSS/PDS). We investigated the effect of the loss of innervation of the multifidus muscle on neuronal nitrite oxide synthetase (n-NOS) and endothelial nitrite oxide synthetase (e-NOS) applying realtime RT-PCR and immunohistochemistry. Our study demonstrates a substantial reduction of n-NOS expression, supporting the view that local denervation of the multifidus is involved in the pathology of FBSS. No regulation of e-NOS was detectable. Interestingly, this change is region-specific and does not occur throughout the entire multifidus segment. This result supports the hypothesis that local denervation of the multifidus muscle is involved in the pathology of FBSS/ PDS.