Chronic axial low back pain is a public health problem and has a high socioeconomic impact. The dorsal ganglion of the second spinal nerve (GDL2) is a cluster of neuronal bodies responsible for sensory afferent inputs from more than 80% of the lumbar region. Low-level laser therapy (LLLT) is proven effective to help relieve pain. Thus, the aim of this project is to determine the effect of LLLT on GDL2 when applied to assist in the diagnosis and treatment of chronic axial low back pain. Methodology: 45 patients will be randomized into three groups: laser, radiofrequency and local anesthetic. The patient will be positioned in a prone horizontal position under anesthetic monitoring. The intervertebral foramen between the second and third lumbar vertebrae will be accessed by percutaneous puncture guided by fluoroscopy. In the local anesthetic group, injection of 1 ml lidocaine without vasoconstrictor will be applied in the tubes G20, 150 mm long and 5 mm active tip in contact with the target. In the radiofrequency group, neuromodulation will be held for 300 seconds at 42oC. In the laser group, the laser Photon III® (DCM) will be applied through optic fiber crossing G18 cannulas, during 84 seconds. The pain score will be assessed by visual analog scale. Temperature will be measured and aspirate periganglionic sample, trans-operatively, to study Interleucins-1β and TNF-alpha assessed by ELISA and genetic evaluation trough RNA seek, RNA isolation and ATP quantification. The data will be evaluated for normality and subjected to appropriate statistical analysis, in order to seek representation, as same as the level of significance of the studied samples.

Inclusion Criteria:

• Chronic low back pain (more than 3 months of nociceptive or neuropathic pain).
• No neurological deficits

Exclusion Criteria:

• Active lumbar cancer
• Active infection
• Coagulation disorders