Effect of Pulsed Mode Radiofrequency on Dorsal Root Ganglion on Tumor Necrotic Factor α Level in Lumbar Disc Related Radicular Pain

Lumbar radiculopathy is a term that describes symptoms of pain, numbness, and/or weakness that radiate along the sciatic nerve from the lower back to the buttocks and leg (1). Lumbar radiculopathy is a relevant health problem that affects quality of life, resulting in high health costs and economic loss worldwide (2). The reported prevalence of sciatica varies widely from 1.2% and 43% in the general population (3).

Although initially believed to be a primary mechanical insult to the nerve root and dorsal root ganglion, lumbar radiculopathy is possibly caused by inflammatory changes in the nerve root (4). The role of cytokine-mediated neuroimmune interactions in the development and persistence of pain has been extensively studied (5,6,7).

Intraneural application of pro-inflammatory cytokines induces behavioral signs associated with pain (8). Anti-inflammatory cytokine treatment effectively reduces hyperalgesia (9). Inflammatory cytokine inhibitors provided long-lasting analgesia in an inflammatory neuropathic pain model. On the basis of these findings, we evaluated whether cytokine profiles differ between severe and mild human sciatica, as well as whether distinct cytokine profiles provide relevant information regarding lumbar radiculopathy pathogenesis. (10,11).

Tumor necrosis factor-alpha (TNF-α) is a pleiotropic cytokine that can stimulate inflammatory responses of synapses and myelin sheath, promote cellular apoptosis because of its cytotoxic effect, and induce nerve swelling and neuropathic pain (12).

TNF-α influences neural survival, exerting both neuroprotective and neurodegenerative actions (13). Following peripheral nerve injury, upregulation of TNF-α expression has been documented in several neuropathic pain models (14).

Pulsed radiofrequency (PRF) is a relatively new developed technique that is a variation of conventional radiofrequency treatment. PRF treatment does not allow temperatures above 42°C at the tip of the electrode. PRF provides advantage avoiding thermal tissue destruction and pain sequelae in management of pain. Recently, it has been recommended for treatment of chronic pain (15).

Electromagnetic field which is thought to be responsible for the clinical effect of pulsed RF spread from active tip of electrode to around the electrode. The most intense part of the electromagnetic field is pointed tip of the electrode (16). It is a minimally invasive technique that involves application of electric fields to nerves to inhibit nociceptive stimuli and prevent pain transmission. PRF can be considered when conventional treatments have intolerable side effects or do not sufficiently relieve pain (17).

Working mechanism of PRF which is recently more preferred technique to treat chronic pain due to not forming tissue damage and less painful procedure is not exactly known but it is considered to act neuromodulation (18).

The aim of this work is to compare the effect of transforaminal injection of Steroids alone versus Radiofrequency pulsed mode on dorsal root ganglion combined with transforaminal steroids injection on TNF-α level in lumbar disc related radicular pain