Transforaminal Epidural Injection of Local Anesthetic and Dorsal Root Ganglion Pulsed Radiofrequency Treatment in Lumbosacral Radicular Pain- A Randomized, Triple-Blind, Active-Control Trial

Low back pain is a very common health hazard. It has added to the economic burden of the world due to not only the usage of health resources but also absenteeism from work. Lumbar radicular pain is one of most common causes of low back pain. The primary modalities of treatment such as oral drug therapy in the form of analgesics and anticonvulsants and physical exercise are associated with poor compliance and increased side-effects. Thus, the role of interventions has come to effect with immediate and long term pain relief. We have compared the efficacy of epidural injections of local anaesthetics and dorsal root ganglion pulsed radiofrequency treatment in the management of lumbar radicular pain.

Pre-enrollment evaluation:

The pain physician posted in the Pain Clinic will take demographic data and a detailed history about the low back pain. After physical examination, pain scores in terms of NRS and functional status according to MODQ will be noted in the Pain Clinic at AIIMS. MRI and/or CT studies will be taken into consideration to correlate with the clinical findings and level of intervention will be decided. Every patient will receive fluoroscopic guided diagnostic selective nerve root blockade with 1ml of 1% lidocaine and if positive response is seen to selective nerve block, they will be recruited for the study group.

Intervention:

After attaching the standard monitors and securing iv access, the patient is made prone. Under all aseptic precautions, 2% preservative-free lignoaine is infiltrated in the skin entry site of designated level determined by both clinical and radiographic evidence of radicular pain. A 10 cm, 22 gauge radiofrequency cannula will be inserted under fluoroscopic guidance. After confirming the final needle position by both AP and lateral view, 0.5 ml of contrast agent will be injected. Once the position of the needle tip is confirmed in the postero-superior quadrant of the intervertebral foramina, the stylet will be removed and replaced by RF probe connected to the RF generator. Final position of the tip of needle (just at the level of DRG) will be confirmed by appropriate sensory stimulation with 50 Hz with 0.4-0.6 V and motor stimulation is done at 2 Hz to determine a threshold of 1.5-2 times greater than sensory threshold (<0.8 V) to avoid placement of the needle near the anterior nerve root. Impedance will be checked to ensure a complete electrical circuit with a range of 200-400 Ohms.

Now, the technician operating the radiofrequency machine will open the sealed opaque envelope containing randomly allocated number. Accordingly, the procedure will be managed as below-

Group LA: 1 ml of Bupivacaine 0.5% will be injected

Group LPRF: 1 ml of Bupivacaine 0.5% will be injected and pulsed radiofrequency will be applied for a period of 120seconds at a frequency of 2 Hz at amplitude of 45V and needle tip temperature of 40-420 C.

The RF machine will be put to silent mode and music will be played to mask any noise during the procedure thus making the patient blind to the procedure.

Post procedure evaluation:

All patients will be observed in the recovery room for one hour. A blinded assessor will follow the patient at 2 weeks, 1, 2, 3 and 6 months post procedure recording NRS, GPE and MODQ score along with employment status and analgesic (opioids and/or NSAIDs) intake.