Lumbosacral pain is a frequently encountered symptom, as the annual prevalence in the general population is reported to be from 9.9 to 25%.The cause of pain occurs when the nerve roots become depressed or stimulated for any reason, such as disc protrusion or spinal stenosis. The initial treatment should start conservatively with oral medications, exercise, and physical therapy.  Transforaminal epidural steroid injection  have been widely adopted to alleviate and control radicular pain in accord with current guidelines. However, sometimes repeated steroid injections have adverse effects such as adrenal depression or hyperglycemia. The duration of pulsed radiofrequency is usually 2-4 cycles total 4-8 minutes (120 seconds for 1 cycle), but the duration is arbitrarily determined.
The purpose of this study is to compare effectiveness of pulsed radiofrequency with 6 minutes vs. 12minutes in patients with chronic lumbosacral radicular pain.

Treatment

This is a randomized, double blind study. Total 68 participants suffering for refractory chronic lumbosacral pain are enrolled in this study. 
After sterile preparation of the needle insertion area, the skin is infiltrated with 1% lidocaine, and 22G 4-in RF cannula with a 10mm curved active tip is advanced under fluoroscopic guidance. Anatomic landmarks are identified, and the cannula is positioned closely to the DRG under fluoroscopic guidance. The tip of the cannula is placed in the dorsal-cranial quadrant of the intervertebral foramen on the lateral image, and the tip is positioned between one-third and halfway to the pedicle column on the anteroposterior image. After positioning the RF probe, the probe is connected to the generator. The final position of the RF probe is confirmed by sensory stimulation (50Hz) threshold < 0.5V. The motor stimulation threshold (2Hz) should be more than 1.5 times greater than the sensory stimulation threshold, and the impedance <  500 Ω is also required. To blind the practitioner, the first practitioner confirmed the correct position of the RF needle and leaves the operation room. After that, the second practitioner applies 6 minutes or 12 minutes of pulsed radiofrequency according to the randomization sheet. In control group, 3 cycles of PRF is performed for 6 minutes (2 minutes/1 cycle). Because the experimental group receives 6 cycles of PRF for 12 minutes, to blind the control group, there is a time interval for 2 minutes after each 1 cycle has been finished. The total intervention time in each group is equally 12 minutes . 
After PRF is performed  , the electrode is removed . After confirmation of epidural spread using a contrast dye, 2-3ml of 1% preservative free lidocaine with 5mg dexamethasone is injected.
Primary outcome is to compare the numeric rating scale after 3 months between the two groups. Secondary outcomes are NRS, medication quantification scale, Oswestry Disability Index, global perceived effect(GPE) after 1,3,6 months.

Arm Label

Target Number of Participant

Arm Type

Arm Description

In control group, 3 cycles of PRF is performed for 6 minutes. There is time interval for 2 minutes after each 1 cycle has been finished. The total intervention time for each group is equally 12minutes. After PRF, contrast dye is injected to confirm epidural spread. And then, 2-3ml of 1% preservative free lidocaine with 5mg dexamethasone is injected.

Arm Label

Target Number of Participant

Arm Type

Arm Description

The experimental group receive 6 cycles of PRF for 12minutes. (2 minutes/1 cycle) After PRF, contrast dye is injected to confirm epidural spread. And then, 2-3ml of 1% preservative free lidocaine with 5mg dexamethasone is injected.

Gender

Age

Description

Chronic lumbosacral radicular pain
-20 years ≤ age <  80 years
-Patients who voluntarily agreed to this clinical study
-chronic lumbosacral radicular pain lasting ≥12weeks
-Numeric rating scale ≥ 4
-Magnetic resonance imaging confirmed spinal stenosis or herniated intervertebral disc

-allergies to radiopaque contrast media or local anesthetics
-coagulopathy, infection, anticoagulants
-mental handicap or psychiatric condition precluding adequate communication
-patients who do not agreed to this clinical study
-pregnancy
-malignancy

Numeric rating scale

3 months after the procedure

Numeric rating scale

Baseline, 1, and 6 months after the procedure

Medication Quantification Scale(MQS)

Baseline, 1, 3, and 6 months after the procedure

ODI (OswestryDisability Index)

Baseline, 1, 3, and 6 months after the procedure

global perceived effect(GPE)

1, 3, and 6 months after the procedure

In this prospective, randomized, double-blinded study, there was no significant difference between groups in pain intensity of leg pain at 3 months after the procedure.