The efficacy of epidural pulsed radiofrequency on radicular pain refractory to dorsal root ganglion pulsed radiofrequency treatment

Abstract

Background: Radicular pain is one of the most common types of pain, with an approximate prevalence ranging from 13 to 40%. The most common cause of radicular pain is a herniated disk or degenerative stenosis in the paramedian zone of the spinal canal, with damage to the nerve root above the foramina. Objective:The aim of this retrospective study was to evaluate the efficacy of epidural pulsed radiofrequency (PRF) in the treatment of radicular pain after failed epidural steroid injection (ESI) and dorsal root ganglion pulsed radiofrequency (DRG-PRF) attempts.Methods: Epidural pulsed radiofrequency was performed on seven patients suffering from radicular pain in L3-S1 dermatomes with anatomical causes, which correlated with the clinical evaluation and radiological findings. PRF was applied in monopolar mode with the following characteristics: frequency 2 Hz (20 ms pulse, 480 ms pause), amplitude 65V, exposure time 360 sec, temperature in the action zone not exceeding 42 degrees Celsius. Results:The effect duration lasted from 4 months to more than one year in 4 patients. The minimum time to relapse was less than 2 weeks, with a maximum duration of more than a year. The absence of pain allowed responders to discontinue basic analgesic therapy. Increasing the activity, rated by them as "substantial" (3 QoL points or more) a month after the procedure, was noted by 5 patients.A year later, the improvement was maintained in 4 patients. Limitations:The main limitation of this study is the small sample size of heterogeneous patients and the absence of a comparison group. Conclusions:Our findings suggest that the epidural PRF is a useful option for treating radicular pain after unsuccessful attempts of the ESI and PRF of DRG for long-term effects. Efficacy of an ePRF can depend not only on the stimulation parameters but also on the point of action.