Pulsed radiofrequency for low-back pain and sciatica

Low-back pain is usually defined as pain, muscle tension, or stiffness localized below the costal margin and above the inferior gluteal folds, with or without leg pain (sciatica). The annual prevalence of low-back pain with leg pain traveling below the knee lies between 9.9% and 25% [1]. About 90% of patients with low-back pain will have symptoms without a clear-specific cause. The presence of nerve root problems is an indicator of possible underlying pathology [2]: the most common cause of lumbar radicular pain is intervertebral disc herniation (DH), followed by failed back surgery (FBSS) and spinal stenosis (SS) [3]. Medication (paracetamol, NSAIDs, opioids) is a possible option for the treatment of radicular pain, but there is a lack of evidence to support the prescription of any particular drug [4]. Noninvasive non – pharmacological interventions, which consist in physical exercise (biomechanical, aerobic, mind-body or a combination of approaches) with or without manual therapy (spinal manipulation, mobilization, and massage) or psychological therapy have outcomes that are often not long-lasting [5,6]. Epidural corticosteroid injection has been widely used in clinical practice for many years, but it should be recommended as a means of reducing pain in the short term although no longterm effects can be expected, with a complication rate ranging between 0% and 9.65%. Transforaminal injection (TFESI) under radiological guidance seems to be more effective than epidural injection [4]. Surgery (discectomy, microdiscectomy, and other microsurgical techniques) is usually recommended in selected patients with severe symptoms and no benefit from conservative treatment, or in case of major neurologic impairment. Surgery provides for a better short-term pain relief as compared to prolonged conservative care, but no significant differences have been found between surgery and conservative treatment after one or 2 years [7]. Moreover, surgery is associated with several side effects [8]. Pulsed radiofrequency (PRF) is a relatively new noninvasive technique that relies on the intermittent administration of high-frequency current, avoiding temperature to rise beyond the critical level of 42°C, described as the threshold for neuronal damage. Thus, PRF is based on a different mechanism of action from conventional continuous radiofrequency (CRF), where temperature easily rises above this critical value because of continuous administration, inducing tissue heating and thermal coagulation.