Pulsed Radiofrequency in Chronic Lumbosacral Radicular Pain

Lumbosacral radicular (LRS) pain is one of the most common health care problem. Up to 5% of the population older than 30 years of age suffer low back pain radiating into the leg, making it probably the most commonly occurring form of neuropathic pain.

Radicular pain has been discerned as the pain arising in a limb or trunk which is caused by ectopic activation of nociceptive afferent fibers in a spinal nerve or its roots or other neuropathic mechanisms. More accurately, radicular pain is a term applied to describe pain that results from the stimulation of, or a disorder of, a nerve root.

Acute lumbosacral radicular pain, caused by disc herniation, improves considerably in the short-term. About three quarters of patients will have symptoms of recovery within 3 months; however, there is a high recurrence rate, and when pain persists after this period the prognosis is rather unfavorable, especially in the female population. Conservative therapy (pharmacotherapy or physiotherapy) is effective in 60% of cases, while the rest of cases progress into chronic pain. This results in a high degree of disability and ending with higher medical expenses.

Patients suffering lumbosacral radicular pain often experience a reduced functionality leading to incapacity to work. A quarter of patients are still out of work 2 years after onset.

Despite its high prevalence and significant impact on quality of life, the optimal conservative treatment for patients with radicular pain is not known. Considering the moderate quality of published evidence, the efficacy and tolerability of pharmacological treatment in primary care for patients with lumbosacral radicular pain is unclear.

In the DRG, there is a process that takes place after being compressed by disc prolapse where a cascade of events within the DRG and upstream within the dorsal horn (DH) of the spinal cord leads to constitutive release of cytokines, production of abnormal ion channels, abnormal ion currents, early and late gene changes, and the development of chronic neuropathic pain. With this knowledge regarding the role of DRG neurons and non-neuronal cells within the DRG in the genesis of neuropathic pain, pharmacologic agents such as tetrodotoxin and non-pharmacologic treatments for neuropathic pain including electrical stimulation (neuromodulation) therapies targeting the DRG have been or are being developed.

Pulsed radiofrequency (PRF) is a therapeutic strategy that has been used by pain practitioners as a non- or minimally autodestructive technique in which short bursts of high-frequency current are applied to nervous tissue.

PRF is delivered in a pulse of 20 ms followed by a silent period of 480 ms to avoid radiofrequency heat lesions, and Pulsed radiofrequency (PRF) treatment uses high-frequency current intermittently and its use adjacent to the dorsal root ganglion (DRG) has been suggested for the treatment of radicular pain.

It was previously demonstrated in other studies that the therapeutic effectiveness of PRF is affected by its parameters and the high-voltage PRF has been promising to enhance the clinical therapeutic effectiveness significantly for patients with neuralgia

Inclusion criteria

• More than 18 years old
• Radiating Leg pain (with or without low back pain)
• Unresponsiveness or partial response to oral medications, physical therapy
• Confirmed by clinical examination and lasting for > 6 months with preoperative Numeric Rating Scales (NRS) score more than 4
• Clinical presentation confirmed by Magnetic resonance imaging showing neural compression.

Exclusion criteria

• Blood coagulopathies
• Infection at the site of puncture,
• History of mental disorder
• History of drug abuse
• MRI not consistent with clinical symptoms
• Radiculopathies with significant motor deficits requiring urgent surgery (e.g., Cauda Equina syndrome).
• Patients affected by central neurological impairment or peripheral distal neuropathies in the lower limbs.