Definition and Overview
Radiofrequency nerve block (RF ablation) is an interventional pain treatment procedure that places a needle-shaped electrode near the target nerve under image guidance and then uses high-frequency current (usually 100 to 500 kHz) to selectively block or control the function of the pain-transmitting nerve.
The procedure is largely divided into continuous radiofrequency (CRF) and pulsed radiofrequency (PRF). The energy method and target temperature applied to the nerves are different for each, and the indications and mechanisms are also different.
Radiofrequency nerve block is applied to a variety of chronic pain conditions, including chronic spinal pain, cervicogenic headaches, and neuropathic pain, and is a useful alternative for patients who do not respond to drug treatment or have difficulty taking long-term medications.
Cause/pathophysiology and mechanism of action
Continuous radio frequency (CRF) generates heat of 60 to 80°C at the electrode tip, causing thermocoagulation of adjacent nerve tissue, permanently blocking pain signal transmission. This method can be selectively applied to sensory nerves (medial branch, etc.) that have clear nerve travel and no motor function.
Pulsatile radiofrequency (PRF) is a method that repeatedly emits high-energy electric pulses for a short period of time, but limits tissue temperature to not exceed 42°C. It is known to regulate nerve function without nerve damage, but the exact mechanism has not yet been fully elucidated. Inhibition of synaptic transmission and induction of gene expression changes (c-fos, ATF3) have been proposed.
Indications
The main indications for radiofrequency nerve block are as follows.
For facet joint syndrome, radiofrequency treatment of the lumbar and cervical medial branches has become a standard procedure. This also applies to sacroiliac joint pain.
Cervicogenic headache is a headache that originates from the posterior joint of the upper cervical spine, and radiofrequency treatment on the medial branch of the cervical spine showed a significant effect in the study.
In trigeminal neuralgia, radiofrequency thermocoagulation of the trigeminal ganglion is applied when drug treatment fails.
Research is being conducted on the application of stellate ganglion radiofrequency to facial pain, complex regional pain syndrome (CRPS), and some autonomic nerve-related symptoms.
PRF is mainly applied to neuropathic pain such as radiculopathy and postherpetic neuralgia.
Treatment method
The procedure is performed in a sterile environment under fluoroscopy or ultrasound imaging guidance. After local anesthesia, an insulated needle electrode is inserted near the target nerve under image guidance.
Once the electrode location is confirmed, the nerve location is accurately confirmed through a stimulation test (sensory 50 Hz, motor 2 Hz), and then thermal coagulation is delivered for 60 to 90 seconds for CRF and electric pulses are delivered for 2 to 6 minutes for PRF.
A single nerve or multiple medial nerves can be treated simultaneously, and pain relief often begins within a few days after the procedure. Some patients may experience a temporary increase in pain immediately after the procedure.
Effectiveness and Evidence
Regarding medial limb radiofrequency of the facet joints of the spine, Manchikanti et al. (2009)'s systematic literature review confirmed that the pain and functional improvement effects after lumbar medial limb radiofrequency treatment lasted for 6 to 12 months.
Regarding cervical medial branch radiofrequency, Lord et al. (1996) published in N Engl J Med that in a randomized double-blind trial, radiofrequency treatment showed significantly better pain reduction compared to placebo in patients with cervical facet joint pain.
In the case of pulsatile radiofrequency, positive results have been reported in radiculopathy and neuropathic pain, but large-scale RCT data on long-term effects compared to CRF are still lacking.
Precautions and prognosis
The duration of the effect of high-frequency nerve block varies depending on the treatment area and the patient's condition. In the case of continuous high-frequency, symptoms may recur due to nerve regeneration after an average of 6 to 12 months. Reoperation is possible, and the effect tends to be maintained even after repeated treatments.
Contraindications include local infection, hemorrhagic tendency (platelet count decrease, taking anticoagulants), and pregnancy. If there are important blood vessels or nerves near the target nerve, precise location confirmation through image guidance is essential.
Complications are rare, but nerve damage, skin burns, infection, and worsening neuralgia after the procedure have been reported. Performing the procedure under appropriate image guidance by an experienced operator increases safety.
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This information is provided for medical educational purposes and is not a substitute for individual medical care or treatment. If you have any symptoms, be sure to seek professional advice. Inquiries: Osang Neurosurgery 1599-5453 | osns.co.kr