Radiofrequency consists in the passage of a high frequency current through a totally insulated cannula, except for the tip, which is the active part and which exerts the therapeutic action. When the current passes through the cannula, the specialist can control the temperature, increasing it to perform the treatment. The temperature increase in a sensitive nerve responsible for pain interrupts the transmission of pain (in the case of thermal radiofrequency at 80º) or as a modification in the transmission (in pulsed radiofrequency at 40º). The treatment is performed under local anesthesia and sedation.
What are the side effects of radiofrequency?
If safety guidelines are followed and the treatment is carried out by expert hands, the side effects are imperceptible. The treatment must be performed in an operating room to maintain asepsis, and with the certainty of knowing exactly where to insert the cannula by radiological control.
There are effects derived from the discomfort of the infiltration, although they are minimal thanks to the local anesthesia and sedation. Occasionally, if the insertion of the cannula is not correctly controlled, an undesired puncture can occur in another structure, which can lead to a hematoma.
Among the safety measures to be followed, it is important to check the sensory and motor stimulation when the cannula is in the proper location and is controlled radiologically. Before proceeding to practice radiofrequency, the patient is asked a few questions and stimulation is performed with parameters in which the patient feels a tingling (paresthesia) in the area where the pain usually occurs. This means that the cannula is in the right place. In addition, to check that it is not a motor nerve, it is asked and visualized if a stronger stimulation is given that no structure (arm, leg) moves when this shock is applied. If so, the cannula should be repositioned.
What are the types of radiofrequency?
There are several types of radiofrequency depending on the type of pain:
- Conventional radiofrequency (RF) also known as thermal radiofrequency. It is a neuroablative technique that causes heat injury. It uses low power current with high frequencies (500,000 Hz). At a temperature of 80ºC it interrupts transmission in the pain pathways.
- Pulsed radiofrequency is a non-neuroablative neuromodulatory technique (RFP), which has expanded the indications as it does not destroy the nerves, nor does it cause residual neuritis. The RFP interrupts the pulsed current to control the temperature in order to remove heat from the tissue. The maximum temperature reached is 40-42 ºC in a time of 120 seconds. Among the main advantages of RFP we find that it is not destructive, so it can be indicated in cases of neuropathic pain or in structures where conventional RF cannot be used.
When is radiofrequency indicated?
Radiofrequency is indicated in cervical, dorsal and lumbar pain, facet pain, discogenic pain (intradiscal radiofrequency), in radiculopathies (DRG radiofrequency: dorsal root ganglion), on peripheral and cranial nerves.
Likewise, this procedure can also be performed in complex regional pain syndromes with sympathetic maintained pain: RF of the stellate ganglion, RF of the lumbar sympathetic chain. RF of Gasser’s ganglion in essential trigeminal neuralgia. RF of the sphenopalatine ganglion in certain cases of migraine. RF of the peripheral nerves: intercostal, suprascapular, of the articular sensory branches of the obturator and femoral nerves.