Pulsed and Water − Cooled Radiofrequency

Khalid Malik, M.D.
Assistant Professor
Department of Anesthesiology
North western University Feinberg School of Medicine
Chicago, Illinois

Introduction - TOP

During conventional radiofrequency (CRF) applications for pain control, a thermal lesion is created adjacent to a nociceptive pathway to interrupt the pain impulses and thus to provide the necessary pain relief. The radiofrequency (RF) currents are applied through an electrode placed in the vicinity of the target neural structure and the passage of RF currents imparts energy to the surrounding tissues raising their temperature. The electrode itself is heated only passively during the RF thermal lesioning. The temperatures above 45°C are known to be neurodestructive;1 therefore during CRF application the tissue temperatures are typically raised to well above these neurodestructive levels i.e., 80°C to 90°C.

However, thermal lesions at these high temperatures cause injury to nerve fibers of all types,2 with the eventual risk of motor weakness, local neuritis and deafferentation pain. To avoid these complications lower temperatures were arbitrarily selected in many studies of the dorsal root ganglia (DRG) lesioning.3 

In one such study no difference in the clinical results was found between CRF applied at 40°C or 67°C.4  The authors of this study concluded that factors other than temperature determined the outcome, and proposed the possible role of electrical energy in causing neuronal dysfunction from RF application.

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