The morphological effects of a radio frequency lesion adjacent to the dorsal root ganglion (RF‐DRG)—an experimental study in the goat

Abstract

Radiofrequency (RF) lesions adjacent to the dorsal root ganglion (DRG) are increasingly used in the treatment of intractable chronic pain of spinal origin. Opinions differ on which nerve fibres are affected by these lesions. Morphological studies have been carried out to assess the effects of radiofrequency lesions on nervous tissue. Interpretation has been difficult, since most studies have been performed under circumstances which are not comparable to the clinical situation. This study was undertaken to investigate morphological effects of RF lesions as they develop in the normal clinical situation. In two goats 22 G 100 mm SMK electrodes with a 5 mm active tip (Radionics) were positioned posterior to the lumber dorsal root ganglia (DRG). Sixty-second 67;C lesions were made on one side. The contralateral side was used as sham operation. The goats were sacrificed 2 weeks after the procedure. The lesions were studied for size as well as for effects on proliferation and regeneration using Ki-67 (MIB-1). Lesions made inside the DRG (23) were 1.8-2.0 mm in size. In these lesions there was a total loss of myelinated fibres. In lesions made adjacent to the DRG there was a significantly higher MIB-1 labelling on the treated side as compared to the sham-treated side. An RF lesion inside the DRG destroys myelinated fibres. A lesion adjacent to the DRG increases MIB-1 activity, indicating proliferation and regeneration after 2 weeks, despite the fact that the lesion was made outside the ganglion.

The Efficiency of Pulsed Radiofrequency Application on L5 and L6 Dorsal Roots in Rabbits Developing Neuropathic Pain

“…When tissue was assessed 2 weeks later with a microscope, researchers observed nerve fiber regeneration and satellite cell proliferation, although no full tissue damage was reported. 22 Whereas PRF temporarily inhibits evoked synaptic activity, conventional RF inhibits this activity. 9 In this study, we tested the antinociceptive properties of PRF in a validated animal model rather than previous studies that have looked mainly at histologic effects of PRF.…”

The genicular nerve: radiofrequency lesion application for chronic knee pain*

“…In the RFN procedure, after placement of the active tip RF needle close to the target nerve, an RF electrode is passed within the needle and alternating electric currents (radiowave frequency) are transferred to the nerve from the RF generator (15). Thus lysis is provided in the target nerve by raising the tissue temperature to 60-80° C (6,15,16). Following the first successful application of RFN in trigeminal neuralgia (17), it was then applied to the sacroiliac joint causing chronic back pain and the facet joints (18,19).…”

Percutaneous, computed tomography guided neurolysis using continuous radiofrequency for pain reduction in oncologic patients

“…Ablation with continuous radiofrequency results in high temperatures (60-80 °C) that promote neurolysis and destroy the target nerves. [8,9] In contrast, application of pulsed radiofrequency maintains the temperature below 42 °C, promoting neuromodulation of the target nerves. [10,11] Both continuous and pulsed radiofrequency modes have been applied for pain reduction in symptomatic cancer patients with refractory pain.…”