Effects of continuous and pulsed radiofrequency applied for 120 and 240 seconds to rats' sciatic nerve.

OBJECTIVES: Radiofrequency (RF) has been used for many years for pain treatment. The effects of RF on nerves and the underlying mechanism of these effects are not clearly understood. The aim of this study is to show the effects of Pulsed (P-RF) and Continuous (C-RF) RF in light and electron microscopy, and to determine the differences between them. METHODS: In this study, a total of 60 Rattus norvegicus rats were used in 6 groups. No procedure was performed on the control group. In the Sham group, the electrodes were placed but no current was applied. P-RF for 120 seconds, P-RF for 240 seconds, C-RF for 120 seconds, and C-RF for 240 seconds at 42 °C were applied respectively to the other groups. Sections obtained from sciatic nerves were examined with light and electron microscopy. RESULTS: Examinations of the Sham, P120, and C120 groups were normal. In P240, some morphological changes were observed, but when all samples were examined, these abnormalities were evaluated as negligible. In C240, severe deformation of both myelinated and non-myelinated nerve fibers was observed under an electron and light microscope. Dramatic structural deformities in Schwann cells were observed. CONCLUSION: P120, P240, and C120 treatments did not produce any deformities in the sciatic nerve. The application of C-RF for 240 seconds produced pathological alterations in the nerve structure.

[Subcutaneous stimulation as additional therapy to spinal cord stimulation in a post-laminectomy syndrome patient]. / Postlaminektomi sendromlu hastada epidural ve subkutan elektrodun kombine uygulanmasi.

Spinal cord stimulation as treatment of chronic low back pain via neuromodulation has been frequently performed in recent years. The dorsal column is stimulated by an electrode placed at the epidural region. In the case presently described, subcutaneous lead was implanted in a patient with failed back syndrome after spinal cord stimulation was inadequate to treat back and gluteal pain. A 65-year-old male had undergone surgery to treat lumbar disc herniation, after which he received physical therapy and multiple steroid injections due to unrelieved pain. He was admitted to the pain clinic with pain radiating to right gluteal muscle and leg. Spinal cord stimulation was performed and, as pain was not relieved, subcutaneous lead was applied to the right cluneal nerve distribution. Following treatment, the patient scored 1-2 on visual analog scale. Pain had been reduced by over 80%. Octad electrode was placed between T8 and T10 vertebrae after Tuohy needle was introduced to intervertebral area between L1 and L2. Paresthesia occurred in the right extremity. Boundaries were determined by area of right gluteal region in which paresthesia did not occur. Octad electrode was placed subcutaneously after vertical line was drawn from center point. Paresthesia occurred throughout the region. Pulse wave was 390-450 msec; frequency was 10-30 Hz. Subcutaneous electrode replacement is effective additional therapy when pain is not relieved by spinal cord stimulation.