Pulsed Radiofrequency Procedure Research Articles

Pulsed Radiofrequency Spinal Cord Neuromodulation for Residual Symptoms after Cervical Surgery

Introduction Cervical decompression, discectomy, fusion, and arthroplasty are treatment modalities of choice for various pathological conditions of cervical spine. Occasionally after these procedures, some degree of neck pain, paresthesia, and/or palsy may still be reported by patients. Pulsed radiofrequency (PRF) neuromodulation of spinal cord dorsal root entry zone, pregangliar and postgangliar nerve root parts, is a well-known invasive pain therapy modality used for a variety of pain symptoms. This study was done to evaluate if a single session, PRF neuromodulation, might be effective in the treatment of residual symptoms after cervical surgical procedures. Materials and Methods Thirty-eight patients from three different clinical settings were included in the study. Eighteen patients have been previously submitted to one- or two-level anterior discectomy and interbody fusion, 10 patients to two or more level anterior discectomy, decompression, and fusion, 7 patients had a one- to two-level arthroplasty performed, while the rest had a posterior decompression with or without instrumented fusion. Upon surgery, 22 patients reported some residual symptoms mainly of neck pain, radiating pain to scapular and/or shoulder area, and 15 of them had only or also paresthesia and/or pain radiating to one or both upper limbs. Four patients also had some degree of residual palsy that did not improve completely after the surgery. The neuromodulation procedure was performed not less than 3 months after the surgery (mean time from surgery to PRF treatment was 4.5 months). In all the cases, the PRF procedure was done by Pasha-catheter that was introduced inside the vertebral channel at the midthoracic level, interlaminary, and under local anesthesia only. In the cases of neck pain, extradural treatment of dorsal root entry zones, pregangliar and occasionally postgangliar nerve fibers at multiple levels from C2 to D1, was done bilaterally. In the cases of symptoms radiating to the upper limbs, the treatment was mainly focused on the side of the symptoms and the treatment was centered on dorsal root entry zones and preganglionic fibers. When the residual palsy was present, the preferred treatment was intrathecal treatment of the dorsal root entry zone and the ganglion area. The mean treatment duration was 58 ± 14 minutes. Except when an intradural modality of treatment was performed, all the patients were discharged on the same day after a 6-hour in-hospital observation. The intradurally treated patients were discharged the next morning. In 3 cases, posttreatment headache was reported in the first 24 hours, while in 10 cases the pain was at the introduction site. No short- or long-term complications were observed. Results At 2-month follow-up, 34 patients reported significant improvement in pain levels while at 1-year follow-up, 29 patients were still reporting significant improvement in pain levels as compared with preoperative status. Preoperative mean VAS value for all the patients was 5.5 ( ± 2) and the 1-year reduction evaluation was 1.5 ( ± 1). Out of the four patients with residual palsy, two patients were found almost free of the palsy, one patient did not improve at all, and another had just partial improvement in the strength. Conclusion The PRF neuromodulation of the spinal cord and gangliar structures seems to be reasonably useful for the treatment of the residual pain and neurological symptoms after different cervical surgical procedures.

The Effect of Pulsed Radiofrequency Applied to the Peripheral Nerve in Chronic Constriction Injury Rat Model.

ObjectiveTo investigate the effect of pulsed radiofrequency (PRF) applied proximal to the injured peripheral nerve on the expression of tumor necrosis factor-α (TNF-α) in a neuropathic pain rat model.MethodsNineteen male Sprague-Dawley rats were used in the study. All rats underwent chronic constriction injury (CCI) procedure. After 7 days of CCI, withdrawal frequency of affected hind paw to mechanical stimuli and withdrawal latency of affected hind paw to heat stimulus were measured. They were randomly divided into two groups: group A, CCI group (n=9) and group B, CCI treated with PRF group (n=10). Rats of group B underwent PRF procedure on the sciatic nerve. Withdrawal frequency and withdrawal latency were measured at 12 hours, and 7 days after PRF. Immunohistochemistry and Western blot analysis were performed using a TNF-α antibody.ResultsBefore PRF, withdrawal frequency and withdrawal latency were not different in both groups. After PRF, withdrawal frequency decreased and withdrawal latency prolonged over time in group B. There was significant interaction between time and group for each withdrawal frequency and withdrawal latency. Group B showed decreased TNF-α immunoreactivity of the spinal cord and sciatic nerve at 7 days.ConclusionPRF applied proximal to the peripheral nerve injury is potentially helpful for the reduction of neuropathic pain by neuromodulation of inflammatory markers.

Pulsed Radiofrequency for the Suprascapular Nerve for Patients With Chronic Headache

Chronic shoulder or suprascapular pain is a disabling phenomenon. Chronic headache is also a disabling phenomenon for many patients. Once it was believed that chronic headache that is attributed to the cervical spine originates from the upper cervical nerve roots (C0-C3). Currently, it is suggested by some authors that the reason for headache in many patients is attributed to the lower cervical nerve roots in the cervical spine. The suprascapular nerve originates from the C5 and C6 nerve roots and supplies the suprascapular and shoulder region. Pulsed radiofrequency (PRF) has gained popularity over recent years as a good clinical tool in treating patients with shoulder/suprascapular pain. It is usually considered as a treatment option after conservative treatment has failed. The purpose of this study was to evaluate whether PRF for the suprascapular nerve has also beneficial effect for patients that have also chronic headache that is attributed to the lower cervical nerve roots. Sixty-nine patients with a follow-up of 1 year who had chronic shoulder/suprascapular pain and chronic headache were examined after they underwent PRF procedures to the suprascapular nerve (either unilateral or bilateral). Forty patients (58%) reported long-term pain relief (1-y follow-up) for the shoulder/suprascapular pain and 31 patients (45%) reported long-term pain relief for the headache. This pain relief was defined as reduction of Visual Analogue Score by at least 30%. No complications were found in this study except for mild discomfort in the treated area which spontaneously resolved up to 3 weeks after the procedure. PRF for the suprascapular nerve is a safe and an effective procedure for patients who suffer from shoulder/suprascapular pain and also for headache that is attributed to the lower cervical nerve roots. It should be tried after conservative treatment has failed.

Pulsed Radiofrequency Application Reduced Mechanical Hypersensitivity and Microglial Expression in Neuropathic Pain Model

Pulsed radiofrequency (PRF) procedure has been used in clinical practice for the treatment of chronic neuropathic pain conditions without neuronal damage. The purpose of this study was to investigate the changes in pain response and glial expression after the application of PRF on a dorsal root ganglion (DRG) in a neuropathic pain model. A neuropathic pain model (14 female Sprague-Dawley [SD] rats; 200-250 g) was made by a unilateral L5 spinal nerve ligation (SNL) and transection on the distal side of the ligation. The development of mechanical and cold hypersensitivity on the hindpaw was established postoperative day 9 (POD 9). The rats were then randomly assigned to the PRF (+) and the PRF (-) groups. Furthermore, PRF (2 bursts/s, duration = 20 milliseconds, output voltage = 45 V) was applied on the ipsilateral DRG for 180 seconds, with a maximum temperature of 42°C, at POD 10. Pain behaviors were tested throughout the 12 days after PRF. We also examined the changes of the spinal glial expression by immunohistochemistry. Significant reduction of mechanical hypersensitivity in the PRF (+) group was observed from day 1 after a single PRF procedure and was maintained throughout the following 12 days. Immunoreactivity for OX42 in the ipsilateral dorsal horn also decreased compared with that of the PRF (-) group. However, cold hypersensitivity and glial fibrillary acidic protein (GFAP) immunoreactivity in the dorsal horn was not affected by a PRF procedure. Our result demonstrated that the mechanical hypersensitivity, induced by L5 SNL, was attenuated by a PRF procedure on the ipsilateral DRG. This analgesic effect may be associated with an attenuation of the microglial activation in the dorsal horn.

The Effect of Pulsed Radiofrequency Current on Mechanical Allodynia Induced with Resiniferatoxin in Rats

Pulsed radiofrequency (PRF) is a popular pain treatment modality. The effect of PRF current on neuropathic pain has not been examined in detail. We investigated the effect of PRF current on mechanical allodynia induced with resiniferatoxin (RTX) in rats, especially regarding the influence of the duration of allodynia before PRF procedures and that of exposure time to PRF. Adult male Sprague-Dawley rats (weighing 250-400 g) received a single intraperitoneal injection of RTX (200 microg/kg) under 2 to 3% sevoflurane anesthesia. Rats in group S(2) (n = 5) were assigned to receive PRF current to the right sciatic nerve for 2 minutes 1 week after RTX treatment; rats in group M(2) (n = 6), PRF current for 2 minutes 3 weeks after RTX treatment; rats in group L(2) (n = 7), PRF current for 2 minutes 5 weeks after RTX treatment; rats in group S(4) (n = 5), PRF current for 4 minutes 1 week after RTX treatment; rats in group S(6) (n = 5), PRF current for 6 minutes 1 week after RTX treatment; and rats in group S(0) (n = 3), no PRF current was delivered. Instead, the needle and electrode were inserted at proper points for 6 minutes 1 week after RTX treatment. All rats were evaluated for sensitivity to mechanical stimulation with von Frey filaments and to thermal stimulation with a thermal testing apparatus and for motor function using placing and grasping reflexes before injection of RTX, every week after injection of RTX, and 1, 2, 3, 4, and 5 weeks after PRF treatment. The paw withdrawal thresholds of both hindpaws 1 week after RTX treatment were significantly lower than the pre-RTX baseline in all groups. In groups S(2), S(4), S(6), and M(2), after PRF procedures, the ipsilateral paw withdrawal thresholds significantly increased. A statistically significant difference was detected between the PRF-treated and PRF-untreated hindpaws. The ipsilateral-contralateral paw withdrawal thresholds after PRF procedures in group S(2) were significantly higher than those in groups M(2) and L(2). Between groups M(2) and L(2), significant differences were found 1, 2, 4, and 5 weeks after PRF procedures. The ipsilateral-contralateral paw withdrawal thresholds in group S(6) were significantly higher than those in groups S(2) and S(4) 5 weeks after PRF procedures. No significant difference was found between groups S(2) and S(4) at any time. After PRF procedures, no difference in the withdrawal latency after heat stimulation and no motor disturbance were observed at any time in all groups. PRF treatment was more effective when applied in the early stages of mechanical allodynia (1 week) in rats. Increased exposure time to PRF current from 2 to 6 minutes showed a significant antiallodynic effect without motor impairment. We propose the application of PRF current for 6 minutes adjacent to the nerve as soon as possible when allodynia appears.

Pulsed Radiofrequency for the Treatment of Occipital Neuralgia

Occipital neuralgia is a paroxysmal nonthrobbing, stabbing pain in the area of the greater or lesser occipital nerve caused by irritation of these nerves. Although several therapies have been reported, no criterion standard has emerged. This study reports on the results of a prospective trial with 6 months of follow-up in which pulsed radiofrequency treatment of the greater and/or lesser occipital nerve was used to treat this neuralgia. Patients presenting with clinical findings suggestive of occipital neuralgia and a positive test block of the occipital nerves with 2 mL of local anesthetic underwent a pulsed radiofrequency procedure of the culprit nerves. Mean scores for pain, quality of life, and medication intake were measured 1, 2, and 6 months after the procedure. Pain was measured by the visual analog and Likert scales, quality of life was measured by a modified brief pain questionnaire, and medication intake was measured by a Medication Quantification Scale. During a 29-month period, 19 patients were included in the study. Mean visual analog scale and median Medication Quantification Scale scores declined by 3.6 units (P = 0.002) and 8 units (P = 0.006), respectively, during 6 months. Approximately 52.6% of patients reported a score of 6 (pain improved substantially) or higher on the Likert scale after 6 months. No complications were reported. Pulsed radiofrequency treatment of the greater and/or lesser occipital nerve is a promising treatment of occipital neuralgia. This study warrants further placebo-controlled trials.

Articular facets syndrome: diagnostic grading and treatment options

Approximately 80% of the adult population suffers from chronic lumbar pain with episodes of acute back pain. The aetiology of this disorder can be very extensive: degenerative scoliosis, spondiloarthritis, disc hernia, spondylolysis, spondylolisthesis and, in the most serious cases, neoplastic or infectious diseases. For several years, the attention of surgeons was focused on the articular facets syndrome (Lilius et al. in J Bone Joint Surg (Br) 71-B:681-684, 1998), characterised clinically by back pain and selective pressure soreness at the level of the facets involved. The instrumental framework highlights widespread zigoapophysary arthritis and hypertrophy/degeneration of articular facets due to a functional overload. This retrospective study analyses the patients who arrived at our observation and were treated with a neuroablation using a pulsed radiofrequency procedure, after a CT-guided infiltration test with anaesthetic and cortisone. From the data collected, it would seem that this procedure allows a satisfactory remission of the clinical symptoms, leaving the patient free from pain; furthermore, this method can be repeated in time.

Pulsed radiofrequency effects on the lumbar ganglion of the rat dorsal root: a morphological light and transmission electron microscopy study at acute stage.

Since the dorsal root ganglia represent the first structure of pain modulation, they are the target of the newest therapies of neuropathic pain. Between these, pulsed radiofrequency (PRF) has been described among the promising non-invasive methods. Although the results encourage the clinical use of this procedure, their mechanism of action is still unclear. Aim of our study was to analyze acute effects of PRF on the rat lumbar ganglion and on nervous fibres running inside it. Clinical works describe PRF treatment as a technique without any visible neurological deficit. The few disposable histological works are contractictory: some describe no signs of cellular damage and some demonstrate visible intracellular modifications. A total of 20 male Wistar rats were deeply anesthesized. Ten were positioned in a stereotactic system, and exposed to PRF at 2 Hz for 30 s after exposition of paravertebral muscles and positioning of a stimulation needle on left L4 ganglion. The other ten were used as controls. After 1 h, the left dorsal root ganglions L3, L4, L5 of the 20 animals were explanted, fixed in 2.5% Karnowsky solution and prepared for light and transmission electron microscopy. At light microscopy no differences between treated and control animals were observed; at transmission electron microscopy, instead, it was possible to observe that T gangliar cells contained an abnormal abundant smooth reticulum with enlarged cisternae and numerous vacuoles; myelinated axons presented pathological features and their myelin coverage was not adherent. Instead, unmyelinated axons appeared normal in shape and dimension and the Schwann cells surrounding it had intact plasmamembrane. Our results, obtained at acute stage, reveal that the PRF procedure should destroy the myelin envelope of nervous fibres. Further future studies, at chronic stage, should give other information on the prognosis of the myelinic damage.

Pulsed Radiofrequency in Lumbar Radicular Pain: Clinical Effects in Various Etiological Groups

The purpose of this study was to evaluate the effectiveness of pulsed radiofrequency (PRF) applied to the lumbar dorsal root ganglion (DRG). A retrospective analysis of 54 consecutive patients who underwent 75 PRF procedures was performed. The patients were divided into three groups according to the etiology of the lesion (herniated disc [HD], spinal stenosis [SS], and failed back surgery syndrome [FBSS]). The analgesic efficacy of the technique was assessed using a 10-point Numeric Rating Scale (NRS) at baseline and, along with the Global Perceived Effect (GPE), at 30, 60, 90, and 180 days. The reduction in medications and the number of complications associated with the technique were assessed. A decrease in the NRS score was observed in patients with HD (P < 0.05) and SS (P < 0.001), but not in those with FBSS. The GPE scores confirmed this finding. No complications were noted. We observed that PRF of the DRG was significantly more efficacious in HD and SS than in FBSS patients. The application of PRF was not effective in FBSS.