Adaptation of an Ultrasound-Guided Technique for Pulsed Radiofrequency on Axillary and Suprascapular Nerves in the Treatment of Shoulder Pain

Efficacy of pulsed radiofrequency on the suprascapular and axillary-circumflex nerve for shoulder pain: A randomised controlled trial

Background and Aims

Painful shoulder is one of the most frequent consultation causes. Multiple treatments have been described to relieve pain, restore range of motion and improve functionality.

Methods

This randomised clinical trial was conducted in 60 patients. The treatment group received combined pulsed radiofrequency (PRF) on suprascapular nerve (SN) and axillary-circumflex nerve (ACN). The control group received PRF on SN only. The primary outcome was pain intensity measured by the Numerical Rating Scale (NRS). The secondary outcomes were the Shoulder Pain and Disability Index (SPADI), the Constant-Murley range of motion scale and Disability of the Arm, Shoulder and Hand (DASH) scale. The patients were monitored at the baseline visit and at 1, 3, 6 and 9 months. A mixed ordinal regression model was estimated to evaluate the association between the study group and pain measured with NRS.

Results

A global decrease in pain at the end of the study was noted. The global baseline NRS was 8.4, and the global final NRS at 9 months of follow-up was 6.2. Combined PRF on SN and ACN was not associated with lower NRS pain scores compared to single SN PRF [odds ratio (OR) =1.04, 95% confidence interval (CI) 0.91-1.20, P = 0.507]. Secondary outcomes showed no significant differences: SPADI (OR = 1.04, 95% CI 0.92-1.18), Constant-Murley (OR = 1.01, 95% CI 0.90-1.14), DASH (OR = 1.04, 95% CI 0.92-1.17).

Conclusion

Combined PRF applied to SN and ACN was not superior to PRF applied to SN alone.

MR thermometry imaging for low intensity focused ultrasound modulation of spinal nervous tissue

OBJECTIVES

Previously in rodent and swine models, we have shown that external low intensity focused ultrasound (liFUS) can be used to modulate pain responses. To ensure no adverse heating events occur with liFUS modulation in a non-invasive manner, we perform initial work in swine to show that magnetic resonance thermometry imaging (MRTI) is capable of measuring <2.0 °C changes at the L5 DRG. Further, we show that our device can be constructed in an MR-compatible fashion to minimize artifact.

METHODS

Three MRTI techniques (referenceless, corrected proton resonance frequency shift (PRFS), and PRFS) were applied to assess accuracy of detecting thermal changes at the L5 DRG in unheated euthanized swine. A region of interest (ROI) that includes the L5 DRG was delineated, within which MRTI temperature changes were spatially averaged (ground truth 0 °C). In separate experiments with phantoms, B0 field-inhomogeneity, RF transmit (B1+) and fast gradient echo (fSPGR) magnitude images were acquired to downselect liFUS device materials that produce the least MRI artifacts.

RESULTS

Referenceless, corrected PRFS, and PRFS MRTI resulted in temperature measurements of 0.8 ± 1.1 °C, 1.1 ± 1.3 °C and 5.2 ± 5 °C, respectively. Both materials caused B0 perturbation but minimal B1+ and MRTI artifacts. The presence of imaging artifacts did not preclude thermal imaging of the region.

SIGNIFICANCE

We provide preliminary data suggesting that referenceless MRTI can adequately detect small thermal changes at the DRG that may occur with neuromodulation, which is one of the first steps in creating a table of safe parameters for liFUS therapy in humans.

Effectiveness and safety of high-voltage pulsed radiofrequency to treat patients with primary trigeminal neuralgia: a multicenter, randomized, double-blind, controlled study

BACKGROUND

Trigeminal neuralgia (TN) is a debilitating pain disorder that still lacks an ideal treatment option. Pulsed radiofrequency (PRF), especially with high output voltage, is a novel and minimally invasive technique. PRF is regarded a promising treatment option for TN patients who respond poorly to medical treatment; however, the available evidence still lacks high quality randomized controlled trials (RCTs). Our study aimed to evaluate the long-term (1 year and 2 years) effects and safety of high-voltage PRF in primary TN patients and provide stronger evidence for TN treatment options.

METHODS

We performed a multicenter, double-blind, RCT in adults (aged 18-75 years) with primary TN who responded poorly to drug therapy or were unable to tolerate the side effects of drug. Eligible participants were randomly assigned (1:1) to receive either high voltage PRF or nerve block with steroid and local anesthetic drugs. The primary endpoint was the 1-year response rate. This trial has been registered in the clinicaltrials.gov website (registration number: NCT03131466).

RESULTS

One hundred and sixty-two patients were screened for enrollment between April 28th,2017 and September1st, 2019, among whom, 28 were excluded. One hundred and thirty-four participants were randomly assigned to either receive high voltage PRF (n = 67) or nerve block (n = 67). The proportion of patients with a positive response at 1-year after the procedure in the PRF group was significantly higher than that in the nerve block group in the intention-to-treat population (73.1% vs. 32.8%, p < 0.001). There was no difference between groups in the incidence of adverse events.

CONCLUSIONS

Our findings support that high voltage PRF could be a preferred interventional choice prior to receiving more invasive surgical treatment or neuro-destructive treatment for TN patients who have poor responses to medical treatment.

TRIAL REGISTRATION

Our study has been registered at ClinicalTrials.gov (trial registration number: NCT03131466).

Low Intensity Focused Ultrasound Increases Duration of Anti-Nociceptive Responses in Female Common Peroneal Nerve Injury Rats

OBJECTIVE

Chronic pain affects 7%-10% of Americans, occurs more frequently and severely in females, and available treatments have been shown to have less efficacy in female patients. Preclinical models addressing sex-specific treatment differences in the treatment of chronic pain have been limited. Here we examine the sex-specific effects of low intensity focused ultrasound (liFUS) in a modified sciatic nerve injury (SNI) model.

MATERIALS AND METHODS

A modified SNI performed by ligating the common peroneal nerve (CPN) was used to measure sensory, behavioral pain responses, and nerve conduction studies in female and male rats, following liFUS of the L5 dorsal root ganglion.

RESULTS

Using the same dose of liFUS in females and males of the same weight, CPN latency immediately after treatment was increased for 50 min in females compared to 25 min in males (p < 0.001). Improvements in mechanical pain thresholds after liFUS lasted significantly longer in females (seven days; p < 0.05) compared to males (three days; p < 0.05). In females, there was a significant improvement in depression-like behavior as a result of liFUS (N = 5; p < 0.01); however, because males never developed depression-like behavior there was no change after liFUS treatment.

CONCLUSIONS

Neuromodulation with liFUS has a greater effect in female rats on CPN latency, mechanical allodynia duration, and depression-like behavior. In order to customize neuromodulatory techniques for different patient phenotypes, it is essential to understand how they may alter sex-specific pathophysiologies.

Pilot study on the effects of low intensity focused ultrasound in a swine model of neuropathic pain

OBJECTIVE

The authors' laboratory has previously demonstrated beneficial effects of noninvasive low intensity focused ultrasound (liFUS), targeted at the dorsal root ganglion (DRG), for reducing allodynia in rodent neuropathic pain models. However, in rats the DRG is 5 mm below the skin when approached laterally, while in humans the DRG is typically 5-8 cm deep. Here, using a modified liFUS probe, the authors demonstrated the feasibility of using external liFUS for modulation of antinociceptive responses in neuropathic swine.

METHODS

Two cohorts of swine underwent a common peroneal nerve injury (CPNI) to induce neuropathic pain. In the first cohort, pigs (14 kg) were iteratively tested to determine treatment parameters. liFUS penetration to the L5 DRG was verified by using a thermocouple to monitor tissue temperature changes and by measuring nerve conduction velocity (NCV) at the corresponding common peroneal nerve (CPN). Pain behaviors were monitored before and after treatment. DRG was evaluated for tissue damage postmortem. Based on data from the first cohort, a treatment algorithm was developed, parameter predictions were verified, and neuropathic pain was significantly modified in a second cohort of larger swine (20 kg).

RESULTS

The authors performed a dose-response curve analysis in 14-kg CPNI swine. Specifically, after confirming that the liFUS probe could reach 5 cm in ex vivo tissue experiments, the authors tested liFUS in 14-kg CPNI swine. The mean ± SEM DRG depth was 3.79 ± 0.09 cm in this initial cohort. The parameters were determined and then extrapolated to larger animals (20 kg), and predictions were verified. Tissue temperature elevations at the treatment site did not exceed 2°C, and the expected increases in the CPN NCV were observed. liFUS treatment eliminated pain guarding in all animals for the duration of follow-up (up to 1 month) and improved allodynia for 5 days postprocedure. No evidence of histological damage was seen using Fluoro-Jade and H&E staining.

CONCLUSIONS

The results demonstrate that a 5-cm depth can be reached with external liFUS and alters pain behavior and allodynia in a large-animal model of neuropathic pain.

Shoulder Ablation Approaches

The shoulder is structurally and functionally complex. Shoulder pain may be refractory to conventional treatments, such as physical therapy, pharmacotherapy, and corticosteroid injections. In such cases, radiofrequency ablation may serve as an alternative treatment plan. Current literature has demonstrated 4 target nerves for ablative therapy: the suprascapular nerve, axillary nerve, lateral pectoral nerve, and subscapular nerve. Special caution is needed when targeting these nerves in order to avoid motor denervation. This article summarizes the current evidence for radiofrequency ablation as a useful treatment option for chronic shoulder pain as well as the described techniques for performing this promising procedure.

A Novel Approach to New-Onset Hemiplegic Shoulder Pain With Decreased Range of Motion Using Targeted Diagnostic Nerve Blocks: The ViVe Algorithm

Introduction: Hemiplegic shoulder pain (HSP) is the most common pain disorder after stroke with incidence estimates of 30–70% and associated with reductions in function, interference with rehabilitation, and a reduced quality of life. Onset may occur as soon as a week after stroke in 17% of patients. Management of HSP represents a complex treatment pathway with a lack of evidence to support one treatment. The pain has heterogeneous causes. In the acute setting, decreased range of motion in the shoulder can be due to early-onset spasticity, capsular pattern stiffness, glenohumeral pathology, or complex regional pain syndrome (CRPS). As contracture can form in up to 50% of patients after stroke, effective management of the painful shoulder and upper limb with decreased range of motion requires assessment of each possible contributor for effective treatment. The anesthetic diagnostic nerve block (DNB) is known to differentiate spasticity from contracture and other disorders of immobility and can be useful in determining an appropriate treatment pathway.

Objective: To create a diagnostic algorithm to differentiate between the causes of HSP in the stiff, painful shoulder in the subacute setting using diagnostic techniques including the Budapest Criteria for CRPS and DNB for spasticity and pain generators.

Results: Examination of each joint in the upper extremity with HSP may differentiate each diagnosis with the use of an algorithm. Pain and stiffness isolated to the shoulder may be differentiated as primary shoulder pathology; sensory suprascapular DNB or intra-articular/subacromial injection can assist in differentiating adhesive capsulitis, arthritis, or rotator cuff injury. CRPS may affect the shoulder, elbow, wrist, and hand and can be evaluated with the Budapest Criteria. Spasticity can be differentiated with the use of motor DNB. A combination of these disorders may cause HSP, and the proposed treatment algorithm may offer assistance in selecting a systematic treatment pathway.

Endoscopic Neuromodulation of Suprascapular Nerve in Chronic Shoulder Pain: A Case Report

Shoulder pain is very frequent, especially in middle-aged male adults. Its treatment may be very problematic, mainly in patients who cannot rest and stop their work. At present, it is treated with analgesics, physiotherapy, infiltration of corticosteroids, and/or radiofrequency neuromodulation of the suprascapular nerve. This may be effective but not easy to do. Its efficacy is limited in time, especially because the approach to the nerve trunk may be problematic for its anatomical nature. Ultrasonography has helped, but it is not always completely helpful, due to the small dimension and the complexity of the anatomical structure. In this case report, we describe a more helpful approach to the nerve trunk using an endoscopic technique. The results are very promising. However, larger studies would be necessary to make clear its usefulness.

Ultrasound-guided pulsed radiofrequency neuromodulation of the suprascapular nerve in partial rotator cuff tears

Background/Aim

Pulsed radiofrequency (PRF) of the suprascapular nerve has been shown to be effective in the treatment of chronic shoulder pain. Ultrasound (US) guidance has gained popularity in regional blocks recently. This study aims to investigate the efficacy of suprascapular nerve pulsed radiofrequency under the guidance of ultrasonography.

Materials and methods

This retrospective study included patients treated with PRF of the suprascapular nerve with a diagnosis of partial rotator cuff tears. The patients were assessed with a numeric rating scale (NRS), the Shoulder Pain and Disability Index (SPADI), and a Likert patient satisfaction score before the treatment and 3 weeks and 6 months following the treatment.

Results

A total of 31 patients was included in the study. The patients’ mean age was 66.8 ± 13.3 years. The mean scores of the NRS, SPADI, and Likert scale before the procedure (7.32 ± 1.1, 69.0 ± 8.5, 1.6 ± 0.6) and at 3 weeks (2.9 ± 2.1, 32.1 ± 17.20, 4 ± 1.2) and 6 months (3.2 ± 2.6, 33.9 ± 20.8, 3.8 ± 1.2) after the procedure were evaluated. We observed significant improvement in NRS, SPADI, and Likert scores at 3 weeks and 6 months following the treatment (P < 0.001).

Conclusion

The study demonstrated that US-guided suprascapular nerve PRF achieves good pain relief and functional improvement in patients with partial rotator cuff tears for at least 6 months.