Remission of hypersensitivity by simple weight load stimuli in a complex regional pain syndrome mouse model

Painful sensitivity of the hand or foot are the most common and debilitating symptoms of complex regional pain syndrome (CRPS). Physical therapy is standard treatment for CRPS, but evidence supporting its efficacy is minimal and it can be essentially impossible for CRPS patients to actively exercise the painful limb. Using the well-characterized distal tibial fracture CRPS mouse model, we compared the therapeutic effects of several weeks of daily hindlimb loading versus rotarod walking exercise. The effects of loading and exercise were evaluated by weekly testing of hind-paw withdrawal thresholds to von Frey fibers and radiant heat, as well as measurements of paw and ankle edema. At 6 weeks after fracture, the mice were killed and the ipsilateral femur, spinal cord and L4/5 dorsal root ganglia, and hind-paw skin collected for PCR assays and paw skin Immunohistochemistry evaluation. Hindlimb loading reduced hind-paw von Frey allodynia and heat hyperalgesia and edema within a week and these effects persisted for at least a week after discontinuing treatment. These therapeutic effects of loading exceeded the beneficial effects observed with rotarod walking exercise in fracture mice. Levels of nerve growth factor and transient receptor potential vanilloid 1 (TRPV1) immunostaining in the hind-paw skin were increased at 6 weeks after fracture, and both loading and exercise treatment reduced increases. Collectively, these results suggest that loading may be an effective and possibly curative treatment in CRPS patients with sensitivity in the affected limb.

Technical guideline for intra-prepontine cisternal drug delivery via spinal puncture through subarachnoid catheterization

OBJECTIVES

The distribution characteristics of intrathecal drugs and the limitation of current catheterization techniques make traditional intrathecal analgesic treatment nearly useless for refractory craniofacial pain, such as trigemina neuralgia. This technical guideline aims to promote the widespread and standardize the application of intra-prepontine cisternal drug delivery via spinal puncture and catheterization.

METHODS

A modified Delphi approach was used to work for this guideline. On the issues related to the intra-prepontine cisternal targeted drug delivery technique, the working group consulted 10 experts from the field with 3 rounds of email feedback and 3 rounds of conference discussion.

RESULTS

For the efficacy and safety of the intra-prepontine cisternal targeted drug delivery technique, a consensus was formed on 7 topics (with an agreement rate of more than 80%), including the principles of the technique, indications and contraindications, patient preparation, surgical specifications for intra-prepontine cisternal catheter placement, analgesic dosage coordination, analgesic management, and prevention and treatment of complications.

CONCLUSIONS

Utilizing the intra-prepontine cisternal drug infusion system to manage refractory craniofacial pain could provide advantages in terms of minimally invasive, secure, and effective treatment. This application can not only alleviate the suffering of individuals experiencing the prolonged pain but also support the maintenance of quality of life and dignity in their final moments, justifiing its widespread dissemination and standardized adoption in domestic and international professional fields.

Neurostimulation for Chronic Pain: A Systematic Review of High-Quality Randomized Controlled Trials With Long-Term Follow-Up

OBJECTIVE

This study aimed to review the best evidence on the long-term efficacy of neurostimulation for chronic pain.

MATERIALS AND METHODS

We systematically reviewed PubMed, CENTRAL, and WikiStim for studies published between the inception of the data bases and July 21, 2022. Randomized controlled trials (RCTs) with a minimum of one-year follow-up that were of high methodologic quality as ascertained using the Delphi list criteria were included in the evidence synthesis. The primary outcome was long-term reduction in pain intensity, and the secondary outcomes were all other reported outcomes. Level of recommendation was graded from I to III, with level I being the highest level of recommendation.

RESULTS

Of the 7119 records screened, 24 RCTs were included in the evidence synthesis. Therapies with recommendations for their usage include pulsed radiofrequency (PRF) for postherpetic neuralgia, transcutaneous electrical nerve stimulation for trigeminal neuralgia, motor cortex stimulation for neuropathic pain and poststroke pain, deep brain stimulation for cluster headache, sphenopalatine ganglion stimulation for cluster headache, occipital nerve stimulation for migraine, peripheral nerve field stimulation for back pain, and spinal cord stimulation (SCS) for back and leg pain, nonsurgical back pain, persistent spinal pain syndrome, and painful diabetic neuropathy. Closed-loop SCS is recommended over open-loop SCS for back and leg pain. SCS is recommended over PRF for postherpetic neuralgia. Dorsal root ganglion stimulation is recommended over SCS for complex regional pain syndrome.

CONCLUSIONS

Neurostimulation is generally effective in the long term as an adjunctive treatment for chronic pain. Future studies should evaluate whether the multidisciplinary management of the physical perception of pain, affect, and social stressors is superior to their management alone.

Scrambler Therapy for Patients With Complex Regional Pain Syndrome: A Case Series

Complex regional pain syndrome is a chronic debilitating pain disorder that is difficult to manage, in part due to its heterogeneous clinical presentation and lack of clearly defined pathophysiology. Patients usually require a multidisciplinary approach to treatment, which can entail pharmacotherapy, physical therapy, behavioral therapy, and interventional pain procedures, such as sympathetic nerve blocks, spinal cord stimulation, and dorsal root ganglion stimulation. However, many patients continue to experience pain refractory to these multimodal strategies. Scrambler therapy (ST) is a noninvasive method of neuromodulation that is applied through cutaneous electrodes, and can alleviate chronic neuropathic pain by stimulating C-fibers and replacing endogenous pain signals with synthetic non-nociceptive signals. Although the use of ST has been reported for several types of refractory central and peripheral neuropathic pain, there is a paucity of data regarding the use of ST for complex regional pain syndrome. We present two patients with complex regional pain syndrome of the right lower extremity, who each underwent ST and experienced significant pain relief and improvement in function and quality of life.

Dorsal root ganglion stimulation for chemotherapy-induced peripheral neuropathy

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) is a common consequence of cancer treatment that can be persistent and difficult to manage. Dorsal root ganglion stimulation (DRG-S) is a recently introduced but understudied treatment modality. This study explored the effect of DRG-S on pain and symptom burden associated with CIPN.

METHODS

Patients with CIPN who underwent a DRG-S trial between January 2017 and August 2022 were identified through chart review after IRB approval was obtained. Demographic data, procedure details, pre-and postoperative scores, including the Numerical Rating Scale (NRS) and Edmonton Symptom Assessment System (ESAS), and duration of follow-up were recorded. Statistical analysis included descriptive statistics and paired t-tests to compare pre-and postoperative scores.

RESULTS

Nine patients with an even mix of solid and hematologic malignancies underwent DRG-S trial and had a statistically significant decrease in NRS scores, with a mean reduction of 2.3 in their average pain (p = 0.014), 2.6 in worst pain (p = 0.023), and 2.1 in least pain (p = 0.018). Eight patients (88.9%) underwent permanent DRG-S implantation. Mean NRS scores remained lower than preoperative baselines through the first year of follow-up. Statistically significant reductions were noted at 3 months in average (2.1, p = 0.006) and least pain scores (1.9, p = 0.045), which further decreased after 6-12 months (average: 3.6, p = 0.049; least: 3.4, p = 0.023). Only the pain component of ESAS scores showed a significant reduction with DRG-S (2.0, p = 0.021). All patients endorsed improved sensation, 75% decreased their pain medication usage, and 37.5% reported complete pain relief by 2 years.

CONCLUSION

Dorsal root ganglion stimulation can be an effective treatment for pain related to CIPN and deserves further investigation.

Ultrasound-controlled cryoneurolysis for peripheral mononeuropathies: a retrospective cohort study

Aim: Cryoneurolysis is a potential therapy for peripheral mononeuropathies, but randomized studies of its effects on the duration of pain reduction are lacking. Methods: This retrospective cohort study evaluated the analgesic effects of cryoneurolysis on patients with refractory peripheral mononeuropathy. We included 24 patients who underwent ultrasound-guided cryoneurolysis between June 2018 and July 2022. The daily maximum pain level was recorded using a numerical rating scale before and 1, 3 and 6 months after the procedure. Results: At 1 month, 54.2% of patients reported pain reduction of at least 30%. This percentage was significantly lower at 3 and 6 months (13.8 and 9.1%, respectively). Conclusion: Our results suggest that repeated cryoneurolysis may be a viable treatment for refractory mononeuropathy. Further investigations are needed.

A National Survey of Institutional Guidelines for the Use of Ketamine, Lidocaine, and Dexmedetomidine for Refractory Pain

Background: Although opioids are used first line for cancer pain and commonly for complex noncancer pain, there are risks associated with their use and not effective for all types of pain. There's a need to identify and develop clinical practice guidelines for nonopioids for the treatment of refractory pain. Methods: Our study collected information from national clinical practice guidelines for ketamine, lidocaine, and dexmedetomidine with the aim to identify consensus among the different practices. Results: Fifteen institutions nationally participated in the study and only nine of those institutions had guidelines and were permitted by their health system to share them. Of the institutions that participated, 44% had guidelines for ketamine and lidocaine, and only two institutions (22%) had guidelines for ketamine, lidocaine, and dexmedetomidine for refractory pain. There were variations in restriction of the level of care and prescribers, dosing, and determination of efficacy. There were trends of consensus in monitoring for side effects. Conclusion: This study serves as a starting point for a snapshot of the use of ketamine, lidocaine, and dexmedetomidine for refractory pain, but further studies and increased participation of institutions are needed to develop consensus clinical practice guidelines.

Case Series: Synergistic Effect of Gabapentin and Adjuvant Pregabalin in Neuropathic Pain

Gabapentin and pregabalin both exert high affinity to the α2δ subunit of the voltage-gated calcium channels which inhibits excitatory neurotransmitter release. The synergistic mechanism was described in rats given combinations of gabapentin and pregabalin. In this case series, we described 2 cases which may illustrate the synergistic effect of gabapentin and pregabalin in treatment resistant neuropathic pain. Low dose pregabalin was added to therapeutic gabapentin to achieve appreciable pain reduction in one case and improved quality of life in another case. Further research with more enrollment and longer study duration may help elucidate the appropriate dosing and potential associated side effects.

Ultrasound-Guided Percutaneous Cryoneurolysis for Post-Thoracotomy Pain Syndrome: A Case Report

Post-thoracotomy pain syndrome (PTPS) is a post-operative thoracotomy complication that is difficult to treat. We describe the first-time use of ultrasound-guided percutaneous cryoneurolysis of the intercostal nerves to successfully treat PTPS refractory to conventional medications and interventions. We report a case of a 40-year-old male with two years of severe PTPS sustained after undergoing a thoracotomy. Treatment with intercostal cryoneurolysis resulted in an immediate 75% improvement in pain for six weeks followed by sustained 50% pain relief for eight weeks. This highlights the potential of this intervention as a radiation-free, safe, and efficacious therapy for chronic PTPS.

Spinal Cord Stimulator Therapy as a Last Resort Option in Refractory Neuropathic Groin Pain: A Case Report

A spinal cord stimulator (SCS) is an excellent therapeutic strategy for many refractory chronic pain cases. They have a multi-faceted effect in providing relief in such indicated cases that include complex regional pain syndrome (CRPS) or failed back surgery syndrome (FBSS). However, if a patient has chronic intractable neuropathic pain outside the standard indications for SCS, can a case be made for trialing SCS as a last resort option? We describe a case where a patient with neuropathic groin pain, refractory to numerous types of procedures and non-interventional modalities, successfully underwent SCS therapy as a last resort option.

Medial Branch Radiofrequency Treatment for Low-Back Pain in Cancer Patients: A Case Series

Cancer patients are increasing in number, with an increased lifespan and advances in cancer treatment. Palliative care physicians often encounter difficulties in caring for patients with pain. In addition to cancer-related pain, patients with cancer may suffer from various musculoskeletal diseases, resulting in significant functional limitations of physical activities of daily living. We present three cases illustrating methods to deal with nonspecific mechanical low-back pain in patients with advanced cancer. We provide our therapeutic experiences, focusing on the usefulness of radiofrequency treatment in palliative care in patients with cancer.

PALLIATIVE TREATMENT OF INTRACTABLE CANCER PAIN

In 10% to 30% cancer-pain cases standard analgesic therapy fails to provide effective pain relief. Interventional techniques, such as peripheral nerve blocks, neuraxial analgesia along with neurolytic blocks may be used for such refractory pain. Peripheral nerve blocks can be used when pain occurs in the territory of one or more peripheral nerves, but rarely as main therapy. Neuraxial analgesia is a valid option for progressive cancer pain, and healthcare possibilities and costs call into question the utility of intrathecal infusion pumps. Neurolysis is the targeted destruction of a nerve or nerve plexus, using chemicals, radiofrequency ablation (RFA), cryoablation, and neurosurgical procedures; however, it rarely completely eliminates pain because patients frequently experience coexisting somatic and neuropathic pain as well. Complex conditions of palliative patients along with limited high-quality randomized controlled trials limit the use of interventional procedures. Even so, some cancer patients benefit from interventional procedures to achieve pain alleviation and consequently improve quality of life.

Dexmedetomidine Continuous Infusion for Refractory Cancer Pain at End of Life: A Case Report

Refractory cancer-related pain at end-of-life (EoL) is multifaceted and may require utilizing medications with different mechanism of actions beyond opioids. We report the successful use of dexmedetomidine in a 63-year old female with recurrent breast cancer and intractable left arm pain and swelling admitted to University of California, San Diego, Health (UC San Diego Health), palliative care unit. Patient's pain and agitation continued to persist and she declined clinically despite efforts to start methadone, continuous infusion opioids, continuous infusion lidocaine and intravenous chlorpromazine by the palliative care team. On hospital day (HD) 11 patient was started on dexmedetomidine continuous infusion for refractory pain per our protocol at UC San Diego Health. The next day the patient appeared much improved in terms of pain and agitation with grimacing and moaning completely resolved. She was able to have some lucid periods and interacting with her family. With the addition of dexmedetomidine to her pain regiment, the patient was able to peacefully die 5 days later. This case report highlights the clinical utility of demedetomidine in a palliative care unit for refractory pain at EoL.

Rescue therapy with novel waveform spinal cord stimulation for patients with failed back surgery syndrome refractory to conventional stimulation: a systematic review and meta-analysis

OBJECTIVE

Conventional spinal cord stimulators (SCSs) have demonstrated efficacy in individuals with failed back surgery syndrome (FBSS). However, a subgroup of patients may become refractory to the effects of conventional waveforms over time. The objective of this study was to systematically review and evaluate the current literature on the use of novel waveform spinal cord stimulation for the management of FBSS refractory to conventional SCSs.

METHODS

A comprehensive electronic search of the literature published in electronic databases, including Ovid MEDLINE and Epub Ahead of Print, Ovid Cochrane Central Register of Controlled Trials, Ovid Cochrane Database of Systematic Reviews, and Scopus, was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The outcomes of interest were reduction in back pain and/or leg pain after conversion from conventional to novel SCSs. Risk of bias was assessed with the Risk of Bias in Nonrandomized Studies of Interventions (ROBINS-I) tool. The strength of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) criteria.

RESULTS

A total of 6 studies with 137 patients with FBSS were identified. Studies were published between 2013 and 2021. The mean ± SD age of the pooled patient sample was 55 ± 10.5 years. All patients who underwent treatment with conventional SCSs were identified. Two studies evaluated the efficacy of high-density spinal cord stimulation, 3 studies evaluated burst spinal cord stimulation, and 1 study assessed multimodal waveforms. The mean difference in back pain scores after conversion from a standard SCS to a novel waveform SCS was 2.55 (95% CI 1.59-4.08), demonstrating a significant reduction in back pain after conversion to novel stimulation. The authors also performed a subgroup analysis to compare burst stimulation to tonic waveforms. In this analysis, the authors found no significant difference in the average reductions in back pain between the 2 groups (p = 0.534).The authors found an I2 statistic equivalent to 98.47% in the meta-regression model used to assess the effect of follow-up duration on study outcome; this value implied that the variability in the data can be attributed to the remaining between-study heterogeneity. The overall certainty was moderate, with a high risk of bias across studies.

CONCLUSIONS

Rescue therapy with novel waveform spinal cord stimulation is a potential option for pain reduction in patients who become refractory to conventional SCSs. Conversion to novel waveform SCSs may potentially mitigate expenses and complications.

Comparison of Spinal Cord Stimulation vs. Dorsal Root Ganglion Stimulation vs. Association of Both in Patients with Refractory Chronic Back and/or Lower Limb Neuropathic Pain: An International, Prospective, Randomized, Double-Blinded, Crossover Trial (BOOST-DRG Study)

While spinal cord stimulation (SCS) is a well-established therapy to address refractory persistent spinal pain syndrome after spinal surgery (PSPS-T2), its lack of spatial selectivity and reported discomfort due to positional effects can be considered as significant limitations. As alternatives, new waveforms, such as burst stimulation and different spatial neural targets, such as dorsal root ganglion stimulation (DRGS), have shown promising results. Comparisons between DRGS and standard SCS, or their combination, have never been studied on the same patients. "BOOST DRG" is the first prospective, randomized, double-blinded, crossover study to compare SCS vs. DRGS vs. SCS+DRGS. Sixty-six PSPS-T2 patients will be recruited internationally in three centers. Before crossing over, patients will receive each stimulation modality for 1 month, using tonic conventional stimulation. After 3 months, stimulation will consist in switching to burst for 1 month, and patients will choose which modality/waveform they receive and will then be reassessed at 6 and 12 months. In addition to our primary outcome based on pain rating, this study is designed to assess quality of life, functional disability, psychological distress, pain surface coverage, global impression of change, medication quantification, adverse events, brain functional imaging and electroencephalography, with the objective being to provide a multidimensional insight based on composite pain assessment.

Wireless Subcutaneous Trigeminal Nerve Field Stimulation for Refractory Trigeminal Pain: A Single Center Experience

INTRODUCTION

Subcutaneous trigeminal nerve field stimulation (sTNFS) is a neuromodulatory treatment for neuropathic trigeminal pain with the ability to reduce the intensity and frequency of pain attacks. However, hardware issues including lead migration, skin erosion, infection, so-called pocket pain at the site of the implanted neurostimulator are reported. Implantable wireless neurostimulation technology promises not only an even less invasive sTNFS treatment and thinner and more flexible electrodes better suited for facial implants, but also provides further advantages such as lack of an implantable neurostimulator and 3T magnetic resonance imaging compatibility.

MATERIAL AND METHODS

All patients who had received trial stimulation with a partially implantable sTNFS system were analyzed for ICHD-3 (3rd edition of the International Classification of Headache Disorders) diagnosis, success of trial stimulation, pre- and postoperative pain intensity, frequency of attacks, complications, and side-effects of sTNFS.

RESULTS

All patients (N = 3) responded to sTNFS (≥50% pain reduction) during the trial period. According to ICHD-3, N = 2 of the patients were classified with trigeminal neuralgia (TN) with concomitant persistent facial pain and N = 1 patient with multiple sclerosis associated TN. The time of the test period was 44 ± 31.24 days (mean ± SD). The average daily duration of stimulation per patient amounted 2.5 ± 2.2 hours (range 1-5). The pain intensity (defined on a visual analog scale) was reduced by 80% ± 17% (mean ± SD). Reduction or cessation in pain medication was observed in all patients. No surgical complications occurred in the long-term follow-up period of 18.84 ± 6 (mean ± SD) months.

CONCLUSION

The partially implantable sTNFS device seems to be safe, effective, and reliable. Compared to conventional devices, the equipment is not limited to the length of trial stimulation. Furthermore, the daily stimulation duration was much shorter compared to previous reports.

Intravenous Ketorolac Infusion for Intractable Pleuritic Pain Secondary to Metastatic Epithelioid Hemangioendothelioma

Background: Epithelioid hemangioendothelioma (EHE) patients can experience severe pain. Nonsteroidal anti-inflammatory drugs, including ketorolac tromethamine, can effectively treat cancer-related pain, provide an opioid-sparing effect, and may be particularly effective for EHE pain. There are limited data describing prolonged (>5 days) continuous intravenous (IV) ketorolac infusion for cancer-related pain and no data on its use in EHE. Case Description: A 67-year-old woman with metastatic hepatic EHE suffered from chronic intractable pleuritic pain unresponsive to trials of nonopioid, opioid, adjuvant medications, and nonpharmacological interventions. In the hospital, continuous IV ketorolac infusion at 3.8 mg/hour (91.2 mg/day) effectively managed pain. With thorough monitoring, the patient was discharged on continuous IV ketorolac infusion at 3 mg/hour (72 mg/day). Infusion continued for 79 days without clinical or laboratory evidence of ketorolac toxicity. Conclusion: Ketorolac tromethamine as a long-term infusion is a potentially viable analgesic for patients with intractable EHE-related pain unresponsive to standard therapies.

The journeys of patients with trigeminal neuralgia on a background of multiple sclerosis

Aim: Multiple sclerosis (MS) is well recognized as a secondary cause for trigeminal neuralgia (TN). In this case series, we detail the management of all the patients with TN and MS (pwTNMS) presenting to a specialist unit. Materials & methods: A prospective patient database was used to extract key clinical data on pharmacological, psychometric and surgical management of 20 pwTNMS. Results: 65% of pwTNMS underwent surgical interventions for management of their pain.12/20 achieved remission periods, through surgery and/or medication. Significant improvement was noted on the global impression of change illustrated by a p < 0.001. Conclusion: pwTNMS require a multifaceted approach combining polypharmacy, surgical interventions and psychological support. Developing self-management skills is crucial if patients are to live well with pain.

The current clinical use of adjuvant analgesics for refractory cancer pain in Japan: a nationwide cross-sectional survey

BACKGROUND

Although adjuvant analgesics are used to treat opioid-refractory cancer pain, there is insufficient evidence to support this practice and limited data to guide the choice depending on cancer pain pathophysiology, dose titration and starting dose. This survey aimed to clarify the current use of adjuvant analgesics for treating opioid-refractory cancer pain.

METHODS

In this cross-sectional study, we sent an online survey questionnaire to 208 certified palliative care specialists. Primary outcomes were (i) effective pathophysiological mechanism of cancer pain and (ii) initiating doses and time period to the first response to each adjuvant analgesic therapy.

RESULTS

In total, 87 (42%) palliative care specialists responded. Of all patients with cancer pain, 40% of patients (median) with refractory cancer pain were prescribed adjuvant analgesics. Additionally, 94.3, 93.1 and 86.2% of palliative care specialists found dexamethasone/betamethasone effective for neuropathic pain caused by tumor-related spinal cord compression, pregabalin effective for malignant painful radiculopathy and dexamethasone/betamethasone effective for brain tumor or leptomeningeal metastases-related headache, respectively. The median starting dose of pregabalin, dexamethasone/betamethasone, lidocaine and ketamine were 75, 4, 200, and 50 mg/day, respectively, and the median time to the first response of those medications were 5, 3, 2 and 3 days, respectively.

CONCLUSIONS

Many palliative care specialists select adjuvant analgesics depending on the pathophysiological mechanism of cancer pain in each case. They used such adjuvant analgesics in low doses for cancer pain with short first-response periods.

[Radiosurgical hypophysectomy in cancer pain treatment. Literature review and clinical case]

Cancer pain is one of the main problem in modern medicine. According European Society for Medical Oncology data, cancer pain prevalence is 64% among patient with terminal stage of disease and in 46% standard pain therapy was ineffective. Radiosurgical hypophysectomy is one of the important and perspective method in cancer pain treatment. This method could be offered patient with chronic disease. According literature review, endocrinology complications were very rare and occurred 10 months after therapy. Value of analgesic effect was 70-90%. In some trials, procedure was effective not only nociceptive, but also in neuropathic pain. More trials require for determination of indications and mechanism of action. The case of successful relief of resistant pain in patient with pancreatic cancer by means of radiosurgical hypophysectomy is described.

Clinical effectiveness of caudal epidural pulsed radiofrequency stimulation in managing refractory chronic leg pain in patients with postlumbar surgery syndrome

BACKGROUND AND OBJECTIVE

We evaluated the effect of caudal epidural pulsed radiofrequency stimulation in patients with chronic lumbosacral radicular pain due to postlumbar surgery syndrome who were unresponsive to at least two epidural steroid injections through the interlaminar, transforaminal, or caudal route.

METHODS

We recruited 25 patients with chronic persistent radicular pain in one or both legs (⩾ 4 on the Numeric Rating Scale [NRS]) despite spinal surgery. They were unresponsive to at least two epidural steroid injections. We retrospectively conducted this study. Electrode needles were placed into the epidural space (S2-3 intervertebral level) through the sacral hiatus, and pulsed radiofrequency stimulation was administered. The outcomes were evaluated using the NRS scores for radicular pain before treatment and 1-3 months after treatment. Successful pain relief was defined as a ⩾ 50% reduction in the scores at 3 months after treatment.

RESULTS

The pain scores changed significantly over time (p< 0.001): pretreatment, 4.9 ± 0.9; 1 month, 3.6 ± 1.4; 2 months, 3.8 ± 1.4; and 3 months, 3.9 ± 1.4. At 1, 2, and 3 months after pulsed radiofrequency (PRF) procedure, the NRS scores were significantly reduced compared with the scores before the treatment. Eight patients (32%) reported successful pain relief at 3 months after treatment.

CONCLUSIONS

Although only 32% of the patients with postlumbar surgery syndrome showed successful pain relief after treatment, the result is encouraging because we recruited only patients unresponsive to repeated epidural steroid injections.

Management of refractory chronic migraine using ultrasound-guided pulsed radiofrequency of greater occipital nerve: Two case reports

RATIONALE

Although various oral medications and procedures are applied for managing migraine, their efficacy remains limited. To control migraine that does not respond to conventional treatments, we conducted pulsed radiofrequency (PRF) stimulation to the greater occipital nerve (GON) in 2 patients.

PATIENT CONCERNS

Patients 1 and 2 complained of chronic throbbing, pulsating, and tight headaches. Their headache intensities scored 8 and 7 on a numeric rating scale (NRS), respectively. Patient 1 experienced the headache bilaterally in the frontal, retro-orbital, parietal, and occipital regions. The initial onset of the symptoms was more than 15 years ago. Patient 2 complained of headaches in the left frontal, retro-orbital, parietal, and occipital regions, which occurred first more than 14 years ago.

DIAGNOSES

According to the International Classification of Headache Disorder-3 beta criteria, the patients were diagnosed with chronic migraine.

INTERVENTIONS

Oral medications, GON block with bupivacaine and dexamethasone, and botulinum toxin injections did not alleviate the patients' migraine.The PRF stimulation on GON was performed under the guidance of ultrasound, at 5 Hz and 5-millisecond pulsed width for 360 seconds at 45 V. The electrode tip temperature was maintained at or below 42°C.

OUTCOMES

Two weeks after applying PRF, the pain was reduced to NRS 3 in both patients, who also reported that the headache became bearable after PRF. The effectiveness of PRF on GON lasted for at least 3 months in both patients, and no adverse effects were observed.

LESSONS

Our findings suggested that the application of PRF on GON can be a useful option for treating refractory chronic migraine.

Cannabinoids and spinal cord stimulation for the treatment of failed back surgery syndrome refractory pain

Objective

This study aimed to evaluate pain and its symptoms in patients with failed back surgery syndrome (FBSS) refractory to other therapies, treated with a combination of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), in association with spinal cord stimulation (SCS).

Settings

Outpatients referred at Pain Unit of San Vincenzo Hospital in Taormina (Italy), between September 2014 and January 2016.

Subjects

Eleven FBSS patients diagnosed with neuropathic pain using the Douleur Neuropathique 4 questionnaire and suffering from moderate to severe chronic refractory pain, and undergoing treatment with SCS and a combination of THC/CBD for 12 consecutive months.

Materials and methods

All the included patients discontinued previous unsuccessful therapy at least 2 months before the beginning of the cannabinoid therapy, with the exception of the SCS that was continued. Patients received a fixed dosage of cannabinoid agonists (THC/CBD) that could be increased subjective to pain control response. A Brief Pain Inventory questionnaire was administered to measure pain and its interference with characteristic dimensions of feelings and functions. The duration of treatment with SCS and THC/CBD combination was 12 months.

Results

Effective pain management as compared to baseline result was achieved in all the cases studied. The positive effect of cannabinoid agonists on refractory pain was maintained during the entire duration of treatment with minimal dosage titration. Pain perception, evaluated through numeric rating scale, decreased from a baseline mean value of 8.18±1.07–4.72±0.9 by the end of the study duration (12 months) (P<0.001).

Conclusion

The results indicate that cannabinoid agonists (THC/CBD) can have remarkable analgesic capabilities, as adjuvant of SCS, for the treatment of chronic refractory pain of FBSS patients.

Low-Dose Ketamine Infusion for Adjunct Management during Vaso-occlusive Episodes in Adults with Sickle Cell Disease: A Case Series

The optimal management of recurrent painful episodes in individuals living with sickle cell disease (SCD) remains unclear. Currently, the primary treatment for these episodes remains supportive, using fluids and intravenous opioid and anti-inflammatory medications. Few reports have described the use of adjunct subanesthetic doses of ketamine to opioids for treatment of refractory pain in SCD. This article reports a retrospective case series of five patients admitted to the intensive care unit (ICU) with prolonged vaso-occlusive episodes (VOEs). Patients were treated with a continuous-infusion of low-dose ketamine (up to 5 µg/kg/min) after insufficient pain control with opioid analgesic therapy. Outcomes studied included impact on opioid analgesic use, a description of ketamine dosing strategy, and an analysis of adverse events due to opioid or ketamine analgesia. Descriptive statistics are provided. During ketamine infusion, patients experienced a lower reported pain score (mean numeric rating scale [NRS] score 7.2 vs. 6.4), reduced opioid-induced adverse effects, and decreased opioid dosing requirements (median reduction of 90 mg morphine equivalents per patient). The average duration of severe pain during admission prior to ketamine therapy was 8 days. Only one of five patients reported an adverse effect (vivid dreams) secondary to ketamine infusion. The Richmond Agitation Sedation Scale (RASS) was assessed throughout therapy, with only one patient experiencing light drowsiness. Low-dose ketamine infusion may be considered as an adjunct analgesic agent in patients with vaso-occlusive episodes who report continued severe pain despite high-dose opioid therapy, particularly those experiencing opioid-induced adverse effects.

Palliative analgesia with topical sevoflurane in cancer-related skin ulcers: a case report

A Caucasian 39-year-old male patient with a poorly-differentiated infiltrating epidermoid penile carcinoma with urethral invasion was diagnosed. The patient received concomitant adjuvant chemotherapy with radiotherapy in the palliative setting, which produced painful ulceration of tumour lesions at loco-regional level (Numerical Rate Scale, NRS=9). The patient consented for treatment with direct topical sevoflurane instillations, at initial doses of 1 mL/cm² of ulcerated area, as per unit protocol. The local use of undiluted sevoflurane achieved a marked reduction of the pain score in both nociceptive and irruptive pains (average NRS=3 immediately post-application). This improvement was corroborated by a decline in total morphine needs, any adverse events associated with major opiates. PGI-I and CGI-I scales were used before and after treatment with topical sevoflurane to assess patient and clinician perceptions of improvement in the quality of life. The pharmacy of our hospital had the responsibility to elaborate pre-loaded syringes with sevoflurane so that the patient was instilled simply and comfortably.

Successful Control of Pain from Malignant Psoas Syndrome by Spinal Opioid with Local Anesthetic Agents

BACKGROUND

Malignant psoas syndrome (MPS) is a rare but distressing pain syndrome observed in advanced cancer patients. Pain due to MPS is often refractory to multimodal analgesic treatment, including opioid analgesics. As only 1 case demonstrating the efficacy of neuraxial analgesia in managing pain due to MPS has been reported, its role in MPS remains uncertain.

CASES

We present 3 cases demonstrating the successful management of pain due to MPS using spinal opioids with local anesthetic agents. All patients were under the care of the palliative care consultation service in an acute care hospital and refractory to multimodal analgesic treatment, including opioid, non-opioid, and adjuvant analgesics. Switching opioid administration to the epidural or intrathecal route with a local anesthetic agent provided good pain control in all 3 patients. Moreover, all patients showed improvements in both Palliative Performance Scale and Functional Independence Measure scores after starting a spinal opioid with a local anesthetic agent.

CONCLUSIONS

The findings in the present cases indicate neuraxial analgesia may be of benefit, in terms of managing pain and improving functional status, in MPS patients with insufficient pain control by multimodal analgesic treatment. Physicians should consider the use of neuraxial analgesia in cases of MPS where pain is uncontrolled with multimodal analgesic treatment to provide the best possible quality of life for patients with MPS.

The effect of intra-articular stimulation by pulsed radiofrequency on chronic sacroiliac joint pain refractory to intra-articular corticosteroid injection: A retrospective study

We investigated the degree of pain reduction following intra-articular (IA) pulsed radiofrequency (PRF) stimulation of the sacroiliac joint (SIJ) in patients with chronic SIJ pain that had not responded to IA corticosteroid injection. Twenty patients were recruited. Clinical outcomes after applying PRF stimulation of the SIJ were evaluated by a numeric rating scale (NRS) and a 7-point Likert scale. The NRS scores significantly changed over time. The NRS scores at 1, 2, and 3 months after PRF were significantly lower than those before PRF. However, 4 of the 20 patients (20%) reported successful pain relief (pain relief of ≥ 50%) and were satisfied with the PRF stimulation at 3 months after treatment. IA PRF stimulation of the SIJ was not successful in most patients (80% of all patients). Based on our results, we cannot recommend this procedure to patients with chronic SIJ pain that was unresponsive to IA SIJ corticosteroid injection. Further studies on the effective mode of PRF stimulation and appropriate patient group, and studies on pain conditions that are most responsive to PRF are needed in the future.

Effect of bipolar pulsed radiofrequency on refractory chronic cervical radicular pain: A report of two cases

RATIONALE

Despite undergoing transforaminal epidural steroid injection (TFESI), many patients complain of persisting cervical radicular pain. For the management of chronic cervical radicular pain, clinicians are widely applying pulsed radiofrequency (PRF) stimulation to dorsal root ganglions (DRGs). To enhance the effect of PRF stimulation, we conducted bipolar PRF stimulation in 2 patients with chronic cervical radicular pain that was refractory to monopolar PRF and repeated TFESIs.

PATIENT CONCERNS

Patients 1 and 2 presented with a numeric rating scale (NRS) score of 7 and 6 for chronic cervical radicular pain, respectively, despite undergoing monopolar PRF and 2 TFESIs.

DIAGNOSES

On cervical magnetic resonance imaging, foraminal stenosis at the right C6-7 and right central to right foraminal disc protrusion on C6-7 were observed in patients 1 and 2, respectively. Two patients showed a positive response on diagnostic right C7 selective nerve root block with 0.5 mL of 1% lidocaine.

INTERVENTIONS

Bipolar PRF stimulation was performed under C-arm fluoroscopy. Two parallel RF cannulas (less than 1 cm apart) were used for DRG stimulation. The PRF treatment was administered at 5 Hz and a 5-ms pulsed width for 360 seconds at 45 V with the constraint that the electrode tip temperature did not exceed 42°C.

OUTCOMES

At the 2-week and 1-month follow-up, after undergoing bipolar PRF, the pain of patient 1 was completely relieved, and at 2, 3, and 6 months, the pain was scored as NRS 2. In patient 2, at the 2-week follow-up after undergoing bipolar PRF, pain severity was reduced from NRS 6 to 2. The effect of bipolar PRF on patient 2 lasted for at least 6 months. No adverse effects were observed in either patient.

LESSONS

Application of bipolar PRF to DRGs seems to be an effective and safe technique for treating refractory chronic cervical radicular pain.

Application of radiofrequency thermocoagulation combined with adriamycin injection in dorsal root ganglia for controlling refractory pain induced by rib metastasis of lung cancer (a STROBE-compliant article)

This study aimed to observe the therapeutic effects and adverse reactions of radiofrequency thermocoagulation combined with adriamycin injection in dorsal root ganglia on lung cancer rib metastasis-related refractory pain which has no response to conventional therapy.This study contained 27 patients with lung cancer rib metastasis-related moderate or severe pain which had no response to conventional therapy. Under computed tomography (CT)-guidance, radiofrequency puncture need reached the corresponding intervertebral foramens to ensure needle point near dorsal root ganglia (DRG) by sensory and motor stimulation tests, and then radiofrequency thermocoagulation was performed on each corresponding DRG followed by injection of 0.5 to 1 mL of adriamycin (0.5%). The conditions of pain and complications were observed before management and 3 days, 1 month, and 3 months after management, respectively.Numerical rating scale (NRS) scores and dosage of morphine were all significantly decreased after management as compared with those before management (all P < 0.01). Although the number of patients with chest wall numbness was significantly increased after management as compared with that before management (all P < 0.01), the degree of chest wall numbness was tolerable. There were no statistical differences between before and after management in nausea and vomiting, and constipation.CT-guided radiofrequency thermocoagulation combined with adriamycin injection in DRG can effectively control lung cancer rib metastasis-related pain which has no response to conventional therapy. This combinatory treatment regimen is featured by better therapeutic effects and a few complications, so it is worthy of being recommended in clinical application.

Features and Role of Minimally Invasive Palliative Procedures for Pain Management in Malignant Pelvic Diseases: A Review

Pain is a common and debilitating symptom in pelvic cancer diseases. Failure in controlling this pain through pharmacological approaches calls for employing multimodal management and invasive techniques. Various strategies are commonly used for this purpose, including palliative radiotherapy, epidural medications and intrathecal administration of analgesic and local anesthetic drugs with pumps, and neural or plexus blockade. This review focuses on the features of minimally invasive palliative procedures (MIPPs), such as radiofrequency ablation, laser-induced thermotherapy, cryoablation, irreversible electroporation, electrochemotherapy, microwave ablation, and cementoplasty as well as their role in palliation of cancer pelvic pain. Despite the evidence of effectiveness and safety of these interventions, there are still many barriers to accessing MIPPs, including the availability of trained staff, the lack of precise criteria of indication, and the high costs.

Clinical Uses of Intrathecal Therapy and Its Placement in the Pain Care Algorithm

Intrathecal drug delivery is an effective treatment option for patients with severe chronic pain who have not obtained adequate analgesia from more conservative therapies (eg, physical therapy, systemic opioids, nonsteroidal anti-inflammatory drugs, antidepressants, and anticonvulsants). This review focuses on, but is not limited to, the 2 agents currently approved by the U.S. Food and Drug Administration for intrathecal analgesia: preservative-free morphine and ziconotide (a nonopioid, selective N-type calcium channel blocker). We describe the appropriate use of intrathecal therapy in the management of severe chronic pain, based on current best practices. Topics addressed here include patient selection, trialing, dosing and titration, adverse event profiles, long-term management, intrathecal therapy for cancer-related pain, and the placement of intrathecal therapy in the pain care algorithm. In appropriately selected patients with chronic pain, intrathecal therapy can provide substantial pain relief with improved functioning and quality of life. Successful long-term management requires ongoing patient monitoring for changes in efficacy and the occurrence of adverse events, with subsequent changes in intrathecal dosing and titration, the addition of adjuvant intrathecal agents, and the use of concomitant oral medications to address side effects, as needed. Based on an infrequent but clinically concerning risk of overdose, granuloma, and other opioid-induced complications, nonopioid therapy with ziconotide may be preferred as a first-line intrathecal therapy in patients without a history of psychosis or allergy.

Efficacy, Safety, and Predictors of Intradiscal Methylene Blue Injection for Discogenic Low Back Pain: Results of a Multicenter Prospective Clinical Series

STUDY DESIGN

Prospective clinical study of intradiscal methylene blue injection for the treatment of lumbar discogenic pain.

OBJECTIVE

The objective of this study was to collect information about efficacy, safety, and acceptability of the intervention, gain and burden of outcome measures, and sample size assumptions for a potential following randomized controlled trial (RCT). If the pilot study demonstrates that this treatment is potentially effective and safe, and the methods and procedures used in this study are feasible, a RCT follows.

SUMMARY OF BACKGROUND DATA

Low back pain (LBP) is a highly common problem with a lifetime prevalence of more than 70%. A substantial part of chronic LBP is attributable to degenerative changes in the intervertebral disc. A recently published RCT assessing the treatment intradiscal injection of methylene blue for chronic discogenic LBP, showed exceptionally good results.

METHODS

Patients were selected on clinical criteria, magnetic resonance imaging, and a positive provocative discogram. The primary outcome measure was mean pain reduction at 6 months.

RESULTS

Fifteen consecutive patients with chronic lumbar discogenic pain enrolled in a multicenter prospective case series in two interventional pain treatment centers in the Netherlands. Six months after the intervention, 40% of the patients claimed at least 30% pain relief. In patients who responded, physical function improved and medication use diminished. We observed no procedural complications or adverse events. Predictors for success were Pfirrmann grading of 2 or less and higher quality of life mental component scores.

CONCLUSIONS

Our findings of 40% positive respondents, and no complications, give reason to set up a randomized, double-blind, placebo-controlled, trial.

Cervical epidural steroid injection for refractory somatic tinnitus

Somatic tinnitus is a common disorder, yet few treatments described in the literature have demonstrated strong efficacy. We report a case of a 61-year-old male with refractory somatic tinnitus, temporally related to a prior bacterial otitis media, wherein auditory symptoms were successfully treated with cervical epidural injections of long-acting corticosteroid. We discuss the proposed mechanism of somatic tinnitus and the means by which neuraxial steroids may inhibit somatic tinnitus symptoms.

A trial of Scrambler therapy in the treatment of cancer pain syndromes and chronic chemotherapy-induced peripheral neuropathy

Neuropathic pain is common among cancer patients and often difficult to treat. This study used Scrambler therapy, a patient-specific electrocutaneous nerve stimulation device, to treat cancer patients with pain. Patients received Scrambler therapy for 10 sessions (one daily) over a two-week period. The primary outcome was changed in pain numerical rating scale (NRS) at one month; secondary outcomes were changes in the Brief Pain Inventory and European Organization for Treatment and Cancer QLC-CIPN-20(EORTC CIPN-20), over time. Thirty-nine patients, mean age 56.5 yr, 16 men and 23 women, were treated over an 18-month period for an average of 9.3 days each. The "now" pain scores reduced from 6.6 before treatment to 4.5 at 14 days, 4.6, 4.8, and 4.6 at 1, 2, and 3 months, respectively (p < 0.001). Clinically important and statistically significant improvements were seen in average, least, and worst pain; BPI interference with life scores, and motor and sensory scales on the EORTC CIPN-20. No adverse effects were observed. In this single arm trial, Scrambler therapy appeared to relieve cancer-associated chronic neuropathic pain both acutely and chronically, and provided sustained improvements in many indicators of quality of life.

Pain

Invasive stimulation of the motor (precentral) cortex using surgically implanted epidural electrodes is indicated for the treatment of neuropathic pain that is refractory to medical treatment. Controlled trials have demonstrated the efficacy of epidural motor cortex stimulation (MCS), but MCS outcome remains variable and validated criteria for selecting good candidates for implantation are lacking. Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive approach that could be used as a preoperative tool to predict MCS outcome and also could serve as a therapeutic procedure in itself to treat pain disorders. This requires repeated rTMS sessions and a maintenance protocol. Other studies have also demonstrated the efficacy of transcranial direct current stimulation (tDCS) in relieving chronic pain syndromes. The most studied target is the precentral cortex, but other targets, such as the prefrontal and parietal cortices, could be of interest. The analgesic effects of cortical stimulation relate to the activation of various circuits modulating neural activities in remote structures, such as the thalamus, limbic cortex, insula, or descending inhibitory controls. In addition to the treatment of refractory neuropathic pain by epidural MCS, new developments of this type of strategy are ongoing, for other types of pain syndrome and stimulation techniques.

Intracerebroventricular opioids for intractable pain

When pain is refractory to systemic opioid and non-opioid analgesic therapy and palliative chemoradiation or ablative or stimulant neurosurgical procedures are not possible, palliative treatment becomes limited, particularly if the patient wishes to be at home at the end of life. Intracerebroventricular (ICV) infusion of morphine in the home setting might be presented as an option. The present article reviews the basic and clinical evidence of the efficacy and safety of ICV administration of opioids. Information was gathered from various bibliographic sources, including PubMed and others, and summarized and evaluated to assess the efficacy and safety of ICV opioids for pain relief. Results from ICV infusion of morphine into terminally ill patients refractory to other pain treatments have been reported since the early 1980s. Good efficacy has been achieved for the vast majority of patients, without serious development of analgesic tolerance. There have also been a low incidence of adverse effects, such as constipation and respiratory depression, and a significant retention of alertness associated with this route of administration. Intracerebroventricular infusion of opioid analgesics thus appears to be a safe and effective therapy for the palliative treatment of refractory pain.