Visually evoked pain and its extinction using virtual reality in a patient with complex regional pain syndrome type II.

ABSTRACT: In this case report, we used virtual reality (VR) to explore pain evoked by only the appearance of being touched (rather than actually being touched) in a person with complex regional pain syndrome type II. Furthermore, we explored the degree to which this visually evoked pain could be extinguished by applying exposure principles in VR. In stage 1, we identified 4 specific scenarios where pain was triggered by visually simulated touch (without physical stimulation) and used these scenarios to quantify baseline sensitivity to visuotactile stimulation. In stage 2, the patient undertook a 12-week virtual exposure program, and the visual triggers were reassessed 3 weeks after the commencement and immediately upon completion of the program. At baseline, severe pain and a profound cold sensation were immediately and consistently evoked in concert with visually simulated touch. At 12-week follow-up, only one of the initially provocative visual stimuli triggered pain and only after 60 seconds of repeated stimulation. Unfortunately, the transfer of desensitisation from VR to the real world was limited. This case report describes the phenomena of visually evoked pain. Moreover, it describes the near complete extinguishing of visually evoked pain through virtual graded exposure. How improvements gained in VR might be better transferred to real-word improvements merits further investigation.

DREZotomy in the treatment of deafferentation pain: review of results and analysis of predictive factors for success. / Drezotomía en el tratamiento del dolor por desaferentización: revisión de resultados y análisis de factores predictores de éxito.

BACKGROUND AND OBJECTIVES: The treatment of deafferentation pain by spinal DREZotomy is a proven therapeutic option in the literature. In recent years, use of DREZotomy has been relegated to second place due to the emergence of neuromodulation therapies. The objectives of this study are to demonstrate that DREZotomy continues to be an effective and safe treatment and to analyse predictive factors for success. PATIENTS AND METHODS: A retrospective study was conducted of all patients treated in our department with spinal DREZotomy from 1998 to 2018. Bulbar DREZotomy procedures were excluded. A visual analogue scale (VAS) and the reduction of routine medication were used as outcome variables. Demographic, clinical and operative variables were analysed as predictive factors for success. RESULTS: A total of 27 patients (51.9% female) with a mean age of 53.7 years underwent DREZotomy. The main cause of pain was brachial plexus injury (BPI) (55.6%) followed by neoplasms (18.5%). The mean time of pain evolution was 8.4 years with a mean intensity of 8.7 according to the VAS, even though 63% of the patients had previously received neurostimulation therapy. Favourable outcome (≥50% pain reduction in the VAS) was observed in 77.8% of patients during the postoperative period and remained in 59.3% of patients after 22 months average follow-up (mean reduction of 4.9 points). This allowed for a reduction in routine analgesic treatment in 70.4% of them. DREZotomy in BPI-related pain presented a significantly higher success rate (93%) than the other pathologies (41.7%) (p=.001). No association was observed between outcome and age, gender, DREZ technique, duration of pain or previous neurostimulation therapies. There were six neurological complications, four post-operative transient neurological deficits and two permanent deficits. CONCLUSION: Dorsal root entry zone surgery is effective and safe for treating patients with deafferentation pain, especially after brachial plexus injury. It can be considered an alternative treatment after failed neurostimulation techniques for pain control. However, its indication should be considered as the first therapeutic option after medical therapy failure due to its good long-term results.

Therapy Habituation at 12 Months: Spinal Cord Stimulation Versus Dorsal Root Ganglion Stimulation for Complex Regional Pain Syndrome Type I and II.

The ACCURATE randomized, controlled trial compared outcomes of dorsal root ganglion (DRG) stimulation versus tonic spinal cord stimulation (SCS) in 152 subjects with chronic lower extremity pain due to complex regional pain syndrome (CRPS) type I or II. This ACCURATE substudy was designed to evaluate whether therapy habituation occurs with DRG stimulation as compared to SCS through 12-months. A modified intention-to-treat analysis was performed to assess percentage pain relief (PPR) and responder rates at follow-up visits (end-of-trial, 1, 3, 6, 9, 12-months postpermanent implant) for all subjects that completed trial stimulation (DRG:N = 73, SCS:N = 72). For both groups, mean PPR was significantly greater at end-of-trial (DRG = 82.2%, SCS =0 77.0%) than all other follow-ups. Following permanent DRG system implantation, none of the time points were significantly different from one another in PPR (range = 69.3-73.9%). For the SCS group, PPR at 9-months (58.3%) and 12-months (57.9%) was significantly less than at 1-month (66.9%). The responder rate also decreased for the SCS group from 1-month (68.1%) to 12-months (61.1%). After stratifying by diagnosis, it was found that only the CRPS-I population had diminishing pain relief with SCS. DRG stimulation resulted in more stable pain relief through 12-months, while tonic SCS demonstrated therapy habituation at 9- and 12-months. Trial Registration: The ACCURATE study was registered at ClinicalTrials.gov with Identifier NCT01923285. PERSPECTIVE: This article reports on an ACCURATE substudy, which found that long-term therapy habituation occurred at 12-months with SCS, but not DRG stimulation, in patients with CRPS. The underlying mechanisms of action for these results remain unclear, although several lines of inquiry are proposed.

Terapia de oxigenación hiperbárica en el tratamiento del dolor / Hyperbaric oxygenation therapy in pain treatment

El dolor crónico constituye un reto terapéutico especial. Se presenta una revisión narrativa sobre el papel del tratamiento de oxigenación hiperbárica (TOHB) en el tratamiento del dolor neuropático, y sus aplicaciones en dolor crónico, síndromes neurosensitivos disfuncionales y oncodolor. El conocimiento de las indicaciones de TOHB en algiología y su aplicación en la práctica médica puede contribuir a mejorar la calidad de vida del paciente. (AU)

Chronic pain represents a special therapeutic challenge. We present a narrative review on the role of Hyperbaric Oxygen Therapy (HBOT) in the treatment of neuropathic pain, and its applications in chronic pain, dysfunctional neurosensitive syndromes and oncological pain. The knowledge of the indications of HBOT in algiology and its application in medical practice can contribute to improve the quality of life of the patient. (AU)

Neuromodulation of the Dorsal Root Ganglion for Chronic Postsurgical Pain.

OBJECTIVE: The objective of this study is to review the available evidence for dorsal root ganglion (DRG) stimulation for the treatment of complex regional pain syndrome type II (CRPS II; peripheral causalgia) associated with chronic neuropathic postsurgical pain (NPP). DESIGN: Available literature was identified through a search of the US National Library of Medicine's Medline database, PubMed.gov. References from published articles also were reviewed for relevant citations. RESULTS: The data published to date support the use of DRG stimulation to treat chronic NPP of the groin, knee, and foot. NPP following procedures such as thoracotomy, hernia surgery, and knee replacement surgery were identified as some of the conditions for which DRG stimulation is likely to be effective. CONCLUSION: DRG stimulation is known to be an effective treatment for focal neuropathic pain. Currently, NPP of the foot, groin, and knee all appear to be the conditions with the most clinical experience, backed by a limited but growing body of evidence. However, prospective studies lag behind real-world clinical experience and are needed to confirm these findings.

Risk Factors Associated with Lead Migration Requiring Revision in Dorsal Root Ganglion Stimulation.

BACKGROUND: Neuromodulation is an evolving therapy for chronic pain. Aiming to meet the limitations of traditional spinal cord stimulation, dorsal root ganglion (DRG) stimulation targets pain in a dermatomal distribution at the site of pain transmission. Despite these advantages, lead migration is a significant complication that hinders the long-term efficacy of DRG stimulation. This study aims to identify risk factors for lead migration requiring revision in DRG stimulation. METHODS: We performed a retrospective review of all subjects who had DRG stimulators implanted at T10-S2 by a single physician over a 2-year period. Their history was reviewed for the following: age, sex, diagnosis, lead placement, reported symptom relief, complications, and postoperative activity. RESULTS: In total, 19 cases of DRG stimulator implantation were identified. All patients reported pain relief, with 84.2% (16/19) describing >50% relief. In total, 31.6% of patients (6/19) developed lead migration and 15.8% of total implanted leads (9/57) migrated. Of the migrated leads, 4% (4/9) occurred at S1 and 33.3% (3/9) occurred at L4. The underlying etiology of lead migration was clear and preventable in 66.7% of patients (4/6). All patients who developed lead migration were women. CONCLUSIONS: Premature activity, hardware manipulation, and female sex appear to be associated with an increased risk for lead migration. Leads on the S1 and L4 locations may be more likely to migrate. Large trials are necessary to gain a more conclusive understanding of these risk factors for lead migration.

Dorsal Root Ganglion Stimulation Is Paresthesia-Independent: A Retrospective Study.

INTRODUCTION: Neuromodulation is an important tool for achieving pain relief in otherwise-intractable neuropathic pain conditions. Dorsal root ganglion (DRG) stimulation, in which primary sensory neurons are stimulated prior to their entry into the spinal canal, provides treatment with high levels of dermatomal specificity and can provide advantages compared to conventional spinal cord stimulation. Although DRG stimulation can produce perceptible paresthesias, many patients operate their systems at subthreshold amplitudes that do not elicit this sensation. Pain relief both with and without paresthesia was investigated in this retrospective analysis. MATERIALS AND METHODS: A retrospective review of all qualifying permanent DRG stimulation systems at a single center over more than a three-year period was completed. Pain (0-10 numeric rating scale) was assessed at baseline, at the end of the trial, and after three, six, and twelve months of treatment. Patients were categorized based on their usage of the stimulator at amplitudes that either did or did not produce paresthesias. RESULTS: Of the 39 patients, 34 (87%) reported having no-paresthesias at any of the follow-up visits. Average pain relief was 73.9% after the trial period and 63.1% after 12 months of treatment. The responder rate (50% or better pain relief) after three months of treatment was more than 80%. Exploratory subgroup analyses showed that similar degrees of pain relief were achieved in numerous body regions and with various pain etiologies. The five patients who reported paresthesias during treatment had pain relief similar to those of the group that did not experience paresthesias. DISCUSSION: Clinically significant and sustained pain relief over more than a period of 12 months was achieved with DRG stimulation programmed at amplitudes below the perceptual level. Thus, the reported analgesia was paresthesia-independent. That good clinical outcomes were observed independent of the generation of paresthesia in DRG stimulation suggests several mechanisms of action, including the inhibition of supraspinal regions involved in somatic paresthesia sensation. The retrospective results presented here posit that future prospective study of DRG stimulation delivered at below the threshold of perceptible paresthesias is warranted.

Comparison of Paresthesia Coverage of Patient's Pain: Dorsal Root Ganglion vs. Spinal Cord Stimulation. An ACCURATE Study Sub-Analysis.

OBJECTIVES: This was a sub-analysis of the ACCURATE clinical trial that evaluated the accuracy and necessity of targeting paresthesia coverage of painful areas with dorsal root ganglion (DRG) stimulation vs. tonic spinal cord stimulation (SCS). MATERIALS AND METHODS: On diagrams of the torso and lower limbs, subjects marked where they felt pain at baseline and paresthesias at three months postimplant. Seventy-five subjects (41 DRG and 34 SCS) with diagrams of sufficient quality were scanned, digitized, and included in this analysis. Subject completed diagrams were digitized and superimposed with a grid of 1398 squares. Quantification of the percentage of bodily areas affected by pain and stimulation induced paresthesias was performed. RESULTS: The percent of painful areas covered by paresthesia was significantly lower for DRG subjects than for SCS subjects (13% vs. 28% of the painful regions, p < 0.05), possibly because significantly more DRG subjects felt no paresthesia during stimulation when compared to SCS subjects (13/41 DRG vs. 3/34 SCS) (p < 0.05). The amount of paresthesia produced outside the painful areas (unrequired paresthesia) was significantly lower in DRG subjects than that of SCS subjects. On average, the percent of unrequired paresthesia was only 20% of the subjects' total painful body surface area in the DRG group compared to 210% in the SCS group (p < 0.01). CONCLUSIONS: The results of this ACCURATE study sub-analysis show that DRG stimulation produces paresthesias, on average, that are less frequent, less intense, with a smaller footprint on the body and less dependent on positional changes.

Motor Cortex Stimulation for Deafferentation Pain.

PURPOSE OF REVIEW: Since the early 1990s, motor cortex stimulation (MCS) has been a unique treatment modality for patients with drug-resistant deafferentation pain. While underpowered studies and case reports have limited definitive, data-driven analysis of MCS in the past, recent research has brought new clarity to the MCS literature and has helped identify appropriate indications for MCS and its long-term efficacy. RECENT FINDINGS: In this review, new research in MCS, repetitive transcranial magnetic stimulation (rTMS), and transcranial direct current stimulation (tDCS) are analyzed and compared with historical landmark papers. Currently, MCS is effective in providing relief to 40-64% of patients, with decreasing analgesic effect over time addressed by altering stimulation settings. rTMS and tDCS, two historic, non-invasive stimulation techniques, are providing new alternatives for the treatment of deafferentation pain, with rTMS finding utility in identifying MCS responders. Future advances in electrode arrays, neuro-navigation, and high-definition tDCS hold promise in providing pain relief to growing numbers of patients. Deafferentation pain is severe, disabling, and remains a challenge for patients and providers alike. Over the last several years, the MCS literature has been revitalized with studies and meta-analyses demonstrating MCS effectiveness and providing guidance in identifying responders. At the same time, rTMS and tDCS, two time-honored non-invasive stimulation techniques, are finding new utility in managing deafferentation pain and identifying good MCS candidates. As the number of potential therapies grow, the clinician's role is shifting to personalizing treatment to the unique pain of each patient. With new treatment modalities, this form of personalized medicine is more possible than ever before.

Dorsal root ganglion stimulation yielded higher treatment success rate for complex regional pain syndrome and causalgia at 3 and 12 months: a randomized comparative trial.

Animal and human studies indicate that electrical stimulation of dorsal root ganglion (DRG) neurons may modulate neuropathic pain signals. ACCURATE, a pivotal, prospective, multicenter, randomized comparative effectiveness trial, was conducted in 152 subjects diagnosed with complex regional pain syndrome or causalgia in the lower extremities. Subjects received neurostimulation of the DRG or dorsal column (spinal cord stimulation, SCS). The primary end point was a composite of safety and efficacy at 3 months, and subjects were assessed through 12 months for long-term outcomes and adverse events. The predefined primary composite end point of treatment success was met for subjects with a permanent implant who reported 50% or greater decrease in visual analog scale score from preimplant baseline and who did not report any stimulation-related neurological deficits. No subjects reported stimulation-related neurological deficits. The percentage of subjects receiving ≥50% pain relief and treatment success was greater in the DRG arm (81.2%) than in the SCS arm (55.7%, P < 0.001) at 3 months. Device-related and serious adverse events were not different between the 2 groups. Dorsal root ganglion stimulation also demonstrated greater improvements in quality of life and psychological disposition. Finally, subjects using DRG stimulation reported less postural variation in paresthesia (P < 0.001) and reduced extraneous stimulation in nonpainful areas (P = 0.014), indicating DRG stimulation provided more targeted therapy to painful parts of the lower extremities. As the largest prospective, randomized comparative effectiveness trial to date, the results show that DRG stimulation provided a higher rate of treatment success with less postural variation in paresthesia intensity compared to SCS.

Steroid atrophy scarring treated with fat grafting in a patient with complex regional pain syndrome: A case report.

Subcutaneous atrophy is a known complication of steroid injections. Excellent results with fat grafting for the treatment of steroid atrophy have been documented. However, the benefit of treating steroid-induced subcutaneous atrophy in an extremity diagnosed with complex regional pain syndrome (CRPS) has not been described. CRPS, known formerly as reflex sympathetic dystrophy or RSD, causalgia, or reflex neurovascular dystrophy, is a severe, progressive musculoskeletal pain syndrome characterized by pain which is disproportionate to the severity of the inciting event, edema, or skin changes. Common treatment modalities include pharmacotherapy, physical therapy, and nerve blocks-each therapy producing varying results. We present a literature review of CRPS and the case of a 15-year-old female who developed CRPS of the left lower leg after arthroscopic debridement with retrograde drilling of an osteochondral lesion. Steroid atrophy of the involved area following a saphenous nerve block complicated the patient's treatment course. The area of atrophy was treated with autologous fat grafting. Following the adipose injection procedure, the patient experienced almost complete resolution of her CPRS-associated pain symptoms, along with improved cosmetic appearance of the area.

Pulsed radiofrequency treatment of complex regional pain syndrome: a case series.

BACKGROUND: Various forms of sympathetic chain neurolysis (sympathectomy) have, at one time or another, held promise as effective treatment options for complex regional pain syndrome (CRPS). Complications, such as worsening pain and the development of new pain syndromes, have prevented sympathectomy from emerging as a standard intervention. In an effort to avoid poor outcomes associated with neurolysis, pulsed radiofrequency (PRF) has been proposed as a potential treatment alternative for a number of chronic neuropathic pain states, including some forms of CRPS. METHODS: The present report describes three cases in which patients diagnosed with lower extremity CRPS type I obtained substantial and lasting intervals of pain relief following PRF of the lumbar sympathetic chain. Over a period of four years, 14 fluoroscopically guided procedures using PRF lesioning of the lumbar sympathetic chain at L2, L3 and L4 were performed in three individuals with CRPS type I of the lower limb. Outcome measures included pre- and post-treatment self-reported pain and medication requirements. RESULTS: Substantial pain relief (>50%) was achieved in 91.7% of PRF applications at three months and 83.3% at six months, with some treatments resulting in persistent relief well beyond 12 months. Medication use decreased to a comparable degree, with discontinuation of opiates after all but three treatments. CONCLUSIONS: PRF lesioning of the lumbar sympathetic chain can be an effective treatment for patients with CRPS type I of the lower extremity, with the potential to provide ≥6 months of substantial pain relief.

The changes of c-Fos expression by motor cortex stimulation in the deafferentation pain model.

The effect of motor cortex stimulation (MCS) therapy for deafferentation pain was evaluated based on c-Fos, a known pain marker. Nineteen mature cats weighing 1.5-3.5 kg were used. Cats were divided into three groups: a deafferentation pain group in which the left trigeminal ganglion was destroyed, an MCS group in which MCS was used following destruction of the trigeminal ganglion, and a control group. Sites and levels of c-Fos expression were examined immunohistochemically. The percentage of c-Fos-positive cells in the left spinal nucleus of the trigeminus, the bilateral insula, and the bilateral operculum increased in both the deafferentation pain and the MCS groups. There were no statistically significant differences between these groups. In the cingulate gyrus, the percentage of c-Fos-positive cells increased bilaterally in the deafferentation pain group and the MCS group, but the increase was greater in the MCS group. The increase in c-Fos-positive cells in the left spinal nucleus of the trigeminus in the deafferentation group may reflect reported electrical hyperactivity. The cingulate gyrus, insula, and parietal operculum were activated after deafferentation. This change (increase in c-Fos positive cells) is related to the development of deafferentation pain. Pain relief due to MCS is not dependent on the suppression of the activated left spinal nucleus of the trigeminus or the descending analgesic mechanism of the brain stem. Activation of the cingulate gyrus appears to be a factor in the analgesic mechanism of MCS.

[Complex regional pain syndrome in a patient with acute drug poisoning: a case report].

We report a case with transition to complex regional pain syndrome (CRPS) caused by nerve injury associated with crush syndrome. The diagnosis was delayed because of coma due to acute drug poisoning. A 44-year-old man had attempted suicide by taking massive amounts of psychotropic drugs 2 days earlier and was transported to our hospital by ambulance. His arms had been compressed due to the prolonged (2 days) consciousness disturbance, and he experienced non-traumatic crush syndrome and rhabdomyolysis. Acute renal failure was prevented with massive infusion and hemofiltration. However, he experienced muscle and nerve injury at the compressed area, which presumably led to CRPS. In cases of suspected crush syndrome associated with acute drug poisoning, it is also important to recognize the possibility of developing CRPS.

Management of chronic pain following nerve injuries/CRPS type II.

Chronic pain affects quality of life and adversely affects functional outcomes. Chronic postoperative pain is a frustrating problem for the surgeon because it ruins a technically perfect procedure, and the surgeon may be unsure of treatment strategies. There is much information on chronic pain and its treatment, but it is often published outside of surgery and diffusion of this information across disciplines is slow. This article synthesizes some of this literature and provides a systematic presentation of the evidence on pain associated with peripheral nerve injury. It highlights the use of perioperative and early intervention to decrease this debilitating problem.

Síndrome de dolor regional complejo / Complex regional pain synndrome

El Síndrome de Dolor Regional Complejo (SDRC) es una enfermedad crónica, que se caracteriza por dolor y alteraciones sensitivas, motoras y autonómicas, a menudo sigue a trauma de un miembro, su curso es variable y, tanto su fisiopatología como el tratamiento, no están claramente establecidos. El objetivo de esta revisión es presentar una actualización de los aspectos generales de la enfermedad y mostrar parte de la evidencia existente en relación a las alternativas terapéuticas de la misma, tanto las conservadoras como las intervencionales. Es importante tener en consideración algunos puntos que limitan el objetivo de obtención de evidencia de buena calidad para el tratamiento de este síndrome. Lo primero es que el diagnóstico es clínico y los criterios para realizarlo han variado en el tiempo. Segundo, es la ausencia de criterios estandarizados para medir los resultados al tratamiento. Y, por último, ya que se trata de un síndrome crónico cuya manifestación principal es el dolor, existe respuesta a placebo...

The Regional Pain Syndrome Complex (CRPS ) is a chronic disease, which is characterized by pain and sensory, motor and autonomic disturbances, often follows trauma, the course and the pathophysiology are variable. The aim of this review is to provide an update on the general aspects of the disease and show the evidence in relation to therapeutic alternatives...

Type II complex regional pain syndrome of the hand resulting from repeated arterial punctures during transradial coronary intervention.

Coronary catheterization using a transradial approach has become a common procedure, as the risks of local complications are low and this procedure affords relatively expeditious postprocedural patient mobilization. Access site complications--such as radial artery spasm, hematoma, and compartment syndrome--have been reported in the literature; however, cases of complex regional pain syndrome (CRPS) of the hand related to the procedure are extremely rare. We describe a case of type II CRPS affecting the hand after a transradial coronary intervention that was complicated by repeated periprocedural arterial punctures. In this case, a 55-year-old woman underwent a percutaneous coronary intervention for the treatment of unstable angina. After successful completion of the procedure, the patient complained of severe pain along the median and radial nerve distributions and resulting disability of the right hand. Although subsequent duplex sonography showed no abnormalities, a nerve conduction study uncovered injury to multiple nerves on the right. A diagnosis of type II CRPS was then made and the patient was treated with a nerve block as well as multiple medical modalities. This case demonstrates a very unusual complication resulting from the transradial approach to percutaneous coronary intervention.