OBJECTIVE: Complex regional pain syndrome (CRPS) is a debilitating chronic condition characterized by severe, nociplastic pain along with various other symptoms. Neuromodulation, particularly electrical stimulation of the dorsal root ganglion (DRG), has emerged as a promising intervention for patients with CRPS unresponsive to conventional treatments. However, little is known about the anatomical characteristics of DRGs in patients with CRPS. This study aimed to assess DRG size in patients with CRPS compared with healthy controls.
METHODS: A retrospective pilot study was conducted in 12 patients with unilateral lower extremity CRPS who have a history of lumbar magnetic resonance imaging, and evaluated DRG sizes bilaterally. Patients were age-, race-, and sex-matched to patients in the control group who were asymptomatic at matched spinal level. DRG sizes were evaluated by a neuroradiologist. Statistical analyses including paired t-tests were performed to compare the difference in DRG size in contralateral sides in patients with CRPS and their matched controls.
RESULTS: Patients with CRPS exhibited a statistically significant reduction in DRG size on the affected side compared with the unaffected side (4.4 mm-4.8 mm, respectively). This difference was significant when compared with the difference observed in healthy controls (4.9 mm-5.0 mm, respectively). In addition, the mean DRG size difference between the affected and unaffected side showed a greater difference in DRG size in patients with CRPS (0.6 mm difference) than in control patients (0.2 mm difference).
CONCLUSIONS: The findings suggest that CRPS is associated with a smaller DRG size in affected dermatomes, potentially indicating neuronal atrophy. Importantly, the study offers insights for DRG stimulation therapy especially among concerns for DRG compression after placement. This pilot study reveals a significant size difference in DRGs between affected and unaffected sides in patients with CRPS compared with controls, highlighting potential implications for treating CRPS. Further research is warranted to validate these findings and explore implications for clinical practice, including optimized neuromodulation strategies.

Lumbar sympathetic ganglion neurolysis (LSGN) has been used for long-term pain relief in patients with complex regional pain syndrome (CRPS). However, the actual effect duration of LSGN has not been accurately measured. This prospective observational study measured the effect duration of LSGN in CRPS patients and investigated the relationship between temperature change and pain relief. After performing LSGN, the skin temperatures of both the maximum pain site and the plantar area in the affected and unaffected limbs were measured by infrared thermography, and pain intensity was assessed before and at 2 weeks, 1 month, and 3 months. The median time to return to baseline temperature was calculated using survival analysis. The skin temperature increased significantly at all-time points relative to baseline in both regions (maximum pain site: 1.4 °C ± 1.0 °C, plantar region: 1.28 °C ± 0.8 °C, all P < 0.001). The median time to return to baseline temperature was 12 weeks (95% confidence interval [CI] 7.7-16.3) at the maximum pain site and 12 weeks (95% CI 9.4-14.6) at the plantar area. Pain intensity decreased significantly relative to baseline, at all-time points after LSGN. In conclusion, the median duration of the LSGN is estimated to be 12 weeks.

BACKGROUND: Complex regional pain syndrome (CRPS) can profoundly affect many aspects of everyday life. Spinal cord stimulation (SCS) is a potential therapeutic option. This retrospective, single-site evaluation explored health-related quality of life (HRQoL) in individuals with CRPS treated with SCS in our Pain Service.
METHODS: All patients aged ≥18 years with fully implanted SCS for CRPS between June 2013 and January 2023 were identified from hospital records. The following data were collected: sex, age, chronic pain diagnosis, CRPS type (I or II), location of CRPS (upper or lower limb), years of CRPS before first SCS implant, SCS system, preimplant and follow-up scores for HRQoL (euroqol 5 dimensions 3 levels [EQ-5D-3L] index score), average pain, worst pain and the influence of pain on aspects of everyday life (all numerical rating scale [NRS]), patient and clinician global impression of change at follow-up, and the occurrence and reasons for revisions and explants. An intention-to-treat approach was used and data statistically analyzed.
RESULTS: The final cohort comprised 83 patients (46 women), with a median (minimum, maximum) follow-up duration of 29 months (seven, 72). There were statistically and clinically significant improvements in HRQoL, despite relatively low pain response rates. The pain response rate was 34% (reduction of ≥30% in average pain NRS); the pain remission rate was 13% (average pain score ≤3 NRS), and all patients had preimplant EQ-5D-3L index values below the population norm of 0.82. However, 60% of patients reported EQ-5D-3L index scores greater than the published minimally important difference of 0.074, and scores were better at follow-up than at preimplant (p < 0.001); 44% of patients and 41% of clinicians reported improved symptoms at the most recent follow-up. Explants occurred in eight of 83 patients (10%).
CONCLUSIONS: Patients had meaningful improvements in HRQoL, which is a key outcome in ascertaining the overall outcome of SCS in CRPS. Randomized controlled clinical trials should build on the findings to improve understanding of the benefits and risks of treating CRPS with SCS.

OBJECTIVE: The aim of this study was to evaluate the benefit of inpatient treatment in reducing disease activity in patients with complex regional pain syndrome (CRPS) who have exhausted outpatient options. Furthermore, the study sought to identify patient-related outcome variables that predict a reduction in disease activity.
METHODS: The primary outcome was disease severity (CRPS Severity Score, range 0-16 points). Secondary outcomes included depression, anxiety, physical function, pain interference, fatigue, sleep disturbance, and the ability to participate in social roles and activities, all of which were assessed using the PROMIS-29. Furthermore, pain catastrophizing, neuropathic pain, quality of life, pain self-efficacy, medication intake, and the patient\'s global impression of change were examined in accordance with current international agreed recommendations, assessed at discharge, 3-month, and 6-month post-discharge. Mixed-effects models were conducted to identify baseline variables associated with CRPS severity.
RESULTS: Twenty-five patients completed the program (mean age 49.28 [SD 11.23] years, 92% females, mean symptom duration 8.5 [SD 6.5] months). Results showed a significant reduction between baseline and discharge of disease activity (CSS -2.36, P < .0001), pain (PROMIS-29 pain -0.88, P = .005), and emotional function (PROMIS-29 depression -5.05, P < .001; fatigue -4.63, P = .002). Moderate evidence for a reduction between baseline and discharge could be observed for pain interference (+2.27, P = .05), social participation (PROMIS-29 + 1.93, P = .05), anxiety (PROMIS-29 -3.32, P = .02) and physical function (PROMIS-29 + 1.3, P = .03). On discharge, 92% of patients (23 of 25) reported improvement in their overall condition. In the follow-up period, medication intake could be reduced after 3 (MQS -8.22, P = .002) and 6 months (MQS -8.69, P = .001), and there was further improvement in social participation after 3 months (PROMIS-29 + 1.72, 0.03) and sleep after 6 months (PROMIS-29 + 2.38, 0.008). In the mixed models, it was demonstrated that patients experiencing less pain at baseline also exhibited lower disease activity.
CONCLUSIONS: The results of this study confirm that inpatient interdisciplinary treatment of CRPS patients improves disease activity, pain, physical function, emotional function, and social participation. Most improvements were maintained for up to 6 months after discharge. The majority of patients reported that their overall condition had improved during the study period.

BACKGROUND: Poststroke complex regional pain syndrome (CRPS) is an important complication in stroke survivors. The identification of factors associated with post-stroke CRPS is important for preventive measures and early diagnosis.
METHODS: A total of 141 first-ever stroke survivors in the subacute stage were retrospectively analyzed. Demographic data, diagnosis time, duration of hospitalization, location of brain lesion, etiology, comorbidities, and blood test findings were investigated. Clinical data included Medical Research Council (MRC) grade, Fugl-Meyer assessment (FMA), National Institute for Health Stroke Scale (NIHSS), Berg Balance Scale (BBS).
RESULTS: Among 141 patients with subacute stroke, 22 were diagnosed with CRPS, with a prevalence of 15.6 %. The mean time to diagnosis was 38.6 (±16.5) days. The prevalence according to the degree of paralysis was 33.3 % in MRC grades 0 and 1, 8.6 % in grade 2, and 0 % in grade 3 or higher. The incidence rates within 1 month after stroke were 1.42 % and 22.47 % between 1 and 3 months after stroke, respectively. The independent risk factors for CRPS were hospitalization duration and FMA, NIHSS, and BBS scores. The sensitivity and specificity of the NIHSS score for predicting post-stroke CRPS were 86.4 % and 59.7 %, respectively, with an optimal cutoff value of 7.5.
CONCLUSIONS: CRPS of the affected upper limb in stroke patients is associated with stroke severity, including paralysis, and the incidence increases over time during the subacute phase. Additionally, having sufficient strength to move through a full range of motion against gravity had a protective effect against CRPS.

UNASSIGNED: Complex Regional Pain Syndrome (CRPS) is a persistent pain condition with low prevalence. Multi-centre collaborative research is needed to attain sufficient sample sizes for meaningful studies. This international observational study: (1) tested the feasibility and acceptability of collecting outcome data using an agreed core measurement set (2) tested and refined an electronic data management system to collect and manage the data.
UNASSIGNED: Adults with CRPS, meeting the Budapest diagnostic clinical criteria, were recruited to the study from 7 international research centres. After informed consent, a questionnaire comprising the core set outcome measures was completed: on paper at baseline (T1), and at 3 or 6 months (T2) using a paper or e-version. Participants and clinicians provided feedback on the data collection process. Clinicians completed the CRPS severity score at T1 and optionally, at T2. Ethical approval was obtained at each international centre.
UNASSIGNED: Ninety-eight adults were recruited (female n=66; mean age 46.6 years, range 19-89), of whom 32% chose to receive the T2 questionnaire in an electronic format. Fifty-five participants completed both T1 and T2. Eighteen participants and nine clinicians provided feedback on their data collection experience.
UNASSIGNED: This study confirmed the questionnaire core outcome data are feasible and practicable to collect in clinical practice. The electronic data management system provided a robust means of collecting and managing the data across an international population. The findings have informed the final data collection tools and processes which will comprise the first international, clinical research registry and data bank for CRPS.

BACKGROUND: Neuroinflammation and maladaptive neuroplasticity play pivotal roles in migraine (MIG), trigeminal autonomic cephalalgias (TAC), and complex regional pain syndrome (CRPS). Notably, CRPS shares connections with calcitonin gene-related peptide (CGRP) in its pathophysiology. This study aims to assess if the documented links between CRPS and MIG/TAC in literature align with clinical phenotypes and disease progressions. This assessment may bolster the hypothesis of shared pathophysiological mechanisms.
METHODS: Patients with CRPS (n = 184) and an age-/gender-matched control group with trauma but without CRPS (n = 148) participated in this case-control study. Participant answered well-established questionnaires for the definition of CRPS symptoms, any headache complaints, headache entity, and clinical management.
RESULTS: Patients with CRPS were significantly more likely to suffer from migraine (OR: 3.23, 95% CI 1.82-5.85), TAC (OR: 8.07, 95% CI 1.33-154.79), or non-classified headaches (OR: 3.68, 95% CI 1.88-7.49) compared to the control group. Patients with MIG/TAC developed CRPS earlier in life (37.2 ± 11.1 vs 46.8 ± 13.5 years), had more often a central CRPS phenotype (60.6% vs. 37.0% overall) and were three times more likely to report allodynia compared to CRPS patients with other types of headaches. Additionally, these patients experienced higher pain levels and more severe CRPS, which intensified with an increasing number of headache days. Patients receiving monoclonal antibody treatment targeting the CGRP pathway for headaches reported positive effects on CRPS symptoms.
CONCLUSIONS: This study identified clinically relevant associations of MIG/TAC and CRPS not explained by chance. Further longitudinal investigations exploring potentially mutual pathomechanisms may improve the clinical management of both CRPS and primary headache disorders.
BACKGROUND: German Clinical Trials Register (DRKS00022961).

OBJECTIVE: There is growing evidence supporting the role of inflammatory mechanisms in complex regional pain syndrome (CRPS). Corticoids, as most effective anti-inflammatory drugs, are widely used in treating inflammation. The aim of this study was to retrospectively assess the efficacy of oral corticoid treatment in CRPS patients.
METHODS: Patients treated at the center of pain medicine in the Erasmus University Medical Centre between January 2015 and January 2020 were approached to partake in this study. Medical records were screened for age, gender, medical history, duration of CRPS, and CRPS severity score. Also, treatment effect, dose and duration, pain scores (NRS), and side effects were extracted from medical records. In addition, global perceived effect was completed in patients treated with corticoids.
RESULTS: Between January 2015 and January 2020, twenty-nine CRPS patients received corticoids and met the inclusion criteria. One extreme outlier was excluded and treatment effect was unknown for one patient. Average daily dose was 28.9 mg (range 10-30 mg) and the mean treatment duration was 10.5 days (7-21 days). Fourteen patients (51.9%) responded positively to treatment and thirteen (48.1%) did not respond. Side effects were reported in five patients (17.9%).
CONCLUSIONS: Corticoid treatment was effective in more than half of the patients. With only mild side effects reported the treatment also appears to be relatively safe. Further research is needed to investigate the efficacy of corticoids in treating (early) CRPS, preferably in an intervention study.

This study aimed to analyze baseline predictors of functional outcomes six weeks and at one year follow-up in patients older than 60 years with complex regional pain syndrome type 1 (CRPS I) after distal radius fracture (DRF).
A total of 120 patients with CRPS I after DRF were prospectively recruited. Presumptive relevant factors were collected and analyzed as potential baseline predictors. Additionally, functional outcomes were assessed at the beginning of physiotherapy treatment, at six weeks after finishing physiotherapy treatment, and at one year follow-up. Patient-Rated Wrist Evaluation; Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire; Jamar dynamometer; and visual analog scale (VAS) were assessed.
All participants completed the study. At 6 weeks, the main results showed an association of lower values of grip strength with female sex (p = 0.010), intra-articular DRFs (p = 0.030), longer immobilization time (p = 0.040), lower levels of physical activity (p < 0.001), higher levels of kinesiophobia (p = 0.010), and anxiety (p = 0.020). At 1-year follow-up, the results showed an association of lower values of DASH with higher BMI (p < 0.001) and longer immobilization time (p < 0.001); and higher values of VAS showed an association with older age (p = 0.010), higher BMI (p = 0.010), and lower levels of physical activity (p = 0.040).
At six weeks, factors such as BMI, immobilization time, physical activity, and kinesiophobia are associated with lower functional outcomes. Additionally, at one year follow-up, BMI, immobilization time, and physical activity continue to be associated with lower functional outcomes in patients with CRPS I after DRF treated conservatively.

BACKGROUND: High dose of corticosteroid has been found beneficial in complex regional pain syndrome type I (CRPS-I). We report the efficacy and safety of prednisolone 20 mg versus 40 mg in CRPS-I in an open label randomized controlled trial.
METHODS: The patients with CRPS-I of the shoulder joint with a CRPS score of ≥8 were included. Their demographic details, comorbidities, and underlying etiology were noted. The severity of CRPS was assessed using a 0-14 CRPS scale, the pain using a 0-10 Visual Analogue Scale (VAS), and sleep quality using a 0-10. Daily Sleep Interference Scale (DSIS). Patients were randomized to prednisolone 40 mg/day (group I) or 20 mg/day (group II) for 14 days, then tapered to 10 mg in group I and to 5 mg in group II by 1 month. Thereafter both groups received prednisolone 5 mg/day for 2 months. The primary outcome was a >50% reduction in VAS score, and secondary outcomes were a reduction in CRPS score, DSIS score, and adverse events.
RESULTS: Fifty patients were included, and their baseline characteristics were comparable. At one month, all the patients had >50% reduction in the VAS score. The effect size was 0.38 (95% CI 0.93-0.20; p = 0.20). On the Kaplan-Mayer analysis, the improvement in the VAS score (Hazard ratio-1.43, 95 % CI-0.80-2.56, p = 0.22) and the CRPS score (HR-0.79,95 % CI-0.45-1.39; p = 0.41) was insignificant between the two groups. The DSIS score improved in group II (HR-1.85,95 % Cl-1.04-3.31,p = 0.04). Group I patients needed frequent adjustment of antidiabetic drugs (14 vs 6; p = 0.04).
CONCLUSIONS: The efficacy of prednisolone 20 mg is not inferior to 40 mg in CRPS-I, and is safe in diabetic patients.
CONCLUSIONS: This is an open label randomized controlled trial with small sample size without a placebo arm.