Morphological macrovascular alterations in complex regional pain syndrome type I demonstrated by increased intima-media thickness
- Nicola Derenthal†1,
- Tim Maecken†2,
- Elena Krumova1, 4,
- Alfried Germing3 and
- Christoph Maier1Email author
© Derenthal et al.; licensee BioMed Central Ltd. 2013
Received: 14 September 2012
Accepted: 3 February 2013
Published: 6 February 2013
Although intima-media thickness (IMT) was increased in several inflammatory diseases, studies investigating whether the inflammatory processes lead to macrovascular alteration with increased IMT in complex regional pain syndrome (CRPS) lack.
Using ultrasound (high-resolution B-mode), we compared bilaterally the IMT of the common carotid artery (CCA-IMT), the radial artery (RA-IMT), the brachial artery (BRA-IMT) and the quotient QRA/CCA, in CRPS type I (n=17), peripheral nerve injury (PNI, n=17) and pain-free controls (PFC, n=22, matched to CRPS by gender, age and traditional cardiovascular risk factors). Statistics: Spearman’s correlation, paired t-test, ANOVA (p<0.05).
Compared to PFC, RA-IMT were significantly increased in both patient groups bilaterally (mean±standard deviation, CRPS affected side vs. PFC dominant side: 0.32±0.08 mm vs. 0.19±0.08 mm, p<0.001; PNI affected side vs. PFC dominant side: 0.27±0.09 mm vs. 0.19±0.08 mm, p< 0.05; CRPS non-affected side vs. PFC non-dominant side: 0.30±0.10 mm vs. 0.19±0.09 mm, p<0.001; PNI non-affected side vs. PFC non-dominant side: 0.25±0.10 mm vs. 0.19±0.09 mm, p<0.05) and QRA/CCA (CRPS affected-side vs. PFC dominant side: 0.49±0.12 vs. 0.30±0.11, p<0.001; PNI affected side vs. PFC dominant side: 0.41±0.10 vs. 0.30±0.11, p<0.05; CRPS non-affected side vs. PFC non-dominant side: 0.43±0.19 vs. 0.30±0.13, p<0.001; PNI non-affected side vs. PFC non-dominant side: 0.39±0.14 vs. 0.30±0.13, p<0.05), and BRA-IMT - only on the affected side in CRPS (CRPS: 0.42±0.06 mm vs. PFC: 0.35±0.08 mm; p<0.05). In CRPS, QRA/CCA was significantly higher on the affected side compared to PNI (p<0.05). However, only CRPS displayed within-group side-to-side differences with a significantly increased RA-IMT and QRA/CCA on the affected side (p<0.05). The CCA-IMT was comparable between all groups and sides.
The increased IMT of peripheral arteries in CRPS suggests ongoing inflammatory process. Until now, only endothelial dysfunction has been reported. The presented morphological macrovascular alterations might explain the treatment resistance of some CRPS patients.
KeywordsComplex regional pain syndrome Macrovascular changes Intima-media thickness Inflammatory alterations
Complex regional pain syndrome type I (CRPS I) occurs as a severe complication after limb trauma without evidence of a peripheral nerve lesion. At the beginning of the disease patients present signs and symptoms like pain, edema, increased skin temperature and redness . The underlying pathomechanisms of CRPS are still unclear, but the clinical signs and symptoms as well as other findings indicate the involvement of inflammatory processes for the development of CRPS . For example, locally increased levels of pro-inflammatory cytokines like tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) were found in the affected limb of CRPS patients compared to the non-affected limb . Furthermore, the systemic mRNA levels of some anti-inflammatory cytokines (interleukin-10) were decreased , whereas the systemic levels of pro-inflammatory neuropeptides including calcitonin gene-related peptide, bradikinin and substance P were increased . Moreover, higher levels of endothelin-1, but low levels of nitric oxide have been described . Furthermore, in CRPS patients with allodynia the concentration of plasma neuropeptid Y was lower on the painful side . Additionally, lower concentration of plasma noradrenalin was found in CRPS patients with widespread allodynia as well as in those with hyperhidrosis .
Increased intima-media thickness (IMT), measured by high-resolution ultrasound, is a non-invasive marker of early arterial wall alteration. It can result from cardiovascular risk factors such as smoking, hypertension, diabetes mellitus and hypercholesterolemia. Anyway, it may not necessarily reflect pathologic changing because it is closely correlated to age . However, an increased IMT of the common carotid artery (CCA-IMT) is directly associated with an increased risk of cardiovascular disease and its measurement is well accepted for clinical research .
Furthermore, there is a strong link between inflammatory markers and increased internal carotid IMT . TNF-α and an increased CCA-IMT were not only positively associated in healthy middle-aged men  but also with inflammatory markers in different autoimmune diseases including rheumatoid arthritis , HIV-infected patients  or in patients with diabetes mellitus .
Modern high-resolution ultrasound systems can depict the macrovascular structure (and change) of intima-media thickness. To our knowledge, there are no studies on the IMT in CRPS, although, there are several reports of microvascular alterations in this disease, e.g. endothelial swelling and changes in the vessel luminal wall detected in a bone biopsy . Furthermore, hypertrophic changes of the basal membrane layers of the capillaries were found in muscle tissue of CRPS patients, analyzed by light and electronic microscopy . Additionally, in CRPS-affected skin the denerved vessels were hypertrophied with an increased size of lumen and thickened multi-laminated walls  and the number of migrated endothelial cells was increased .
The objective of the present prospective study was to investigate morphologic macrovascular alterations in patients with unilateral CRPS of the upper extremity by assessing the IMT of the radial, brachial and common carotid artery bilaterally in comparison to patients with unilateral peripheral nerve injury and matched pain-free controls using high-resolution ultrasonography.
Patients and pain-free controls
Patients with peripheral nerve injury (n=17)
Pain-free controls (n= 22)
Gender (female, n (%))
53 ± 14
53 ± 14
52 ± 13
Affected side (right), n (%)
Diagnosis, n (%)
CRPS I, 17 (100%)
Neuralgia of median nerve, 6 (36%)
Neuralgia of ulnar nerve, 5 (30%)
Neuralgia of radial nerve, 5 (30%)
Neuralgia of median, ulnar, radial nerve, 1 (6%)
Precipitating event, n (%)
Carpal tunnel syndrome
Current analgesics, n°
Other non-opioid analgesics
Cardiovascular risk factors, n (%)°
Patients with cardiovascular risk factors, n (%)
Pain duration (months)
16 ± 13 (4…60)#
97 ± 12 (4…360)#
Patients < 12 months pain duration, n (%)
10 (60%) #
1 (6%) #
Current pain intensity (examination day, NRS 0–10)
4 ± 0
5 ± 4
Maximal pain intensity (examination day, NRS 0–10)
6 ± 4
7 ± 4
Patients with positive symptom categories, n (%) ° *
Patients with positive sign categories, n (%) ° *
In-house cut-off reference values of nerve conduction studies
Distal motor latencies (m/s)
Conduction velocity (m/s)
22 pain-free controls (PFC) served for a second control group. They were recruited from February 2010 until January 2011 among students, hospital staff or their relatives and were matched to the CRPS patients by gender, age (± five years) and common cardiovascular risk factors (cigarette smoking, diabetes mellitus, hypertension and hypercholesterolemia). Except from the matched cardiovascular risk factors all subjects were healthy without a history of trauma, neurological, vascular or inflammatory disease. After performing the Edinburgh inventory for assessment of handedness with the PFC group, the dominant hand was defined as test side (analogue to the affected side in the patients). Thus, the dominant side of the healthy subjects was compared to the affected side of both patient groups and the non-dominant side was compared to the non-affected side of both patient groups .
While performing the measurements the sonographer was not blinded to the clinical information.
Investigations and measurements
To avoid inter-observer variability the study measurements were restricted to one examiner (ND) and were performed after a training phase with twenty other subjects with an experienced sonographer (TM). The correlation between the results obtained from TM and ND was analyzed with Spearman’s rank correlation coefficients (r=0.958, p<0.0001). A Bland-Altman-analysis showed no significant differences.
Intima-media thickness (IMT)
IMT measurements were performed on the subjects lying in supine position with the head in neutral position. The arms were in a slightly abducted, resting position with unclenched hands. A high-resolution ultrasound-system with a linear array was used (Sonosite Erlangen, Germany, HFLx38 13-6MHz). IMT-far-wall-measurements of the CCA were bilaterally performed according to the Mannheim-Consensus-protocol  using the SonoCalc-IMT-Software (version 4.1; long-axis-view of the CCA, one cm distal the bulb in a region free of plaques). The IMT is defined as the distance between the beginning of the tunica intima (far wall) and the beginning of the tunica adventitia. For reproducible measurements a high-quality image acquisition was used along a minimum length of 10 mm of an arterial segment as required . The mean IMT was calculated by three consecutive examinations. IMT-far-wall-measurements of the brachial and radial artery were performed on both sides in a similar manner like those of the CCA (linear-probe set to highest resolution (Sonosite HFLx38 13-6MHz), SonoCalc-IMT-Software, multiple automatic measurements on 1 cm IMT). The BRA-IMT-measurements were performed while subjects were lying in supine position, the arm slightly abducted and rotated in resting position with unclenched hand (most comfortable position for study subject and investigator). Three consecutive examinations in long-axis-view of the BRA were performed bilaterally, whereas the linear array was positioned about 3–5 cm proximal the elbow. RA-IMT measurements were performed in the same manner. The transducer was positioned in the distal third of the forearm.
Quotient of the IMT of the radial and carotid artery (QRA/CCA)
For statistical analysis the Statistica®-Software was used (StatSoft® Inc., Tulsa, Oklahoma, USA). P-values <0.05 were considered statistically significant, p-values <0.01 highly significant. Descriptive statistics were performed for all variables. Mann–Whitney-U-test was performed to compare metric variables (e.g. age, duration of disease, pain intensity). Shapiro-Wilks W-Test was used to test normal distribution of the parameters. After confirming normal distribution for all IMT-values using the Shapiro-Wilks W-Test, t-test for paired samples was conducted to investigate body side differences within the groups. Group comparisons of each body side were analyzed using a one-way analysis of variance (ANOVA). Levene’s test was performed to assess the equality of variance between the different samples. The post-hoc test (LSD) was performed to detect significant group differences. The correlations between mean IMT and disease duration and pain intensity were analyzed with Spearman’s rank correlation coefficients.
The gender proportion, the mean age and the number of cardiovascular risk factors were comparable between the three groups. The proportion of patients with affection of the right or left hand as well as the reported current and maximal pain intensity were also similar in both patient groups. CRPS patients had a significantly shorter duration of disease (p<0.001) compared to patients with PNI. The pain duration was less than 12 months in only one patient of the PNI group vs. ten of the CRPS patients (p<0.001, Table 1).
Mean common carotid intima-media thickness
One-way ANOVA analyzing between group differences
Between groups effect
CCA-IMT mean affected side (mm)
CCA-IMT mean non-affected side (mm)
BRA-IMT mean affected side (mm)
BRA-IMT mean non-affected side (mm)
RA-IMT mean affected side (mm)
RA-IMT mean non- affected side (mm)
QRA/CCA affected side
*, #, +
QRA/CCA non-affected side
Mean brachial intima-media thickness
Mean radial intima-media thickness
Quotient of the IMT of the radial and carotid artery (QRA/CCA)
Correlation between IMT and disease duration and pain intensity for both patient groups
CCA-IMT, BRA-IMT and RA-IMT did neither correlate with disease duration nor with pain intensity in the CRPS group and PNI group.
To our knowledge, this is the first study revealing morphological macrovascular alterations in CRPS patients measured by ultrasonography. The RA-IMT and the QRA/CCA were increased bilaterally compared to pain-free controls (PFC) both in CRPS and in PNI patients. The BRA-IMT of the affected side was increased only in CRPS patients compared to PFC. CRPS patients had a significantly higher QRA/CCA on the affected side compared to PNI patients. Only in CRPS the QRA/CCA and RA-IMT of the affected side were increased compared to the non-affected side. The CCA-IMT did not differ between all groups and sides.
Carotid IMT measurement by B-mode ultrasound is a common, reproducible and well accepted technique to evaluate the vascular status of patients . In contrast to the carotid artery, peripheral IMT measurements have not been well established yet, probably due to difficulties in measuring the very small radial IMT-values (mean RA-IMT of 0.19±0.08 mm compared to 0.64±0.12 mm of the CCA-IMT in our pain-free controls). Unfortunately, the used software allowed no post-examination measurement of the intima-media-thickness. Therefore the blinding of assessment was impossible. However, Ku et al. demonstrated that RA-IMT ultrasound using frequencies of 12 MHz (13 MHz in the present study) is feasible and produced significant correlations to histological examinations . There are only a few other studies of RA-IMT [22, 23] or BRA-IMT measurements that use ultrasound. Despite this limited experience, RA-IMT above 0.25 mm is regarded to be increased . The mean RA-IMT of our PFC group was is in the same range of normotensive subjects as previously reported (0.19±0.02 mm)  and the mean RA-IMT of our patient groups were above or equal to 0.25 mm, indicating the validity of our RA-IMT results.
To eliminate the impact of atherosclerotic diseases we generated the QRA/CCA and matched our pain-free controls to CRPS patients on cardiovascular risk factors as well as age. Age for itself leads to an increase of 0.010 mm/y in the CCA both in males and females . However, there were no significant differences in age between the groups in the present study; therefore, IMT differences between the groups cannot be solely explained by age effects.
Several studies have observed functional vascular abnormalities in CRPS , e.g. impaired endothelial function demonstrated using acetylcholine- and sodium nitroprusside-induced vasodilation combined with laser Doppler flowmetry . In contrast, only a few authors described morphological abnormalities in the microvascular system. Our results of increased RA- and BRA-IMT are in line with the previously described microvascular alterations such as endothelial swelling and changes in the vessel luminal wall found in a human bone biopsy ; furthermore, extraordinary vascular hypertrophy characterized by severely thickened multi-laminated walls was found through immunohistochemical analysis of CRPS-affected skin  or an increased number of migrated endothelial cells .
Beside the vascular changes, there is also some evidence for inflammatory alterations in CRPS patients [3, 4] and the important role of inflammatory processes for the development of this disease , including increased local concentration of inflammatory markers in the affected extremity of CRPS patients [3, 4]. However, only a few studies give hints not only for local but also for systemic inflammatory processes in CRPS [28, 29], such as increased levels of IL-8 and tumor-necrosis-factor receptor I/II in the affected arm of patients with acute CRPS I without significant differences compared to the non-affected arm . Six years after disease onset the difference of TNF-α and IL-6-levels between the affected and the non-affected side was not significant anymore .
We hypothesize, that an increased IMT in CRPS patient is a sign of inflammatory processes. Unfortunately, we did not measure inflammatory mediators in the serum in our patients. However, we found a significantly increased radial IMT in the affected side compared to the non-affected side, in line with the previously reported high local concentration of inflammatory markers only in the affected extremity . In accordance with these local findings we have observed unilaterally increased BRA-IMT only on the affected side. Similarly to the clinical signs and symptoms, which are presented mainly in the distal part of the affected limb, we have also observed a gradient in the macrovascular changes, which were more pronounced on the distal than on the proximal limb: The CCA-IMT was bilaterally not increased, while we found an unilateral moderate increase in the BRA-IMT and a more pronounced increase in the RA-IMT suggesting a local process in the distal limb. However, also the radial IMT of the non-affected side was significantly increased compared to PFC without having any signs or symptoms on that side, which could be in accordance with previous results indicating a systemic process. Merely in CRPS patients not only radial IMT but also brachial IMT was significantly increased in the affected side compared to PFC. However there was no significant difference between the affected and non-affected side, which is a further hint for a systemic process. However, the maximal IMT alteration in our study is located at the radial artery on the affected side. Even though our controls were matched to age, gender and risk factors, we found the highest QRA/CCA in CRPS patients indicating disease specific alterations. Thus, our findings suggest both a systemic and local inflammatory process. According to our hypothesis that inflammation might induce increased IMT in CRPS, several studies demonstrated the association between inflammatory markers such as TNF-α or IL-6 and an increased IMT of the CCA [10–12, 14]. In contrast, to our knowledge there are no studies that examined the correlation between inflammatory signs and increased radial or brachial IMT.
Unexpectedly, we found an increased RA-IMT also in the PNI group compared to PFC, however without significant side differences in contrast to the CRPS group. In painful peripheral neuropathies significantly higher blood levels of IL-2 mRNA and TNF-α mRNA were measured compared to healthy subjects . Furthermore, changes in plasma cytokines (IL-2, TNF) after nerve injury have been described . To our knowledge, there are no studies which have observed intima-media thickening in patients with nerve injury. Although in our study the IMT of PNI patients was also increased, CRPS patients displayed the highest IMT. This was also supported by a significantly higher QRA/CCA of the affected side in CRPS patients compared to PNI patients.
It is important to notice that CRPS patients had significantly shorter mean disease duration than PNI patients. In only one patient of the PNI group vs. ten of the CRPS group the pain duration was less than 12 months. However, the disease duration in both groups was widely ranging (4–60 months in CRPS; 4–360 months in PNI), but neither CCA-IMT, nor BRA-IMT or RA-IMT correlated with disease duration in both patient groups. In other inflammatory diseases there was a positive correlation between disease duration and IMT . However, there are hints that carotid intima-media thickening and radial wall hypertrophy are reversible . We did not find a correlation between IMT and pain intensity probably because all our patients received a pain treatment and we did not included an untreated control group. Moreover, nine CRPS and two PNI patients were excluded from our study due to the impossibility to perform the ultrasound scan because of severe hyperalgesia and allodynia. Thus, these dropout-patients may result in an underestimation of our findings. However, assuming that the intima-media thickening results from inflammatory processes, our findings are in line with previous studies reporting absent correlation between inflammatory mediators and clinical course or outcome with high interindividual variation . In our study it was impossible to prove the association between clinical signs and IMT because clinical signs were presented by nearly or more than 80% of the CRPS patients except from vasomotor signs (Table 1). However, patients with or without vasomotor signs did not show a difference in all mean IMT-values.
Our study was a cross-sectional analysis which served as a pilot project and which may not clarify completely the correlation of IMT-alterations and disease duration, pain intensity or clinical signs and symptoms by now. Even though the benefit of long-term measurement of carotid IMT progression to predict cardiovascular events is still under debate , longitudinal radial artery scan studies in CRPS within the first year after disease onset are necessary at the next step, having in mind the fast disease progression. Longitudinal studies are needed to analyze the time course of these alterations from the early to later stages of the disease as well as to examine whether an increased IMT of CRPS patients is reversible and, in case it is, if this reversibility is accompanied by clinical improvement. Repeated IMT-measurements may be used to test the effectiveness of CRPS-treatment. Future studies should also be combined with measurements of inflammatory mediators to prove a possible association between increased IMT and inflammatory markers. However, it should be considered that IMT measurements are limited by hyperalgesia and allodynia in CRPS patients as well as by the need for a physician with profound skills in sonography. In addition to that, our unexpected observation of locally enlarged IMT in PNI patients should be reevaluated in patients with different types of nerve injury with a greater sample size and with simultaneously measurements of inflammatory markers.
In conclusion, we examined macrovascular alterations in CRPS patients using high-resolution sonography demonstrating for the first time bilaterally increased radial and unilaterally increased brachial IMTs. Further longitudinal studies are required to prove whether these alterations can be used as diagnostic or prognostic markers.
This work is part of the doctoral thesis of Nicola Derenthal.
Complex regional pain syndrome
Common carotid artery
- QRA/CCA :
Quotient of the IMT of the radial artery and common carotid artery
Peripheral nerve injury
Tumor necrosis factor alpha
Patients with injury of the median nerve
Patients with injury of the radial and ulnar nerve
Compound muscle action potential
Sensory nerve action potential.
We thank Thomas Grau for his support in designing the study and Peter Zahn in revising the paper.
- Harden RN, Bruehl S, Perez RS, Birklein F, Marinus J, Maihofner C, Lubenow T, Buvanendran A, Mackey S, Graciosa J, et al: Validation of proposed diagnostic criteria (the “Budapest Criteria”) for Complex Regional Pain Syndrome. Pain. 2010, 150 (2): 268-274. 10.1016/j.pain.2010.04.030.View ArticlePubMedPubMed CentralGoogle Scholar
- Birklein F, Schmelz M: Neuropeptides, neurogenic inflammation and complex regional pain syndrome (CRPS). Neurosci Lett. 2008, 437: 199-202. 10.1016/j.neulet.2008.03.081. IrelandView ArticlePubMedGoogle Scholar
- Huygen FJ, De Bruijn AG, De Bruin MT, Groeneweg JG, Klein J, Zijlstra FJ: Evidence for local inflammation in complex regional pain syndrome type 1. Mediators Inflamm. 2002, 11 (1): 47-51. 10.1080/09629350210307.View ArticlePubMedPubMed CentralGoogle Scholar
- Uceyler N, Eberle T, Rolke R, Birklein F, Sommer C: Differential expression patterns of cytokines in complex regional pain syndrome. Pain. 2007, 132: 195-205. 10.1016/j.pain.2007.07.031. NetherlandsView ArticlePubMedGoogle Scholar
- Groeneweg JG, Huygen FJ, Heijmans-Antonissen C, Niehof S, Zijlstra FJ: Increased endothelin-1 and diminished nitric oxide levels in blister fluids of patients with intermediate cold type complex regional pain syndrome type 1. BMC Musculoskelet Disord. 2006, 7: 91-10.1186/1471-2474-7-91.View ArticlePubMedPubMed CentralGoogle Scholar
- Drummond PD, Finch PM, Edvinsson L, Goadsby PJ: Plasma neuropeptide Y in the symptomatic limb of patients with causalgic pain. Clin Auton Res. 1994, 4 (3): 113-116. 10.1007/BF01845774.View ArticlePubMedGoogle Scholar
- Drummond PD, Finch PM, Smythe GA: Reflex sympathetic dystrophy: the significance of differing plasma catecholamine concentrations in affected and unaffected limbs. Brain. 1991, 114 (Pt 5): 2025-2036.View ArticlePubMedGoogle Scholar
- Zanchetti A, Bond MG, Hennig M, Neiss A, Mancia G, Dal Palu C, Hansson L, Magnani B, Rahn KH, Reid J, et al: Risk factors associated with alterations in carotid intima-media thickness in. J Hypertens. 1998, 16 (7): 949-961. 10.1097/00004872-199816070-00008.View ArticlePubMedGoogle Scholar
- O’Leary DH, Polak JF: Intima-media thickness: a tool for atherosclerosis imaging and event prediction. Am J Cardiol. 2002, 90 (10C): 18L-21L.View ArticlePubMedGoogle Scholar
- Thakore AH, Guo CY, Larson MG, Corey D, Wang TJ, Vasan RS, D’Agostino RB, Lipinska I, Keaney JF, Benjamin EJ, et al: Association of multiple inflammatory markers with carotid intimal medial thickness and stenosis (from the Framingham Heart Study). Am J Cardiol. 2007, 99: 1598-1602. 10.1016/j.amjcard.2007.01.036. United StatesView ArticlePubMedGoogle Scholar
- Skoog T, Dichtl W, Boquist S, Skoglund-Andersson C, Karpe F, Tang R, Bond MG, de Faire U, Nilsson J, Eriksson P, et al: Plasma tumour necrosis factor-alpha and early carotid atherosclerosis in healthy middle-aged men. Eur Heart J. 2002, 23: 376-383. 10.1053/euhj.2001.2805.View ArticlePubMedGoogle Scholar
- Del Rincon I, Williams K, Stern MP, Freeman GL, O’Leary DH, Escalante A: Association between carotid atherosclerosis and markers of inflammation in rheumatoid arthritis patients and healthy subjects. Arthritis Rheum. 2003, 48 (7): 1833-1840. 10.1002/art.11078.View ArticlePubMedGoogle Scholar
- Ross AC, Rizk N, O’Riordan MA, Dogra V, El-Bejjani D, Storer N, Harrill D, Tungsiripat M, Adell J, McComsey GA: Relationship between inflammatory markers, endothelial activation markers, and carotid intima-media thickness in HIV-infected patients receiving antiretroviral therapy. Clin Infect Dis. 2009, 49 (7): 1119-1127. 10.1086/605578.View ArticlePubMedPubMed CentralGoogle Scholar
- Kang ES, Kim HJ, Kim YM, Lee S, Cha BS, Lim SK, Lee HC: Serum high sensitivity C-reactive protein is associated with carotid intima-media thickness in type 2 diabetes. Diabetes Res Clin Pract. 2004, 66 (1): S115-120. IrelandView ArticlePubMedGoogle Scholar
- Lagier R: Partial algodystrophy of the knee. An anatomico-radiological study of one case. J Rheumatol. 1983, 10 (2): 255-260.PubMedGoogle Scholar
- van der Laan L, ter Laak HJ, Gabreels-Festen A, Gabreels F, Goris RJ: Complex regional pain syndrome type I (RSD): pathology of skeletal muscle and peripheral nerve. Neurology. 1998, 51 (1): 20-25. 10.1212/WNL.51.1.20.View ArticlePubMedGoogle Scholar
- Albrecht PJ, Hines S, Eisenberg E, Pud D, Finlay DR, Connolly MK, Pare M, Davar G, Rice FL: Pathologic alterations of cutaneous innervation and vasculature in affected limbs from patients with complex regional pain syndrome. Pain. 2006, 120 (3): 244-266. 10.1016/j.pain.2005.10.035.View ArticlePubMedGoogle Scholar
- Groeneweg JG, Antonissen CH, Huygen FJ, Zijlstra FJ: Expression of endothelial nitric oxide synthase and endothelin-1 in skin tissue from amputated limbs of patients with complex regional pain syndrome. Mediators Inflamm. 2008, 2008: 680981-View ArticlePubMedPubMed CentralGoogle Scholar
- Wuppenhorst N, Maier C, Frettloh J, Pennekamp W, Nicolas V: Sensitivity and specificity of 3-phase bone scintigraphy in the diagnosis of complex regional pain syndrome of the upper extremity. Clin J Pain. 2010, 26 (3): 182-189. 10.1097/AJP.0b013e3181c20207.View ArticlePubMedGoogle Scholar
- Oldfield RC: The assessment and analysis of handedness: the Edinburgh inventory. Neuropsychologia. 1971, 9 (1): 97-113. 10.1016/0028-3932(71)90067-4.View ArticlePubMedGoogle Scholar
- Touboul PJ, Hennerici MG, Meairs S, Adams H, Amarenco P, Bornstein N, Csiba L, Desvarieux M, Ebrahim S, Fatar M, et al: Mannheim carotid intima-media thickness consensus (2004–2006). An update on behalf of the Advisory Board of the 3rd and 4th Watching the Risk Symposium, 13th and 15th European Stroke Conferences, Mannheim, Germany, 2004, and Brussels, Belgium, 2006. Cerebrovasc Dis. 2007, 23 (1): 75-80. 10.1159/000097034.View ArticlePubMedGoogle Scholar
- Ku YM, Kim YO, Kim JI, Choi YJ, Yoon SA, Kim YS, Song SW, Yang CW, Chang YS, Bang BK: Ultrasonographic measurement of intima-media thickness of radial artery in pre-dialysis uraemic patients: comparison with histological examination. Nephrol Dial Transplant. 2006, 21: 715-720. 10.1093/ndt/gfi214. EnglandView ArticlePubMedGoogle Scholar
- Mourad JJ, Girerd X, Boutouyrie P, Laurent S, Safar M, London G: Increased stiffness of radial artery wall material in end-stage renal disease. Hypertension. 1997, 30 (6): 1425-1430. 10.1161/01.HYP.30.6.1425.View ArticlePubMedGoogle Scholar
- Keymel S, Heinen Y, Balzer J, Rassaf T, Kelm M, Lauer T, Heiss C: Characterization of macro-and microvascular function and structure in patients with type 2 diabetes mellitus. Am J Cardiovasc Dis. 2011, 1 (1): 68-75.PubMedPubMed CentralGoogle Scholar
- Howard G, Sharrett AR, Heiss G, Evans GW, Chambless LE, Riley WA, Burke GL: Carotid artery intimal-medial thickness distribution in general populations as evaluated by B-mode ultrasound. ARIC Investigators. Stroke. 1993, 24 (9): 1297-1304. 10.1161/01.STR.24.9.1297.View ArticlePubMedGoogle Scholar
- Groeneweg G, Huygen FJ, Coderre TJ, Zijlstra FJ: Regulation of peripheral blood flow in Complex Regional Pain Syndrome: clinical implication for symptomatic relief and pain management. BMC Musculoskelet Disord. 2009, 10: 116-10.1186/1471-2474-10-116.View ArticlePubMedPubMed CentralGoogle Scholar
- Schattschneider J, Hartung K, Stengel M, Ludwig J, Binder A, Wasner G, Baron R: Endothelial dysfunction in cold type complex regional pain syndrome. Neurology. 2006, 67 (4): 673-675. 10.1212/01.wnl.0000229931.40631.31.View ArticlePubMedGoogle Scholar
- Wesseldijk F, Huygen FJ, Heijmans-Antonissen C, Niehof SP, Zijlstra FJ: Six years follow-up of the levels of TNF-alpha and IL-6 in patients with complex regional pain syndrome type 1. Mediators Inflamm. 2008, 2008: 469439-View ArticlePubMedPubMed CentralGoogle Scholar
- Schinkel C, Gaertner A, Zaspel J, Zedler S, Faist E, Schuermann M: Inflammatory mediators are altered in the acute phase of posttraumatic complex regional pain syndrome. Clin J Pain. 2006, 22: 235-239. 10.1097/01.ajp.0000169669.70523.f0. United StatesView ArticlePubMedGoogle Scholar
- Uceyler N, Rogausch JP, Toyka KV, Sommer C: Differential expression of cytokines in painful and painless neuropathies. Neurology. 2007, 69: 42-49. 10.1212/01.wnl.0000265062.92340.a5. United StatesView ArticlePubMedGoogle Scholar
- Wells MR, Racis SP, Vaidya U: Changes in plasma cytokines associated with peripheral nerve injury. J Neuroimmunol. 1992, 39 (3): 261-268. 10.1016/0165-5728(92)90260-R.View ArticlePubMedGoogle Scholar
- Giles JT, Post WS, Blumenthal RS, Polak J, Petri M, Gelber AC, Szklo M, Bathon JM: Longitudinal predictors of progression of carotid atherosclerosis in rheumatoid arthritis. Arthritis Rheum. 2011, 63 (11): 3216-3225. 10.1002/art.30542.View ArticlePubMedPubMed CentralGoogle Scholar
- Girerd X, Giannattasio C, Moulin C, Safar M, Mancia G, Laurent S: Regression of radial artery wall hypertrophy and improvement of carotid artery compliance after long-term antihypertensive treatment in elderly patients. J Am Coll Cardiol. 1998, 31: 1064-1073. 10.1016/S0735-1097(98)00043-6. United StatesView ArticlePubMedGoogle Scholar
- Schinkel C, Scherens A, Koller M, Roellecke G, Muhr G, Maier C: Systemic inflammatory mediators in post-traumatic complex regional pain syndrome (CRPS I) - longitudinal investigations and differences to control groups. Eur J Med Res. 2009, 14 (3): 130-135. 10.1186/2047-783X-14-3-130.View ArticlePubMedPubMed CentralGoogle Scholar
- Lorenz MW, Polak JF, Kavousi M, Mathiesen EB, Volzke H, Tuomainen TP, Sander D, Plichart M, Catapano AL, Robertson CM, et al: Carotid intima-media thickness progression to predict cardiovascular events in the general population (the PROG-IMT collaborative project): a meta-analysis of individual participant data. Lancet. 2012, 379: 2053-2062. 10.1016/S0140-6736(12)60441-3.View ArticlePubMedPubMed CentralGoogle Scholar
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2377/13/14/prepub
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.