CRPS Bugle | Update on the latest research on complex regional pain syndrome #CRPS #RSD

ImageHappy New Year! — and now just into 2014 by a few hours, the first CRPS Bugle of the year. I anticipate another 12 months of advancement in the understanding of pain neurobiology, and new ways of thinking about pain so we can tackle the problem with increasing effectiveness. 

Here are some recent studies:

Complex regional pain syndrome type I of the knee: A systematic literature review.

Eur J Pain. 2013 Dec 17. doi: 10.1002/j.1532-2149.2013.00434.x. — van Bussel CM, Stronks DL, Huygen FJ.


In our Center for Pain Medicine, a group of patients reported to have symptoms possibly attributable to complex regional pain syndrome (CRPS) of only the knee(s). Therefore, this study aimed to investigate whether the literature reports on patients with CRPS type I in the knee(s) alone and, if so, to summarize the reported diagnostics, aetiology and treatment strategies of CRPS of the knee(s). Medline, Embase, Cochrane Library, PubMed and Web of Science were searched for articles focusing on a painful disorder of the knee, most likely CRPS type I. Screening on title and abstract was followed by full-text reading and searching of reference lists to determine the final set of relevant articles. Of the 513 articles identified, 31 met the inclusion criteria. These articles reported on a total of 368 patients diagnosed with CRPS of the knee(s) based on the diagnostic criteria used at the time of publication. Knee surgery, especially arthroscopic surgery, was the most common inciting event in developing CRPS of the knee(s). Various treatment strategies were applied with variable outcomes. In conclusion, the scientific literature does report cases of CRPS type I of only the knee(s). This applies when using the diagnostic criteria prevailing at the time of publication and, obviously for a smaller number of cases, also when using the current Budapest criteria set. Arthroscopic knee surgery is described multiple times as the inciting event. We recommend to include CRPS of the knee in future research on the aetiological mechanisms of and optimal treatment for CRPS.

RS — this is a very useful contribution to the literature. I have seen a number of cases of CRPS that involve the knee joint. It is worth noting that the Budapest Criteria should be used for diagnosis. The oft omitted descriptions of the CRPS experience include an altered sense of the knee, and usually beyond the boundaries of the joint, in addition to varying degrees of neglect and denial. Many people with persisting knee pain will also demonstrate aversion, not wishing to look directly, touch or be touched, each of these triggering withdrawal and perhaps a feeling of nausea or a shudder such as that felt in response to a knife screeching across a plate. Restoring a normal body sense is key to recovery, at least due to the brain’s need to integrate senses and the threat value of altered functioning to diminish as both the physical sense of the body changes and the mental processing of what is happening becomes less burdensome. 


Health-related quality of life in 975 patients with Complex Regional Pain Syndrome type 1

Pain. 2013 Dec 13. pii: S0304-3959(13)00665-9. doi: 10.1016/j.pain.2013.12.017 — van Velzen GA, Perez RS, van Gestel MA, Huygen FJ, Kleef MV, Eijs FV, Dahan A, van Hilten JJ, Marinus J.


There are limited data available on health related quality of life (QoL) of patients with complex regional pain syndrome (CRPS). In the present study we examined QoL in 975 CRPS patients attending six different clinics in the Netherlands. QoL was assessed using the SF-36 with the mental health summary score (MHS) and the physical health summary score (PHS) as dependent variable. Influence of gender, type of affected limb, disease duration, pain scores, CRPS severity and the employed set of diagnostic criteria was investigated. We found the lowest scores of QoL in the physical domains of the SF-36, with lower limb CRPS patients reporting poorer results than patients with an affected upper limb. Influence of gender on QoL was not found and correlations of QoL with disease duration and the CRPS severity score were weak. Pain correlated moderately with QoL. In addition, patients fulfilling stricter diagnostic criteria (i.e., the Budapest criteria) had lower QoL scores than patients fulfilling less strict criteria (i.e., the Orlando criteria). We conclude that loss of QoL in CRPS patients is mainly due to reduced physical health. A comparison with data available from the literature shows that CRPS patients generally report poorer QoL than patients with other chronic pain conditions, particularly in the physical domains. Pain correlated moderately with QoL and therefore deserves on-going attention by physicians. Lastly, patients meeting the diagnostic Budapest criteria have lower QoL scores than patients meeting the Orlando criteria, highlighting the impact of different sets of criteria on population characteristics.


Sensitivity and specificity of 3-phase bone scintigraphy in the diagnosis of complex regional pain syndrome of the upper extremity.

Clin J Pain. 2010 Mar-Apr;26(3):182-9. doi: 10.1097/AJP.0b013e3181c20207 — Wüppenhorst N, Maier C, Frettlöh J, Pennekamp W, Nicolas V.


Joint and bone alterations are seldom mentioned in the diagnostic criteria for complex regional pain syndrome (CRPS) even though they are important for long-term outcome. Altered periarticular bone metabolism can be detected by 3-phase bone scintigraphy (TPBS). Although frequently examining the diagnostic efficacy of TPBS is debatable.

In all, 78 TPBS (45 CRPS/33 control group) were evaluated qualitatively and quantitatively. Sensitivity and specificity of the qualitative blinded reviewer analysis (n=57) compared with quantitative region of interest (ROI)-based analysis over the metacarpophalangeal, proximal, and distal interphalangeal joints (n=74) were evaluated. Patients’ sex, age, duration of CRPS, inciting event, extent of joint alteration, and handedness were included as covariables.

Qualitative blinded reviewer TPBS analysis had a high specificity (83%-100%). However, sensitivity was 31% to 50%. Interrater reliability was moderate (kappa score 0.56). Using the ROI-based evaluation, the highest sensitivity (69%) and specificity (75%) (ROI score > or =1.32) was shown for phase 3, whereas sensitivity of phases 1 and 2 rapidly declined to 50%. Duration of CRPS until TPBS was the only variable with significant impact on ROI scores of phase 3 (F=23.7; P=0.000; R=0.42). ROI scores declined with increasing duration of CRPS.

In conclusion, TPBS is a highly specific tool for diagnosing CRPS of the upper limb. ROI evaluation of phase 3 within the first 5 months after onset of CRPS is an appropriate additional diagnostic tool to confirm or exclude CRPS of the upper extremity.

RS: a slightly older study that looks at the possibility of a diagnostic tool for CRPS beyond the criteria determined by signs and symptoms (Budapest). The next paper (below) suggests that caution is prudent — often in the literature a finding is countered with further data that throws up a different view, nonetheless an important development in the route to understanding the role of BS in diagnosis.


Concordance of qualitative bone scintigraphy results with presence of clinical complex regional pain syndrome 1: meta-analysis of test accuracy studies.

Eur J Pain. 2012 Nov;16(10):1347-56. doi: 10.1002/j.1532-2149.2012.00137.x — Ringer R, Wertli M, Bachmann LM, Buck FM, Brunner F.


To date, no attempt has been made to investigate the agreement between qualitative bone scintigraphy (BS) and the presence of complex regional pain syndrome 1 (CRPS 1) and the agreement between a negative BS in the absence of CRPS 1.

To summarize the existing evidence quantifying the concordance of qualitative BS in the presence or absence of clinical CRPS 1.

We searched Medline, Embase, Dare and the Cochrane Library and screened bibliographies of all included studies.

We selected diagnostic studies investigating the association between qualitative BS results and the clinical diagnosis of CRPS 1. The minimum requirement for inclusion was enough information to fill the two-by-two tables.

Twelve studies met our inclusion criteria and were included in the meta-analysis. The pooled mean sensitivity of 12 two-by-two tables was 0.87 (95% CI, 0.68-0.97) and specificity was 0.69 (95% CI, 0.47-0.85). The pooled mean sensitivity for the subgroup with clearly defined diagnostic criteria (seven two-by-two tables) was 0.80 (95% CI, 0.44-0.95) and specificity was 0.73 (95% CI, 0.40-0.91).

Based on this study, clinicians must be advised that a positive BS is not necessarily concordant with presence of absence or CRPS 1. Given the moderate level of concordance between a positive BS in the absence of clinical CRPS 1, discordant results potentially impede the diagnosis of CRPS 1.


Objective sensory evaluation of the spread of complex regional pain syndrome.

Pain Physician. 2013 Nov-Dec;16(6):581-91 — Edinger L, Schwartzman RJ, Ahmad A, Erwin K, Alexander GM.

The spread of complex regional pain syndrome (CRPS) has been well documented. Many severe refractory long-standing patients have total body pain (TBP) that evolved from a single extremity injury.

The purpose of this study was to document by objective sensory threshold testing the extent of body area involvement in 20 long-standing patients with CRPS who have TBP.

A comparison of sensory threshold testing parameters between 20 long-standing refractory patients with CRPS who have TBP versus 10 healthy participants.

Twenty patients with CRPS who stated that they suffered from total body pain were chosen from the Drexel University College of Medicine CRPS database. They were compared to 10 healthy participants that were age and gender matched to the patients with CRPS. The sensory parameters tested were: skin temperature; static and mechanical allodynia; thermal allodynia; mechanical hyperalgesia; after sensations following all sensory tests. The sites chosen for testing in the patients with CRPS were the most painful area in each of 8 body regions that comprised the total body area.

Five patients with CRPS had signs of CRPS over 100% of their body (20%). One patient had pain over 87% and another had pain over 90% of their body area. The average percentage of body involvement was 62% (range 37% – 100%). All patients with CRPS had at least one sensory parameter abnormality in all body regions. All patients with CRPS had lower pain thresholds for static allodynia in all body areas, while 50% demonstrated a lower threshold for dynamic allodynia in all body regions compared to the healthy participants. Cold allodynia had a higher median pain rating on the Likert pain scale in all body areas versus healthy participants except for the chest, abdomen, and back. Eighty-five percent of the patients with CRPS had a significantly lower pain threshold for mechanical hyperalgesia in all body areas compared to the healthy participants. After sensations occurred after all sensory parameters in the extremities in patients with CRPS.

The primary limitations of this study would be the variability of self-reported data (each subject’s assessment of pain/ discomfort to a tested parameter) and the challenge to uniformly administer each parameter’s assessment since simple tools and not precision instruments were used (with the exception of skin temperature).

TBP and objective sensory loss occur in 20% of patients with refractory long-standing CRPS.

RS: In CRPS and other chronically painful conditions it is common to find other sensitivities including the functional pain syndromes, more-so in women, including irritable bowel syndrome, pelvic pain, migraines and persisting aches and pains with a varying degree of impact and suffering. 



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