CRPS-like presentations & neuropathic pain

I see a number of cases that feature some of the signs and symptoms of CRPS but would not be actually diagnosed as CRPS according to the Budapest criteria. For example, tendinopathy, neuropathies, post-surgery and following a nerve injury. The latter you may say could underpin CRPS II. There has always been difficulty suggesting that CRPS I is devoid of a nerve injury as of course nerves are ‘soft tissue’ and can easily be damaged during an injury. Of course when a nerve is injured neuropathic pain can be a consequence concurrent with the nociceptive pain.

Immobilisation can lead to similar symptoms including pain, altered movement, atrophy and vasomotor changes. One must consider the fact that for tissues to be healthy they require movement. Change in use of a body part will have a number of consequences including actual tissue change alongside issues of movement. Movement-based problems will be as a result of the altered tissue properties, cortical change and also a willingness to move. Fear avoidance, catastrophising and a belief that movement that hurts is a sign that damage is being done. This scenario can be played out in a number of conditions such as Achilles tendinopathy, tennis elbow, RSI and others.

Neuropathic pain is ‘pain arising as a direct consequence of a lesion or disease affecting the somatosensory system’ NeuPSIG

Neuropathic pain measures are a useful way of determining whether there is a neuropathic component. Commonly used are the s-LANSS and painDETECT – shown below – alongside a thorough assessment. A recent paper discusses the NeuPSIG assessment guidelines.

painDETECT Questionaire

s-LANSS

When neuropathic pain is found to be part of the presentation, this can guide treatment including medication and therapy. The former needs to be attended to with a plan that is fully understood by the patient: how the medication works, how to use it and how to gradually reduce the dosage. The latter includes techniques such as graded motor imagery, 2-point discrimination and desensitisation techniques at a peripheral and central level.

RS www.specialistpainphysio.com

CRPS Budapest Diagnostic Criteria

A        The patient has continuing pain which is disproportionate to the inciting event

Sensory          Allodynia (to light touch and/or temperature sensation and/or deep somatic pressure and/or joint movement) and/or hyperalgesia (to pinprick)

Vasomotor          Temperature asymmetry (more than 1 deg.) and/or skin colour changes and/or skin colour asymmetry

Sudomotor/oedema          Oedema and/or sweating changes and/or sweating asymmetry

Motor/trophic         Decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair/nail/skin)

Signs – see or feel a problem

Symptoms – patient reports a problem

B          The patient has at least one sign in two or more of the categories

C          The patient reports at least one symptom in three or more of the categories

D         No other diagnosis can better explain the signs and symptoms

Literature

Pain Med. 2007 May-Jun;8(4):326-31.

Proposed new diagnostic criteria for complex regional pain syndrome.

Rehabilitation Institute of Chicago, Northwestern University, Chicago, Illinois, USA. nharden@ric.org

This topical update reports recent progress in the international effort to develop a more accurate and valid diagnostic criteria for complex regional pain syndrome (CRPS). The diagnostic entity of CRPS (published in the International Association for the Study of Pain’s Taxonomy monograph in 1994; International Association for the Study of Pain [IASP]) was intended to be descriptive, general, and not imply etiopathology, and had the potential to lead to improved clinical communication and greater generalizability across research samples. Unfortunately, realization of this potential has been limited by the fact that these criteria were based solely on consensus and utilization of the criteria in the literature has been sporadic at best. As a consequence, the full potential benefits of the IASP criteria have not been realized. Consensus-derived criteria that are not subsequently validated may lead to over- or underdiagnosis, and will reduce the ability to provide timely and optimal treatment. Results of validation studies to date suggest that the IASP/CRPS diagnostic criteria are adequately sensitive; however, both internal and external validation research suggests that utilization of these criteria causes problems of overdiagnosis due to poor specificity. This update summarizes the latest international consensus group’s action in Budapest, Hungary to approve and codify empirically validated, statistically derived revisions of the IASP criteria for CRPS.

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Pain. 2010 Aug;150(2):268-74. Epub 2010 May 20.

Validation of proposed diagnostic criteria (the “Budapest Criteria”) for Complex Regional Pain Syndrome.

Rehabilitation Institute of Chicago, Chicago, IL 60611, USA. nharden@ric.org

Current IASP diagnostic criteria for CRPS have low specificity, potentially leading to overdiagnosis. This validation study compared current IASP diagnostic criteria for CRPS to proposed new diagnostic criteria (the “Budapest Criteria”) regarding diagnostic accuracy. Structured evaluations of CRPS-related signs and symptoms were conducted in 113 CRPS-I and 47 non-CRPS neuropathic pain patients. Discriminating between diagnostic groups based on presence of signs or symptoms meeting IASP criteria showed high diagnostic sensitivity (1.00), but poor specificity (0.41), replicating prior work. In comparison, the Budapest clinical criteria retained the exceptional sensitivity of the IASP criteria (0.99), but greatly improved upon the specificity (0.68). As designed, the Budapest research criteria resulted in the highest specificity (0.79), again replicating prior work. Analyses indicated that inclusion of four distinct CRPS components in the Budapest Criteria contributed to enhanced specificity. Overall, results corroborate the validity of the Budapest Criteria and suggest they improve upon existing IASP diagnostic criteria for CRPS.

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Pain. 2010 Dec;151(3):870-6. Epub 2010 Oct 20.

Development of a severity score for CRPS.

Center for Pain Studies, Rehabilitation Institute of Chicago, Chicago, IL 60611, USA. nharden@ric.org

The clinical diagnosis of Complex Regional Pain Syndrome (CRPS) is a dichotomous (yes/no) categorization necessary for clinical decision-making. However, such dichotomous diagnostic categories do not convey an individual’s subtle and temporal gradations in severity of the condition, and have poor statistical power when used as an outcome measure in research. This study evaluated the validity and potential utility of a continuous type score to index severity of CRPS. Psychometric and medical evaluations were conducted in 114 CRPS patients and 41 non-CRPS neuropathic pain patients. Based on the presence/absence of 17 clinically-assessed signs and symptoms of CRPS, an overall CRPS Severity Score (CSS) was derived. The CSS discriminated well between CRPS and non-CRPS patients (p<.001), and displayed strong associations with dichotomous CRPS diagnoses using both IASP diagnostic criteria (Eta=0.69) and proposed revised criteria (Eta=0.77-0.88). Higher CSS was associated with significantly higher clinical pain intensity, distress, and functional impairments, as well as greater bilateral temperature asymmetry and thermal perception abnormalities (p’s<.05). In an archival prospective dataset, increases in anxiety and depression from pre-surgical baseline to 4 weeks post-knee arthroplasty were found to predict significantly higher CSS at 6- and 12-month follow-up (p’s<.05). Results indicate the CSS corresponds with and complements currently accepted dichotomous diagnostic criteria for CRPS, and support its validity as an index of CRPS severity. Its utility as an outcome measure in research studies is also suggested, with potential statistical advantages over dichotomous diagnostic criteria.

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Eur J Pain. 2011 Sep;15(8):830.e1-8. Epub 2011 Feb 22.

Distribution of signs and symptoms of Complex Regional Pain Syndrome type I in patients meeting the diagnostic criteria of the International Association for the Study of Pain.

Department of Anesthesiology, VU University Medical Center, Amsterdam, The Netherlands. rdh.deboer@vumc.n

The aim of the present study was to describe the occurrence of signs and symptoms in CRPS I patients meeting the IASP (Orlando) criteria, assess the occurrence of signs and symptoms in relation to disease duration and compare these to historical data based on a different diagnostic criteria set. Six hundred and ninety-two ambulatory patients meeting the IASP criteria for CRPS I referred to the outpatient clinics of five participating centers were included in this cross-sectional study. Characteristics were recorded in a standardized fashion and categorized according to the factor structure proposed by Bruehl/Harden. Subgroups were classified according to the duration of complaints and compared to historical data as described by Veldman et al. The Chi-square test corrected for multiple comparisons was used for statistical analysis. The prevalence of sensory signs was higher in patients with longer disease duration, especially for the allodynia’s and hyperalgesia (all p<0.001). Signs in vasomotor (color difference; p=0.0007) and sudomotor (edema; p<0.0001) subgroups were less frequently present in patients with longer disease duration (i.e. >6 months). Prevalences of signs in the motor subgroup were all higher (p<0.0001) in patients with longer disease duration, except for limited range of motion. Occurrence of signs was significantly lower (<0.001) than those reported by Veldman et al., except for hyperesthesia and dystonia. Occurrence rates may vary at different time points after onset of CRPS, which may be of influence for diagnosing patients with novel derived diagnostic criteria. We argue for a mechanism based description of CRPS I based on one set of uniform generally accepted diagnostic criteria in future studies.

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CRPS Review 20th February 2012

A selection of papers to peruse:

Predictors of Pain Relieving Response to Sympathetic Blockade in Complex Regional Pain Syndrome Type 1

Anesthesiology: January 2012 – Volume 116 – Issue 1 – p 113–121
doi: 10.1097/ALN.0b013e31823da45f Pain Medicine

van Eijs, Frank M.D.*; Geurts, José M.Sc.†; van Kleef, Maarten M.D., Ph.D.‡; Faber, Catharina G. M.D., Ph.D.§; Perez, Roberto S. Ph.D.‖; Kessels, Alfons G.H. M.D., M.Sc.#; Van Zundert, Jan M.D., Ph.D.**

Abstract
Background: Sympathetic blockade with local anesthetics is used frequently in the management of complex regional pain syndrome type 1(CRPS-1), with variable degrees of success in pain relief. The current study investigated which signs or symptoms of CRPS-1 could be predictive of outcome. The incidence of side effects and complications of sympathetic blockade also were determined prospectively.
Methods: A prospective observational study was done of 49 patients with CRPS-1 in one extremity only and for less than 1-yr duration who had severe pain and persistent functional impairment with no response to standard treatment with medication and physical therapy.
Results: Fifteen (31%) patients had good or moderate response. The response rate was not different in patient groups with cold or warm type CRPS-1 or in those with more or less than 1.5°C differential increase in skin temperature after sympathetic blockade. Allodynia and hypoesthesia were negative predictors for treatment success in CRPS-1. There were no symptoms or signs of CRPS-1 that positively predicted treatment success. A majority of patients (84%) experienced transient side effects such as headache, dysphagia, increased pain, backache, nausea, blurred vision, groin pain, hoarseness, and hematoma at the puncture site. No major complications were reported.
Conclusions: The presence of allodynia and hypoesthesia are negative predictors for treatment success. The selection of sympathetic blockade as treatment for CRPS-1 should be balanced carefully between potential success and side effect ratio. The procedure is as likely to cause a transient increase in pain as a decrease in pain. Patients should be informed accordingly.

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Motor control in complex regional pain syndrome: A kinematic analysis

http://dx.doi.org/10.1016/j.pain.2011.12.018

  • J.C.M. Schildera, , ,
  • A.C. Schoutenb, c,
  • R.S.G.M. Perezd,
  • F.J.P.M. Huygene,
  • A. Dahanf,
  • L.P.J.J. Noldusg,
  • J.J. van Hiltena,
  • J. Marinusa

Abstract

This study evaluated movement velocity, frequency, and amplitude, as well as the number of arrests in three different subject groups, by kinematic analysis of repetitive movements during a finger tapping (FT) task. The most affected hands of 80 patients with complex regional pain syndrome (CRPS) were compared with the most affected hands of 60 patients with Parkinson disease (PD) as well as the nondominant hands of 75 healthy control (HC) subjects. Fifteen seconds of FT with thumb and index finger were recorded by a 60-Hz camera, which allowed the whole movement cycle to be evaluated and the above mentioned movement parameters to be calculated. We found that CRPS patients were slower and tapped with more arrests than the two other groups. Moreover, in comparison with the hands of the HC subjects, the unaffected hands of the CRPS patients were also impaired in these domains. Impairment was not related to pain. Dystonic CRPS patients performed less well than CRPS patients without dystonia. In conclusion, this study shows that voluntary motor control in CRPS patients is impaired at both the affected as well as the unaffected side, pointing at involvement of central motor processing circuits.

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Psychological factors associated with self-perceived pain-related disability among individuals diagnosed with complex regional pain syndrome

by Mann, Jeffrey C., Psy.D., ADLER SCHOOL OF PROFESSIONAL PSYCHOLOGY, 2010, 107 pages; 3452691

Abstract:

Over the last several decades the importance of psychological factors in understanding pain-related disability has grown tremendously. Research has explored many psychological constructs and their relationship to pain related disability with several constructs emerging as clinically significant. The research conducted to date has predominantly focused on individuals with conditions such as low-back, arthritis, or other forms of musculoskeletal pain. To date, there is no research examining the predominant psychological constructs with a population of individuals diagnosed with Complex Regional Pain Syndrome (CRPS). This study had two primary purposes: (a) To examine the relationship between pain catastrophizing, pain helplessness, active coping, passive coping and self-perceived, pain-related disability, (b) to determine the amount of variance in self-perceived, pain-related disability accounted for by pain catastrophizing, pain helplessness, active coping, and passive coping. The research sample included 102 individuals diagnosed with CRPS being treated at a pain clinic. The instruments used to measure the independent variables were: Pain Helplessness Index (PHI), Pain Catastrophizing Scale (PCS), and the Coping Strategies Questionnaire (CSQ). The dependent variable was measured with the Perceived Disability Scale (PDS). Correlation analysis indicated that pain catastrophizing, pain helplessness, and passive coping are all positively correlated with self-perceived, pain-related disability. Multiple regression results indicated that pain catastrophizing, and pain helplessness account for 15.3% of the variance in self-perceived, pain-related disability. Active coping and passive coping did not account for a statistically significant portion of the variance. The findings of this study demonstrate the importance of pain catastrophizing and pain helplessness when treating individuals diagnosed with CRPS and raises doubt about the utility of active coping and the detriment of passive coping. Further investigation is needed to determine the efficacy of interventions focused on modifying pain catastrophizing and pain helplessness as a indirect method of decreasing self-perceived disability.

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Mast Cells: Source of Inflammation in Complex Regional Pain Syndrome?

Mast Cells: Source of Inflammation in CRPS

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Targeting Cortical Representations in the Treatment of Chronic Pain: A Review

  1. G. Lorimer Moseley
  2. Herta Flor

Recent neuroscientific evidence has confirmed the important role of cognitive and behavioral factors in the development and treatment of chronic pain. Neuropathic and musculoskeletal pain are associated with substantial reorganization of the primary somatosensory and motor cortices as well as regions such as the anterior cingulate cortex and insula. What is more, in patients with chronic low back pain and fibromyalgia, the amount of reorganizational change increases with chronicity; in phantom limb pain and other neuropathic pain syndromes, cortical reorganization correlates with the magnitude of pain. These findings have implications for both our understanding of chronic pain and its prevention and treatment. For example, central alterations may be viewed as pain memories that modulate the processing of both noxious and nonnoxious input to the somatosensory system and outputs of the motor and other response systems. The cortical plasticity that is clearly important in chronic pain states also offers potential targets for rehabilitation. The authors review the cortical changes that are associated with chronic pain and the therapeutic approaches that have been shown to normalize representational changes and decrease pain and discuss future directions to train the brain to reduce chronic pain.

RSout of these papers this is the one that I am most interested in reading. A number of the techniques that I use in the clinic for CRPS are targeting the changes in the brain, including Graded Motor Imagery, 2-point discrimination training, sensorimotor integration and mindfulness. We are both obliged and wise to consider why is it that the brain continues to protect a body part(s) and how has this happened? Herta Flor talks about learning and memory in pain and the conditioning process. Reinforcements for particular beliefs and behaviours can start early after an injury or initiation of a pain state. In these stages we must seek to prevent pathological beliefs developing by using focused education, promote useful behaviours that are reinforced and set goals that sit alongside processes of healing and recovery.

Specialist Pain Physio Clinics in London for CRPS

Musings on Pain – a dialogue between the brain and the foot

This is a conversation between a brain and a foot. The foot has been a problem for some time now, years even.

The foot was injured at a railway station early one winter’s morning before the sun had appeared. In the distance I could see the usual people waiting on the platform, sheltering under their hats and behind raised collars. Making my way across the concourse, my shoes were barely gripping the floor. It was clear to see that others had skidded in their haste. The rain had only just stopped.

Although it is a foot that hurts, it is not a foot that hurts. What does that mean? Regular readers will remember that pain is a brain experience 100% of the time. The pain is a response by the brain to a perceived threat and allocated an anatomical location via the cortical maps. In this sense, the brain is creating the experience like all other conscious experiences and making it real. This is the best biological response that the brain can muster at that moment for that particular situation. So, although the foot hurts, the foot doesn’t hurt, it is the brain telling you that you need to do something with the foot by making it hurt. Via the brain. Mmm. See Lorimer Moseley talking below:

 

Pain mechanisms (2)

Keith Smart has been looking at a mechanisms-based approach to pain. As you may recall from the first piece on pain mechanisms and previous writings, I am a proponent of the view that we should be thinking about pain mechanisms. There are significant advantages to elucidating the underpinning physiological and pathology including understanding the patient’s description of their experience and to be able to focus treatment upon the mechanism(s) for more successful outcomes. Below are the papers by Keith Smart and others who have looked at pain mechanisms.

RS www.specialistpainphysio.com

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Clin J Pain. 2011 Oct;27(8):655-63. doi: 10.1097/AJP.0b013e318215f16a.

The Discriminative validity of “nociceptive,” “peripheral neuropathic,” and “central sensitization” as mechanisms-based classifications of musculoskeletal pain.

Source

St Vincent’s University Hospital, Elm Park, Dublin, Ireland. k.smart@ucd.ie

Abstract

OBJECTIVES:

Empirical evidence of discriminative validity is required to justify the use of mechanisms-based classifications of musculoskeletal pain in clinical practice. The purpose of this study was to evaluate the discriminative validity of mechanisms-based classifications of pain by identifying discriminatory clusters of clinical criteria predictive of “nociceptive,” “peripheral neuropathic,” and “central sensitization” pain in patients with low back (± leg) pain disorders.

METHODS:

This study was a cross-sectional, between-patients design using the extreme-groups method. Four hundred sixty-four patients with low back (± leg) pain were assessed using a standardized assessment protocol. After each assessment, patients’ pain was assigned a mechanisms-based classification. Clinicians then completed a clinical criteria checklist indicating the presence/absence of various clinical criteria.

RESULTS:

Multivariate analyses using binary logistic regression with Bayesian model averaging identified a discriminative cluster of 7, 3, and 4 symptoms and signs predictive of a dominance of “nociceptive,” “peripheral neuropathic,” and “central sensitization” pain, respectively. Each cluster was found to have high levels of classification accuracy (sensitivity, specificity, positive/negative predictive values, positive/negative likelihood ratios).

DISCUSSION:

By identifying a discriminatory cluster of symptoms and signs predictive of “nociceptive,” “peripheral neuropathic,” and “central” pain, this study provides some preliminary discriminative validity evidence for mechanisms-based classifications of musculoskeletal pain. Classification system validation requires the accumulation of validity evidence before their use in clinical practice can be recommended. Further studies are required to evaluate the construct and criterion validity of mechanisms-based classifications of musculoskeletal pain.

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J Man Manip Ther. 2010 Jun;18(2):102-10.

The reliability of clinical judgments and criteria associated with mechanisms-based classifications of pain in patients with low back pain disorders: a preliminary reliability study.

Source

UCD School of Public Health, Physiotherapy and Population Science, University College Dublin, Ireland.

Abstract

Mechanisms-based classifications of pain have been advocated for their potential to aid understanding of clinical presentations of pain and improve clinical outcomes. However, the reliability of mechanisms-based classifications of pain and the clinical criteria upon which such classifications are based are not known. The purpose of this investigation was to assess the inter- and intra-examiner reliability of clinical judgments associated with: (i) mechanisms-based classifications of pain; and (ii) the identification and interpretation of individual symptoms and signs from a Delphi-derived expert consensus list of clinical criteria associated with mechanisms-based classifications of pain in patients with low back (±leg) pain disorders. The inter- and intra-examiner reliability of an examination protocol performed by two physiotherapists on two separate cohorts of 40 patients was assessed. Data were analysed using kappa and percentage of agreement values. Inter- and intra-examiner agreement associated with clinicians’ mechanisms-based classifications of low back (±leg) pain was ‘substantial’ (kappa  = 0.77; 95% confidence interval (CI): 0.57-0.96; % agreement  = 87.5) and ‘almost perfect’ (kappa  = 0.96; 95% CI: 0.92-1.00; % agreement = 92.5), respectively. Sixty-eight and 95% of items on the clinical criteria checklist demonstrated clinically acceptable (kappa ⩾ 0.61 or % agreement ⩾ 80%) inter- and intra-examiner reliability, respectively. The results of this study provide preliminary evidence supporting the reliability of clinical judgments associated with mechanisms-based classifications of pain in patients with low back (±leg) pain disorders. The reliability of mechanisms-based classifications of pain should be investigated using larger samples of patients and multiple independent examiners.

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Man Ther. 2011 Nov 8. [Epub ahead of print]

Self-reported pain severity, quality of life, disability, anxiety and depression in patients classified with ‘nociceptive’, ‘peripheral neuropathic’ and ‘central sensitisation’ pain. The discriminant validity of mechanisms-based classifications of low back (±leg) pain.

Source

St Vincent’s University Hospital, Elm Park, Dublin 4, Ireland.

Abstract

Evidence of validity is required to support the use of mechanisms-based classifications of pain clinically. The purpose of this study was to evaluate the discriminant validity of ‘nociceptive’ (NP), ‘peripheral neuropathic’ (PNP) and ‘central sensitisation’ (CSP) as mechanisms-based classifications of pain in patients with low back (±leg) pain by evaluating the extent to which patients classified in this way differ from one another according to health measures associated with various dimensions of pain. This study employed a cross-sectional, between-subjects design. Four hundred and sixty-four patients with low back (±leg) pain were assessed using a standardised assessment protocol. Clinicians classified each patient’s pain using a mechanisms-based classification approach. Patients completed a number of self-report measures associated with pain severity, health-related quality of life, functional disability, anxiety and depression. Discriminant validity was evaluated using a multivariate analysis of variance. There was a statistically significant difference between pain classifications on the combined self-report measures, (p = .001; Pillai’s Trace = .33; partial eta squared = .16). Patients classified with CSP (n = 106) reported significantly more severe pain, poorer general health-related quality of life, and greater levels of back pain-related disability, depression and anxiety compared to those classified with PNP (n = 102) and NP (n = 256). A similar pattern was found in patients with PNP compared to NP. Mechanisms-based pain classifications may reflect meaningful differences in attributes underlying the multidimensionality of pain. Further studies are required to evaluate the construct and criterion validity of mechanisms-based classifications of musculoskeletal pain.

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Pain. 2011 Jul;152(7):1511-6. Epub 2011 Mar 10.

Identifying neuropathic back and leg pain: a cross-sectional study.

Source

School of Rehabilitation Sciences, Faculty of Health and Social Care Sciences, St. George’s University of London/Kingston University, Cranmer Terrace, London SW17 0RE, UK. I.Beith@sgul.kingston.ac.uk

Abstract

Low back pain is a widespread debilitating problem with a lifetime prevalence of 80%, with the underlying pain mechanism unknown in approximately 90% of cases. We used the painDETECT neuropathic pain screening questionnaire to identify likely pain mechanisms in 343 patients with low back pain with or without leg pain in southeastern England referred for physiotherapy. We related the identified possible pain mechanisms nociceptive, unclear, and neuropathic to standardised measures of pain severity (Numeric Rating Scale), disability (Roland Morris Low Back Pain Disability Questionnaire), anxiety and depression (Hospital Anxiety and Depression Scale), and quality of life (Short Form 36 Health Survey Questionnaire Version 2). In addition, we investigated any relationship between these possible pain mechanisms and leg pain, passive straight leg raise, and magnetic resonance imaging evidence confirming or eliminating nerve root compression. A total of 59% of participants (n=204) reported likely nociceptive pain, 25% (n=85) unclear, and 16% (n=54) possible neuropathic pain. The possible neuropathic pain group reported significantly higher pain, disability, anxiety, and depression, reduced quality of life and passive straight leg raise compared to the other pain groups (P<.05). A total of 96% of participants with possible neuropathic pain reported pain radiating to the leg (76% below the knee); however, leg pain was still more common in patients with nociceptive pain, suggesting that leg pain is sensitive to, but not specific to, possible neuropathic pain. No relationship was demonstrated between possible neuropathic pain and evidence for or absence of nerve root compression on magnetic resonance imaging scans. These findings suggest possible neuropathic pain is less common in low back pain patients referred through primary care and clarifies the usefulness of clinical tests for identifying possible neuropathic pain.

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J Pain. 2011 Oct;12(10):1080-7. Epub 2011 Jul 23.

The neuropathic components of chronic low back pain: a prospective multicenter study using the DN4 Questionnaire.

Source

INSERM U 987, Centre d’Evaluation et de Traitement de la Douleur, Hôpital Ambroise Paré, APHP, Boulogne-Billancourt, France. nadine.attal@apr.aphp.fr

Abstract

The present study investigated the neuropathic components of chronic low back pain (LBP) in patients with and without lower limb pain using the DN4 questionnaire and confirmed its psychometric properties. Patients (n = 132) from 11 French multidisciplinary pain or rheumatology centers were classified by a first investigator into 4 groups derived from the Quebec Task Force Classification of Spinal Disorders (QTFSD): group 1 (pain restricted to the lumbar area); group 2 (pain radiating proximally); group 3 (pain radiating below the knee without neurologic signs); and group 4 (pain radiating towards the foot in a dermatomal distribution, with neurological signs, corresponding to typical radiculopathy). A second investigator applied the DN4 questionnaire to the lower limb (groups 2 to 4) and lower back. A comparison of groups 1 and 4 confirmed the psychometric properties of DN4 (sensitivity 80%; specificity 92%, for a cutoff of 4/10, similar to other neuropathic conditions). In the lower limb, the proportion of patients with neuropathic pain (NP) was related to the distality of pain radiation (15, 39, and 80% in groups 2, 3 and 4, respectively; P < .0001). In the lower back, the proportion of patients with NP was higher for patients with typical radicular pain compared with the other groups (P = .006). Thus, typical radiculopathy has similar characteristics as other neuropathic conditions and is confirmed as the commonest neuropathic syndrome in LBP patients. The observation that neuropathic and nociceptive components of LBP vary in the back and lower limb probably accounts for the discrepancies of reported prevalence rates of NP in LBP. As this study was essentially based on a questionnaire, future studies combining standard clinical sensory testing, specific questionnaires, and more objective assessment of the sensory lesion are now required to further investigate the neuropathic component of chronic LBP. PERSPECTIVE: This study confirms the psychometric properties of the DN4 questionnaire to assess neuropathic pain in patients with low back pain. Neuropathic mechanisms largely contribute to pain in the lower limb as compared to the back, but neuropathic pain is not restricted to typical radiculopathy. This may have significant implications for the choice of treatment strategy in these patients.

Pain mechanisms

Understanding pain mechanisms is the key to effective treatment. The mechanisms that have been studied, written about in science journals and discussed with patients include nociceptive pain, inflammatory pain, neuropathic pain and central sensitisation. Elucidating which are playing a role in the patient’s experience allows the doctor to prescribe the right medication and the modern physical therapist to address the issues of pain in a biopsychosocial manner. I will now clarify the latter point.

In taking a detailed history, observing patterns of movement and protection, assessing the state of the nervous system and health of the body systems, understanding behaviours and the beliefs behind them and learning of the influences upon the individual’s pain experience, one can know about the likely pain mechanisms underpinning the experience. From here the treatment strategies can be chosen to target these mechanisms. For example, top-down approaches for central sensitisation focus on the change in the properties of the central nervous system. The interventions themselves are observant of the amplification that occurs in the spinal cord and higher centres and would seek to dampen the responses with input to the brain that is perceived as normal or non-threatening. This could include sensory stimulation or movements outside of the receptive field, education to reduce fear of movement or imagery to name but a few. Inflammatory pain can also be treated with a top-down approach but local tissue based strategies would also be used. Just to note that the separation of the ‘top end’ (brain and spinal cord) from ‘bottom end’ (tissues) is really a false dichotomy as all conscious experiences are from the brain including what we see and what we feel.

Stephen McMahon and David Bennett, both experts in the field of pain science from King’s College London, produced a poster that describes these mechanisms – click here to visit the page in Nature Reviews Neuroscience. This is what they say about it:

Pain is an unpleasant sensation resulting from the intricate interplay between sensory and cognitive mechanisms. Chronic pain, resulting from disease or injury, affects nearly every fifth person in the Western world, constituting an enormous burden for the individual and society. Sensitization of pain signalling systems is a key feature of chronic pain and results in normally non-painful stimuli eliciting pain. Such sensory changes can occur not just at the sites of injury, but in surrounding normal tissues. This and other observations suggest that sensitization occurs within the CNS as well as within nociceptor terminals. Here we consider the consequences of noxious stimulus applied to our unfortunate builder’s hand, from sensory transduction to pain perception. We describe the structural and functional elements present at different levels of the nociceptive system, as well as some of the changes occurring in chronic pain states. Although our poster highlights a flow of information from the periphery to the CNS, it should be noted that higher brain centres exert both inhibitory and facilitatory controls on lower ones. The challenge for the next decade will be to effectively translate this knowledge into the development of novel analgesic agents for better pain relief.

Richmond StaceSpecialist Pain Physio Clinics, London & Surrey

“We – are – family….” Pain and significant others

Although pain is personal and only felt by the individual, the effects pervade to those closely around. It appears to be a two-way street though, with significant others having an impact upon levels of physical activity and evidence of similar attentional biases in chronic pain patients and their caregivers. Have a look at the papers below:

Pain. 2012 Jan;153(1):62-7. Epub 2011 Oct 15.

Do main caregivers selectively attend to pain-related stimuli in the same way that patients do?

Source

Family Research Institute, Shahid Beheshti University, G.C., Tehran, Iran.

Abstract

Despite increasing interest in the attentional biases of pain patients towards pain-related stimuli, there have been no investigations of whether the main caregivers of chronic pain patients also selectively attend to pain-related information. We compared the attentional biases to painful or happy faces of 120 chronic pain patients, 118 caregivers, and 50 controls. Analyses found that both patients and caregivers demonstrated biases towards painful faces that were not observed in control participants or to happy faces. Those patients and caregivers who were high in fear of pain demonstrated greater biases than those low in fear of pain, and the biases of the high-in-fear-of-pain group differed significantly from zero. When sub-groups of caregivers were compared, it was found that biases towards painful faces were not observed for those caregivers who accurately identified the level of pain the patient currently reported. In contrast, those caregivers who overestimated or underestimated the patients’ pain demonstrated biases that were significantly greater than zero. These results add to the growing weight of evidence suggesting that biases towards pain-related stimuli are observed in chronic pain patients, but that the nature of the stimuli is important. In addition, the results suggest that caregivers, particularly those who either under- or overestimate the level of pain that the patient reports, also demonstrate similar biases. Future research should investigate the links between caregivers’ biases and the way in which caregivers respond to pain.

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Pain. 2011 Nov;152(11):2521-7. Epub 2011 Aug 27.

Factors contributing to physical activity in a chronic low back pain clinical sample: a comprehensive analysis using continuous ambulatory monitoring.

Source

Department of Psychology, Eastern Michigan University, Ypsilanti, MI, USA. kalschul@uw.edu

Abstract

Back pain is one of the most common causes of disability in industrialized nations. Despite this, the variables that contribute to disability are not well understood and optimal measurement strategies of disability have not yet been determined. The present study sought to comprehensively assess the strongest predictors of physical activity as a proxy for disability. New patients in a chronic pain specialty clinic completed questionnaires to assess the predictors of physical activity and engaged in 5 days of home data collection wearing an accelerometer to assess physical activity in daily life, which is how disability was operationalised in this study. Analysis of repeated measures patient data revealed that, of 3 composite variables each representing a theoretical model, the model representative of operant factors significantly predicted physical activity. Subsequent analyses showed that pain sensitivity, fear avoidance, and solicitous spousal responses account for a significant amount of the variance in physical activity. These findings suggest that external sources of reinforcement or punishment may serve to influence physical behavior beyond that of internal cues such as fear avoidance or pain. Implications for treatment are discussed, including the potential benefits of specifically incorporating the patient’s sources of operant reinforcement or punishment into treatment.

RS Comment:

To be truly biopsychosocial, significant others and their influences must be considered. Positive strategies to involve and educate care givers, families and friends should form part of the treatment programme. I recommend that all those involved should develop an understanding of the issues of pain. We often listen to and subscribe to the beliefs of those closest to us and this powerful dynamic can be of real benefit. On occasion I am asked whether partners can attend the sessions. I encourage this participation as well as teaching techniques that are required to be used regularly at home, for example desensitisation strategies.

Neuropathic Pain: The pharmacological management of neuropathic pain in adults in non-specialist settings (3/10)

Neuropathic Pain

The Pharmacological Management of Neuropathic Pain in Adults in Non-Specialist Settings

Click here for the NICE Guidelines: Neuropathic Pain 2010

NICE Clinical Guidelines, No. 96

Centre for Clinical Practice at NICE (UK).

Copyright © 2010, National Institute for Health and Clinical Excellence.

Excerpt

This clinical guideline covers the management of neuropathic pain conditions in adults (aged 18 or over) in primary care and secondary care, excluding specialist pain management clinics. The aim of the guideline is to provide clear recommendations to healthcare professionals in non-specialist settings on the treatment and management of neuropathic pain. This includes recommendations on appropriate and timely referral to specialist pain services and/or condition-specific services. In general, regarding neuropathic pain as a ‘blanket condition’, irrespective of the underlying cause, is helpful and practical for both non-specialist healthcare professionals and patients. However, condition-specific recommendations and research recommendations have been made where robust evidence on clinical and cost effectiveness exists for specific conditions, or where the evidence is clearly uncertain. The guideline excludes acute pain arising directly (in the first 3 months) from trauma or orthopaedic surgical procedures.

Musings on pain – a book in progress (a)

I think and read about pain extensively. Not just the physiology of pain, but the whole affect upon the individual who can suffer in a multitude of ways. We have our own meaning of pain, although most people who I meet have difficulty attaching a sense of meaning to their experience. Broadly speaking, in persisting cases, the pain is deemed to be a thoroughly negative acquaintance that has hung around far too long.

The unwanted house guest, the irritating fly, the frustrating official or an enduring hammering from next door on a quiet Sunday afternoon.

Pain is an emotional and a sensory experience by definition and affected by the physical, the psychological and the social aspects of life, hence the contemporary term ‘biopsychosocial’. There are many influences, a number of which we are not even conscious of at the time. It just hurts.

Click here

Spending a great deal of time with patients,
Listening and hearing the stories of pain and suffering,
Looking and seeing the movement and behaviour changes,
The guarding and protection,
By the brain that must be revealed as the source.

I have heard some incredible histores told to me by the person sitting in front. Listening to the story from the beginning, although often they do not realise that the start point was long ago, I am piecing together the threads and connections. Some of these may seem irrelevant but are actually playing a role in the current time. Every piece of information is received and scrutinsed, nothing discarded until one is certain that there is no involvement.

The classic pain text

This book is a collection of my observations and thoughts about pain. All of these fall back on the contemporary understanding of pain that was really ignited by Pat Wall and Ron Melzack. It is no longer enough or acceptable to think about pain without considering the active role of the brain and the integrated networks of neurons within the brain that can be termed the ‘pain matrix’. However, we do not wish to be too neurocentric about pain and must wisely think about the immune system, endocrine system and autonomic nervous system within our contruct of how the body is protecting itself. For the brain’s ability to defend us is magnificent, our healing powers incredible and our ability to learn phenomenal. Together this creates opportunity, certainly in treating and understanding pain. The emotional centres (limbic system) and prefrontal cortex that are part of the pain matrix can be targeted with ‘informational therapy’ that is high quality pain education that permits deep learning about the body. Changing activity in the matrix will change pain. This does not negate the need to nourish the tissues (muscles, tendons, ligaments etc.) with movement, hands-on treatment and exercise, but we are urged by the science of pain to look beyond the tissues.

RS

CRPS papers February 2012

Welcome to the early February literature review, a run-down of the latest papers addressing complex regional pain syndrome.

Clin Med. 2011 Dec;11(6):596-600.

Complex regional pain syndrome in adults: concise guidance.

Source

King’s College London School of Medicine.

Abstract

Complex regional pain syndrome (CRPS) is a debilitating, painful condition in a limb associated with sensory, motor, autonomic, skin and bone abnormalities. Pain is typically the leading symptom, but is often associated with limb dysfunction and psychological distress. Prompt diagnosis and early treatment is required to avoid secondary physical problems related to disuse of the affected limb and the psychological consequences of living with undiagnosed chronic pain. UK guidelines have recently been developed for diagnosis and management in the context of primary and secondary care. The purpose of this concise guideline is to draw attention to these guidelines. Information in this article has been extracted from the main document and adapted to inform the management of CRPS as it presents to physicians in the course of their daily practice.

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Rheumatology (Oxford). 2011 Oct;50(10):1739-50. Epub 2011 Jun 28.

Complex regional pain syndrome in adults.

Source

Pain Research Group and Centre for Immune Studies in Pain, Department of Translational Medicine, University of Liverpool, UK. reasgoebel@rocketmail.com

Abstract

Complex regional pain syndrome (CRPS) is a highly painful, limb-confined condition, which arises usually after trauma. It is associated with a particularly poor quality of life, and large health-care and societal costs. The causes of CRPS remain unknown. The condition’s distinct combination of abnormalities includes limb-confined inflammation and tissue hypoxia, sympathetic dysregulation, small fibre damage, serum autoantibodies, central sensitization and cortical reorganization. These features place CRPS at a crossroads of interests of several disciplines including rheumatology, pain medicine and neurology. Significant scientific and clinical advances over the past 10 years hold promise both for an improved understanding of the causes of CRPS, and for more effective treatments. This review summarizes current concepts of our understanding of CRPS in adults. Based on the results from systematic reviews, treatment approaches are discussed within the context of these concepts. The treatment of CRPS is multidisciplinary and aims to educate about the condition, sustain or restore limb function, reduce pain and provide psychological intervention. Results from recent randomized controlled trials suggest that it is possible that some patients whose condition was considered refractory in the past can now be effectively treated, but confirmatory trials are required. The review concludes with a discussion of the need for additional research.

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J Neural Transm. 2011 Apr;118(4):599-603. Epub 2010 Dec 29.

Thermal hypesthesia in patients with complex regional pain syndrome related dystonia.

Source

Department of Neurology, Leiden University Medical Center, P.O. Box 9600, 2300 RC, Leiden, The Netherlands.

Abstract

The quantitative thermal test showed cold and warmth hypesthesia without increased heat pain sensitivity in the affected limbs of complex regional pain syndrome (CRPS) patients with tonic dystonia (n = 44) in comparison with healthy controls with a similar age and sex distribution (n = 35). The degrees of cold and warmth hypesthesia were strongly correlated. We conclude that dysfunction in small nerve fiber (i.e., C and Aδ) processing is present in patients with CRPS-related dystonia.

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Musculoskeletal Care. 2011 Jun 12. doi: 10.1002/msc.211. [Epub ahead of print]

An Exploration of the Support Person’s Perceptions and Experiences of Complex Regional Pain Syndrome and the Rehabilitation Process.

Source

University of Plymouth, Plymouth, UK.

Abstract

We explored the perceptions and experiences of those who support a relative or friend with complex regional pain syndrome (CRPS), a chronic pain condition of unknown aetiology usually affecting a single limb. Semi-structured interviews were analysed using interpretative phenomenological analysis, and four superordinate themes are presented here. These themes describe the efforts of carers to make sense of CRPS and the rehabilitation process, to be sensitive to the discomfort of the person with CRPS and to respond in an attuned and helpful way. CRPS had become integrated into the carers’ lives as they sought to monitor, protect and motivate the person they supported. The themes are discussed in relation to each other and to extant literature, including work on social support and adjustment to chronic illness, and the clinical implications are explored.

RS comment: I actively encourage participation of significant other(s) in the treatment process. Behaviours of the sufferer are very likely to be influenced by the partner/spouse, hence this dynamic requires attention. This maybe in the form of joint education sessions or simply attendance of the sessions to develop understanding and positive affirmations.

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Pain. 2012 Jan 14. [Epub ahead of print]

Metallothionein deficiency in the injured peripheral nerves of complex regional pain syndrome as revealed by proteomics.

Source

Department of Biomedical Engineering, Sapporo Medical University School of Medicine, Sapporo, Japan; Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan.

Abstract

Complex regional pain syndrome (CRPS) is characterized by persistent and severe pain after trauma or surgery; however, its molecular mechanisms in the peripheral nervous system are poorly understood. Using proteomics, we investigated whether injured peripheral nerves of CRPS patients have altered protein profiles compared with control nerves. We obtained nerve samples from 3 patients with CRPS-2 who underwent resection of part of an injured peripheral nerve. Sural nerves from fresh cadavers with no history of trauma or neuropathic pain served as controls. Proteomic analysis showed that the number and functional distribution of proteins expressed in CRPS and control nerves was similar. Interestingly, metallothionein was absent in the injured nerves of CRPS-2, although it was readily detected in control nerves. Western blotting further confirmed the absence of metallothionein in CRPS-2 nerves, and immunohistochemistry corroborated the deficiency of metallothionein expression in injured nerves from 5 of 5 CRPS patients and 2 of 2 patients with painful neuromas. In contrast, all control nerves, including 5 sural nerves from fresh cadavers and 41 nerves obtained from surgically resected tumors, expressed MT. Furthermore, expression of S100 as a marker for Schwann cells, and neurofilament M as a marker of axons was comparable in both CRPS-2 and controls. Metallothioneins are zinc-binding proteins that are probably involved in protection against injury and subsequent regeneration after CNS damage. Their absence from the injured peripheral nerves of patients with CRPS-2 suggests a potential pathogenic role in generating pain in the damaged peripheral nerves.

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Rev Bras Anestesiol. 2011 Jul-Aug;61(4):425-33.

Incidence of regional pain syndrome after carpal tunnel release. Is there a correlation with the anesthetic technique?

Source

Rehabilitation Sciences, Anesthesiologist of Hospital SARAH, Brasília. veve@sarah.br

Abstract

BACKGROUND AND OBJECTIVES:

Complex regional pain syndrome (CRPS) previously known as reflex sympathetic dystrophy refers to a set of signs and symptoms that include pain, increased sweating, and vasomotor instability. Pain is usually triggered by a noxious stimulus in a peripheral nerve, which is disproportionate to the triggering stimulus. Its development after surgery is not uncommon varying with the type of intervention. An incidence of 2.1 to 5% has been reported after carpal tunnel release (CTR). Sympathetic blockade may prevent the onset of CRPS. However, there is no study validating this technique to prevent CRPS after CTR. The objective of the present study was to define the incidence of CRPS after CTR and its relationship with four anesthetic techniques.

METHODS:

Patients were randomly distributed to undergo one of the following techniques: general anesthesia, regional intravenous anesthesia with lidocaine, regional intravenous anesthesia with lidocaine and clonidine, or axillary plexus block. Postoperatively, they were followed-up by a nurse who was unaware of the anesthetic technique used, and follow-up was done through electronic patient records for up to 6 months after the anesthesia. During this period signs and symptoms typical of CRPS were investigated and, if positive, treatment was instituted. A descriptive evaluation using the chi-square test was performed.

RESULTS:

Three-hundred and one patients were investigated. Twenty-five of them developed CRPS, an incidence of 8.3%. Predominance was not observed among the anesthetic techniques used. Other factors such as smoking, profession, and other concomitant diseases were also investigated, and none showed a relationship with the development of post-CTR CRPS.

CONCLUSIONS:

Complex regional pain syndrome has an incidence of 8.3% after CTR surgery without association with the anesthetic techniques investigated.

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