Reflex Sympathetic Dystrophy

Complex regional pain syndrome and functional neurological disorders - time for reconciliation

There have been many articles highlighting differences and similarities between complex regional pain syndrome (CRPS) and functional neurological disorders (FND) but until now the discussions have often been adversarial with an erroneous focus on malingering and a view of FND as 'all in the mind'. However, understanding of the nature, frequency and treatment of FND has changed dramatically in the last 10-15 years. FND is no longer assumed to be only the result of 'conversion' of psychological conflict but is understood as a complex interplay between physiological stimulus, expectation, learning and attention mediated through a Bayesian framework, with biopsychosocial predisposing, triggering and perpetuating inputs. Building on this new 'whole brain' perspective of FND, we reframe the debate about the 'psychological versus physical' basis of CRPS. We recognise how CRPS research may inform mechanistic understanding of FND and conversely, how advances in FND, especially treatment, have implications for improving understanding and management of CRPS.

Local anaesthetic sympathetic blockade for complex regional pain syndrome

BACKGROUND

This review is an update of a previously published review in the Cochrane Database of Systematic Reviews, 2005, Issue 4 (and last updated in the Cochrane Database of Systematic Reviews, 2013 issue 8), on local anaesthetic blockade (LASB) of the sympathetic chain to treat people with complex regional pain syndrome (CRPS).

OBJECTIVES

To assess the efficacy of LASB for the treatment of pain in CRPS and to evaluate the incidence of adverse effects of the procedure.

SEARCH METHODS

For this update we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2015, Issue 9), MEDLINE (Ovid), EMBASE (Ovid), LILACS (Birme), conference abstracts of the World Congresses of the International Association for the Study of Pain, and various clinical trial registers up to September 2015. We also searched bibliographies from retrieved articles for additional studies.

SELECTION CRITERIA

We considered randomised controlled trials (RCTs) that evaluated the effect of sympathetic blockade with local anaesthetics in children or adults with CRPS compared to placebo, no treatment, or alternative treatments.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. The outcomes of interest were reduction in pain intensity, the proportion who achieved moderate or substantial pain relief, the duration of pain relief, and the presence of adverse effects in each treatment arm. We assessed the evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation) and created a 'Summary of findings' table.

MAIN RESULTS

We included an additional four studies (N = 154) in this update. For this update, we excluded studies that did not follow up patients for more than 48 hours. As a result, we excluded four studies from the previous review in this update. Overall we included 12 studies (N = 461), all of which we judged to be at high or unclear risk of bias. Overall, the quality of evidence was low to very low, downgraded due to limitations, inconsistency, imprecision, indirectness, or a combination of these.Two small studies compared LASB to placebo/sham (N = 32). They did not demonstrate significant short-term benefit for LASB for pain intensity (moderate quality evidence).One small study (N = 36) at high risk of bias compared thoracic sympathetic block with corticosteroid and local anaesthetic versus injection of the same agents into the subcutaneous space, reporting statistically significant and clinically important differences in pain intensity at one-year follow-up but not at short term follow-up (very low quality evidence).Of two studies that investigated LASB as an addition to rehabilitation treatment, the only study that reported pain outcomes demonstrated no additional benefit from LASB (very low quality evidence).Eight small randomised studies compared sympathetic blockade to various other active interventions. Most studies found no difference in pain outcomes between sympathetic block versus other active treatments (low to very low quality evidence).One small study compared ultrasound-guided LASB with non-guided LASB and found no clinically important difference in pain outcomes (very low quality evidence).Six studies reported adverse events, all with minor effects reported.

AUTHORS' CONCLUSIONS

This update's results are similar to the previous versions of this systematic review, and the main conclusions are unchanged. There remains a scarcity of published evidence and a lack of high quality evidence to support or refute the use of local anaesthetic sympathetic blockade for CRPS. From the existing evidence, it is not possible to draw firm conclusions regarding the efficacy or safety of this intervention, but the limited data available do not suggest that LASB is effective for reducing pain in CRPS.

Pathological mechanism of musculoskeletal manifestations associated with CRPS type II: an animal study

Patients with complex regional pain syndrome (CRPS) often complain of abnormal sensations beyond the affected body part, but causes of this spread of musculoskeletal manifestations into contiguous areas remain unclear. In addition, immobilization can predispose to the development of CRPS. We examined functional, biochemical, and histological alterations in affected parts, including contiguous zones, using an animal model. Ten-week-old male Wistar rats were assigned to 5 groups: a normal group receiving no treatment, a sham operation group with surgical exploration, an immobilization group with surgical exploration plus internal knee joint immobilization, a surgical neuropathy group prepared by spinal nerve ligation (SNL) of the left L5 nerve root, and a surgical neuropathy+immobilization group with simultaneous SNL and knee joint immobilization. Mechanical allodynia and knee contracture were compared between groups, and tissues were harvested for histological assessments and gene and protein expression analyses. Neither surgical procedures nor immobilization induced detectable mechanical sensitivity. However, the addition of nerve injury resulted in detectable mechanical allodynia, and immobilization not only accelerated hyperalgesia, but also resulted in muscle fibrosis. Nerve growth factor (NGF) and other mediators of neurogenic inflammation were highly expressed not only in denervated muscles, but also in innervated muscles in contiguous areas, suggesting the spread of NGF production beyond the myotome of the injured nerve. Transforming growth factor β was involved in the development of contracture in CRPS. These findings imply that neuroinflammatory components play major roles in the progression and dispersion of both sensory pathologies and pathologies that are exacerbated by immobilization.

Local anaesthetic sympathetic blockade for complex regional pain syndrome

BACKGROUND

This is an update of the original Cochrane review published in The Cochrane Library, 2005, Issue 4, on local anaesthetic blockade (LASB) of the sympathetic chain used to treat complex regional pain syndrome (CRPS).

OBJECTIVES

To assess the efficacy of LASB for the treatment of pain in CRPS and to evaluate the incidence of adverse effects of the procedure.

SEARCH METHODS

We updated searches of the Cochrane Pain, Palliative and Supportive Care Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) on the Cochrane Library (Issue 11 of 12, 2012), MEDLINE (1966 to 22/11/12), EMBASE (1974 to 22/11/12), LILACS (1982 to 22/11/12), conference abstracts of the World Congresses of the International Association for the Study of Pain (1995 to 2010), and various clinical trial registers (inception to 2012). We also searched bibliographies from retrieved articles for additional studies.

SELECTION CRITERIA

We considered for inclusion randomised controlled trials (RCTs) that evaluated the effect of sympathetic blockade with local anaesthetics in children or adults with CRPS.

DATA COLLECTION AND ANALYSIS

The outcomes of interest were reduction in pain intensity levels, the proportion who achieved moderate or substantial pain relief, the duration of pain relief, and the presence of adverse effects in each treatment arm.

MAIN RESULTS

We included an additional 10 studies (combined n = 363) in this update. Overall we include 12 studies (combined n = 386). All included studies were assessed to be at high or unclear risk of bias.Three small studies compared LASB to placebo/sham. We were able to pool the results from two of these trials (intervention n = 23). Pooling did not demonstrate significant short-term benefit for LASB (in terms of the risk of a 50% reduction of pain scores).Of two studies that investigated LASB as an addition to rehabilitation treatment, the only study that reported pain outcomes demonstrated no additional benefit from LASB.Eight small randomised studies compared sympathetic blockade to another active intervention. Most studies found no difference in pain outcomes between sympathetic block and other active treatments.Only five studies reported adverse effects, all with minor effects reported.

AUTHORS' CONCLUSIONS

This update has found similar results to the original systematic review. There remains a scarcity of published evidence to support the use of local anaesthetic sympathetic blockade for CRPS. From the existing evidence it is not possible to draw firm conclusions regarding the efficacy or safety of this intervention but the limited data available do not suggest that LASB is effective for reducing pain in CRPS.

Treatment of Complex Regional Pain Syndrome (CRPS) using low dose naltrexone (LDN)

Complex Regional Pain Syndrome (CRPS) is a neuropathic pain syndrome, which involves glial activation and central sensitization in the central nervous system. Here, we describe positive outcomes of two CRPS patients, after they were treated with low-dose naltrexone (a glial attenuator), in combination with other CRPS therapies. Prominent CRPS symptoms remitted in these two patients, including dystonic spasms and fixed dystonia (respectively), following treatment with low-dose naltrexone (LDN). LDN, which is known to antagonize the Toll-like Receptor 4 pathway and attenuate activated microglia, was utilized in these patients after conventional CRPS pharmacotherapy failed to suppress their recalcitrant CRPS symptoms.

Psychologic factors in the development of complex regional pain syndrome: history, myth, and evidence

OBJECTIVE

The present paper examines the literature that addresses psychologic aspects involved in complex regional pain syndrome from a historic perspective to provide a rationale for the emergence of psychologic theories to explain its pathogenesis. The support of such perspective is then analyzed through the review of evidence-based studies.

METHODS

A review of the literature from a historic perspective was presented since its first description to the present time, including the clinical presentation and associated symptoms. An evidence-based approach was used to review the literature on complex regional pain syndrome and psychologic factors associated with the etiology or as predictors in the development of the disorder.

RESULTS

After reviewing the literature on the history and the myths associated with complex regional pain syndrome, a hypothesis is provided based on an analysis of the Zeitgeist in the development of the psychologic theory associated with the disorder. We also concluded there is no evidence to support a linear relationship that establishes a psychologic predisposition to develop the disorder.

DISCUSSION

An analysis of the Zeitgeist when complex regional pain syndrome was first described helps to understand the long-standing theories associated with a psychological theory of its etiology. This understanding should help to undermine the perpetuation of such claims which may contribute to undertreatment and misdiagnosis. To be consistent with todays Zeitgeist we must incorporate psychologic aspects, which while not causal in nature or exclusive of complex regional pain syndrome, are strongly associated with a wide spectrum of chronic pain disorders.

Psychological features of patients with complex regional pain syndrome type I related dystonia

The objective of this study was to evaluate psychological features in severely affected patients with complex regional pain syndrome type I- (CRPS-I) related dystonia. Personality traits, psychopathology, dissociative experiences, the number of traumatic experiences, and quality of life were studied in 46 patients. Findings were compared with two historical psychiatric control groups [54 patients with conversion disorder (CD) and 50 patients with affective disorders (AD)] and normative population data. The CRPS-I patients showed elevated scores on the measures for somatoform dissociation, traumatic experiences, general psychopathology, and lower scores on quality of life compared with general population data, but had significantly lower total scores on the measures for personality traits, recent life events, and general psychopathology compared with the CD and AD patients. Rates of early traumatic experiences were comparable with the CD and AD patients, and the level of somatoform dissociation was comparable to the CD patients, but was elevated in comparison to the AD patients. Early traumatic experiences were reported in 87% of the CRPS-I patients and were found to be moderately related to somatoform dissociative experiences, indicating that early traumatic experiences might be a predisposing, although not a necessary factor for the development of CRPS-I-related dystonia. Although the psychological profile of the patients with CRPS-I-related dystonia shows some elevations, there does not seem to be a unique disturbed psychological profile on a group level.

Pain Drawing in the Assessment of Neurogenic Pain and Dysfunction in the Neck/Shoulder Region: Inter-Examiner Reliability and Concordance with Clinical Examination

BACKGROUND

The pain drawing (PD) has proven to have good inter-examiner reliability and high sensitivity in assessing neurogenic pain and dysfunction (NP) originating from the lower back. Studies on its use in the neck/shoulder region have not been found.

OBJECTIVES

To investigate inter-examiner reliability of a first impression assessment of NP in the neck/shoulder region using a simplified PD made by the patient. Also, to investigate concordance between first impression assessment and a final assessment based on a complete clinical examination.

DESIGN

A clinical trial on 50 primary care patients with discomfort in the neck/shoulder region assessed by two independent examiners. One examiner was experienced in assessing the PD and the other was not. A first impression assessment was based solely on the PD. A final assessment was based on clinical examination also including history interviews, physical examinations, and possible radiological reports. NP was considered if at least two physical examination findings indicated neurological deficit in the area of discomfort. Concordance between the first impression assessment and the final assessment was calculated as sensitivity with the final assessment as the key.

RESULTS

Inter-examiner reliability based solely on the first impression assessment of the pain drawing reached 88% overall agreement and a sensitivity of 90%. Signs of NP were found in 92% of the patients according to the final assessment. Two thirds of the patients added to their pain drawing during the history interview.

CONCLUSIONS

First impression assessment of the PD seems to be a reliable, easily learned, and sensitive diagnostic method for assessing NP in the neck/shoulder region. NP may be greatly underestimated, especially as patients withhold symptoms of discomfort when they fill in the PD.

Local anesthetic sympathetic blockade for complex regional pain syndrome

BACKGROUND

Local anesthetic blockade of the sympathetic chain is widely used to treat reflex sympathetic dystrophy (RSD) and causalgia. These two pain syndromes are now conceptualized as variants of a single entity: complex regional pain syndrome (CRPS). A recent meta-analysis of the topic has been published. However, this study only evaluated studies in English language and therefore it could have overlooked some randomized controlled trials.

OBJECTIVES

This systematic review had three objectives: to determine the likelihood of pain alleviation after sympathetic blockade with local anesthetics in the patient with CRPS; to assess how long any benefit persists; and to evaluate the incidence of adverse effects of the procedure.

SEARCH STRATEGY

We searched the Cochrane Pain, Palliative and Supportive Care Register, the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, LILACS, and conference abstracts of the World Congresses of the International Association for the Study of Pain. Bibliographies from retrieved articles were also searched for additional studies.

SELECTION CRITERIA

We considered for inclusion randomized controlled trials that evaluated the effect of sympathetic blockade with local anesthetics in children or in adult patients to treat RSD, causalgia, or CRPS.

DATA COLLECTION AND ANALYSIS

The outcomes of interest were the number of patients who obtained at least 50% of pain relief shortly after sympathetic blockade (30 minutes to 2 hours) and 48 hours or later. We also assessed the presence of adverse effects in each treatment arm. A random effects model was used to combine the studies.

MAIN RESULTS

Two small randomized double blind cross over studies that evaluated 23 subjects were found. The combined effect of the two trials produced a relative risk (RR) to achieve at least 50% of pain relief 30 minutes to 2 hours after the sympathetic blockade of 1.17 (95% CI 0.80-1.72). It was not possible to determine the effect of sympathetic blockade on long-term pain relief because the authors of the two studies evaluated different outcomes.

AUTHORS' CONCLUSIONS

This systematic review revealed the scarcity of published evidence to support the use of local anesthetic sympathetic blockade as the 'gold standard' treatment for CRPS. The two randomized studies that met inclusion criteria had very small sample sizes, therefore, no conclusion concerning the effectiveness of this procedure could be drawn. There is a need to conduct randomized controlled trials to address the value of sympathetic blockade with local anesthetic for the treatment of CRPS.

The Challenge to Manage Reflex Sympathetic Dystrophy/Complex Regional Pain Syndrome

The challenge to understand reflex sympathetic dystrophy/complex regional pain syndrome may require a better understanding of the complex relationship between the central and peripheral nervous systems. There is no comprehensive hypothesis that clearly explains the etiology and no uniformly successful treatment method. This brief summary of the challenge reviews some of what is known, hypothesizes a possible etiologic mechanism, and proposes 10 common-sense principles for management that recognizes the handicap of limited knowledge.

Chronic pain: physiological, diagnostic, and management considerations

Neuropathic pain is a neuropsychiatric condition in which pain is initiated or caused by a primary lesion or dysfunction in the nervous system. Understanding the complexity of neuropathic pain becomes the cornerstone for appropriate diagnosis and management. Diagnosis must take into account comorbid conditions. Successful management depends on realistic patient and physician expectations and an individualized, multidisciplinary approach.

Fibromyalgia as a sympathetically maintained pain syndrome

Abnormal activity of the sympathetic nervous system may be involved in the pathogenesis of chronic pain syndromes. This article reviews the animal studies of sympathetically induced pain behavior, the controversy of sympathetically maintained pain in clinical practice, and the dysautonomic nature of fibromyalgia (FM). FM has neuropathic pain features (stimuli-independent pain state accompanied by allodynia and paresthesias). The proposal of FM as a sympathetically maintained pain syndrome is based on the controlled studies showing that patients with FM display signs of relentless sympathetic hyperactivity and that the pain is submissive to sympathetic blockade and is rekindled by norepinephrine injections. Dysautonomia also may explain the multisystem features of FM.

Impaired self-perception of the hand in complex regional pain syndrome (CRPS)

To investigate neglect, extinction, and body-perception in patients suffering from complex regional pain syndrome (CRPS). So-called 'neglect-like' symptoms have been reported in CRPS, however no studies have yet analyzed this phenomenon which might substantiate the theory of the central nervous system involvement in the pathophysiology of CRPS. A total of 114 patients with CRPS of the upper limb underwent bedside neurological examination. 'Neglect-like' symptoms were determined by asking all patients what kind of feeling they had toward the affected hand (feeling of foreignness). Hemispatial neglect was tested with the line bisection task in 29 patients and sensory extinction to simultaneous stimulation in 40 patients. The ability to identify fingers after tactile stimulation was tested in 73 patients. Independently of the affected side and disease duration, 54.4% of the patients reported that their hand felt 'foreign' or 'strange'. The ability to identify fingers was impaired in 48% on the affected hand and in 6.5% on the unaffected hand ( X(2) = 33.52, df = 1, p < 0.0001). These findings were related to pain intensity, illness duration and the extent of sensory deficits. No typical abnormalities indicating neglect were found in the line bisection test. Sensory extinction was normal in all patients. A large proportion of CRPS patients have disturbances of the self-perception of the hand, indicating an alteration of higher central nervous system processing. There are no indicators that classic neglect or extinction contribute to these findings. Physical therapy of such patients should take this observation into consideration.

Psychological aspects of interventional therapy

This discussion is not, nor could it hope to be, an exhaustive examination of all of the various interventional therapies. Instead, it is intended to highlight the potential contribution of psychosocial factors. These factors may vary to some degree or another depending on the specific procedure, but clearly play a role whenever the desired outcome involves a reduction in subjective pain, alteration in the adaptiveness with which the patient responds to the experience of pain, and quality of life. Many notables, including Dr. Michael Cousins, have echoed the importance of incorporating interventional therapies into an interdisciplinary approach. Yet, there seems to be a preponderance of "block shops". Even when used for diagnostic or prognostic purposes, the impact of psychosocial variables and the potential relevance of a meaningful behavioral or psychologic evaluation cannot be overstated. It is easy to understand how the reader might conclude that immersing oneself in the minutiae of all these variables could lead to a feeling of intellectual paralysis when it comes to evaluating the data and arriving at a conclusion or diagnosis. However, ignoring these psychosocial variables and their complex interaction does not constitute a solution. This is particularly true in considering discography where, depending on the criteria applied, the percent of "false positives" can vary from 0% to as much as 40%. The implication for the performing of "unnecessary" spine surgery is obvious. The thoughtful practitioner will be mindful of the role of psychosocial variables in so far as they are thought to be relevant in a particular case. The overall contribution of psychosocial variables to the application of interventional therapies for the diagnosis and treatment of pain can be overlooked and ignored, but not denied. A certain percentage of patients will respond in a predictable, desirable or positive fashion purely on a statistical basis. Historically, and there seems to be no reason to believe this will change in the immediate future, the degree to which the psychosocial variables are considered is left up to the interventionalist. Some are content to perform a directed procedure or therapy concerned only, and sometimes to a less than sufficient degree, with the technical adequacy of the procedure. Others will appreciate the role of human factors including those of the practitioner and patient alike, and strive not only for a statistically derived outcome but the best possible outcome for a given patient. Psychosocial factors can sometimes take on the character of "nuisance variables". However, it is hard not to wonder how much care each would want to have given to these factors if one were on the other end of the needle.

Development of a neuropathic pain questionnaire

Ongoing efforts to develop mechanisms-based assessment and treatment of chronic pain have been hindered by the lack of assessment tools differentially sensitive to various phenomena underlying different mechanisms of pain. This study describes the development of an assessment instrument intended to measure neuropathic pain based on qualities of pain as they are inferred from pain descriptors. Subjects were 528 chronic pain patients from several clinics. Of these, 149 had strictly neuropathic pain, while 233 had non-neuropathic pain. Subjects completed a 32 item preliminary questionnaire, which asked them to rate their usual pain on multiple descriptors, as well as the degree to which their pain differed in response to various internal and external factors. This preliminary questionnaire was submitted to factor analysis, and this yielded 6 factors. Representatives of each of these factors were combined with additional items that demonstrated significant differences between neuropathic and non-neuropathic pain groups, to yield a 12 item Neuropathic Pain Questionnaire (NPQ). These items were able to differentiate neuropathic pain patients from non-neuropathic pain patients in a holdout sample with 66.6% sensitivity and 74.4% specificity. The newly developed instrument, NPQ, may be used for the initial screening of neuropathic pain patients. It also has the ability to provide a quantitative measure for the descriptors important in the diagnosis and assessment of neuropathic pain. Consequently, it can be used for monitoring of neuropathic pain treatments and as an outcome measure.

Complex regional pain syndrome type I: incidence and prevalence in Olmsted county, a population-based study

The objective of this study is to undertake a population based study on the incidence, prevalence, natural history, and response to treatment of complex regional pain syndrome (CRPS). All Mayo Clinic and Olmsted Medical Group medical records with codes for reflex sympathetic dystrophy (RSD), CRPS, and compatible diagnoses in the period 1989-1999 were reviewed as part of the Rochester Epidemiology Project. We used IASP criteria for CRPS. The study population was in the Olmsted County, Minnesota (1990 population, 106,470). The main outcome measures were CRPS I incidence, prevalence, and outcome. Seventy-four cases of CRPS I were identified, resulting in an incidence rate of 5.46 per 100,000 person years at risk, and a period prevalence of 20.57 per 100,000. Female:male ratio was 4:1, with a median age of 46 years at onset. Upper limb was affected twice as commonly as lower limb. All cases reported an antecedent event and fracture was the most common trigger (46%). Excellent concordance was found between symptoms and signs and vasomotor symptoms were the most commonly present. Three phase bone scan and autonomic testing diagnosed the condition in >80% of cases. Seventy-four percent of patients underwent resolution, often spontaneously. CRPS I is of low prevalence, more commonly affects women than men, the upper more than the lower extremity, and three out of four cases undergo resolution. These results suggest that invasive treatment of CRPS may not be warranted in the majority of cases.

Defining the therapeutic role of local anesthetic sympathetic blockade in complex regional pain syndrome: a narrative and systematic review

OBJECTIVE

There is growing controversy on the value of blocking the sympathetic nervous system for the treatment of complex regional pain syndromes (CRPS). The authors sought to evaluate the efficacy of sympathetic blockade with local anesthetic in these syndromes. In addition, they performed a comprehensive review of the pathophysiology and other treatments for CRPS.

DESIGN

Systematic review of the literature was performed. MEDLINE was searched from 1966 through 1999. The authors identified only three randomized controlled trials (RCTs) that evaluated sympathetic blockade with local anesthetic, but because of differences in study design they were unable to pool the study data. The authors therefore included nonrandomized studies and case series.

INTERVENTIONS

Studies were included if local anesthetic sympathetic blockade was used in at least 10 patients. Studies were excluded if continuous infusion techniques, somatic nerve blocks, or combined sympatholytic therapies were evaluated.

OUTCOME MEASURES

Pain relief was classified as full, partial, or absent. The lack of a comparison group in the studies allowed only the calculation of distribution of the response categories, and the sum of the pooled rates does not equal 100%.

RESULTS

Twenty-nine studies were included that evaluated 1,144 patients. Nineteen studies were retrospective, 5 prospective case series, 3 RCTs, and 2 nonrandomized controlled studies. The quality of the publications was generally poor. Twenty-nine percent of patients had full response, 41% had partial response, and 32% had absent response. It was not possible to estimate the duration of pain relief.

CONCLUSIONS

This review raises questions as to the efficacy of local anesthetic sympathetic blockade as treatment of CRPS. Its efficacy is based mainly on case series. Less than one third of patients obtained full pain relief. The absence of control groups in case series leads to an overestimation of the treatment response that can explain the findings.

Quantitative sensory testing, neurophysiological and psychological examination in patients with complex regional pain syndrome and hemisensory deficits

Based on bed-side neurological testing, it has recently been shown that 33% of chronic complex regional pain syndrome (CRPS) type I patients exhibit sensory impairments, which extend past the painful area of the affected limb in a hemisensory distribution (Pain, 80 (1999) 95). In the present study, the clinically observed changes in touch and temperature sensations on the side of the body ipsilateral to the affected limb were investigated quantitatively. Neurophysiological and psychological examinations were conducted to detect changes in the peripheral and central nervous system as well as psychopathological abnormalities. In 40 patients with CRPS, a bed-side neurological examination was performed. Quantitative sensory testing was conducted at five locations on each side of the body. The evaluation of touch thresholds was performed using von Frey filaments (n=40). To measure cool, warm and heat pain thresholds quantitatively, a thermal stimulator using a Peltier-element was used (n=28). With respect to clinical findings, the initiating trauma and severity of abnormalities on nerve conduction testing, three patients were diagnosed as having a reliable CRPS II (causalgia) and five patients a possible CRPS II. Thirty-two patients were diagnosed as having a CRPS I.On clinical examination, 15 patients revealed generalized sensory deficits on the side of the body ipsilateral to the affected limb (hemisensory deficit, n=12; sensory impairment in the upper quadrant of the body, n=3). Patients with these generalized sensory deficits had a significantly longer illness duration (P<0.05) and a significantly higher percentage of mechanical allodynia/hyperalgesia than patients with spatially restricted sensory deficits (n=25) (P<0.05). In patients with generalized sensory impairment, thresholds for touch, warm and cold sensations, and for heat pain were significantly increased at all five locations tested ipsilaterally compared with the contralateral body side, except for the cool threshold on the chest and the heat pain threshold distally on the affected limb. In patients with sensory deficits limited to the affected limb, the touch threshold was significantly higher only in the distal part of the affected limb when compared with the contralateral limb. In these patients, thermal testing revealed almost no differences in cool, warm and heat pain thresholds when comparing both sides. Repeated thermal testing conducted in five patients with generalized sensory impairment reproduced the significant differences between both sides for cool, warm and heat pain thresholds. However, the correlation between the results obtained in the first and second examinations was poor. Neurophysiological recordings revealed pathological results in 46% for nerve conduction studies, 24% for somatosensory evoked potentials and 39% for sympathetic skin response. For all methods applied, there was no statistically significant difference in the incidence of pathological results between patients with generalized and patients with spatially restricted sensory abnormalities. Psychological examination using the structured clinical interview on DSM-IV (SKID) demonstrated a high frequency of affective and anxiety disorders, however, without significant differences between both groups.We conclude that hemisensory impairment in patients with CRPS Type I is probably related to functional disturbances in processing of noxious events in the thalamus and may be a clinical correlate of subcortical brain plasticity in chronic pain.

Reflex sympathetic dystrophy with hidradenitis suppurativa exacerbation: a case report

Reflex sympathetic dystrophy (RSD) or complex regional pain syndrome type 1, is characterized by spontaneous pain or allodynia and hyperalgesia disproportionate to the inciting event, multiperipheral nerve involvement, edema, vasomotor or sudomotor change, and possible loss of function. It has been described in relation to various insults, including a number of infectious and inflammatory conditions. We report a case of a patient who developed RSD 1 week after an exacerbation of hidradenitis suppurativa, a rare chronic inflammatory disease of apocrine sweat glands. The patient responded well to a combination of range-of-motion exercises, thermal modalities, and oral steroids. Hidradenitis suppurativa should be considered when searching for an etiology of new onset RSD.

Abnormal movements in complex regional pain syndrome: assessment of their nature

Abnormal movements may be a clinical feature in complex regional pain syndrome (CRPS), but their basic nature is unclear. Between August 1989 and September 1998, patients fulfilling diagnostic criteria for CRPS (I or II) and displaying abnormal movements were entered into a prospective study. Fifty-eight patients, 39 women and 19 men, met entry criteria; 47 had sustained a minor physical injury at work. The patients exhibited various combinations of dystonic spasms, coarse postural or action tremor, irregular jerks, and, in one case, choreiform movements. Patients underwent rigorous clinical and laboratory evaluation aimed at characterizing their neurological disturbance. Surprisingly, no case of CRPS II but only cases of CRPS type I displayed abnormal movements. In addition to an absence of evidence of structural nerve, spinal cord, or intracranial damage, all CRPS I patients with abnormal movements typically exhibited pseudoneurological (nonorganic) signs. In some cases, malingering was documented by secret surveillance. This study highlights abnormal movements in CRPS as constituting a key clinical feature that differentiates CRPS I from CRPS II. They are consistently of somatoform or malingered origin, signaling an underlying psychoneurological disorder responsible for the entire CRPS profile.

Complex regional pain syndrome: becoming more or less complex?

Complex regional pain syndrome (CRPS) is the newest name for the confusing conditions of reflex sympathetic dystrophy and causalgia. The epidemiology and the signs and symptoms of these conditions are discussed. Although much is only poorly understood about the aetiology of CRPS, the roles of neuropathic pain, prolonged inflammation and psychological factors are becoming clearer. Physical therapies remain the lynchpin of management but the roles of anti-inflammatory medication, sympathectomies and a team approach are emphasized.

Causalgia and reflex sympathetic dystrophy: does the sympathetic nervous system contribute to the generation of pain?

The striking response of causalgia and reflex sympathetic dystrophy (RSD) to sympatholytic procedures together with signs of autonomic nervous system abnormalities suggest that the sympathetic efferent system can generate or enhance pain (sympathetically maintained pain, SMP). This concept is supported by human and animal experiments indicating that sympathetic activity and catecholamines can activate primary afferent nociceptors. Some clinical evidence, however, calls the SMP concept into question and alternative explanations have been advanced. In this review, we describe the clinical features of causalgia and RSD and the evidence for sympatholytic efficacy. The major barrier to proving the SMP concept is that all available sympatholytic procedures are problematic. We conclude that, although the weight of current evidence supports the SMP concept and its relevance to causalgia and RSD, it remains unproven by scientific criteria. More careful adherence to diagnostic criteria and well-controlled trials of sympatholysis are needed to finally settle the issue.

Thermographic diagnostics in equine back pain

Infrared thermographic imaging (ITI) is the most sensitive objective imaging currently available for the detection of back disease in horses. It is, however, only a physiological study primarily of vasomotor tone overlying other superficial tissue factors. Interpretation requires extreme care in imaging protocol and in understanding the significance of altered sympathetic nervous tone and the sympathetic distribution. Most discussions on back pain have centered on nociception and inflammatory events. ITI provides information and localization for more significant than diagnosing areas of hot spots. Chronic back pain usually involves vasoconstriction at the affected sites and from ITI studies in man, we have an opportunity to appreciate chronic pain phenomena that involves non-inflammatory events. These occur commonly in horses, but are still seldom recognized and treated.

Personality assessment of patients with complex regional pain syndrome type I

OBJECTIVE

There is controversy regarding the importance of psychological/psychiatric factors in the development of the Complex Regional Pain Syndrome (CRPS). Our objective was to determine whether CRPS type I patients were psychiatrically different from other chronic pain patients, with particular attention to personality pathology.

DESIGN

A standardized clinical assessment of all major psychiatric categories, including personality disorders, was performed on 25 CRPS type I patients and a control group of 25 patients with chronic low back pain from disc-related radiculopathy.

MEASURES

Both sections of the Structured Clinical Interview for the Diagnostic and Statistical Manual (3rd ed., rev.) and the visual analog scale.

RESULTS

Both groups were similar in terms of pain intensity and duration. Statistical analysis showed both groups to have a significant amount of major psychiatric comorbidity, in particular major depressive disorder, and a high incidence of personality disorders. Therefore, intense chronic pain was associated with significant psychiatric comorbidity in both groups and in similar proportions.

CONCLUSION

The high incidence of personality pathology in both groups may represent an exaggeration of maladaptive personality traits and coping styles as a result of a chronic, intense, state of pain.

Central nervous system abnormalities in complex regional pain syndrome (CRPS): clinical and quantitative evidence of medullary dysfunction

OBJECTIVE

Sensory and motor abnormalities are common among patients with complex regional pain syndrome (CRPS). The purpose of the present study was to define and characterize these abnormalities and to develop a hypothesis regarding the area of the central nervous system from which they derive.

DESIGN

Data were acquired from study subjects using clinical examination and quantitative assessment of neurological function. Subjects were divided into four groups. CRPS patients were differentiated into two groups based on the presence or absence of sensory deficit on the face to clinical examination. The other two groups were composed of patients with other chronic pain syndromes and normal individuals without chronic pain or disability. Clinical and quantitative data were compared between groups.

PATIENTS

One hundred forty-five CRPS patients, 69 patients with other pain conditions, and 26 normal individuals were studied.

RESULTS

A high incidence of trigeminal hypoesthesia was observed in CRPS patients. CRPS patients with trigeminal hypoesthesia manifested bilateral deficits of sensory function, with a predominant hemilateral pattern. These patients also manifested bilateral motor weakness with a more prominent hemiparetic pattern. Both sensory and motor deficits were greatest ipsilateral to the painful side of the body. These features differed significantly from those of CRPS patients lacking clinical trigeminal deficit, other pain patients, and normals. A lower cranial nerve abnormality (sternocleidomastoid weakness) and a myelopathic feature (Hoffman's reflex) were more common in CRPS patients with trigeminal hypoesthesia.

CONCLUSIONS

Nearly half of CRPS patients had abnormalities of spinothalamic, trigeminothalamic, and corticospinal function that may represent dysfunction of the medulla. One-third of the remaining CRPS patients had neuroimaging evidence of spinal cord or brain pathology. The majority of CRPS patients in this study have measurable abnormalities of the sensory and motor systems or neuroimaging evidence of spinal cord or brain dysfunction.

Do patient and physician expectations predict response to pain-relieving procedures?

OBJECTIVE

To evaluate the relationships between patient and physician pretreatment expectations of pain relief and subsequent pain relief reported by chronic pain patients immediately after treatment.

DESIGN

Prospective study of consecutive patients undergoing a procedure in a pain clinic for treatment of chronic pain. Patients rated their current pain level and their expectation of pain relief immediately prior to undergoing a procedure (e.g., intravenous drug infusion, nerve block) for the treatment of chronic pain. Simultaneously and independently, the treating physician completed a similar questionnaire. At completion of the procedure, patients rated their current pain level and degree of pain relief.

SETTING

University of Washington Multidisciplinary Pain Center procedure suite.

PATIENTS

Forty-six consecutive chronic pain patients.

INTERVENTION

Intravenous drug infusions and nerve blocks.

OUTCOME MEASURES

Current pain and pain relief ratings.

RESULTS

Patients' pain relief expectation ratings were not correlated significantly with their postprocedure pain relief ratings or pre-post procedure changes in pain ratings. However, a statistically significant correlation was found between physician expectations of pain relief and patient pain relief ratings and patient pre-post procedure changes in pain.

CONCLUSIONS

The results of this study suggest that physicians are better predictors than are patients of patients responses to these procedures and/or that physicians may somehow subtly communicate their expectations to patients during the procedure, and these expectations then influence patient response. Patient pretreatment expectations may not always play a significant role in nonspecific treatment effects.

Medical and pharmacologic management of upper extremity neuropathic pain syndromes

Written from a neurologic and therapeutically conservative perspective, this review advocates fundamentally medical and pharmacologic management of upper extremity neuropathic pain syndromes, including chronic regional pain syndromes, formerly classified reflex sympathetic dystrophy (RSD) and causalgia. Mandatory steps include, first, a prompt serious attempt to localize the nerve lesion whenever possible using complete, sophisticated neurologic examinations, then thoughtfully selected conventional neurophysiologic and radiologic tests. Strongly discouraged are promiscuous use of "RSD" to describe all neuropathic pains, and diagnostic reliance upon thermography and uncontrolled sympathetic blocks. Conservative multidisciplinary diagnostic and treatment teams should often possess a nucleus of neurologist and hand therapist, plus additional consultants including psychiatric. Every physician and therapist managing neuropathic pain must consider psychologic and wellness issues within their responsibilities. Prompt referral to an experienced surgeon is crucial for decompression or repair of relevant, significant, objectively proven (ideally neurophysiologically) nerve and root lesions. Ambiguous professional colloquialisms, "central pain" and "central sensitization," unfortunately provide value-laden pretexts for premature invasive treatments, and animate the truly dreadful concept "central RSD". Various classes of conventional oral non-narcotic adjuvant analgesics are reviewed, and the inevitability of their empiric, non-formulaic administration. No patient-specific, rationally-identifiable molecular receptor/switch can be deduced clinically or tripped mechanistically to terminate chronic pain. Two promising new non-narcotic centrally-active medications, gabapentin and tramadol, are highlighted as harbingers of future progress. The neglected subtle art of prescription writing is stressed, particularly for medication-sensitive patients. Medical cost containment should promote critical, long overdue outcomes studies comparing conservative and invasive pain treatments.

Complex regional pain syndromes: including "reflex sympathetic dystrophy" and "causalgia"

"Reflex sympathetic dystrophy" and "causalgia" are now classified by the International Association for the Study of Pain as Complex Regional Pain Syndromes I and II. Sympathetically maintained pain is a frequent but variable component of these syndromes, as the sympathetic and somatosensory pathways are no longer functionally distinct. Pain is the cardinal feature of CRPS, but the constellation of symptoms and signs may also include sensory changes, autonomic dysfunction, trophic changes, motor impairment and psychological changes. Diagnosis is based on the clinical picture, with additional information regarding the presence of sympathetically maintained pain or autonomic dysfunction being provided by carefully performed and interpreted supplemental tests. Clinical experience supports early intervention with sympatholytic procedures (pharmacological or nerve block techniques), but further scientific data is required to confirm the appropriate timing and relative efficacy of different procedures. Patients with recurrent or refractory symptoms are best managed in a multi-disciplinary pain clinic as more invasive and intensive treatment will be required to minimize ongoing pain and disability.

Effect of intravenous sodium amytal on cutaneous limb temperatures and sympathetic skin responses in normal subjects and pain patients with and without Complex Regional Pain Syndromes (type I and II). I

This study examined the effects of intravenous administration of sodium amytal (SA), a medium action barbiturate, on cutaneous limb temperatures and sympathetic skin responses (SSR) to electrical stimulation. Eight normal volunteers and 13 patients with musculoskeletal pain, somatoform pain disorders or nerve/root injury (with findings strictly limited to the distribution of the distribution of the involved nerve) were compared to 15 patients with Complex Regional Pain syndromes (one of whom had documented nerve injury). The Complex Regional Pain Syndromes (CRPS) patients were characterized by the presence of severe diffuse limb pain and extraterritorial sensory, sudomotor and vasomotor abnormalities (i.e., not confined to the site of injury or the distribution of the injured nerve). The CRPS patients were different from the normal controls and the non-CRPS patients in their tendency to warm significantly many of their limbs (not just the symptomatic ones). SSR were reduced or lost in a few limbs only in all three groups, irrespective of the increase or decrease of limb temperature and the side of symptoms. We argue that the enhanced thermogenic effect of SA in CRPS patients is due to generalized central changes of thermoregulatory control specifically in this group.