CRPS Research update May 2012

Here’s a selection of the latest papers looking at complex regional pain syndrome (CRPS):

Pain Pract. 2012 Apr 11. doi: 10.1111/j.1533-2500.2012.00539.x. [Epub ahead of print]

Ultrasound Appearance of Forearm Muscles in 18 Patients With Complex Regional Pain Syndrome 1 of the Upper Extremity.

Vas LC, Pai R, Radhakrishnan M.

Abstract

Objective:   To explore the potential diagnostic utility of musculoskeletal ultrasonography (USG) changes in complex regional pain syndrome type 1 (CRPS-1) of the upper extremity. Methods:  With informed consent, 18 consecutive patients referred to our institution with CRPS-1 of the upper limb were examined with ultrasound scanning of both upper limbs. Qualitative comparison of the scan of the forearm muscles of the affected side with the unaffected side was made. Results:  The muscles affected by CRPS-1 demonstrated increased echogenecity. The outlines of the muscles were either indistinct or completely obliterated. A group of several muscles appeared like one homogenous, hyperechoic mass, with loss of normal architecture. Compared with the unaffected side, the muscle thickness on the CRPS-1 side measured by calipers on ultrasound was reduced irrespective of the duration of disability or disuse of the hand. The flexors and extensor muscles of the forearm were maximally affected. Conclusion:  Ultrasonography provides useful anatomical information, regarding structure, kinesiology, and gross pathological changes of muscle, that may prove useful in understanding the motor impairment associated with CRPS-1. USG shows promise as a cost-effective bedside tool for the diagnosis of CRPS-1 and in guiding physical therapy.

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Psychoneuroendocrinology. 2012 Mar 23. [Epub ahead of print]

Hypothalamic-pituitary-adrenal axis function in patients with complex regional pain syndrome type 1.

Park JY, Ahn RS.

Abstract

An exaggerated inflammatory process is considered an important pathophysiological feature of complex regional pain syndrome type 1 (CRPS-1). The hypothalamic-pituitary-adrenal (HPA) axis serves as a negative feedback mechanism for inflammatory processes. The present study examined the HPA axis function in patients with CRPS-1 by a determination of cortisol concentrations in saliva. Three sets of saliva samples were sequentially collected from 24 patients with CRPS-1 during medication (on-Med), 72h after stopping medication (off-Med) and 8h after the oral administration of 1mg dexamethasone. One set of saliva samples was collected from healthy controls. The cortisol awakening response (CAR) and diurnal cortisol decline (DCD) were used as indices for HPA axis function. Cortisol levels during the post-awakening period in patients were increased following withdrawal of medications. The CAR during the off-Med condition was disappeared after administration of dexamethasone. Among the examined CRPS-related numerical variables, the frequency of spontaneous pain attacks showed relationships with the indices of HPA axis function. After classifying the patients into two subgroups, we observed that the CAR and DCD in patient who had a relatively high frequency of spontaneous pain attacks (subgroup 5≤) were lower and less steep than those in patient who had a relatively low frequency of spontaneous pain attacks (subgroup 0-4) for the on- and off-Med conditions. The CAR and DCD in subgroup 5≤ during their off-Med condition were comparable to those in controls. These results suggest that the increase in frequency of spontaneous pain attacks is associated with a reduced CAR and flattened DCD in patients CRPS-1.

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Int J Rehabil Res. 2012 Jun;35(2):138-45.

Modified graded motor imagery for complex regional pain syndrome type 1 of the upper extremity in the acute phase: a patient series.

Lagueux E, Charest J, Lefrançois-Caron E, Mauger ME, Mercier E, Savard K, Tousignant-Laflamme Y.

Abstract

Complex regional pain syndrome (CRPS) is a pathologic condition in which the painful experience is disproportionate in time and intensity in comparison with the inciting event. At present, the pathophysiology of CRPS is not well understood. Several studies have indicated that cortical reorganization plays a role in the persistence of the symptoms. A new promising approach, graded motor imagery (GMI), seems to be effective, but there are limited data for the CRPS-1 upper extremity population. The aim of this study was to demonstrate the effectiveness of a modified GMI (mGMI) protocol based on the work of Moseley to reduce pain and enhance functional capacities for a population with nonchronic CRPS-1 of the upper extremity. The following outcome measures were used to assess the clinical effectiveness: pain (short form of the McGill Pain Questionnaire), grip force (Martin vigorimeter), perception of upper extremity function (Disabilities of the Arm, Shoulder and Hand Questionnaire), and patient’s global impression of change. All outcomes at T4 were compared with the baseline data (T0) using the Mann-Whitney test and the χ test (nonparametric tests). Seven patients were recruited for the study. At the end of the mGMI (T4), we obtained significant results for the decrease in the pain experienced in the last 7 days (visual analog scale; P=0.046), improvement in the affected extremity grip force (P=0.042), and the patient’s global impression of change (P=0.015). However, the data of the perception of upper extremity function (Disabilities of the Arm, Shoulder and Hand Questionnaire) were not clinically or statistically significant. Our results indicate that this mGMI protocol seems to be a promising therapeutic modality to reduce pain. However, more investigations are needed to determine whether mGMI has a significant impact on upper extremity function

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Pain. 2012 May;153(5):1063-73. Epub 2012 Mar 16.

Cognitive correlates of “neglect-like syndrome” in patients with complex regional pain syndrome.

Kolb L, Lang C, Seifert F, Maihöfner C.

Abstract

Patients with complex regional pain syndrome (CRPS) often show distinct neurocognitive dysfunctions, which were initially termed “neglect-like symptoms.” So far, particularly the patients’ feelings about the affected extremity, motor, and sensory aspects of the “neglect-like symptoms” have been investigated, possibly pointing to a disturbed body schema. Because patients with classical neurological neglect show diminished awareness regarding the perception of their body, as well as of the space around them, our hypothesis was that CRPS patients exhibit some signs of personal neglect and extrapersonal visuospatial problems over and beyond those seen in patients simply suffering from limb pain. We used quantitative sensory testing and motor assessment aimed at detecting motor and sensory loss, a standardized questionnaire calculating a neglect score, and applied a detailed neuropsychological test battery assessing different parietal lobe functions, including visual neglect. We examined 20 CRPS patients and 2 matched control groups, one consisting of healthy subjects and the other one of patients with limb pain other than CRPS. Results show significant higher neglect scores for CRPS patients and the pain control group, but interestingly, CRPS patients and pain patients were indistinguishable. The results of the neuropsychological test battery did not demonstrate systematic variances, which would be indicative of a classical neurological neglect in CRPS patients, even though there were 3 CRPS patients who differed ⩾2 SD from the mean of our healthy control group, with poorer results in ⩾3 different tests. We assume that the “neglect-like syndrome” in most CRPS patients is different from typical neglect.

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Eur J Pain. 2012 Mar 9. doi: 10.1002/j.1532-2149.2012.00120.x. [Epub ahead of print]

Perceptions of the painful body: The relationship between body perception disturbance, pain and tactile discrimination in complex regional pain syndrome.

Source

Faculty of Dentistry, McGill University, Montreal, Canada; The Royal National Hospital for Rheumatic Diseases NHS Foundation Trust, Bath, UK.

Abstract

BACKGROUND:

Disturbances in body perception are increasingly acknowledged as a feature of complex regional pain syndrome (CRPS). Conventional treatments have limited success particularly among those with long-standing disease. Understanding the relationship between body perception disturbance, pain and tactile acuity might provide insight into alternative avenues for treatment. The aim of this study was to test the hypotheses that (1) body perception disturbance is positively related to pain and (2) decreased tactile acuity is related to increased body perception disturbance.

METHODS:

A controlled observational design was used to measure these features among those with CRPS of one arm. The extent of body perception disturbance was assessed using the Bath CRPS body perception disturbance scale and pain was measured using the neuropathic pain symptom inventory. Two-point discrimination threshold testing was performed as a measure of tactile acuity.

RESULTS:

Findings confirmed both hypotheses. Body perception disturbance was found to positively correlate with pain such that those in greater pain had more extensive body perception disturbance (r = 0.57, p < 0.01). Furthermore, a positive correlation was revealed between body perception disturbance and two-point discrimination thresholds (r = 0.5, p < 0.025) so those with greater body perception disturbance had worse tactile acuity. Interestingly, those with longer disease duration had significantly greater body perception disturbance (r = 0.66, p < 0.001).

CONCLUSION:

Aberrant central processing is suggested as the neural correlate of body perception disturbance and tactile impairment. The exact relationship between body perception disturbance, pain and tactile acuity and how they may be modulated for pain relief requires further exploration

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