Chronic Complex Regional Pain Syndrome Research Articles

Impairments and activity limitations in subjects with chronic upper-limb complex regional pain syndrome type I

Schasfoort FC, Bussmann JB, Stam HJ. Impairments and activity limitations in subjects with chronic upper-limb complex regional pain syndrome type I. Arch Phys Med Rehabil 2004;85:557–66. Objective To determine the degree of impairments and activity limitations and their interrelationship in complex regional pain syndrome type I (CRPS type I). Design Cross-sectional study interrelating impairments and objectively measured activity limitations. Setting Ambulatory and home environment. Participants Thirty nonacute upper-limb CRPS type I subjects. Interventions Not applicable. Main outcome measures Sensory, motor, and autonomic impairments, as well as activity-limitation outcome measures. The latter were objectively measured with a novel upper-limb activity monitor (based on ambulatory accelerometry). Results All subjects were impaired to some degree but with a large variability with respect to magnitude. Regarding activity limitations, the involved upper limb was clearly less active (lower intensity and percentage of activity) than the noninvolved side. Impaired active range of motion (adjusted R 2 range, 18%–39%) and grip strength (adjusted R 2 range, 12%–45%) were the most important factors explaining variance in activity limitations. Conclusions All subjects were still impaired nearly 3 years after the causative event. The involved upper limb was also clearly less active than the noninvolved side, especially when the subjects were sitting and when the dominant side was involved. The more impairments a subject had, especially motor impairments, the more activity limitations were present.

MULTIDISCIPLINARY PAIN ABSTRACTS: 36 . Neurology (36)

In this study, the authors assessed mirror visual feedback (MVF) to test the hypothesis that incongruence between motor output and sensory input produces complex regional pain syndrome (CRPS) (type I) pain. Eight subjects were studied over 6 weeks with assessments including two controls (no device and viewing a non‐reflective surface) and the intervention (MVF). Pain severity and vasomotor changes were recorded. The control stages had no analgesic effect. MVF in early CRPS had an immediate analgesic effect and in intermediate disease led to a reduction in stiffness. At 6 weeks, normalization of function and thermal differences had occurred. No change was found in chronic CRPS. In early CRPS (type I), visual input from a moving, unaffected limb re‐establishes the pain‐free relationship between sensory feedback and motor execution. Trophic changes and a less plastic neural pathway preclude this in chronic disease.

Chronic pain patients are impaired on an emotional decision-making task

Chronic pain can result in anxiety, depression and reduced quality of life. However, its effects on cognitive abilities have remained unclear although many studies attempted to psychologically profile chronic pain. We hypothesized that performance on an emotional decision-making task may be impaired in chronic pain since human brain imaging studies show that brain regions critical for this ability are also involved in chronic pain. Chronic back pain (CBP) patients, chronic complex regional pain syndrome (CRPS) patients, and normal volunteers (matched for age, sex, and education) were studied on the Iowa Gambling Task, a card game developed to study emotional decision-making. Outcomes on the gambling task were contrasted to performance on other cognitive tasks. The net number of choices made from advantageous decks after subtracting choices made from disadvantageous decks on average was 22.6 in normal subjects ( n=26), 13.4 in CBP patients ( n=26), and −9.5 in CRPS patients ( n=12), indicating poor performance in the patient groups as compared to the normal controls ( P<0.004). Only pain intensity assessed during the gambling task was correlated with task outcome and only in CBP patients ( r=−0.75, P<0.003). Other cognitive abilities, such as attention, short-term memory, and general intelligence tested normal in the chronic pain patients. Our evidence indicates that chronic pain is associated with a specific cognitive deficit, which may impact everyday behavior especially in risky, emotionally laden, situations.

MULTIDISCIPLINARY PAIN ABSTRACTS: 35. Neurology (35)

The aim of the present case series was to examine whether changes in regional cerebral blood flow (rCBF) induced by electroconvulsive therapy (ECT) in the thalamus are related to the efficacy of ECT. Four chronic pain patients with complex regional pain syndrome (CRPS) type I (age 33 to 58 years) who had failed to respond to standard pain treatments received a course of ECT. To investigate the possible mechanisms of the analgesic effect of ECT on chronic CRPS type I, the authors measured significant changes in the rCBF of the thalamus using technetium‐99 methyl cysteinate dimer single photon emission computed tomography (99mTc ECD SPECT), before and after ECT and compared these values between responders and nonresponders. Two of four patients responded to ECT. 99mTc ECD SPECT showed that the mean contralateral thalamus‐to‐cerebellum ratio increased 11.5% after ECT compared with the ratio before ECT in the two responders, but remained unchanged in nonresponders. The results from the SPECT suggest that normalization of the balance of rCBF in the thalamus may be related to the analgesic efficacy of the ECT on CRPS type I.

Tissue hypoxia in complex regional pain syndrome

Untreated complex regional pain syndrome (CRPS) may progress from acute stages with increased hair and nail growth in the affected limb to chronic stages with atrophy of the skin, muscles and bones. The aim of this study was to investigate whether tissue hypoxia could be one mechanism responsible for this late CRPS symptoms. Nineteen patients with CRPS and two control groups (healthy control subjects, surgery patients with edema) participated in this study. Skin capillary hemoglobin oxygenation (HbO 2) was measured non-invasively employing micro-lightguide spectrophotometry (EMPHO). The EMPHO probe was mounted force-controlled onto the skin of the affected and unaffected hand. HbO 2 was measured at rest and during postischemic reactive hyperemia. HbO 2 did not differ between the right (58.20%±1.12) and left (57.79%±1.31, ns) hand in control subjects. However, in patients, HbO 2 of the affected side (36.63%±2.16) was significantly decreased as compared to the clinically unaffected side (46.35%±2.97, P<0.01). As compared to controls, HbO 2 in CRPS was reduced on both sides ( P<0.001). Postischemic hyperoxygenation was impaired on the affected side in CRPS (60.81%±2.90) – as compared to the unaffected side (67.73%±1.50, P<0.04) and to controls (68.63%±0.87, P<0.005). The unaffected limb in CRPS did not differ from controls. Despite skin edema, pre- (49.06%±2.02) and postsurgery HbO 2 (53.15%±4.44, ns) were not different in the second control group. Our results indicate skin hypoxia in CRPS. Impairment of nutritive blood flow in the affected limb may be one factor contributing to atrophy and ulceration in chronic CRPS. The investigation of patients after surgery revealed that edema could not be the only reason for hypoxia.

Proton magnetic resonance spectroscopy of the thalamus in chronic complex regional pain syndrome (CRPS) type-1 patients

AbstractRecent reports have suggested that reduced thalamic blood flow and functional alterations in thalamic pain processing circuits may be important components in chronic neuropathic pain. The purpose of the present study was to examine neural activity in the thalamus in chronic CRPS (complex regional pain syndrome) type-1 patients, using proton magnetic resonance spectroscopy (1H-MRS). We performed 1H-MRS with a 1.5T MR system on a 2 × 2 × 2-cm voxel in the thalamus bilaterally, in five CRPS type-1 patients and six normal control subjects. We measured the N-acetylaspartate to creatine (NAA/Cr) ratio, which reflects neural activity, using 1H-MRS. The mean NAA/Cr ratio in the thalamus contralateral to the side of pain decreased significantly, compared to the mean NAA/Cr ratio of the ipsilateral side and the normal control subjects. Our results using 1H-MRS suggest that chronic CRPS type-1 seems to be associated with abnormal balance of neural activity of the thalamus.

Changes in regional cerebral blood flow in the thalamus after electroconvulsive therapy for patients with complex regional pain syndrome type 1 (preliminary case series)

Background and Objectives: The aim of the present case series was to examine whether changes in regional cerebral blood flow (rCBF) induced by electroconvulsive therapy (ECT) in the thalamus are related to the efficacy of ECT. Four chronic pain patients with complex regional pain syndrome (CRPS) type-1 (age, 33 to 58 years) who had failed to respond to standard pain treatments received a course of ECT. To investigate the possible mechanisms of the analgesic effect of ECT on chronic CRPS type-1, we measured significant changes in the rCBF of the thalamus using technetium-99m ethyl cysteinate dimer single photon emission computed tomography (99mTc ECD SPECT), before and after ECT and compared these values between responders and nonresponders. Results: Two of 4 (50.0%) patients responded to ECT treatment (response defined as a reduction of at least 60% on the visual analog scale [VAS]). 99mTc ECD SPECT showed that the mean contralateral thalamus-to-cerebellum ratio increased 11.5% after ECT compared with the ratio before ECT in the 2 responders, but remained unchanged in nonresponders. Conclusions: The results from the SPECT suggest that normalization of the balance of rCBF in the thalamus may be related to the analgesic efficacy of the ECT on CRPS Type-1. Reg Anesth Pain Med 2002;27:529-532.

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.

Child Abuse and Dissociation in Patients with Complex Regional Pain Syndrome

&gt;OBJECTIVE: In the absence of a proven medical explanation for the chronic pain syndrome Complex Regional Pain Syndrome type I (CRPS I), this study explored a hypothetical link between childhood physical and sexual abuse, and the subsequent development of CRPS I. The hypothesis predicts the existence of a subpopulation of CRPS I patients with a high frequency of dissociative experiences corresponding to a history of childhood trauma.DESIGN: To test this theory, CRPS I patients attending the Auckland Hospital Pain Clinic, Auckland, New Zealand were assessed by self‐report questionnaires for their frequency of dissociative experiences and for a history of childhood abuse. The data were compared with those of a low back pain control group and a healthy, pain‐free control group.RESULTS: CRPS I patients were not unusually dissociative and had not experienced significantly higher rates of childhood abuse than the general population. Two of the 18 CRPS I patients were highly dissociative; both reported childhood sexual abuse.CONCLUSIONS: A trauma‐dissociation pathway to CPRS I was not found. The desirability of screening for that subpopulation of CPRS I sufferers who may have been abused is discussed.

Complex regional pain syndrome (reflex sympathetic dystrophy and causalgia): management with the calcium channel blocker nifedipine and/or the α-sympathetic blocker phenoxybenzamine in 59 patients

Complex Regional Pain Syndrome (CRPS) is the new name for entities formerly known mostly as Reflex Sympathetic Dystrophy and Causalgia. Treatment of CRPS with either the calcium channel blocker nifedipine or the α-sympathetic blocker phenoxybenzamine was assessed in 59 patients, 12 with early stages of CRPS, 47 with chronic stage CRPS. In the early stage CRPS patients, 3 of 5 were cured with nifedipine and 8 of 9 (2 of whom had earlier received nifedipine) with phenoxybenzamine, for a cure rate of 92% (11 out of 12). In the chronic stage CRPS patients, 10 of 30 were cured with nifedipine; phenoxybenzamine cured 7 of 17 patients when administered as a first choice and another 2 ofof 7 patients who received nifedipine earlier, for a total late stage success rate of 40% (19 out of 47). The most common side effects necessitating discontinuing the drug were headaches for nifedipine and orthostatic dizziness, nausea and diarrhoea for phenoxybenzamine. All male patients on phenoxybenzamine experienced impotence, but this did not lead to discontinuing this agent and immediately disappeared after stopping the drug. These results once again stress the importance of early recognition of CRPS, and treatment with either of these drugs could be considered as a first choice for early CRPS, especially because in this series this treatment was not combined with physical therapy making it very cost-effective. In the chronic stage of CRPS, treatment with these drugs was much less successful (40%), even though it was always combined with physical therapy, but it can still be considered, either as a first choice or when other types of treatment have failed.