Differential effects of expressive anger regulation on chronic pain intensity in CRPS and non-CRPS limb pain patients

Research has shown that the anger management styles of both anger-in (suppression of anger) and anger-out (direct verbal or physical expression of anger) may be associated with elevated chronic pain intensity. Only the effects of anger-out appear to be mediated by increased physiological stress responsiveness. Given the catecholamine-sensitive nature of pain mechanisms in complex regional pain syndrome (CRPS), it was hypothesized that anger-out, but not anger-in, would demonstrate a stronger relationship with chronic pain intensity in CRPS patients than in non-CRPS chronic pain patients. Thirty-four chronic pain patients meeting IASP criteria for CRPS and 50 non-CRPS (predominantely myofascial) limb pain patients completed the McGill Pain Questionnaire-Short Form (MPQ), the Anger Expression Inventory (AEI), and the Beck Depression Inventory (BDI). Analyses revealed no diagnostic group differences in mean scores on the anger-in (AIS) and anger-out (AOS) subscales of the AEI, or on the BDI (values of P>0.10). Results of general linear model analyses revealed significant AOS x diagnostic group interactions on both the sensory (MPQ-S) and affective (MPQ-A) subscales of the MPQ (values of P<0.05). In both cases, higher AOS scores were associated with more intense chronic pain in the CRPS group, but with less intense pain in the non-CRPS limb pain group. Inclusion of BDI scores as a covariate did not substantially alter the AOS x diagnostic group interactions, indicating that these AOS interactions were not due solely to overlap with negative affect. Although higher AIS scores were associated with elevated MPQ-A pain intensity as a main effect (P<0.05), no significant AIS x diagnostic group interactions were detected (values of P>0.10). The AIS main effect on MPQ-A ratings was accounted for entirely by overlap with negative affect. Results are consistent with a greater negative impact of anger-out on chronic pain intensity in conditions reflecting catecholamine-sensitive pain mechanisms, presumably due to the association between anger-out and elevated physiological stress responsiveness. These results further support previous suggestions that anger-in and anger-out may affect pain through different mechanisms.

Functional improvement after physiotherapy with a continuous infusion of local anaesthetics in patients with complex regional pain syndrome

Three patients were referred to our pain clinic with evidence of complex regional pain syndrome in their extremities. Two presented at the atrophic stage with joint contractures. Multiple analgesics had been prescribed without long-lasting relief. Physiotherapy was required to improve physical activity but was severely limited by pain. We instituted local anaesthetic infusion with the possibility of self-supplementation to facilitate physiotherapy; two via brachial plexus catheters for hand pain and one via epidural catheter for knee pain. Although their resultant pain scores were variable after cessation of local anaesthetic infusion, all the affected joints exhibited marked improvement in range of movement. We propose that this technique is a useful option for patients in all stages of complex regional pain syndrome where the emphasis is now directed toward functional improvement.

Physical therapy and cognitive-behavioral treatment for complex regional pain syndromes

Complex regional pain syndromes (CRPS; type 1, reflex sympathetic dystrophy, and type 2, causalgia) involve persistent pain, allodynia, and vasomotor signs. We conducted a prospective, randomized, single-blind trial of physical therapy (PT) and cognitive-behavioral treatment for children and adolescents with CRPS. Children 8 to 17 years of age (n = 28) were randomly assigned to either group A (PT once per week for 6 weeks) or group B (PT 3 times per week for 6 weeks). Both groups received 6 sessions of cognitive-behavioral treatment. Assessments of pain and function were repeated at two follow-up time periods. Outcomes were compared at the three time points through the use of parametric or nonparametric analysis of variance and post hoc tests. All five measures of pain and function improved significantly in both groups after treatment, with sustained benefit evident in the majority of patients at long-term follow-up. Recurrent episodes were reported in 50% of patients, and 10 patients eventually received sympathetic blockade. Most children with CRPS showed reduced pain and improved function with a noninvasive rehabilitative treatment approach. Long-term functional outcomes were also very good.

[Multidimensional, nonlinear pain concept. A broad approach for explaining and understanding complex pain syndromes]

The traditional mechanistic, deterministic, point-to-point-model of Descartes with its modifications of specificity, intensity, pattern and gate-control-theory turned out to be suitable for acute pain. Symptomatic pain as a result of a lesion or organic disease has to be differentiated principally from multifactorial pain syndromes. They can be regarded as open dynamic systems. The implication of consciousness of chronic pain patients with its essential intentionality opens degrees of freedom for the patients on the one hand, but uncertainty in the response to treatment measures, compliance and prognosis on the other hand. For complex regional pain, for chronifying syndromes and for the majority of chronic pain states the non-deterministic, non-linear, multidimensional pain concept is proposed.

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.

Course of symptoms and quality of life measurement in Complex Regional Pain Syndrome: a pilot survey

Few data have been published regarding the natural history, course of symptoms, and quality of life in Complex Regional Pain Syndrome (CRPS). To obtain preliminary data regarding these important issues in CRPS, a set of patient self-report questionnaires were mailed to patients with the diagnosis of CRPS who had been assessed and/or treated at a tertiary university-based pain center in the United States. Self-reports of demographic information, symptoms, the Neuropathic Pain Scale, and a modified Brief Pain Inventory (mBPI) were received from 31 CRPS patients. Approximately 75% of patients reported initial symptoms of pain, swelling, coldness, and color changes. An additional 71% had weakness and inability to move the extremity as initial symptoms. Weakness at some time during their course of CRPS was described by 97%. A majority reported no overall improvement or worsening of symptoms over time (mean 3.3 years). The pain descriptors with the highest mean values were "deep" (6.4/10), "unpleasant" (6.4), "sensitive" (5.7), "surface" (5.4), and "dull" (5.3) pains. Significant sleep disturbance was reported by 80%. CRPS had a severe impact on quality of life, with substantial interference reported in 9 of 10 mBPI activity items by a majority of these patients. These findings should be viewed with caution and should not be generalized to the entire CRPS population because the cohort was small and select. A large multicenter prospective study needs to be performed to validate these preliminary findings.

Experimental tissue acidosis leads to increased pain in complex regional pain syndrome (CRPS)

The aim of this study was to investigate the role of local acidosis in the generation of pain in complex regional pain syndrome (CRPS). We investigated ten patients with CRPS of the upper extremity with a mean duration of the disease of 43 weeks (range 4-280 weeks) and ten control subjects for sensitivity to infusion of fluids with low pH (pH 6.1). Another group of five CRPS patients and three healthy controls was investigated using the same protocol but neutral infusion fluid (pH 7.4). A motorized syringe pump was installed for a constant infusion of synthetic interstitial fluid (SIF, either acidified (pH 6.1) or neutral) into the skin at the back of the hands and, thereafter, into the interosseus I muscle on both sides. A flow rate of 30 ml/h was chosen for intradermal and 7.5 ml/h for intramuscular infusion over a period of 10 min. The magnitude of pain was rated on an electronic visual analogue scale. Patients were requested to give their ratings every 10 s during the whole stimulation period. The ratings were normalized as fractions of individual grand mean values. We found significantly increased pain perception during infusion of acidified SIF on the affected side in CRPS patients. Low pH fluid into the skin was significantly more painful between 4 and 6 min (ipsi 1.27 normalized rating (NR) (0. 19-1.94), contra 0.31 NR (0.03-0.51), P<0.02) and between 8 and 10 min (ipsi 1.38 NR (0.19-1.94), contra 0.08 NR (0-0.27), P<0.03) on the affected side, while analysis over the whole stimulation period just failed to reach statistical significance (ipsi 281 area under the curve (AUC) (187-834), contra 87 AUC (28-293), P=0.059). Low pH infusion into the muscle was significantly more painful on the affected side during the whole infusion time (ipsi 861 AUC (308-1377), contra 190 AUC (96-528), P<0.01). The quality of the deep pain during infusion into the muscle was described by the patients as very similar to the CRPS-related pain. In controls we found no side differences of pain intensity during low pH stimulation. Neutral SIF evoked no pain at all, neither in CRPS patients (ipsi 0 AUC, contra 0 AUC) nor in healthy controls. Our results suggest that hyperalgesia to protons is present in patients with CRPS. Further, we could demonstrate that pain is not only restricted to the skin but is also generated in deep somatic tissue of the affected limb.

Lumbar sympathetic block for sympathetically maintained pain: changes in cutaneous temperatures and pain perception

Lumbar sympathetic block (LSB) is used in the management of sympathetically maintained pain states. We characterized cutaneous temperature changes over the lower extremities after LSB. Additionally, we examined the effects of iohexol, a radio-opaque contrast medium, on temperature changes and pain relief. After institutional review board approval and written, informed consent, 28 LSBs were studied in 17 patients. Iohexol or normal saline was injected in a randomized, double-blinded fashion before bupivacaine. Lower extremity cutaneous temperatures were measured. Pain, allodynia, interference with daily function, and perceived pain relief were reported in a subset of 15 LSBs for 1 wk after the block. The distal lower extremity ipsilateral to the LSB had the greatest magnitude (8.7 degrees +/- 0.8 degrees C) and rate (1.1 degrees +/- 0.2 degrees C/min) of temperature change. The great toe temperature was within 3 degrees C of core temperature within 35 min after LSB. There were no differences in temperature change between the groups. The iohexol group had greater relief of pain until the morning of the first postblock day (P = 0.002) and longer perceived relief of pain (P = 0.01). The maximum temperature of the great toe correlated with allodynia relief (P = 0.0007). Thus clinicians should expect ipsilateral toe temperatures to increase to within approximately 3 degrees C of core temperature. Iohexol does not alter the efficacy of LSB and may improve relief of symptoms. The magnitude of temperature change may predict relief of allodynia.

IMPLICATIONS

Cutaneous toe temperatures approaching core temperature provide a useful monitor of lumbar sympathetic block and may predict relief of sympathetically maintained pain. Iohexol will not compromise temperature changes or pain relief.

Complex regional pain syndrome with selective emotional sudomotor failure

We report a patient with sympathetically maintained pain following a mild limb injury. Only emotional sudomotor failure was found in the painful limb. Thermoregulatory vasomotor function was intact. However, the patient had other target-specific sympathetic lesions, including thermoregulatory vasomotor failure in a different limb, not associated with pain. We hypothesize that the sympathetic failure preceded the symptoms and that the mild injury may have provoked collateral sprouting of emotional sudomotor fibres, coupling them with somatic sensory fibres to cause continuous pain.

Neurological findings in complex regional pain syndromes--analysis of 145 cases

Early diagnosis is a prerequisite for a successful treatment of complex regional pain syndrome (CRPS). In order to describe neurological symptoms which characterize CRPS, we evaluated 145 patients prospectively. Two-thirds of these were women, the mean age at time of investigation was 50.4 years. CRPS followed limb trauma, surgery and nerve lesion. Employing the current IASP criteria 122 patients were classified as CRPS I and 23 as CRPS II. All patients were assessed clinically pain was quantified using the McGill pain questionnaire, skin temperature was measured by an infrared thermometer and a subgroup of 57 patients was retested in order to determine thermal thresholds (QST). Of our patients 42% reported stressful life events in a close relationship to the onset of CRPS and 41% had a history of chronic pain before CRPS. The latter group of patients gave a higher rating of CRPS pain (P<0.05). The major symptoms were pain at rest in 77% and hyperalgesia in 94%. Typical pain was deep in the limb having a tearing character. Patients getting physical therapy had significantly less pain than those without (P<0.04). Autonomic signs were frequent (98%) and often changed with the duration of CRPS. Skin temperature was warmer in acute and colder in chronic stages (P<0.001). Likewise edema had a higher incidence in acute stages (P<0.001). We found no correlation between pain and autonomic dysfunction. Motor dysfunction (present in 97%) included weakness, tremor, exaggerated tendon reflexes, dystonia or myoclonic jerks. QST revealed increased warm perception thresholds (P<0.02) and decreased cold pain thresholds (P<0.03) of the affected limb. The detailed knowledge of clinical features of CRPS could help physicians early to recognize the disease and thus to improve therapy outcome.

New developments in rehabilitation of neuropathic pain syndromes

The common medical treatments of neuropathic pain, medication and nerve blocks, are often only partially effective in providing significant and long-term pain relief. Patients suffering chronic pain often fall prey to associated emotional suffering, functional impairment, and difficulties in multiple areas of their lives, including family disruption, social withdrawal, and vocational disability. An interdisciplinary approach to pain management draws on the skills of physical and occupational therapists, pain psychologists, biofeedback specialists, and vocational counselors. It focuses on both pain management and functional restoration, and should be considered standard treatment for chronically painful conditions. Interdisciplinary pain management views the patient as an active agent, responsible for learning and applying self-management techniques for controlling pain, with the staff assuming a teaching and consulting role. Although much more labor intensive, interdisciplinary pain management is more effective over time in managing chronic pain, in preventing unnecessary emotional and physical impairment, and in controlling overall medical costs.