An international study to explore the feasibility of collecting standardised outcome data for Complex Regional Pain Syndrome: recommendations for an international clinical research registry

Introduction

Complex Regional Pain Syndrome (CRPS) is a persistent pain condition with low prevalence. Multi-centre collaborative research is needed to attain sufficient sample sizes for meaningful studies. This international observational study: (1) tested the feasibility and acceptability of collecting outcome data using an agreed core measurement set (2) tested and refined an electronic data management system to collect and manage the data.

Methods

Adults with CRPS, meeting the Budapest diagnostic clinical criteria, were recruited to the study from 7 international research centres. After informed consent, a questionnaire comprising the core set outcome measures was completed: on paper at baseline (T1), and at 3 or 6 months (T2) using a paper or e-version. Participants and clinicians provided feedback on the data collection process. Clinicians completed the CRPS severity score at T1 and optionally, at T2. Ethical approval was obtained at each international centre.

Results

Ninety-eight adults were recruited (female n=66; mean age 46.6 years, range 19-89), of whom 32% chose to receive the T2 questionnaire in an electronic format. Fifty-five participants completed both T1 and T2. Eighteen participants and nine clinicians provided feedback on their data collection experience.

Conclusion

This study confirmed the questionnaire core outcome data are feasible and practicable to collect in clinical practice. The electronic data management system provided a robust means of collecting and managing the data across an international population. The findings have informed the final data collection tools and processes which will comprise the first international, clinical research registry and data bank for CRPS.

Quantitative Dynamic Allodynograph-A Standardized Measure for Testing Dynamic Mechanical Allodynia in Chronic Limb Pain

BACKGROUND

Dynamic mechanical allodynia (DMA) is both a symptom and a central sensitization sign, yet no standardized method for quantifying the DMA area has been reported. This study aimed to establish psychometric properties for Quantitative Dynamic Allodynography (QDA), a newly developed protocol measuring the DMA area as a percentage of the body surface.

METHODS

Seventy-eight patients aged 18-65 diagnosed with chronic complex regional pain syndrome (CRPS) participated in this study. Test-retest reliability was conducted twice, one week apart (N = 20), and inter-rater (N = 3) reliability was conducted on 10 participants. Disease severity (CRPS Severity Score, CSS), pain intensity (VAS), and quality of life (SF-36) measures were utilized to test construct validity.

RESULTS

High inter-rater reliability (intraclass correlation coefficient (ICC) = 0.96, p < 0.001) and test-retest reliability (r = 0.98, p < 0.001) were found. Furthermore, the QDA score was found to be correlated with the CSS (r = 0.47, p < 0.001), VAS (r = 0.37, p < 0.001), and the SF-36 physical health total (r = -0.47, p < 0.001) scores.

CONCLUSION

The QDA is the first developed reliable and valid protocol for measuring DMA in a clinical setting and may be used as a diagnostic and prognostic measure in clinics and in research, advancing the pain precision medicine approach.

Central Sensitization and Psychological State Distinguishing Complex Regional Pain Syndrome from Other Chronic Limb Pain Conditions: A Cluster Analysis Model

Complex regional pain syndrome (CRPS) taxonomy has been updated with reported subtypes and is defined as primary pain alongside other chronic limb pain (CLP) conditions. We aimed at identifying CRPS clinical phenotypes that distinguish CRPS from other CLP conditions. Cluster analysis was carried out to classify 61 chronic CRPS and 31 CLP patients based on evoked pain (intensity of hyperalgesia and dynamic allodynia, allodynia area, and after-sensation) and psychological (depression, kinesiophobia, mental distress, and depersonalization) measures. Pro-inflammatory cytokine IL-6 and TNF-α serum levels were measured. Three cluster groups were created: ‘CRPS’ (78.7% CRPS; 6.5% CLP); ‘CLP’ (64.5% CLP; 4.9% CRPS), and ‘Mixed’ (16.4% CRPS; 29% CLP). The groups differed in all measures, predominantly in allodynia and hyperalgesia (p < 0.001, η² > 0.58). ‘CRPS’ demonstrated higher psychological and evoked pain measures vs. ‘CLP’. ‘Mixed’ exhibited similarities to ‘CRPS’ in psychological profile and to ‘CLP’ in evoked pain measures. The serum level of TNF-αwas higher in the ‘CRPS’ vs. ‘CLP’ (p < 0.001) groups. In conclusion, pain hypersensitivity reflecting nociplastic pain mechanisms and psychological state measures created different clinical phenotypes of CRPS and possible CRPS subtypes, which distinguishes them from other CLP conditions, with the pro-inflammatory TNF-α cytokine as an additional potential biomarker.

Pain Catastrophizing Mediates the Association Between Mindfulness and Psychological Distress in Chronic Pain Syndrome

AIM

Trait mindfulness has been found to be inversely associated with emotional distress such as depression and anxiety among patients suffering from pain. The current study investigated the putative mechanisms underlying these associations by examining whether pain catastrophizing mediates the association between mindfulness and psychological distress and whether this model differs in patients suffering from chronic pain compared to patients experiencing nonchronic pain in a medical rehabilitation setting.

METHODS

Forty-eight patients in their subacute stage of recovery participated in the study. Seventeen participants had a diagnosis of chronic pain. Trait mindfulness was assessed using the Mindful Attention Awareness Scale, pain catastrophizing was assessed using the Pain Catastrophizing Scale, depression symptoms were assessed using the Patient Health Questionnaire, and anxiety was assessed using the Generalized Anxiety Disorder scale. Two mediation models were used, with pain catastrophizing mediating the association between mindfulness and depression and anxiety.

RESULTS

Catastrophizing significantly mediated the association between trait mindfulness and depression (P < 0.05, confidence interval [CI] = -0.35, -0.05). Catastrophizing also mediated the relationship between trait mindfulness and anxiety (P < 0.05, CI = -0.34, -0.04). Two moderated mediation models were tested, in which pain catastrophizing fully mediated the relationship between trait mindfulness and depression and anxiety, but only in patients with chronic pain.

CONCLUSIONS

The negative association between trait mindfulness and psychological distress may thus be partly attributed to pain catastrophizing: individuals high in trait mindfulness engage in less catastrophic thinking and therefore experience less distress. Importantly, this was only observed in the patients with chronic pain. These results further underscore the need to cope with pain catastrophizing and encourage mindfulness among patients with chronic pain.

A pilot study on the electrophysiological monitoring of patient's engagement in post-stroke physical rehabilitation

Introduction: This study discusses the feasibility of an electrophysiological monitor for patient engagement during rehabilitation sessions. While patient engagement has a significant clinical role, it is not obvious how its real-time monitoring could be used.Objective: We designed this study to provide further support for the feasibility of such a tool based on the Brain Engagement Index (BEI), and to discuss clinical usefulness and its evaluation.Methods: The study involved 30 patients during post-stroke rehabilitation. Each patient underwent two sessions with BEI monitoring. In one session the therapist received real-time feedback from the monitor and in the other he did not. The BEI was compared to video-based evaluation of temporary functional change from the session start to its end and with a rater-based evaluation of the level of engagement evoked by the exercises in the session.Results: Irrespective of whether feedback is used, there is association between BEI and temporary functional change as well as with evaluated engagement. Furthermore, the contribution of the BEI monitor to rehabilitation may be demonstrated.Conclusions: It would be challenging to establish directly the monitor's contribution in large-scale studies. Nevertheless, it might be sufficient to demonstrate that the monitor provides important information regarding patient engagement.Implication for RehabilitationThis work presents an easy-to-use electrophysiological index for monitoring patient engagement in real-time.Enhanced engagement is of utmost importance for effective rehabilitation.The ability to identify in real-time barriers to engagement is expected to be of great contributive value.

A multi-centre study to explore the feasibility and acceptability of collecting data for complex regional pain syndrome clinical studies using a core measurement set: Study protocol

OBJECTIVES

This international, multicentre study will inform the final data collection tools and processes which will comprise the first international, clinical research registry for complex regional pain syndrome (CRPS). This study will: (a) test the feasibility and acceptability of collecting outcome measurement data using a patient reported, questionnaire core measurement set (COMPACT [Core Outcome Measurement set for complex regional PAin syndrome Clinical sTudies]); and (b) test and refine an electronic data management system to collect and manage the data.

METHODS

A maximum of 240 adults, meeting the Budapest diagnostic clinical criteria for CRPS type I or II, will be recruited across eight countries. The COMPACT questionnaire will be completed on two occasions: at baseline (T1) and 6 months later (T2). At T2, participants will choose to complete COMPACT using a paper or electronic version. Participants will be asked to feed back on their experience of completing COMPACT via a questionnaire. A separate questionnaire will ask clinicians to feed back their experience of data collection.

ANALYSIS

The study is not aiming to derive statistically significant data but to ascertain the practicalities of collecting data, using the COMPACT questionnaire set, across a range of different cultures and populations. At the end of the study, a single workshop will be convened to review the findings and agree the final documents and processes for the international registry.

Proximal myofascial pain in patients with distal complex regional pain syndrome of the upper limb

BACKGROUND

Patients suffering from complex regional pain syndrome (CRPS) endure myofascial-related pain in at least 50% of cases.

AIMS

To evaluate the association of upper limb CRPS with myofascial pain in muscles that might influence arm or hand pain, and to evaluate whether the paraspinal skin and subcutaneous layers' tenderness and allodynia are associated with CRPS.

METHODS

A case-control study comprising 20 patients presenting with upper limb CRPS, and 20 healthy controls matched for sex and age, were evaluated in the thoracic paraspinal area and myofascial trigger points (MTrPs) (infraspinatus, rhomboids, subclavius, serratus posterior superior and pectoralis minor) via a skin rolling test.

RESULTS

The prevalence of MTrPs in the affected extremity of the subjects was significantly higher than in the right limb of the controls: 45% exhibited active and latent MTrPs in the infraspinatus muscle (χ² = 11.613, p = 0.001); 60% in active and latent MTrPs in the subclavius muscle (χ² = 17.143, p < 0.001); and in the pectoralis minor muscle (χ2 = 13.786, p < 0.001). In addition, 55% of the cases exhibited active and latent MTrPs in the serratus posterior superior muscle (χ² = 15.172, p < 0.001). Significant differences between the groups in skin texture and pain levels (p = 0.01, p < 0.001, respectively) demonstrated that CRPS patients felt more pain, and their skin and subcutaneous layers were much tighter than in the healthy controls.

CONCLUSION

There is a high prevalence of MTrPs in the shoulder and upper thoracic area muscles in subjects who suffer from CRPS. We recommend adding an MTrPs evaluation to the standardized examination of these patients.

Sensory modulation dysfunction is associated with Complex Regional Pain Syndrome

OBJECTIVE

Complex Regional Pain Syndrome (CRPS), a chronic pain condition, develops mainly after limb trauma and severely inhibits function. While early diagnosis is essential, factors for CRPS onset are elusive. Therefore, identifying those at risk is crucial. Sensory modulation dysfunction (SMD), affects the capacity to regulate responses to sensory input in a graded and adaptive manner and was found associated with hyperalgesia in otherwise healthy individuals, suggestive of altered pain processing.

AIM

To test SMD as a potential risk factor for CRPS.

METHODS

In this cross-sectional study, forty-four individuals with CRPS (29.9±11 years, 27 men) and 204 healthy controls (27.4±3.7 years, 105 men) completed the Sensory Responsiveness Questionnaire-Intensity Scale (SRQ-IS). A physician conducted the CRPS Severity Score (CSS), testing individuals with CRPS.

RESULTS

Thirty-four percent of the individuals with CRPS and twelve percent of the healthy individuals were identified to have SMD (χ2 (1) = 11.95; p<0.001). Logistic regression modeling revealed that the risk of CRPS is 2.68 and 8.21 times higher in individuals with sensory over- and sensory under-responsiveness, respectively, compared to non-SMD individuals (p = 0.03 and p = 0.01, respectively).

CONCLUSIONS

SMD, particularly sensory under-responsiveness, might serve as a potential risk factor for CRPS and therefore screening for SMD is recommended. This study provides the risk index probability clinical tool a simple evaluation to be applied by clinicians in order to identify those at risk for CRPS immediately after injury. Further research is needed.

Recommendations for a first Core Outcome Measurement set for complex regional PAin syndrome Clinical sTudies (COMPACT)

Complex regional pain syndrome (CRPS) is a persistent pain condition that remains incompletely understood and challenging to treat. Historically, a wide range of different outcome measures have been used to capture the multidimensional nature of CRPS. This has been a significant limiting factor in the advancement of our understanding of the mechanisms and management of CRPS. In 2013, an international consortium of patients, clinicians, researchers, and industry representatives was established, to develop and agree on a minimum core set of standardised outcome measures for use in future CRPS clinical research, including but not limited to clinical trials within adult populations. The development of a core measurement set was informed through workshops and supplementary work, using an iterative consensus process. "What is the clinical presentation and course of CRPS, and what factors influence it?" was agreed as the most pertinent research question that our standardised set of patient-reported outcome measures should be selected to answer. The domains encompassing the key concepts necessary to answer the research question were agreed as follows: pain, disease severity, participation and physical function, emotional and psychological function, self-efficacy, catastrophizing, and patient's global impression of change. The final core measurement set included the optimum generic or condition-specific patient-reported questionnaire outcome measures, which captured the essence of each domain, and 1 clinician-reported outcome measure to capture the degree of severity of CRPS. The next step is to test the feasibility and acceptability of collecting outcome measure data using the core measurement set in the CRPS population internationally.

Neuropsychological Markers of Suicidal Risk in the Context of Medical Rehabilitation

While great strides have been made to advance the understanding of the neurobiology of suicidal behavior (SB), the neural and neuropsychological mechanisms associated with SB are not well understood. The purpose of the current study is to identify neurocognitive markers of SB in the context of medical rehabilitation. The performances of 39 patients at a medical rehabilitation center, aged 21-78, were examined on a series of neurocognitive executive tasks-decision-making (Iowa Gambling Task - IGT), mental flexibility (WCST), response inhibition (SST) and working memory (digit span). Self-report questionnaires were administered, for Suicidal behaviors, depression, Anxiety, and PTSD as well as perceived social support. Suicidal participants performed more poorly on the IGT. A mediation analysis presented a significant direct effect of decision making on suicidal risk (p < 0.14) as well as significant indirect effect of decision making on suicidal risk that was mediated by the depressive symptoms (95% BCa CI [-0.15, -0.018]) with a medium effect size (κ² = 0.20, 95% BCa CI [0.067, 0.381]). Despite the complexity of relationship between decision-making and suicidal risk, these results suggest that clinicians should routinely assess decision-making abilities in adults at risk for suicide due to the fact that impaired decision-making may increase suicidal risk above and beyond that conferred by depression.

An Auditory Brain-Computer Interface Based on the Self-Regulation of Slow Cortical Potentials

Objectives. Communication support for severely paralyzed patients with visual impairment is needed. Therefore, the feasibility of a brain-computer interface (BCI) using auditory stimuli alone, based on the self-regulation of slow cortical potentials (SCPs), was investigated. Methods. Auditory stimuli were used for task and feedback presentation in an SCP self-regulation paradigm. Voluntarily produced SCP responses and measures of communication performance were compared between 3 groups (total of N = 59) of visual, auditory, and cross-modal visual-auditory modality. Electroencephalogram recordings and training from Cz-mastoids were carried out on 3 consecutive sessions. Data of 1500 trials per subject were collected. Results. Best performance was achieved for the visual, followed by the auditory condition. The performance deficit of the auditory condition was partly due to decreased self-produced positivity. Larger SCP response variability also accounted for lower performance of the auditory condition. Cross-modally presented stimuli did not lead to significant learning and control of SCP. Conclusions. Brain-computer communication using auditory stimuli only is possible. Smaller cortical positivity achieved in the auditory condition, as compared to the visual condition, may be a consequence of increased selective attention to simultaneously presented auditory stimuli. To optimize performance, auditory stimuli characteristics may have to be adapted. Other suggestions for enhancement of communication performance with auditory stimuli are discussed.

Detailed behavioral assessment promotes accurate diagnosis in patients with disorders of consciousness

Introduction: Assessing the awareness level in patients with disorders of consciousness (DOC) is made on the basis of exhibited behaviors. However, since motor signs of awareness (i.e., non-reflex motor responses) can be very subtle, differentiating the vegetative from minimally conscious states (which is in itself not clear-cut) is often challenging. Even the careful clinician relying on standardized scales may arrive at a wrong diagnosis.

Aim: To report our experience in tackling this problem by using two in-house use assessment procedures developed at Reuth Rehabilitation Hospital, and demonstrate their clinical significance by reviewing two cases.

Methods: (1) Reuth DOC Response Assessment (RDOC-RA) –administered in addition to the standardized tools, and emphasizes the importance of assessing a wide range of motor responses. In our experience, in some patients the only evidence for awareness may be a private specific movement that is not assessed by standard assessment tools. (2) Reuth DOC Periodic Intervention Model (RDOC-PIM) – current literature regarding assessment and diagnosis in DOC refers mostly to the acute phase of up to 1 year post injury. However, we have found major changes in responsiveness occurring 1 year or more post-injury in many patients. Therefore, we conduct periodic assessments at predetermined times points to ensure patients are not misdiagnosed or neurological changes overlooked.

Results: In the first case the RDOC-RA promoted a more accurate diagnosis than that based on standardized scales alone. The second case shows how the RDOC-PIM allowed us to recognize late recovery and promoted reinstatement of treatment with good results.

Conclusion: Adding a detailed periodic assessment of DOC patients to existing scales can yield critical information, promoting better diagnosis, treatment, and clinical outcomes. We discuss the implications of this observation for the future development and validation of assessment tools in DOC patients.

Motor imagery group practice for gait rehabilitation in individuals with post-stroke hemiparesis: a pilot study

BACKGROUND

Stroke is the leading cause of adult disability, with walking impairment being a devastating indicator of chronic post-stroke hemiparesis. Limited resources exist for individual treatments; therefore, the delivery of safe group exercise therapy is highly desired.

OBJECTIVE

To examine whether the application of group-based motor imagery practice to community-dwelling individuals with chronic hemiparesis improves gait.

METHODS

Sixteen individuals with chronic hemiparesis from two community centers participated in the study, with eight from each center. Four participants in each center received five weeks of the experimental intervention, consisting of group-based motor imagery exercises of gait tasks, followed by five weeks of control treatment of motor imagery exercises for the affected upper extremity. Four other subjects in each center received the same treatments in reverse order. Pre- and post intervention measurements included clinical and biomechanical gait parameters.

RESULTS

Comparisons within (pre- vs. post) and between treatments (experimental vs. control) indicated no significant change in any gait variable. Nevertheless, the verbal reports of most participants alluded to satisfaction with the experimental intervention and to an increase in self-confidence.

CONCLUSIONS

Despite the lack of evidence for the effectiveness of group-based motor imagery practice in improving gait among individuals with chronic hemiparesis, the contrast between the measured outcomes and the positive verbal reports merits further inquiry.

Complex regional pain syndrome, alexithymia, and psychological distress

OBJECTIVE

This study aims to elucidate the relationships between alexithymia, psychological distress, and pain in persons with complex regional pain syndrome (CRPS).

METHODS

Participants were 60 Israeli adults ages 19-65. This is a cross sectional study with a comparison group. Alexithymia, psychological distress, and pain were assessed in 30 individuals with CRPS in comparison to 30 gender- and age-matched persons with lower back pain (LBP). Assessments included the Toronto Alexithymia Scale, Hospital Anxiety and Depression Scale, and two subscales of the McGill Pain Questionnaire.

RESULTS

Persons with CRPS had significantly higher ratings of psychological distress and of alexithymia when compared to LBP controls. Pain severity was significantly associated with higher levels of alexithymia and psychological distress among persons with CRPS, but not among controls. Alexithymia and pain severity correlations were significantly different between the two groups. In persons with CRPS, the relationships between alexithymia and pain severity and between difficulty identifying feelings and pain were not confounded by psychological distress.

CONCLUSIONS

To our knowledge, this is the first cross sectional study providing empirical evidence on the relationship between alexithymia and CRPS. From the perspective of conceptualizing alexithymia as an outcome of CRPS, findings highlight the importance of early CRPS diagnosis and support the provision of care that addresses pain-related psychological distress and alexithymia among CRPS patients. Also, findings underscore the need to generate alternative, non-physical avenues, such as learning to identify feelings for processing pain, in order to reduce pain among persons with CRPS.

Dual-channel functional electrical stimulation improvements in speed-based gait classifications

Background

Functional electrical stimulation (FES) is becoming an accepted treatment method for enhancing gait performance in patients who present with gait difficulties resulting from hemiparesis. The purpose of this study was to test whether individuals with hemiparesis who have varied gait speeds, which place them in different functional categories, benefit to the same extent from the application of FES.

Methods

Thirty-six subjects with chronic hemiparesis demonstrating foot-drop and deficits in knee and/or hip control were fitted with a dual-channel FES system activating the dorsiflexors and hamstring muscles. Gait was assessed during a 2-minute walk test with and without stimulation. A second assessment was conducted after 6 weeks of daily use. Analysis was performed with the subjects stratified into three functional ambulation classes according to their initial gait categories.

Results

The dual-channel FES improved the gait velocity of all three subgroups. No minimal gait velocity was required in order to gain benefits from FES. For example, subjects with limited household ambulation capabilities improved their gait speed by 63.3% (from 0.30 ± 0.09 m/sec to 0.49 ± 0.20 m/sec; P < 0.01), while subjects with functional community ambulation capabilities improved their gait speed by 25.5% (from 0.90 ± 0.11 m/sec to 1.13 ± 0.22 m/sec; P < 0.01).

Conclusion

Dual-channel FES positively affects gait velocity in patients with chronic hemiparesis, regardless of their initial gait velocity. Furthermore, gait velocity gains may be large enough to change an individual’s ambulation status to a higher functional category.

Effects of dual-channel functional electrical stimulation on gait performance in patients with hemiparesis

The study objective was to assess the effect of functional electrical stimulation (FES) applied to the peroneal nerve and thigh muscles on gait performance in subjects with hemiparesis. Participants were 45 subjects (age 57.8 ± 14.8 years) with hemiparesis (5.37 ± 5.43 years since diagnosis) demonstrating a foot-drop and impaired knee control. Thigh stimulation was applied either to the quadriceps or hamstrings muscles, depending on the dysfunction most affecting gait. Gait was assessed during a two-minute walk test with/without stimulation and with peroneal stimulation alone. A second assessment was conducted after six weeks of daily use. The addition of thigh muscles stimulation to peroneal stimulation significantly enhanced gait velocity measures at the initial and second evaluation. Gait symmetry was enhanced by the dual-channel stimulation only at the initial evaluation, and single-limb stance percentage only at the second assessment. For example, after six weeks, the two-minute gait speed with peroneal stimulation and with the dual channel was 0.66 ± 0.30 m/sec and 0.70 ± 0.31 m/sec, respectively (P < 0.0001). In conclusion, dual-channel FES may enhance gait performance in subjects with hemiparesis more than peroneal FES alone.

A novel technique for conduction studies of the infrapatellar nerve

OBJECTIVE

To introduce a noninvasive method for electrodiagnostic evaluation of the infrapatellar nerve (IPN).

DESIGN

A prospective cohort study.

SETTING

Electrodiagnostic laboratory, rehabilitation department, Hadassah University Hospital.

PARTICIPANTS

A total of 38 healthy adults; 57 asymptomatic limbs were studied.

METHODS

Sensory nerve action potential of the IPN was recorded with surface electrodes placed 2.5 cm below the distal pole of the patella and 2 cm medially from the medial border of the patellar tendon. Transcutaneous antidromic electrical stimulation of IPN was applied above the medial femoral condyle and 8-10 cm proximally from the active surface electrode.

RESULTS

The sensory nerve action potential mean (n = 38) onset latency was 1.69 ± 0.32 ms. Peak latency was 2.36 ± 0.47 ms, and amplitude was 6.96 ± 3.68 μV.

CONCLUSIONS

This article describes a novel and simple technique for IPN conduction electrodiagnostic examination. The method used provides a new tool to evaluate IPN injury in reference to anterior or inferior knee pain with associated sensory deficit.

Psychophysical correlates in adults with sensory modulation disorder

PURPOSE

Individuals with sensory modulation disorder (SMD) demonstrate abnormal responses to naturally occurring stimuli in a manner that interferes with daily life activities. This study is the first study applying quantitative sensory testing to characterize the somatosensory sensitivity of adults with SMD.

METHOD

One hundred and fifty one adults (68 males and 83 females) were tested comparing 91 SMD to 60 SMD-free, control individuals. Group placement (SMD vs. SMD-free) was determined using the Sensory Responsiveness Questionnaire (SRQ). Sensory detection thresholds for skin warming, cooling, punctate dynamic tactile sensation, vibration and thermal pain thresholds for heat and cold stimuli were determined at several body sites. Pinprick pain and prickliness were also assessed, as well as the duration and intensity of the after-sensations of prickliness and pain evoked by the prickly stimuli.

RESULTS

Compared to control adults, individuals with SMD showed significantly higher pain intensity to prickle stimuli, marginally higher pain intensity to pinprick and hypoesthesia to punctate dynamic tactile sensation at one of two sites tested.

CONCLUSIONS

These results are in line with our previous study that investigated children with SMD using the same stimuli, and found similar results. We suggest a CNS involvement as the underlying mechanisms in SMD.

Validation of proposed diagnostic criteria (the "Budapest Criteria") for Complex Regional Pain Syndrome

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

Validation of proposed diagnostic criteria (the "Budapest Criteria") for Complex Regional Pain Syndrome

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

The Participation in Childhood Occupations Questionnaire (PICO-Q): a pilot study

There is a need, among practitioners and researchers, for a feasible, user-friendly assessment tool that evaluates overall participation and guides intervention. This paper describes the process of construction and development of the Participation in Childhood Occupations Questionnaire (PICO-Q) and the establishment of its primary psychometric properties. The 22-item instrument measures the level, enjoyment, and frequency of performance for children's participation in daily occupations in a variety of environments. The questionnaire was completed by the mothers of 41 children between the ages of 6 and 10 years (24 children with and 17 children without sensory modulation disorder). Cronbach's alpha varied from. 86 to. 89, indicating internal consistency of items. Test-retest reliability varied from. 69 to. 86, indicating that the instrument provides a stable measurement over time. The PICO-Q was found to differentiate between children with and without participation restrictions. The PICO-Q shows initial reliability and validity and has both research and clinical application potential.

Is there a relationship between light touch-pressure sensation and functional hand ability?

PURPOSE

To investigate and compare the level of light touch-pressure sensation as tested via the Semmes Weinstein monofilament (SWM) test with the level of functional hand ability.

METHODS

Twenty-seven persons with isolated sensory deficit due to leprosy and 31 healthy controls were tested in the Occupational Therapy department of a hospital for patients with Hansen's disease. Palmar light touch thresholds were determined by SMW testing. Functional hand ability was tested via the Jebsen-Taylor Hand Function Test (JTHFT) and the Functional Dexterity Test (FDT). All participants were measured by manual muscle testing (MMT) to exclude any motor impairment. Data analysis compared sensory thresholds and level of functional hand ability between the two groups and examined the relationship between the variables.

RESULTS

In the group with sensory deficit, the sensory thresholds were significantly higher than in the control group. Significant correlations were found between the sensory thresholds measured by the SWM test and the FDT and JTHFT scores, with higher correlations found for tasks entailing manipulation of small objects.

CONCLUSIONS

The findings support the existence of a relationship between sensory light touch thresholds tested by the Semmes Weinstein monofilaments (SWMs) and hand function. However, the SWM test alone is not sufficient as an indicator of hand function and must therefore be supplemented with other hand function tests.

Development and psychometric properties of the Sensory Responsiveness Questionnaire (SRQ)

PURPOSE

Individuals with Sensory Modulation Disorder (SMD) are characterized by an inability to normally grade the degree, intensity and nature of their responses to sensory input and are limited in their ability to fully participate in daily life activities, and attain optimal quality of life. Most existing diagnostic tools are intended for paediatric populations. A questionnaire that assesses the intensity of the affective-emotive responsiveness of adults to stimuli in all sensory modalities and the frequency of such responses for diagnosing adults with disorders in sensory modulation is necessary. This article describes the development and assessment of the psychometric properties of a novel instrument, the Sensory Responsiveness Questionnaire (SRQ), for this purpose (see Appendix).

METHOD

The SRQ evolved through three developmental phases (Pilot, Version-I, and the most recent Version-II). Each phase comprised several studies conducted to further refine the instrument and to examine its psychometric properties with adults with Sensory Modulation Disorder versus SMD-free individuals (n=39 for the pilot version, n=399 for Version-I, and n=48 for Version-II).

RESULTS

The scales of Version-II indicated high test-retest reliability, moderate criterion validity and strong significant construct validity.

CONCLUSION

There is strong indication that the SRQ can be used to diagnose adults with SMD.

The Participation in Childhood Occupations Questionnaire (PICO-Q): a pilot study

There is a need, among practitioners and researchers, for a feasible, user-friendly assessment tool that evaluates overall participation and guides intervention. This paper describes the process of construction and development of the Participation in Childhood Occupations Questionnaire (PICO-Q) and the establishment of its primary psychometric properties. The 22-item instrument measures the level, enjoyment, and frequency of performance for children's participation in daily occupations in a variety of environments. The questionnaire was completed by the mothers of 41 children between the ages of 6 and 10 years (24 children with and 17 children without sensory modulation disorder). Cronbach's alpha varied from. 86 to. 89, indicating internal consistency of items. Test-retest reliability varied from. 69 to. 86, indicating that the instrument provides a stable measurement over time. The PICO-Q was found to differentiate between children with and without participation restrictions. The PICO-Q shows initial reliability and validity and has both research and clinical application potential.

Sensory modulation disorder: a risk factor for participation in daily life activities

Participation in childhood daily functional performance was examined in 78 children: 44 with sensory modulation disorder (SMD); (33 males, 11 females; mean age 7y 6mo [SD 1.20]) and 34 without SMD (18 males, 16 females; mean age 7y 8mo [SD 1.33]). Group classification was determined using two measures: the Short Sensory Profile (SSP) and the Full-form Sensory Profile. Parents completed a battery of caregiver questionnaires. Children with SMD scored significantly lower on all three participation scales than the control group. A high correlation was observed between level of activity performance of the Participation in Childhood Occupations Questionnaire (PICO-Q) and the SSP, and a moderate correlation was observed between the Enjoyment of Performance of the PICO-Q and the SSP. A low correlation was observed between Frequency of Performance of the PICO-Q and the SSP. Logistic regression indicated that all three participation scales (level of activity performance, level of enjoyment of the activity, and frequency of performance of the activity) are significantly associated with group classification, with odds ratios of 3.13, 2.05, and 1.73 respectively. These findings are the first, to our knowledge, to confirm claims of limited participation in daily activities among children with SMD. Our results have significant clinical implications and provide support for the need for practitioners and caregivers of children with SMD to facilitate participation.

Does passive leg activity influence oxygen saturation and activity in sedentary elderly adults?

This study aimed to investigate whether any physiological changes might have a clinically significant effect on function in sedentary, institutionalized, older adults treated by a passive training program. A total of 18 subjects (mean age 60.7 +/- 3.4) with intellectual disability (ID) participated. We measured SpO2 (arterial oxygen saturation) before, during, and after passive training, and used Barthel Index to measure daily living activities. The general trend indicated that inactive people with ID evidenced a continual increase in SpO2% levels and some functional gains during passive treatment, with superiority to manual passive treatment compared to mechanical active passive training. For current clinical practice, most sedentary patients who experience clinically significant deconditioning and desaturation can benefit from passive treatment.

Neuronal mechanisms underlying control of a brain-computer interface

Brain-computer interfaces (BCIs) enable humans or animals to communicate or control external devices without muscle activity using electric brain signals. The BCI used here is based on self-regulation of slow cortical potentials (SCPs), a skill that most people and paralyzed patients can acquire with training periods of several hours up to months. The neurophysiological mechanisms and anatomical sources of SCPs and other event-related brain potentials have been described but the neural mechanisms underlying the self-regulation skill for the use of a BCI are unknown. To uncover the relevant areas of brain activation during regulation of SCPs, the BCI was combined with functional magnetic resonance imaging. The electroencephalogram was recorded inside the magnetic resonance imaging scanner in 12 healthy participants who learned to regulate their SCP with feedback and reinforcement. The results demonstrate activation of specific brain areas during execution of the brain regulation skill allowing a person to activate an external device; a successful positive SCP shift compared with a negative shift was closely related to an increase of the blood oxygen level-dependent response in the basal ganglia. Successful negativity was related to an increased blood oxygen level-dependent response in the thalamus compared with successful positivity. These results may indicate learned regulation of a cortico-striatal-thalamic loop modulating local excitation thresholds of cortical assemblies. The data support the assumption that human subjects learn the regulation of cortical excitation thresholds of large neuronal assemblies as a prerequisite for direct brain communication using an SCP-driven BCI. This skill depends critically on an intact and flexible interaction between the cortico-basal ganglia-thalamic circuits.

Correlation of intact sensibility and neuropathic pain-related behaviors in eight inbred and outbred rat strains and selection lines

In some rat strains, total hindpaw denervation triggers autotomy, a behavior of self mutilation presumably related to neuropathic pain. Partial sciatic ligation (PSL) in rats produces tactile allodynia and heat hyperalgesia but not autotomy. Our aims in this study were to examine: (1) whether sensibility of intact rats to noxious and non-noxious stimuli is strain-dependent; (2) whether sensibility of intact rats could predict levels of autotomy, or of allodynia and hyperalgesia in the PSL model; and (3) whether autotomy levels are correlated with levels of allodynia or hyperalgesia. Here we report that in two inbred rat strains (Lewis and Fisher 344), two outbred rat strains (Sabra and Sprague-Dawley) and four selection lines of rats (Genetically Epilepsy-Prone Rats, High Autotomy, Low Autotomy and Flinders Sensitive Line), tactile sensitivity and response duration to noxious heat of intact animals were strain-dependent. Levels of autotomy following hindpaw denervation and of allodynia and hyperalgesia in the PSL model were also strain-dependent. Thus, these traits are determined in part by genetic factors. Sensory sensibility of intact rats was not correlated with levels of autotomy following total denervation, or allodynia and hyperalgesia following partial denervation. We suggest that preoperative sensibility of intact rats is not a predictor of levels of neuropathic disorders following nerve injury. Likewise, no correlation was found between autotomy, allodynia and hyperalgesia, suggesting that neuropathic pain behaviors triggered by nerve injury of different etiologies are mediated by differing mechanisms.

Preoperative open field behavior predicts levels of neuropathic pain-related behavior in mice

Exploratory open field (OF) activity was assessed in seven different mouse strains and selection lines. We counted the number of beam interruptions made by three cagemate mice at a time. This assay tests reactivity to aversive stimuli, anxiety and emotionality. One hindlimb was then totally denervated by transecting the sciatic and saphenous nerves on one side, and autotomy, a behavior thought to be related to neuropathic pain, was quantified over 35 days. We report that OF activity and autotomy are highly variable across different strains/lines. These results reaffirm the genetic control of these behaviors. We also found that these behaviors are inversely and significantly correlated. We suggest that common genetically-determined neural mechanisms may underlie anxiety, emotionality and neuropathic pain in mice.

A novel computerized system for analyzing motor and social behavior in groups of animals

We present here the VMB Tracking System, a novel method for tracking locomotor activity, posture, thigmotactic scanning behavior and social interactions of up to eight animals at a time, at a high resolution (up to+/-0.1 mm). We used a commercially available computerized system that is considerably cheaper than other available methods. This system utilizes a basic personal computer controlling three transponders ('towers') fixed in space above the tested area, where animals as small as rats stroll freely in their normal habitat or in an experimental arena. Each tower emits infra-red (IR) pulses to a transponder ('button') adhered to a plastic mount glued to a shaved area of skin on the animal's back. When the button detects the IR pulses it responds with a button-specific ultrasonic signal that is fed back to the towers. The 3D location of the buttons is calculated by triangulation. Movement parameters of each button, such as displacement trajectory, time, speed and acceleration, can be displayed on-line and stored for off-line analysis. This system can be used to track animals in any lighting conditions, and to assess drug effects on the CNS, neuromuscular junction or muscle. As an example we demonstrate the ataxic effects of pentobarbital in rats.

Experimental pressure pain in patients with complex regional pain syndrome, Type I (reflex sympathetic dystrophy)

Research in animals shows that the levels of neuropathic pain expression is genetically associated with a characteristic response profile to sensory stimuli. The aim of the present investigation was to examine if pressure algometry can identify a specific pain sensitivity profile in patients with complex regional pain syndrome, Type I (reflex sympathetic dystrophy), and to distinguish complex regional pain syndromes from other chronic pain dysfunction syndromes. Pressure pain threshold and pain tolerance measured at the sternum in 17 patients with complex regional pain syndrome, Type I (reflex sympathetic dystrophy), were compared with values obtained in 13 patients suffering from other chronic pain dysfunction syndromes and in a control group of 24 pain-free volunteers. The pressure algometer consisted of a force displacement transducer with a 0.25 cm2 tip connected to a recorder. The rate of force application was 1 kg/0.25 cm2/s. The difference between threshold and tolerance was defined as the pain sensitivity range. Young patients with complex regional pain syndrome (<40 yr) demonstrated a significantly higher mean pain sensitivity range compared with young subjects who had chronic pain or who were pain-free. Mean threshold and tolerance values were significantly lower in patients with complex regional pain syndrome (2.7+/-1.0 kg (mean +/- standard deviation) and 5.4+/-2.0 kg, respectively) and in patients suffering from other chronic pain syndromes (2.6+/-1.1 and 4.6+/-1.7 kg) than in healthy subjects (5.4+/-2.3 and 8.4+/-2.6 kg). Women in the chronic pain group exhibited a significantly lower pressure pain threshold than all other subgroups. Regardless of group, women exhibited lower pressure pain tolerance than men. In conclusion, the study contained herein shows a specific pain sensitivity profile to experimental stimuli behavior in young patients with complex regional pain syndrome expressed by a large pressure pain sensitivity range, at a location away from the painful area. However, one single pressure pain measurement over the sternum is insufficient for differentiation of patients with complex regional pain syndrome from those with chronic pain because of intersubject variation.

Brief electrical stimulation of c-fibers in rats produces thermal hyperalgesia lasting weeks

Nerve injury produces neuropathic pain in some humans, but the nature of the signal triggering the pain is still unknown. When injured, many afferent fibers emit a prolonged discharge of action potentials. This input triggers pain disorders in rats following some, but not other types of total and partial nerve injury. In the present study we report that similar sensory disorders develop in rats by electrically stimulating an intact sciatic nerve. Robust thermal hyperalgesia and weak mechanical allodynia developed rapidly, lasting 3-5 weeks thereafter, but only when activating C-fibers. Thus, a discharge mimicking injury discharge in C-fibers, in the absence of any intended damage to the stimulated nerve, is sufficient to alter chronically central processing of sensory input.

Differential sensory-motor effects of pentobarbital in intact rats genetically selected for high vs. low neuropathic pain-related behaviour

Denervation of the hindpaw in rodents triggers autotomy, a behaviour of licking, scratching and self-mutilation of the denervated paw. This behaviour has been used as a model of paraesthesia, dysaesthesia and neuropathic pain. HA and LA rats are lines that have been genetically selected for high or low levels of autotomy, respectively. Compared to intact LA rats, HA rats are more sensitive to convulsions induced by pentylenetetrazol (PTZ), a blocker of the chloride channel associated with the GABA(A) receptor. Here we tested whether an acute administration of a sedative but not anaesthetic dose of pentobarbital (PB) would differentiate between these rat lines, in a number of sensory and motor tests performed in intact rats. This drug was tested since in contrast to PTZ, PB enhances central nervous system (CNS) inhibition by increasing chloride flux through the same channel. We found that PB was significantly more ataxic, antinociceptive, and reduced touch sensitivity in LA rats, compared to HA rats. These results suggest that HA and LA rats genetically differ in the levels of central inhibitions mediated by the GABA system presumably at the chloride channel. This difference may be associated with the dichotomous expression of neuropathic pain in these rat lines.

Behavior of F-response and determination of actively involved motoneurons

Fifteen nerves were examined in 10 healthy subjects, using a collision technique with 2 stimulation pulses of different intensity on the same point. The F-waves which occurred after the antidromic activation of the motor neuron cells by the first supramaximal pulse were blocked on their return pathway by the collision with the depolarization induced by the second pulse. The progressive decrement of the voltage of the second stimulus allowed, the transmission of the recurrent discharge along motor fibers with a lower depolarization threshold. The amplitude and the persistence of the F-waves increased (p < 0.05 and p < 0.001 respectively), while their latency decreased (p < 0.01) concurrent with the liberation of additional motor neurons with a lower threshold of depolarization. These findings suggest that the F-wave may be elicited in motoneuron of different depolarization threshold but primarily in larger and faster nerve fibers, with a lower threshold of depolarization.

Assessment of pain threshold and pain tolerance in women in labour and in the early post-partum period by pressure algometry

The changes in the pressure pain threshold (PPThr) and pressure pain tolerance (PPTol) in 41 parturients have been studied during the active phase of labour and in the early post-partum period. The sensitivity to pressure stimuli was examined with an electronic pressure algometer placed on the sternum during the interval between painful contractions, after extradural analgesia and 24 h after childbirth. Prior to extradural analgesia, mean (+/- SD), PPThr and PPTol were 4.9 +/- 1.6 kg 0.25 cm-2 and 6.9 +/- 1.8 kg 0.25 cm-2, respectively. Similar values were recorded 1 h after induction of the extradural block when the pain of labour was abolished. At 24 h post-delivery, a significant decrease in both PPThr and PPTol was noted (P < 0.001). The lack of influence of extradural analgesia on pressure algometry values, and the elevated sensitivity to pain in the early post-partum period, may be related to the influence of pregnancy and labour on the appreciation of pain.

Electronic pressure algometry of deep pain in healthy volunteers

Deep pressure pain threshold (PPT) and pressure pain tolerance (PPtol) were measured by pressure algometry at the mastoid processes, external malleoli, and sternum in 24 healthy volunteers. The algometer consisted of a force displacement transducer with a 0.25 cm2 pressure tip linked to a recorder. The rate of force application was approximately 1kg/sec/0.25cm2. High intersubject variation was noted at all sites for both PPT and PPtol. Mean PPT and PPtol values at the sternum were 5.2kg +/- 2.1 and 8.1kg +/- 2.4, respectively, and significantly higher than at the other sites. PTT did not differ significantly between the sexes or between dominant and nondominant sides. PPtol, on the other hand, was lower in the women, but significantly so only at the malleoli. On repeat examination, comparison between the mean values at each site showed no statistical differences in any instance. Pressure algometry, as used in this study in healthy subjects, proved a reliable technique for the estimation of deep PPT and PPtol values. It may possibly serve for screening the response to experimental pain in various groups of pain patients.

Diagnostic value of computer analysis of multipeaked EMG spikes

Computer analysis of absolute number of peaks per second and the number of peaks in the multipeaked spikes/sec was carried out in the EMG interference recordings of 5 healthy, 6 myopathic and 8 neuropathic subjects. The purpose of the study was to detect diagnostically different patterns. A spike was considered multipeaked if it had 6 or more peaks. The amplitude of elimination (baseline) was examined at 1: 5, 1: 10 and 1: 15 of the average amplitude per second. Both the number of peaks and the number of peaks in multipeaked spikes in the neuropathic and myopathic muscles showed statistically significant differences when compared to healthy muscles. This technique could give an indication for the differential diagnosis of myopathic, neuropathic or healthy state of the muscle.

Fourier series analysis of the electrophysiological pattern of fatigue in healthy human beings, after curare administration

Real time computer analysis of the electrophysiological development of muscular fatigue after small doses of d-tubocurarine (TC), has been examined in anesthetized human beings. As compared to a decrease of frequency in the control measurements, previous studies have shown an increase of the frequency of spikes after TC administration. The present experiments were carried out on the biceps brachii of 8 healthy human volunteers maintained in isometric contraction against a constant counter load until complete fatigue occurred. The Fourier spectrum analysis showed a statistically significant shift to lower frequencies before, and a milder statistically non significant shift after TC. These results may indicate that under mild curarization the early phase of muscular contraction requires a higher number of large motor units and thus, at a later stage of the contraction the pool of available large motor units becomes smaller. This conclusion supports the hypothesis that mild curarization causes a state of initial muscular fatigue.

Comparison of the electrophysiological pattern of fatigue between athletes required to perform explosive and endurance sports

The electrophysiological behavior of an isometric contraction sustained to fatigue, was examined in 6 long distance runners and 9 athletes involved in explosive (burst) sports, by on line computer analysis of the electrical activity of vastus medialis, rectus femoris and vastus lateralis. The experiments were carried out with a counterload of 50% of the maximal strength of the muscle. The duration of spike increased and the frequency decreased in the 3 examined muscles, in both types of sport. In the burst sports the changes of value of both parameters were statistically significant in the 3 muscles. In endurance sports the variations of duration were not significant and the changes of frequency were statistically significant only in the vastus lateralis. These results could be explained by the gradual activation of motor units of more strikingly different sizes in burst sports. Thus it may be speculated that prolonged training in burst sports may result in the automatic mobilization of higher number of small motor units, for the initiation of contraction while in endurance sports the onset of contraction is more gradual and carried out by large motor units.

Effect of filter setting on the electromyographic parameters of muscles contracting to fatigue

The effects of various filter settings on the electrophysiological behavior of the development of muscular fatigue were studied. Eleven healthy volunteers were examined during isometric contraction of biceps brachii and rectus femoris against a constant load until fatigue occurred. The electrical activity was taped and computer processing was carried out at the basic setting of 15-5000 cycles and at low (15-200 Hz) and high (200-5000 Hz) frequence filter. The results support the hypothesis that in the low range of frequencies there is a high density of large slow motor units, while in the high range of frequencies there are numerous small fast motor units.

Proximal monomelic amyotrophy of the upper limb

A 30-year-old patient of Central European origin, suffering from monomelic amyotrophy, is presented. The disease was characterized by proximal weakness of one upper limb, mainly of the shoulder girdle, accompanied by atrophy. The electrodiagnostic examination revealed signs of partial denervation in the presence of normal motor and sensory conduction. The disease, which is probably of the anterior horn cells, had a benign course and good prognosis, as evident from repeated examinations during a follow-up of eight years.