Validity and responsiveness of the French version of the Örebro musculoskeletal pain screening questionnaire in chronic low back pain

The assessment of a broad range of biopsychosocial aspects is important in the rehabilitation of patients with chronic low back pain (CLBP) for the prediction of outcome as well as for evaluation. The objective of this study was to test the responsiveness, construct validity and predictive value of the A-rebro Musculoskeletal Pain Screening Questionnaire (OMPSQ) compared to other instruments widely used to assess biopsychosocial aspects in patients with CLBP. 111 patients with CLBP admitted to an inpatient rehabilitation completed a set of questionnaires on biopsychosocial aspects at baseline and at discharge. Ninety-eight patients responded at three months for an assessment of the return to work status. Responsiveness of the OMPSQ, the ability to detect change in the construct of interest, was investigated by a set of hypotheses on correlations with widely used questionnaires. We tested the hypothesis that the changes in the OMPSQ would vary along with the responses in the Patient's Global Impression of Change. Prediction of disability at discharge, work status at three months and time to return to work was evaluated with linear, logistic and cox regression models. The OMPSQ showed good predictive values for disability and return to work and construct validity of the instrument was corroborated. Seventy-nine percent of our hypotheses for responsiveness could be confirmed, with the OMPSQ showing the second highest change during the rehabilitation. The OMPSQ can also be applied in patients with CLBP, but for the assessment of change in psychosocial variables one should add specific questionnaires

Thermal Detection Thresholds of Aδ- and C-Fibre Afferents Activated by Brief CO2 Laser Pulses Applied onto the Human Hairy Skin

Brief high-power laser pulses applied onto the hairy skin of the distal end of a limb generate a double sensation related to the activation of Aδ- and C-fibres, referred to as first and second pain. However, neurophysiological and behavioural responses related to the activation of C-fibres can be studied reliably only if the concomitant activation of Aδ-fibres is avoided. Here, using a novel CO2 laser stimulator able to deliver constant-temperature heat pulses through a feedback regulation of laser power by an online measurement of skin temperature at target site, combined with an adaptive staircase algorithm using reaction-time to distinguish between responses triggered by Aδ- and C-fibre input, we show that it is possible to estimate robustly and independently the thermal detection thresholds of Aδ-fibres (46.9±1.7°C) and C-fibres (39.8±1.7°C). Furthermore, we show that both thresholds are dependent on the skin temperature preceding and/or surrounding the test stimulus, indicating that the Aδ- and C-fibre afferents triggering the behavioural responses to brief laser pulses behave, at least partially, as detectors of a change in skin temperature rather than as pure level detectors. Most importantly, our results show that the difference in threshold between Aδ- and C-fibre afferents activated by brief laser pulses can be exploited to activate C-fibres selectively and reliably, provided that the rise in skin temperature generated by the laser stimulator is well-controlled. Our approach could constitute a tool to explore, in humans, the physiological and pathophysiological mechanisms involved in processing C- and Aδ-fibre input, respectively

Maturational changes in the thermoalgesic system in humans from childhood to adulthood revealed by CO(2) laser evoked brain potentials following cutaneous heat stimuli.

Possible maturational changes in the thermoalgesic system were studied by reaction times (RT) and late (Adelta-fibre) laser evoked potentials (LEPs) following CO(2) laser heat stimulation of the hand in healthy children (n=12) and young adults (n=12). In children (10+/-2 years) LEPs presented a negative-positive complex with maximum amplitude (peak-to-peak 71+/-35 microV) at the vertex and latencies of 248+/-82 and 433+/-104 ms, respectively. As compared to adults (24+/-3 years), children had a significant increased peak-to-peak amplitude (+25.7 microV; P=0.03) although no difference in latencies and topography. Median RT (710 ms) was also significantly increased (+312 ms; P<0.005) in children. A decrease in RT and late LEP amplitude from childhood to adulthood may reflect aspects of maturation in sensory processing of the thermoalgesic system

Physical activity and endogenous pain modulation in older people: a scoping review protocol.

This scoping review aims to provide a systematic overview of the existing literature on physical activity and endogenous pain modulation (EPM), assessed using conditioned pain modulation (CPM), with a specific focus on older people with chronic pain. Approximately 20% of the European population reports chronic pain, highlighting the problem of chronic pain in the general population. This prevalence increases to 50% in older people. Physical activity is one of the most frequently used treatments for pain management and relief. A possible mechanism underlying the positive effects of physical activity on pain may be related to its influence on EPM. The study will map (i) types of physical activity used to study its effect on EPM in older people; (ii) intervention protocols investigating physical activity and EMP, measured using CPM, in older people experiencing pain; and (iii) knowledge gaps requiring further research or interventions adapted to older people with pain. This review will consider studies of people aged 60 years or older, using CPM to examine the effect of physical activity on EPM. All types of care settings will be eligible. This review will be conducted in accordance with the JBI methodology for scoping reviews. The following databases will be searched: MEDLINE (Ovid), CINAHL (EBSCOhost), Embase, Cochrane Library, Web of Science, JBI Evidence Synthesis, PsycINFO, and PEDro. Open Science Framework: https://osf.io/e7ndy/

Test-retest reliability of thermal quantitative sensory testing on two sites within the L5 dermatome of the lumbar spine and lower extremity.

INTRODUCTION: Quantitative sensory testing (QST) is widely used in human research to investigate the integrity of the sensory function in patients with pain of neuropathic origin, or other causes such as low back pain. Reliability of QST has been evaluated on both sides of the face, hands and feet as well as on the trunk (Th3-L3). In order to apply these tests on other body-parts such as the lower lumbar spine, it is important first to establish reliability on healthy individuals. The aim of this study was to investigate intra-rater reliability of thermal QST in healthy adults, on two sites within the L5 dermatome of the lumbar spine and lower extremity. METHODS: Test-retest reliability of thermal QST was determined at the L5-level of the lumbar spine and in the same dermatome on the lower extremity in 30 healthy persons under 40 years of age. Results were analyzed using descriptive statistics and intraclass correlation coefficient (ICC). Values were compared to normative data, using Z-transformation. RESULTS: Mean intraindividual differences were small for cold and warm detection thresholds but larger for pain thresholds. ICC values showed excellent reliability for warm detection and heat pain threshold, good-to-excellent reliability for cold pain threshold and fair-to-excellent reliability for cold detection threshold. ICC had large ranges of confidence interval (95%). CONCLUSION: In healthy adults, thermal QST on the lumbar spine and lower extremity demonstrated fair-to-excellent test-retest reliability

Determination of nerve conduction velocity of C-fibres in humans from thermal thresholds to contact heat (thermode) and from evoked brain potentials to radiant heat (CO2 laser).

This study was designed to estimate and compare nerve conduction velocity (NCV) of cutaneous heat-sensitive C-fibres obtained using two methods. The first is a method based on reaction times to different rates of temperature change produced by a large contact thermode (Thermotest). The second is a novel method based on ultra-late-evoked brain potentials to CO2 laser stimuli with tiny beam sections (< 0.25 mm2), allowing selective and direct activation of very slow conducting afferents. Both methods were applied on three sites of the right leg (foot, knee and thigh) of ten healthy subjects. When based on the reaction times to contact heat, NCV estimations were 0.4 +/- 0.22 m/s for the proximal segment (knee-thigh) and 0.6 +/- 0.23 m/s for the distal segment (foot-knee). When based on the difference in latency of the ultra-late positivity of laser-evoked brain potentials, NCV estimations were respectively 1.4 +/- 0.77 m/s and 1.2 +/- 0.55 m/s. For both methods, the difference in NCV between proximal and distal limb segments was not significant. Although both methods give NCV estimations within the range of C-fibres, the systematic difference between NCV obtained from each method may result from the activation of subpopulations of C-fibres with different NCV depending on the method of stimulation (low-threshold thermal receptors by the thermode and thermal nociceptors by the CO2 laser). Considering the difficulty of investigating peripheral fibres with slow conduction velocities (C-fibres) in humans, the methods used in the present study may be useful tools in both experimental and clinical situations

Dipole analysis of ultralate (C-fibres) evoked potentials after laser stimulation of tiny cutaneous surface areas in humans (vol 298, pg 41, 2001)

Ultralate (C-fibres) laser evoked potentials (LEP) can be obtained by stimulation of a tiny skin surface area (0.23 mm(2)). Since their generators are unknown up to now, we performed brain source analyses of ultralate LEPs using high resolution electroencephalography (64 channels) and a realistic head model that was based on individual magnetic resonance images. Ultralate LEPs were characterized by a negative-positive complex with a large positive component maximal at the vertex. Source analysis revealed that ultralate LEPs could be explained by two dipole sources in the upper bank of the contralateral and ipsilateral Sylvian fissure (SII) and one dipole in the median region corresponding to the anterior cingulate gyrus

Scalp topography of ultralate (C-fibres) evoked potentials following thulium YAG laser stimuli to tiny skin surface areas in humans.

AIM: To investigate (1) the scalp topography of ultralate laser evoked potentials (LEPs) related to C-fibre activation, which can directly be obtained by thulium YAG (Tm YAG) laser stimulation of tiny skin surface areas (about 0.23 mm(2)) and (2) the influence of the performance of a motor task on ultralate LEPs. METHODS: Laser stimuli were applied to the dorsum of the left hand. LEPs were recorded with 58 scalp electrodes from 9 healthy subjects in two different conditions, with and without a reaction time (RT) task (press a button upon detection). RESULTS: On high resolution electroenchephalogram recordings, ultralate LEPs were characterized by a broad positive component (peak latency: 1133+/-91 ms) with maximum amplitude about the vertex. Moreover, the performance of a RT task had no influence on latency, amplitude and topographical patterns of two maps chosen at the positive peak latency in ultralate LEPs. Nevertheless, a negative inflexion (latency 1300 ms) appeared after the positive component in the task condition possibly reflecting movement-related potentials. CONCLUSION: Tm YAG laser stimulation of tiny skin surface areas allows recording the dynamic scalp topography of ultralate (C-fibres) LEPs, with or without the performance of a RT task