Anne F. Mannion

Cross-cultural adaptation, reliability, and validity of the German version of the Pain Catastrophizing Scale

OBJECTIVE In patients with chronic pain, catastrophizing is a significant determinant of self-rated pain intensity and disability. The Pain Catastrophizing Scale (PCS) was developed to assist with both treatment planning and outcome assessment; to date, no German version has been validated. METHODS A cross-cultural adaptation of the PCS into German was carried out, strictly according to recommended methods. A questionnaire booklet containing the PCS, visual analogue scales (numeric rating scale) for pain intensity and general health, the ZUNG self-rating depression scale, the Modified Somatic Perception Questionnaire (MSPQ), the Fear Avoidance Beliefs Questionnaire (FABQ), and the Roland-Morris (RM) disability questionnaire was completed by 111 patients with chronic low back pain (mean age, 49 years), 100 of which also completed it again 7 days later. RESULTS Cronbachs alpha (internal reliability) for the three subsections of the PCS--helplessness, magnification, rumination--and for the whole questionnaire (PCSwhole) were .89, .67, .88, and .92, respectively. The intraclass correlation coefficients of agreement for the reproducibility were .81, .67, .78, and .80, respectively. The PCSwhole scores correlated with the other scores as follows: pain intensity r=.26, general health r=-.29, ZUNG r=.52, MSPQ r=.53, FABQactivity r=.51, FABQwork r=.61 and RM r=.57. Factor analysis revealed three factors, with an almost identical factor structure to that reported in previous studies. CONCLUSION The psychometric properties of our German version of the PCS were comparable to those reported in previous studies for the original English version. It represents a valuable tool in the assessment of German-speaking chronic low back pain patients.

Abdominal muscle size and symmetry at rest and during abdominal hollowing exercises in healthy control subjects

The symmetry of, and physical characteristics influencing, the thickness of the lateral abdominal muscles at rest and during abdominal exercises were examined in 57 healthy subjects (20 men, 37 women; aged 22–62 years). M‐mode ultrasound images were recorded from the abdominal muscles at rest and during abdominal hollowing exercises in hook‐lying. The fascial lines bordering the transvs. abdominis, obliquus internus and obliquus externus were digitized and the absolute thickness, relative thickness (% of total lateral thickness) and contraction ratio (thickness during hollowing/thickness at rest), as well as the asymmetry (difference between sides expressed as a percent of the smallest value for the two sides) for each of these parameters were determined for each muscle. Both at rest and during hollowing, obliquus internus was the thickest and transvs. abdominis the thinnest muscle. There were no significant differences between left and right sides for group mean thicknesses of any muscle; however, individual asymmetries were evident, with mean values for the different muscles ranging from 11% to 26%; asymmetry was much less for the contraction ratios (mean % side differences, 5–14% depending on muscle). Body mass was the most significant positive predictor of absolute muscle thickness, for all muscles at rest and during hollowing, accounting for 30–44% variance. Body mass index explained 20–30% variance in transvs. abdominis contraction ratio (negative relationship). The influence of these confounders must be considered in comparative studies of healthy controls and back pain patients, unless groups are very carefully matched. Asymmetries observed in patients should be interpreted with caution, as they are also common in healthy subjects.

Association between catastrophizing and self-rated pain and disability in patients with chronic low back pain.

BACKGROUND Catastrophizing plays an important role in models of pain chronicity, showing a consistent correlation with both pain intensity and disability. It is conceivable that these associations are mediated or confounded by other psychological attributes. OBJECTIVE To examine the relative influence of catastrophizing and other psychological variables on pain and disability in patients with chronic low back pain. METHODS Seventy-eight patients completed the Pain Catastrophizing Scale, Roland Morris Disability Questionnaire, Fear-Avoidance Beliefs Questionnaire (work/activity), Modified Somatic Perception Questionnaire, Modified Zung Depression Scale, and Pain Intensity scale. RESULTS Catastrophizing was significantly correlated with both Pain intensity and Roland and Morris Disability, and with all other psychological variables (all p < 0.001). However, multiple regression analyses showed that Catastrophizing explained no significant variance in Pain intensity beyond that explained by the unique contributions of Modified Somatic Perception and Fear-Avoidance Beliefs (work) and explained no further variance in Disability beyond that explained by the unique contributions of Fear-Avoidance Beliefs (work) and Depression. CONCLUSION These findings are consistent with previous models proposing that negative psychological attributes are associated with greater perceptions of pain and disability. Nonetheless, our study indicates that measures of catastrophizing show notable measurement overlap in multivariate models.

A new method for the noninvasive determination of abdominal muscle feedforward activity based on tissue velocity information from tissue Doppler imaging

Rapid arm movements elicit anticipatory activation of the deep-lying abdominal muscles; this appears modified in back pain, but the invasive technique used for its assessment [fine-wire electromyography (EMG)] has precluded its widespread investigation. We examined whether tissue-velocity changes recorded with ultrasound (M-mode) tissue Doppler imaging (TDI) provided a viable noninvasive alternative. Fourteen healthy subjects rapidly flexed, extended, and abducted the shoulder; recordings were made of medial deltoid (MD) surface EMG and of fine-wire EMG and TDI tissue-velocity changes of the contralateral transversus abdominis, obliquus internus, and obliquus externus. Muscle onsets were determined by blinded visual analysis of EMG and TDI data. TDI could not distinguish between the relative activation of the three muscles, so in subsequent analyses only the onset of the earliest abdominal muscle activity was used. The latter occurred <50 ms after the onset of medial deltoid EMG (i.e., was feedforward) and correlated with the corresponding EMG onsets (r = 0.47, P < 0.0001). The mean difference between methods was 20 ms and was likely explained by electromechanical delay; limits of agreement were wide (-40 to +80 ms) but no greater than those typical of repeated measurements using either technique. The between-day standard error of measurement of the TDI onsets (examined in 16 further subjects) was 16 ms. TDI yielded reliable and valid measures of the earliest onset of feedforward activity within the anterolateral abdominal muscle group. The method can be used to assess muscle dysfunction in large groups of back-pain patients and may also be suitable for the noninvasive analysis of other deep-lying or small/thin muscles.

TISSUE DOPPLER IMAGING FOR DETECTING ONSET OF MUSCLE ACTIVITY

Tissue Doppler imaging (TDI) is typically used to image and quantify tissue motion. We investigated whether this method would serve as a viable alternative to surface electromyography (EMG) in providing a reliable and valid measure of the onset of muscle activity. Ten healthy subjects performed maximal knee extension exercises at 0°/s (isometric), 60°/s, 120°/s, 180°/s, and 240°/s (5 times each, on each side), using an isokinetic dynamometer. Simultaneous EMG and TDI velocity (superimposed on motion‐mode ultrasound cine‐loops) recordings were made from vastus lateralis. All tests were repeated 1 week later. There was a good correlation between the onset times determined with TDI velocity and EMG: r = 0.78 (day 1), and r = 0.80 (day 2) (each P < 0.001). The mean difference (and SD) in muscle onset time between the two methods (TDI minus EMG) was −20.3 ± 31.0 ms (day 1) and −17.4 ± 27.2 ms (day 2). TDI represents a reliable and valid measure of detecting onset of muscle activity. The mean difference between EMG and TDI onset times (approximately 20 ms) is likely explained by electromechanical delay. TDI represents a viable method for measuring the onset of muscle activity; it may offer a non‐invasive alternative to fine‐wire EMG for use with small or deep muscles. Muscle Nerve, 2008

Ultrasound Tissue Doppler Imaging Reveals No Delay in Abdominal Muscle Feed-Forward Activity During Rapid Arm Movements in Patients With Chronic Low Back Pain

Study Design. Cross-sectional study. Objective. Comparison of the timing of onset of lateral abdominal muscle activity during rapid arm movements in patients with nonspecific chronic low back pain (cLBP) and back-pain-free controls. Summary of Background Data. Rapid movements of the arm are normally associated with prior activation of trunk-stabilizing muscles in readiness for the impending postural perturbation. Using invasive intramuscular electromyography techniques, studies have shown that this feed-forward function is delayed in some patients with low back pain (LBP). Ultrasound tissue Doppler imaging (TDI) provides an ultrasound method for quantifying muscle activation in a noninvasive manner, allowing investigation of larger groups of patients and controls. Methods. Ninety-six individuals participated (48 patients with cLBP and 48 matched LBP-free controls). During rapid shoulder flexion, abduction, and extension, surface electromyographic signals from the deltoid and motion-mode TDI images from the contralateral lateral abdominal muscles were recorded simultaneously. The onset of muscle activity was given by changes in the tissue velocity of the abdominal muscles, as measured with TDI. Pain and disability in the patients were assessed using standardized questionnaires. Data were analyzed using repeated measures analysis of variance. Results. In both groups, feed-forward activity of the lateral abdominal muscles was recorded during arm movements in all directions. The main effect of “group membership” revealed no significant difference between the groups for the earliest onset of abdominal muscle activity (P = 0.398). However, a significant “group × body side” interaction (P = 0.015) was observed, and this was the result of earlier onsets in the cLBP group than controls for the abdominal muscles on the right (but not left) body side. No relationship was found between the time of onset of the earliest abdominal muscle activity and pain intensity, pain frequency, pain medication usage, or Roland Morris disability scores. Conclusion. Patients with cLBP did not show a delayed onset of feed-forward activation of the lateral abdominal muscles during rapid arm movements. Earlier activation was observed for one body side compared with the controls. However, the clinical relevance of this finding remains obscure, especially because there was no relationship between the onset of activation and any clinical parameters.

Comparison of neuromuscular adjustments associated with sustained isometric contractions of four different muscle groups.

The extent and characteristics of muscle fatigue of different muscle groups when subjected to a similar fatiguing task may differ. Thirteen healthy young men performed sustained contractions at 50% maximal voluntary contraction (MVC) force until task failure, with four different muscle groups, over two sessions. Per session, one upper limb and one lower limb muscle group were tested (knee extensors and thumb adductor, or plantar and elbow flexors). Changes in voluntary activation level and contractile properties were derived from doublet responses evoked during and after MVCs before and after exercise. Time to task failure differed (P < 0.05) between muscle groups (220 ± 64 s for plantar flexors, 114 ± 27 s for thumb adductor, 77 ± 25 s for knee extensors, and 72 ± 14 s for elbow flexors). MVC force loss immediately after voluntary task failure was similar (-30 ± 11% for plantar flexors, -37 ± 13% for thumb adductor, -34 ± 15% for knee extensors, and -40 ± 12% for elbow flexors, P > 0.05). Voluntary activation was decreased for plantar flexors only (from 95 ± 5% to 82 ± 9%, P < 0.05). Potentiated evoked doublet amplitude was more depressed for upper limb muscles (-59.3 ± 14.7% for elbow flexors and -60.1 ± 24.1% for thumb adductor, P < 0.05) than for knee extensors (-28 ± 15%, P < 0.05); no reduction was found in plantar flexors (-7 ± 12%, P > 0.05). In conclusion, despite different times to task failure when sustaining an isometric contraction at 50% MVC force for as long as possible, diverse muscle groups present similar loss of MVC force after task failure. Thus the extent of muscle fatigue is not affected by time to task failure, whereas this latter determines the etiology of fatigue.

Goal attainment scaling as a measure of treatment success after physiotherapy for chronic low back pain

OBJECTIVES In some chronic conditions, patient-specific tools with individualized items have proved to be more sensitive outcome instruments than fixed-item tools; their use has not yet been investigated in chronic low back pain (cLBP). METHODS Eleven males and 21 females [mean age 44.0 (12.3) years] with cLBP, undergoing a spine-stabilization physiotherapy programme, completed the Roland Morris (RM) Disability Scale and a 0-10 pain scale pre- and post-therapy. Post-therapy, goal attainment scaling (GAS) scores were calculated regarding achievement of 2-6 priority GAS goals established pre-therapy; global outcome of therapy was assessed on a 5-point Likert scale. RESULTS Approximately one-fifth of the individualized goals were not covered by items of the RM. Of the 121 individualized goals, 41 (34%) were achieved at the expected level, 42 (35%) were exceeded and 38 (31%) were not reached. GAS scores correlated with change scores for pain (r = 0.61, P < 0.0001) and RM (r = 0.49, P = 0.006). Sixty-five per cent of the patients had a successful outcome according to GAS (i.e. a score >or=50); 55%, according to global outcome (therapy helped/helped a lot); 39%, according to the RM score change (score decrease >or=30%); and 44%, according to the pain score change (score decrease >or=30%). CONCLUSIONS GAS demonstrates the achievement of important goals undetected by fixed-item measures and is a valid and sensitive outcome measure for assessing the success of rehabilitation in patients with cLBP.