Christine C. Wright

Gender differences in pressure pain threshold in healthy humans.

&NA; Aims of investigation: To quantify the magnitude of putative gender differences in experimental pressure pain threshold (PPT), and to establish the relevance of repeated measurements to any such differences. Methods: Two separate studies were undertaken. A pressure algometer was used in both studies to assess PPT in the first dorsal interosseous muscle. Force was increased at a rate of 5 N /s. In study 1, two measurements were taken from 240 healthy volunteers (120 males, 120 females; mean age 25 years) giving a power for statistical analysis of &bgr;=0.80 at &agr;=0.01. In study two, 30 subjects (15 males, 15 females mean age 28 years) were randomly selected from study one. Fourteen repeated PPT measurements were recorded at seven, 10 min intervals. Mean PPT data for gender groups, from both studies, were analysed using analysis of covariance with repeated measures, and age as the covariate. Results: The mean PPT for each of the two measurements in study one showed a difference between gender of 12.2 N (f=30.5 N, m=42.7 N) and 12.8 N (f=29.5 N, m=42.3 N), respectively, representing a difference of 28% with females exhibiting a lower threshold. In study two, the mean difference calculated from 14 PPT repeated measurements over a 1 h period was comparable to that in study one at 12.3 N (range 10.4–14.4 N) again females exhibited the lower threshold. The differences in mean PPT values between gender were found to be significant in both study one, at (P<0.0005, F=37.8, df=1) and study two (P=0.01, F=7.6, df=1). No significant differences were found in either study with repeated measurement (P=0.892 and P=0.280), or on the interaction of gender and repeated measurement after controlling for age (P=0.36 and P=0.62). Conclusion: Healthy females exhibited significantly lower mean PPTs in the first dorsal interosseous muscle than males, which was maintained for fourteen repeated measures within a 1 h period. This difference is likely to be above clinically relevant levels of change, and it has clear implications for the use of different gender subjects in laboratory based experimental designs utilising PPT as an outcome measure.

Sensory stimulation (TENS): effects of parameter manipulation on mechanical pain thresholds in healthy human subjects

&NA; Transcutaneous electrical nerve stimulation (TENS) is a popular form of electrostimulation. Despite an extensive research base, there remains no consensus regarding the parameter selection required to achieve maximal hypoalgesic effects. The aim of this double blind, sham‐controlled study was to investigate the relative hypoalgesic effects of different TENS parameters (frequency, intensity and stimulation site) upon experimentally induced mechanical pain. Two hundred and forty participants were recruited in order to provide statistical analysis with 80% power at &agr;=0.05. Subjects were randomised to one of the six TENS groups, a control, and a sham TENS group (n=30, 15 males, 15 females, per group). TENS groups differed in their combinations of stimulation; frequency (4 or 110 Hz), intensity (‘to tolerance’ or ‘strong but comfortable’) and stimulation site (segmental–over the distribution of the radial nerve or, extrasegmental–over acupuncture point ‘gall bladder 34’, or a combination of both segmental and extrasegmental). Pulse duration was fixed at 200 &mgr;s. Stimulation was delivered for 30 min and subjects were then monitored for a further 30 min. Mechanical pain threshold (MPT) was measured using a pressure algometer and taken from the first dorsal interosseous muscle of the dominant hand, ipsilateral to the stimulation site. MPT measures were taken, at baseline, and at 10‐min intervals for 60 min. Difference scores were analysed using repeated measures and one‐way ANOVA and relevant post hoc tests. Low frequency, high intensity, extrasegmental stimulation produced a rapid onset hypoalgesic effect, which increased during the stimulation period (P<0.0005 control and sham) and was sustained for 30 min post‐stimulation (P<0.0005control, P=0.024sham). Whilst high frequency, ‘strong but comfortable’ intensity, segmental stimulation produced comparable hypoalgesic levels during stimulation, this effect was not sustained post‐stimulation. Stimulation at a combination of the two sites did not produce any greater hypoalgesic effects. These results may have implications for the clinical use of sensory stimulation.

Reproducibility and repeatability: errors of three groups of physiotherapists in locating spinal levels by palpation

Location of spinal levels by palpation is an essential part of physiotherapy assessment and treatment of spinal musculoskeletal conditions. This study aimed to (i) investigate the reproducibility and repeatability of three groups of physiotherapists in locating three randomly selected spinal levels by palpation, (ii) explore whether these groups were palpating similar points at each level, and (iii) investigate whether there were differences in palpation across the spinal levels tested. Reproducibility was estimated using a convenience sample of 30 physiotherapists: 13 undergraduate students, 10 clinicians, and seven manual therapists (MTs). Repeatability was investigated using six physiotherapists (two students, two clinicians and two MTs). Each therapist palpated the spinous processes (C5, T6, L5) once for reproducibility, and 10 times for repeatability, on each asymptomatic model. The skin overlying the spinal levels was marked with an invisible pen. Using an ultra-violet light, marks were transcribed onto transparent plastic strips for analysis, and the distances were measured with an electronic caliper. Repeated measures analyses of variance (ANOVA) indicated poor reproducibility across therapists at all spinal levels (F=18.43, P=0.001), but good repeatability within therapists (F=2.09, P=0.161). Students produced different mean locations of their palpatory marks from the other two groups in two spinal levels. Clinicians and MTs were more reproducible than students, and located similar levels. Palpation of L5 spinous process presented the most difficulty, for all groups. Further research is needed to compare different methods of palpation and explore whether reproducibility can be improved.

Level of distress in a recurrent low back pain population referred for physical therapy.

Study Design. Recruitment phase of a randomized clinical trial. Objectives. To review the published literature on the use of the distress risk assessment method in different back pain populations and healthcare settings and compare results with those obtained from the current trial. Summary of Background. Psychological distress in low back pain is commonplace, and distress increases the relative risk of poor outcome with physical treatment alone. The Distress and Risk Assessment Method is a tool for use in the clinical setting to assist in the identification of distress and clinical decision-making. Methods. The Distress Risk Assessment Method and Roland Morris Disability Questionnaire were used to assess eligibility of patients with recurrent low back pain for recruitment into a randomized clinical trial examining different physical therapy approaches. Results. In total, 221 patients were assessed, resulting in 212 correctly complete questionnaires. Of those 212, 71 (33%) showed evidence of marked distress (41 depressed and 30 somatic). Functional disability, measured using the Roland Morris Disability Questionnaire, was higher for the distressed group (mean 14.1, SD 4.8, range 3–23) than the nondistressed group (mean 8.0, SD 5.1, range 0–21). Distress and anxiety measured using the distress risk assessment method were correlated to self-reported back-related functional disability. Conclusions. Distress associated with low back pain is common with one third of patients referred for physical therapy at the units studied exhibiting a level of distress that increased their relative risk of poor outcome by 3 to 4 times. Clinically, screening this group of patients may help indicate when liaison with other professionals is appropriate and possibly identify those patients who may be too distressed to respond to physical therapy intervention alone.

Transcranial direct current stimulation for the reduction of clinical and experimentally induced pain: a systematic review and meta-analysis.

Objectives:To evaluate the effectiveness of transcranial direct current stimulation on clinical and experimental pain, and to identify the most beneficial stimulation parameters. Methods:Predefined search using key terms of information sources including: MEDLINE, EMBASE, CAB Abstracts, and PsychINFO, Cochrane Register of Controlled Trials, CINAHL, and PeDRO databases; reference lists of retrieved articles, journal contents, and conference proceedings. Two reviewers independently searched and evaluated publications. English and non-English controlled trials that applied direct current stimulation to the brain published before September 30, 2010 were included. Studies using magnetic stimulation or pulsed currents were excluded. Results:Trials investigating experimental pain in healthy participants (n=6) used a wide variety of stimulation and outcome parameters that did not allow a synthesis across outcome parameters. Trials investigating chronic pain (n=8) used anodal motor cortex stimulation of 1 or 2 mA intensity, either as a single dose or on a maximum of 10 consecutive days. Four trials on chronic pain were excluded due to a high risk of bias. A meta-analysis of 4 trials on chronic pain found a pooled effect size of −2.29 with a 95% confidence interval of −3.5 to −1.08. This effect does just reach minimal clinically important difference recommendations. Discussion:The level of evidence for the efficacy of transcranial direct current stimulation in experimental and chronic pain reduction is low. Evidence from high quality randomized controlled trials is required before this treatment should be recommended.

PSYCHOMETRIC PROPERTIES OF THE ROSENBERG SELF-ESTEEM SCALE AMONG PEOPLE WITH ARTHRITIS

After 30 years of use the factor structure of the Rosenberg Self-esteem Scale remains the subject of debate. Most studies have focused on school-aged or undergraduate students. There are few psychometric data for older people or for those with disabilities. This study compared the factor structures of the Rosenberg Self-esteem Scale among 117 adults with arthritis and 185 undergraduate students. A two-factor solution provided the best fit for both samples, although the item content of the factors differed slightly Further investigation is required to assess whether the difference is due to age or the presence of physical disability. Nonetheless, the scale discriminated well between students and adults with arthritis.

Genetic Algorithms and the Design of Experiments

The genetic algorithm (GA) has most often been viewed from a biological perspective. The metaphors of natural selection, cross-breeding and mutation have been helpful in providing a framework in which to explain how and why they work. However, most practical applications of GAs are in the context of optimization, where alternative approaches may prove more effective. In attempting to understand how GAs function as optimizers, several alternative viewpoints have been suggested. In this paper we discuss one of these in some detail—one in which GAs are regarded as a form of sequential experimental design.

Survey of current physiotherapy practice for patients undergoing lumbar spinal fusion in the United Kingdom.

Study Design. Descriptive survey methodology employed a SurveyMonkey online questionnaire. Objective. To evaluate UK National Health Service physiotherapy practice for lumbar spinal fusion surgery. Summary of Background Data. An increasing rate of surgery and high level of patient dis-satisfaction focus attention to rehabilitation of patients undergoing lumbar spinal fusion. Inconclusive, very low-quality evidence for the effectiveness of physiotherapy management after lumbar spinal fusion exists. Best practice, therefore, remains unclear. Limited comparability of outcomes and retrieval of only 2 trials reflected a lack of research and considerable heterogeneity. An evaluation of current practice is required, to inform a future trial to evaluate a best practice physiotherapy intervention. Methods. Eligible participants were all physiotherapists working with patients undergoing spinal fusion. A previous survey and recent systematic review informed questions. Statistical analyses included responder characteristics and preplanned descriptive analyses. Thematic analysis was conducted on open-ended question data. Results. The 83.5% response rate was good. Findings illustrated varied provision relating to assessment and management of patients pre- and postoperatively. Physiotherapists employed limited use of protocols or guidelines, partly attributed to the poor evidence base for this surgery. Scope of practice included exercise, advice, listing for surgery, and ordering investigations. Patient education played an important role. Patient-centered practice was important, although constraints owing to limited resources (staffing, poor evidence, base/lack of protocols) were evident. Conclusion. Current UK pre- and postoperative physiotherapy practice for lumbar spinal fusion is described. It is not clear whether patients who are seen by physiotherapists have improved outcomes, owing to variability of practice, physiotherapy being delivered in a range of locations at a range of times postoperatively, and limited use of outcome measures. The findings support the need for a randomized clinical trial evaluating effectiveness of a best practice physiotherapy management intervention. Level of Evidence: 3

Evaluation of the Test-retest Reliability of the Short-form McGill Pain Questionnaire

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A Pragmatic Randomised Controlled Trial of Specific Spinal Stabilisation Exercises in the Management of Recurrent Lumbar Spine Pain and Dysfunction – Pilot results

N E Foster, C Wright School of Health and Social Science, Coventry University Aims: The particular problem of recurrent low back pain (LBP), estimated at between 20% and 69% for one-year prevalence (Von Korff et al, 1993) and the associated escalating costs have highlighted the need to provide efficient, cost-effective interventions. Studies have suggested that addressing the muscular dysfunction shown to exist in subjects with LBP improves both objective and subjective outcomes of treatment (O’Sullivan et al, 1997). A pilot trial was undertaken in order to complete power calculations for the sample size required for a study examining the effect of incorporating specific spinal stabilisation exercises (SSSE) within the treatment of recurrent LBP, and assess the appropriateness of exclusion criteria.