Examining the role of intrinsic and reflexive contributions to ankle joint hyper-resistance treated with botulinum toxin-A.

BACKGROUND: Spasticity, i.e. stretch hyperreflexia, increases joint resistance similar to symptoms like hypertonia and contractures. Botulinum neurotoxin-A (BoNT-A) injections are a widely used intervention to reduce spasticity. BoNT-A effects on spasticity are poorly understood, because clinical measures, e.g. modified Ashworth scale (MAS), cannot differentiate between the symptoms affecting joint resistance. This paper distinguishes the contributions of the reflexive and intrinsic pathways to ankle joint hyper-resistance for participants treated with BoNT-A injections. We hypothesized that the overall joint resistance and reflexive contribution decrease 6 weeks after injection, while returning close to baseline after 12 weeks. METHODS: Nine participants with spasticity after spinal cord injury or after stroke were evaluated across three sessions: 0, 6 and 12 weeks after BoNT-A injection in the calf muscles. Evaluation included clinical measures (MAS, Tardieu Scale) and motorized instrumented assessment using the instrumented spasticity test (SPAT) and parallel-cascade (PC) system identification. Assessments included measures for: (1) overall resistance from MAS and fast velocity SPAT; (2) reflexive resistance contribution from Tardieu Scale, difference between fast and slow velocity SPAT and PC reflexive gain; and (3) intrinsic resistance contribution from slow velocity SPAT and PC intrinsic stiffness/damping. RESULTS: Individually, the hypothesized BoNT-A effect, the combination of a reduced resistance (week 6) and return towards baseline (week 12), was observed in the MAS (5 participants), fast velocity SPAT (2 participants), Tardieu Scale (2 participants), SPAT (1 participant) and reflexive gain (4 participants). On group-level, the hypothesis was only confirmed for the MAS, which showed a significant resistance reduction at week 6. All instrumented measures were strongly correlated when quantifying the same resistance contribution. CONCLUSION: At group-level, the expected joint resistance reduction due to BoNT-A injections was only observed in the MAS (overall resistance). This observed reduction could not be attributed to an unambiguous group-level reduction of the reflexive resistance contribution, as no instrumented measure confirmed the hypothesis. Validity of the instrumented measures was supported through a strong association between different assessment methods. Therefore, further quantification of the individual contributions to joint resistance changes using instrumented measures across a large sample size are essential to understand the heterogeneous response to BoNT-A injections.

Socio-economic determinants of healthcare costs in early life: a register-based study in the Netherlands.

BACKGROUND: Children with low socioeconomic status (SES) have an increased risk of a suboptimal start in life with ensuing higher healthcare costs. This study aims to investigate the effects of individual- (monthly household income) and contextual-level SES (household income and neighborhood deprivation), and perinatal morbidity (preterm birth and small for gestational age ((<10th percentile), SGA)) on healthcare costs in early life (0-3 years of age). METHODS: Individual-linked data from three national registries (Perinatal Registry Netherlands, Statistics Netherlands, and Healthcare Vektis) were obtained of all children born between 2011 and 2014 (N = 480,471) in the Netherlands. Binomial logistic regression was used to model annual healthcare costs as a function of their household income (per €1000), neighborhood deprivation index (range - 13.26 - 10.70), their perinatal morbidity and demographic characteristics. Annual healthcare cost were dichotomized into low healthcare costs (Q1-Q3 below €1000) and high healthcare costs (Q4 €1000 or higher). RESULTS: Children had a median of €295 annual healthcare costs, ranging from €72 to €4299 (5-95%). Binomial logistic regression revealed that for every €1000 decrease in monthly household income, the OR for having high healthcare costs is 0.99 (0.99-0.99). Furthermore, for every one-unit increase in neighborhood deprivation the OR for having high healthcare costs increase 1.02 (1.01-1.02). Finally, the model revealed an OR of 2.55 (2.48-2.61) for preterm born children, and an OR of 1.44 (1.41-1.48) for children SGA, to have high healthcare costs compared to their healthy peers. CONCLUSION: More neighborhood deprivation was directly related to higher healthcare costs in young children. On top of this, lower household income was consistently and independently related to higher healthcare costs. By optimizing conditions for low SES populations, the impact of low SES circumstances on their healthcare costs can be positively influenced. Additionally, policies that influence more timely and appropriate healthcare use in low SES populations can reduce healthcare costs further.

Standard set of network outcomes for traumatic spinal cord injury: a consensus-based approach using the Delphi method.

STUDY DESIGN: Consensus study. OBJECTIVES: The purpose of this study is to define a standardized (network) outcomes set for traumatic spinal cord injury (t-SCI), covering the patient journey from acute to chronic rehabilitation phase, including patient-relevant outcomes, adequate measurement instruments, as well as case-mix and risk factors. SETTING: Acute Spinal Cord Injury (ASCI) Unit Nijmegen, the Netherlands. METHODS: A modified Delphi method was performed, including a multidisciplinary panel of 19 health-care professionals with experience in t-SCI management. Formal consensus was reached after two web-based surveys, a face-to-face meeting, and a final confirmation round (threshold consensus: 70%). RESULTS: In the first two Delphi rounds, 18/19 invited panelists (94.7%) responded and 10 panelists participated in the final meeting. The prefinal set was confirmed by all panelists. The standard set encompasses the three-tiered outcome hierarchy and consists of patient-reported and clinician-reported outcome domains and measurement instruments. Consensus was reached to include survival, degree of health or recovery, time to recovery, and return to normal activities, disutility of care or treatment process, sustainability of health and nature of recurrences, and long-term consequences of therapy. A measurement schedule was defined as well as for proposed casemix and risk factors, including demographics, clinical status, and treatment process. CONCLUSION: A standard set of network outcomes is developed that could be implemented in hospitals and rehabilitation centers involved in the treatment of t-SCI. Using this standard set, comparison of the quality of care is possible and prognostic prediction of outcomes of treatment is feasible, so that each patient receives the right care at the right time in the right place.

Impaired foot placement strategy during walking in people with incomplete spinal cord injury.

BACKGROUND: Impaired balance during walking is a common problem in people with incomplete spinal cord injury (iSCI). To improve walking capacity, it is crucial to characterize balance control and how it is affected in this population. The foot placement strategy, a dominant mechanism to maintain balance in the mediolateral (ML) direction during walking, can be affected in people with iSCI due to impaired sensorimotor control. This study aimed to determine if the ML foot placement strategy is impaired in people with iSCI compared to healthy controls. METHODS: People with iSCI (n = 28) and healthy controls (n = 19) performed a two-minute walk test at a self-paced walking speed on an instrumented treadmill. Healthy controls performed one extra test at a fixed speed set at 50% of their preferred speed. To study the foot placement strategy of a participant, linear regression was used to predict the ML foot placement based on the ML center of mass position and velocity. The accuracy of the foot placement strategy was evaluated by the root mean square error between the predicted and actual foot placements and was referred to as foot placement deviation. Independent t-tests were performed to compare foot placement deviation of people with iSCI versus healthy controls walking at two different walking speeds. RESULTS: Foot placement deviation was significantly higher in people with iSCI compared to healthy controls independent of walking speed. Participants with iSCI walking in the self-paced condition exhibited 0.40 cm (51%) and 0.33 cm (38%) higher foot placement deviation compared to healthy controls walking in the self-paced and the fixed-speed 50% condition, respectively. CONCLUSIONS: Higher foot placement deviation in people with iSCI indicates an impaired ML foot placement strategy in individuals with iSCI compared to healthy controls.

Using Sensor Technology to Measure Gait Capacity and Gait Performance in Rehabilitation Inpatients with Neurological Disorders.

The aim of this study was to objectively assess and compare gait capacity and gait performance in rehabilitation inpatients with stroke or incomplete spinal cord injury (iSCI) using inertial measurement units (IMUs). We investigated how gait capacity (what someone can do) is related to gait performance (what someone does). Twenty-two inpatients (11 strokes, 11 iSCI) wore ankle positioned IMUs during the daytime to assess gait. Participants completed two circuits to assess gait capacity. These were videotaped to certify the validity of the IMU algorithm. Regression analyses were used to investigate if gait capacity was associated with gait performance (i.e., walking activity and spontaneous gait characteristics beyond therapy time). The ankle positioned IMUs validly assessed the number of steps, walking time, gait speed, and stride length (r ≥ 0.81). The walking activity was strongly (r ≥ 0.76) related to capacity-based gait speed. Maximum spontaneous gait speed and stride length were similar to gait capacity. However, the average spontaneous gait speed was half the capacity-based gait speed. Gait capacity can validly be assessed using IMUs and is strongly related to gait performance in rehabilitation inpatients with neurological disorders. Measuring gait performance with IMUs provides valuable additional information about walking activity and spontaneous gait characteristics to inform about functional recovery.

Assessment of the Shank-to-Vertical Angle While Changing Heel Heights Using a Single Inertial Measurement Unit in Individuals with Incomplete Spinal Cord Injury Wearing an Ankle-Foot-Orthosis.

Previous research showed that an Inertial Measurement Unit (IMU) on the anterior side of the shank can accurately measure the Shank-to-Vertical Angle (SVA), which is a clinically-used parameter to guide tuning of ankle-foot orthoses (AFOs). However, in this context it is specifically important that differences in the SVA are detected during the tuning process, i.e., when adjusting heel height. This study investigated the validity of the SVA as measured by an IMU and its responsiveness to changes in AFO-footwear combination (AFO-FC) heel height in persons with incomplete spinal cord injury (iSCI). Additionally, the effect of heel height on knee flexion-extension angle and internal moment was evaluated. Twelve persons with an iSCI walked with their own AFO-FC in three different conditions: (1) without a heel wedge (refHH), (2) with 5 mm heel wedge (lowHH) and (3) with 10 mm heel wedge (highHH). Walking was recorded by a single IMU on the anterior side of the shank and a 3D gait analysis (3DGA) simultaneously. To estimate validity, a paired t-test and intraclass correlation coefficient (ICC) between the SVAIMU and SVA3DGA were calculated for the refHH. A repeated measures ANOVA was performed to evaluate the differences between the heel heights. A good validity with a mean difference smaller than 1 and an ICC above 0.9 was found for the SVA during midstance phase and at midstance. Significant differences between the heel heights were found for changes in SVAIMU (p = 0.036) and knee moment (p = 0.020) during the midstance phase and in SVAIMU (p = 0.042) and SVA3DGA (p = 0.006) at midstance. Post-hoc analysis revealed a significant difference between the ref and high heel height condition for the SVAIMU (p = 0.005) and knee moment (p = 0.006) during the midstance phase and for the SVAIMU (p = 0.010) and SVA3DGA (p = 0.006) at the instant of midstance. The SVA measured with an IMU is valid and responsive to changing heel heights and equivalent to the gold standard 3DGA. The knee joint angle and knee joint moment showed concomitant changes compared to SVA as a result of changing heel height.

Feasibility of a Sensor-Based Technological Platform in Assessing Gait and Sleep of In-Hospital Stroke and Incomplete Spinal Cord Injury (iSCI) Patients.

Recovery of the walking function is one of the most common rehabilitation goals of neurological patients. Sufficient and adequate sleep is a prerequisite for recovery or training. To objectively monitor patients' progress, a combination of different sensors measuring continuously over time is needed. A sensor-based technological platform offers possibilities to monitor gait and sleep. Implementation in clinical practice is of utmost relevance and has scarcely been studied. Therefore, this study examined the feasibility of a sensor-based technological platform within the clinical setting. Participants (12 incomplete spinal cord injury (iSCI), 13 stroke) were asked to wear inertial measurement units (IMUs) around the ankles during daytime and the bed sensor was placed under their mattress for one week. Feasibility was established based on missing data, error cause, and user experience. Percentage of missing measurement days and nights was 14% and 4%, respectively. Main cause of lost measurement days was related to missing IMU sensor data. Participants were not impeded, did not experience any discomfort, and found the sensors easy to use. The sensor-based technological platform is feasible to use within the clinical rehabilitation setting for continuously monitoring gait and sleep of iSCI and stroke patients.

Efficacy of Walking Adaptability Training on Walking Capacity in Ambulatory People With Motor Incomplete Spinal Cord Injury: A Multicenter Pragmatic Randomized Controlled Trial.

BACKGROUND AND OBJECTIVE: Balance and walking capacity are often impaired in people with motor incomplete spinal cord injury (iSCI), frequently resulting in reduced functional ambulation and participation. This study aimed to assess the efficacy of walking adaptability training compared to similarly dosed conventional locomotor and strength training for improving walking capacity, functional ambulation, balance confidence, and participation in ambulatory people with iSCI. METHODS: We conducted a 2-center, parallel-group, pragmatic randomized controlled trial. Forty-one people with iSCI were randomized to 6 weeks of (i) walking adaptability training (11 hours of Gait Real-time Analysis Interactive Lab (GRAIL) training-a treadmill in a virtual reality environment) or (ii) conventional locomotor and strength training (11 hours of treadmill training and lower-body strength exercises). The primary measure of walking capacity was maximal walking speed, measured with an overground 2-minute walk test. Secondary outcome measures included the Spinal Cord Injury Functional Ambulation Profile (SCI-FAP), the Activities-specific Balance Confidence (ABC) scale, and the Utrecht Scale for Evaluation of Rehabilitation-Participation (USER-P). RESULTS: No significant difference in maximal walking speed between the walking adaptability (n = 17) and conventional locomotor and strength (n = 18) training groups was found 6 weeks after training at follow-up (-0.05 m/s; 95% CI = -0.12-0.03). In addition, no significant group differences in secondary outcomes were found. However, independent of intervention, significant improvements over time were found for maximal walking speed, SCI-FAP, ABC, and USER-P restrictions scores. Conclusions. Our findings suggest that walking adaptability training may not be superior to conventional locomotor and strength training for improving walking capacity, functional ambulation, balance confidence, or participation in ambulatory people with iSCI. TRIAL REGISTRATION: Dutch Trial Register; Effect of GRAIL training in iSCI.

Early Maternal Caregiving Capacities in Highly Vulnerable, Multi-Problem Families.

Caregiving capacities may be an important link between multi-problem circumstances and adverse child development. This study aims to assess caregiving capacities and their correlations in highly vulnerable, multi-problem families in Rotterdam, the Netherlands. Caregiving capacity (overall, emotional and instrumental) was prospectively assessed in 83 highly vulnerable women using video-observations of daily caregiving tasks, six week postpartum. Supporting data were collected at three time points: at inclusion, six weeks after inclusion and six weeks postpartum, and these included psychological symptoms, self-sufficiency, problematic life domains, home environment, income, depression, anxiety and stress. Pregnancy- and delivery-related information was collected from obstetric care professionals. Maternal caregiving scores averaged below adequate quality. Mothers living in an unsafe home environment (B = 0.62) and mothers with more problematic life domains (≤3 domains, B = 0.32) showed significantly higher instrumental caregiving capacities. Other variables were not related to caregiving capacities. Caregiving capacity in this highly vulnerable population was below adequate quality. However, in most cases there was no significant association between caregiving and the variables related to vulnerability. This means that a potential association between vulnerability and caregiving capacities might be driven by the interaction between several problems, rather than the type or number of problems.

Incidence of urinary tract infection following initiation of intermittent catheterization among patients with recent spinal cord injury in Germany and the Netherlands.

Objective: To assess incidence of urinary tract infection (UTI) among patients with recent spinal cord injury (SCI) who initiated intermittent catheterization (IC).Design: Retrospective chart review.Setting: Two European SCI rehabilitation centers.Participants: Seventy-three consecutive patients with recent SCI who initiated IC.Outcome measures: Incidence of UTI, using six different definitions, each based on microbiology ± symptomatology ± mention of UTI . Rates were expressed in terms of numbers of UTIs per 100 patient-months (PMs). Attention was focused on first-noted UTI during the three-month follow-up, as assessed with each of the six definitions.Results: Fifty-eight percent of patients (n = 33) met ≥1 definitions for UTI during follow-up (rate: 31.5 UTIs per 100 PMs), ranging from 14% (5.3 per 100 PMs; definition requiring bacteriuria, pyuria, and presence of symptoms) to 45% (22.7 per 100 PMs; definition requiring "mention of UTI"). Ten cases were identified using the definition that required bacteriuria, pyuria, and symptoms, whereas definitions that required bacteriuria and either pyuria or symptoms resulted in the identification of 20-25 cases. Median time to UTI ranged from 42 days ("mention of UTI") to 81 days (definition requiring bacteriuria and ≥100 leukocytes/mm3).Conclusion: Depending on definition, 14% to 45% of patients with recent SCI experience UTI within three months of initiating IC. Definitions requiring bacteriuria and either pyuria or symptoms consistently identified about twice as many cases as those that required all three conditions. Standardizing definitions may help improve detection, treatment, and prevention of UTI within this vulnerable population.

Insight into the process of postpartum care utilisation and in-home support among vulnerable women in the Netherlands: an in-depth qualitative exploration.

OBJECTIVE: To gain insight into the process of postpartum care utilisation and in-home support among vulnerable women. DESIGN, METHOD, PARTICIPANTS AND SETTING: A qualitative interview study was conducted among 23 pregnant and postpartum vulnerable women in the Netherlands, following a grounded theory approach. Women were determined as vulnerable by their healthcare providers. Theoretical sampling of participants was applied and was alternated by data analysis to include information-rich cases until saturation was achieved. RESULTS: A conceptual framework of postpartum care utilisation was generated consisting of three phases: pregnancy, early postpartum period and late postpartum period. Within these phases, information provision, parenting self-efficacy and social network were identified as overarching themes. Perceived inadequate information on content of postpartum care posed a major barrier to forming realistic expectations during pregnancy and hindered its utilisation. Low self-efficacy facilitated postpartum care utilisation. All women experienced increased self-efficacy during and after postpartum care. Support from a social network influenced expectations regarding the added value of postpartum care during pregnancy, and lowered actual utilisation during the postpartum period. The costs of postpartum care and the role of the maternity care assistant acted as general barriers or facilitators influencing the three overarching themes and therefore postpartum care utilisation indirectly. CONCLUSIONS: Our findings suggest that postpartum care utilisation among vulnerable women may be improved by considering the particular phase and relevant themes applying to individual women, and adapt care accordingly. We recommend to provide comprehensive, understandable information and to emphasise the gains of postpartum care in improving self-efficacy for vulnerable women. Moreover, involving a woman's social network in postpartum care may add value to this care for this population.

Bed Sensor Technology for Objective Sleep Monitoring Within the Clinical Rehabilitation Setting: Observational Feasibility Study.

BACKGROUND: Since adequate sleep is essential for optimal inpatient rehabilitation, there is an increased interest in sleep assessment. Unobtrusive, contactless, portable bed sensors show great potential for objective sleep analysis. OBJECTIVE: The aim of this study was to investigate the feasibility of a bed sensor for continuous sleep monitoring overnight in a clinical rehabilitation center. METHODS: Patients with incomplete spinal cord injury (iSCI) or stroke were monitored overnight for a 1-week period during their in-hospital rehabilitation using the Emfit QS bed sensor. Feasibility was examined based on missing measurement nights, coverage percentages, and missing periods of heart rate (HR) and respiratory rate (RR). Furthermore, descriptive data of sleep-related parameters (nocturnal HR, RR, movement activity, and bed exits) were reported. RESULTS: In total, 24 participants (12 iSCI, 12 stroke) were measured. Of the 132 nights, 5 (3.8%) missed sensor data due to Wi-Fi (2), slipping away (1), or unknown (2) errors. Coverage percentages of HR and RR were 97% and 93% for iSCI and 99% and 97% for stroke participants. Two-thirds of the missing HR and RR periods had a short duration of ≤120 seconds. Patients with an iSCI had an average nocturnal HR of 72 (SD 13) beats per minute (bpm), RR of 16 (SD 3) cycles per minute (cpm), and movement activity of 239 (SD 116) activity points, and had 86 reported and 84 recorded bed exits. Patients with a stroke had an average nocturnal HR of 61 (SD 8) bpm, RR of 15 (SD 1) cpm, and movement activity of 136 (SD 49) activity points, and 42 reported and 57 recorded bed exits. Patients with an iSCI had significantly higher nocturnal HR (t18=-2.1, P=.04) and movement activity (t18=-1.2, P=.02) compared to stroke patients. Furthermore, there was a difference between self-reported and recorded bed exits per night in 26% and 38% of the nights for iSCI and stroke patients, respectively. CONCLUSIONS: It is feasible to implement the bed sensor for continuous sleep monitoring in the clinical rehabilitation setting. This study provides a good foundation for further bed sensor development addressing sleep types and sleep disorders to optimize care for rehabilitants.

Gait Stability Training in a Virtual Environment Improves Gait and Dynamic Balance Capacity in Incomplete Spinal Cord Injury Patients.

Many patients with incomplete spinal cord injury (iSCI) have impaired gait and balance capacity, which may impact daily functioning. Reduced walking speed and impaired gait stability are considered important underlying factors for reduced daily functioning. With conventional therapy, patients are limited in training gait stability, but this can be trained on a treadmill in a virtual environment, such as with the Gait Real-time Analysis Interactive Lab (GRAIL). Our objective was to evaluate the effect of 6-weeks GRAIL-training on gait and dynamic balance in ambulatory iSCI patients. In addition, the long-term effect was assessed. Fifteen patients with chronic iSCI participated. The GRAIL training consisted of 12 one-hour training sessions during a 6-week period. Patients performed 2 minute walking tests on the GRAIL in a self-paced mode at the 2nd, and 3rd (baseline measurements) and at the 12th training session. Ten patients performed an additional measurement after 6 months. The primary outcome was walking speed. Secondary outcomes were stride length, stride frequency, step width, and balance confidence. In addition, biomechanical gait stability measures based on the position of the center of mass (CoM) or the extrapolated center of mass (XCoM) relative to the center of pressure (CoP) or the base of support (BoS) were derived: dynamic stability margin (DSM), XCoM-CoP distance in anterior-posterior (AP) and medial-lateral (ML) directions, and CoM-CoP inclination angles in AP and ML directions. The effect of GRAIL-training was tested with a one-way repeated measures ANOVA (α = 0.05) and post-hoc paired samples t-tests (α = 0.017). Walking speed was higher after GRAIL training (1.04 m/s) compared to both baseline measurements (0.85 and 0.93 m/s) (p < 0.001). Significant improvements were also found for stride length (p < 0.001) and stability measures in AP direction (XCoM-CoPAP (p < 0.001) and CoM-CoPAP-angle (p < 0.001)). Stride frequency (p = 0.27), step width (p = 0.19), and stability measures DSM (p = 0.06), XCoM-CoPML (p = 0.97), and CoM-CoPML-angle (p = 0.69) did not improve. Balance confidence was increased after GRAIL training (p = 0.001). The effects were remained at 6 months. Increased walking speed, stride length, AP gait stability, and balance confidence suggest that GRAIL-training improves gait and dynamic balance in patients with chronic iSCI. In contrast, stability measures in ML direction did not respond to GRAIL-training.

Targeted social care for highly vulnerable pregnant women: protocol of the Mothers of Rotterdam cohort study.

INTRODUCTION: Social vulnerability is known to be related to ill health. When a pregnant woman is socially vulnerable, the ill health does not only affect herself, but also the health and development of her (unborn) child. To optimise care for highly vulnerable pregnant women, in Rotterdam, a holistic programme was developed in close collaboration between the university hospital, the local government and a non-profit organisation. This programme aims to organise social and medical care from pregnancy until the second birthday of the child, while targeting adult and child issues simultaneously. In 2014, a pilot in the municipality of Rotterdam demonstrated the significance of this holistic approach for highly vulnerable pregnant women. In the 'Mothers of Rotterdam' study, we aim to prospectively evaluate the effectiveness of the holistic approach, referred to as targeted social care. METHODS AND ANALYSIS: The Mothers of Rotterdam study is a pragmatic prospective cohort study planning to include 1200 highly vulnerable pregnant women for the comparison between targeted social care and care as usual. Effectiveness will be compared on the following outcomes: (1) child development (does the child show adaptive development at year 1?) and (2) maternal mental health (is maternal distress reduced at the end of the social care programme?). Propensity scores will be used to correct for baseline differences between both social care programmes. ETHICS AND DISSEMINATION: The prospective cohort study was approved by the Erasmus Medical Centre Ethics Committee (ref. no. MEC-2016-012) and the first results of the study are expected to be available in the second half of 2019 through publication in peer-reviewed international journals. TRIAL REGISTRATION NUMBER: NTR6271; Pre-results.

Response to Comment on "Estimating the reproducibility of psychological science".

Gilbert et al. conclude that evidence from the Open Science Collaboration's Reproducibility Project: Psychology indicates high reproducibility, given the study methodology. Their very optimistic assessment is limited by statistical misconceptions and by causal inferences from selectively interpreted, correlational data. Using the Reproducibility Project: Psychology data, both optimistic and pessimistic conclusions about reproducibility are possible, and neither are yet warranted.

Relationships between coping strategies and lumbar muscle activity in subjects with chronic low back pain.

BACKGROUND: Concerning chronic low back pain (CLBP), different cognitive-behavioral models have hypothesized that coping strategies play a role in the chronification of pain by changes in physical activity. Strategies such as avoidance - or persistent coping may be related to changes in (lumbar) muscle activity. AIM: Investigate the different coping strategies present in CLBP and whether these are differentially related to lumbar muscle activity during walking. METHODS: In a cross sectional study, 63 subjects with CLBP walked on a treadmill at 3.8 km/h. Coping strategies were measured with the Dutch version of the Coping Strategies Questionnaire and three factors were identified with principal component analysis. Surface electromyography data of the erector spinae were obtained and smooth rectified electromyography (SRE) values were averaged per periods of swing and double support. The ratio of SRE values (swing/double support) was used as a measure of relaxation. The relation between SRE values and coping strategies was analyzed with random coefficient analysis. RESULTS: Three coping strategies (i.e. "catastrophizing", "distraction" and "persistence and control") could be discerned. "Catastrophizing" was positively related to (natural logarithm) SRE values (beta=0.06, 95% CI=0.01-0.10; R(2)=7.7%). "Distraction" was negatively associated with SRE ratios (beta=-0.03, 95% CI=-0.05 to -0.01; R(2)=7.5%). No relation was found between "persistence and control" and SRE values or ratios. CONCLUSIONS: In CLBP, a maladaptive coping strategy like "catastrophizing" is related to increased lumbar muscle activity, and an adaptive strategy like "distraction" to increased lumbar muscle relaxation during walking.

Back muscle activation patterns in chronic low back pain during walking: a "guarding" hypothesis.

OBJECTIVES: To investigate whether patients with chronic low back pain (CLBP) show "guarded" movements during walking. It is hypothesized that guarding will be reflected by increased lumbar muscle activity during all periods of stride and secondary, relatively lesser relaxation during periods of swing compared with double support. Furthermore, it is hypothesized that higher levels of perceived fear and disability are related to increased muscle activity and less relative relaxation. MATERIALS AND METHODS: In a cross-sectional study 63 patients with CLBP and 33 healthy controls walked on a treadmill at 3.8 km/h. Surface electromyography (sEMG) data of the erector spinae were obtained and smoothed rectified sEMG (SRE) values were calculated per period of swing and double support. The ratio of SRE values in swing to double support was used as a measure of relative relaxation (SRE ratio). In addition, the relationship between SRE values, the Roland Morris Disability Questionnaire, and the Tampa Scale for Kinesiophobia was analyzed in patients with CLBP. RESULTS: Mean SRE values were significantly higher in patients with CLBP than in controls both during periods of double support and swing. SRE ratios were not significantly different between groups. Results showed no influence of disability or fear of movement on either SRE values or ratios. DISCUSSION: In patients with CLBP, increased lumbar muscle activity during all periods of stride, with comparable alteration between swing and double support, suggests difficulties with total muscle relaxation. On the basis of this evaluation, it is concluded that patients with CLBP show a guarding mechanism during walking. No relationship is found between perceived fear, disability, and muscle activity.

Lumbar and abdominal muscle activity during walking in subjects with chronic low back pain: support of the "guarding" hypothesis?

It has been hypothesized that changes in trunk muscle activity in chronic low back pain (CLBP) reflect an underlying "guarding" mechanism, which will manifest itself as increased superficial abdominal - and lumbar muscle activity. During a functional task like walking, it may be further provoked at higher walking velocities. The purpose of this cross sectional study was to investigate whether subjects with CLBP show increased co-activation of superficial abdominal - and lumbar muscles during walking on a treadmill, when compared to asymptomatic controls. Sixty-three subjects with CLBP and 33 asymptomatic controls walked on a treadmill at different velocities. Surface electromyography data of the erector spinae, rectus abdominis and obliquus abdominis externus muscles were obtained and averaged per stride. Results show that, compared to asymptomatic controls, subjects with CLBP have increased muscle activity of the erector spinae and rectus abdominis, but not of the obliquus abdominis externus. These differences in trunk muscle activity between groups do not increase with higher walking velocities. In conclusion, the observed increased trunk muscle activity in subjects with CLBP during walking supports the guarding hypothesis.

Multidisciplinary rehabilitation treatment of patients with chronic low back pain: a prognostic model for its outcome.

OBJECTIVES: (1) To determine if treatment outcome in chronic low back pain can be predicted by a predefined multivariate prognostic model based on consistent predictors from the literature and (2) to explore the value of potentially prognostic factors further. METHODS: Data were derived from a randomized controlled trial on the effect of a multidisciplinary rehabilitation program for chronic low back pain compared with usual care. The primary outcome measure was the Roland and Morris Disability Questionnaire and secondary outcomes were the Physical and Mental Component Summary Scales, derived from the Short Form Health Survey. Outcomes were expressed as the differences between baseline and follow-up (8 wk and 6 mo) values. A confirmatory and an exploratory model were defined. Baseline predictors included in the confirmatory model were pain intensity, work status, and Multidimensional Pain Inventory subgroup membership. The exploratory model included sick leave, compensation, depression, and fear-avoidance beliefs. Statistical analysis was performed using multiple linear regression analysis. RESULTS: One hundred and sixty-three patients participated in the study. More pain was prognostic for more improvement in the rehabilitation group. No value was found for work status or the Multidimensional Pain Inventory subgroups. For the exploratory model, more depression and fear-avoidance beliefs predicted more improvement after rehabilitation. The explained variance ranged from 18.5% to 43.8% depending on the length of follow-up evaluation, the treatment group, and the outcome variable of interest. DISCUSSION: The results of this study do not support the construction of a clinical prediction model. Future confirmative studies of homogeneous rehabilitation treatments and outcome measures are needed to shed more light on relevant prognostic factors.

A systematic review of sociodemographic, physical, and psychological predictors of multidisciplinary rehabilitation-or, back school treatment outcome in patients with chronic low back pain.

STUDY DESIGN: A systematic review. OBJECTIVE: To determine predictors of outcome of multidisciplinary rehabilitation-or back school treatment for patients with chronic low back pain. SUMMARY OF BACKGROUND DATA: Numerous reviews have been performed to gain insight into which patients benefit from which treatment. However, no review has systematically focused on predictors from multiple domains (i.e., sociodemographic, physical, and psychological), or on treatment outcome measured as activity limitation or participation restriction. METHODS: Studies were found by searching medical and psychological databases, and screening references. Two reviewers independently assessed the methodological quality using standard criteria. Studies were only included if they met a predefined level of internal validity. A qualitative analysis was performed. RESULTS: Heterogeneity among studies in patient characteristics, predictors, treatment, and outcomes limited evidence. All reviewed studies were descriptive or exploratory in nature. Consistent evidence was found for the predictive value of pain intensity (more pain--> worse outcome), several work-related parameters (e.g., high satisfaction--> better outcome), and coping style (less active coping--> better outcome). Other sociodemographic and physical variables consistently lacked predictive value. No consistent evidence was found for other psychological variables. CONCLUSIONS: It is impossible to define a generic set of predictors of outcome of multidisciplinary rehabilitation and back schools for patients with chronic low back pain because the reviewed studies were descriptive or exploratory in nature, and most predictors were only studied once. Nevertheless, for several predictors, consistent evidence was found. Large confirmatory studies are needed to test the value of these predictors.