Francine Dumas

Brain activations during motor imagery of locomotor‐related tasks: A PET study

Positron emission tomography (PET) was used to study the involvement of supraspinal structures in human locomotion. Six right‐handed adults were scanned in four conditions while imagining locomotor‐related tasks in the first person perspective: Standing (S), Initiating gait (IG), Walking (W) and Walking with obstacles (WO). When these conditions were compared to a rest (control) condition to identify the neural structures involved in the imagination of locomotor‐related tasks, the results revealed a common pattern of activations, which included the dorsal premotor cortex and precuneus bilaterally, the left dorsolateral prefrontal cortex, the left inferior parietal lobule, and the right posterior cingulate cortex. Additional areas involving the pre‐supplementary motor area (pre‐SMA), the precentral gyrus, were activated during conditions that required the imagery of locomotor movements. Further subtractions between the different locomotor conditions were then carried out to determine the cerebral regions associated with the simulation of increasingly complex locomotor functions. These analyses revealed increases in rCBF activity in the left cuneus and left caudate when the W condition was compared to the IG condition, suggesting that the basal ganglia plays a role in locomotor movements that are automatic in nature. Finally, subtraction of the W from the WO condition yielded increases in activity in the precuneus bilaterally, the left SMA, the right parietal inferior cortex and the left parahippocampal gyrus. Altogether, the present findings suggest that higher brain centers become progressively engaged when demands of locomotor tasks require increasing cognitive and sensory information processing. Hum. Brain Mapping 19:47–62, 2003.

Mechanisms of disturbed motor control in ankle weakness during gait after stroke

This study investigated the role of paresis, excessive antagonist coactivation, increased muscle-tendon passive stiffness and spasticity in the reduced stance phase plantarflexor moment (Mmax) and swing phase dorsiflexion during gait (DFmax) in subjects with a recent (<6 months post-stroke) hemiparesis (patients). The gait pattern of the paretic and non-paretic sides was evaluated in 30 patients (aged 57.8+/-10.8 years), whereas only one side was evaluated in 15 healthy controls (aged 59.1+/-9.8 years) while walking at natural and very slow speeds. Peak plantarflexor moment (Mmax) and peak medial gastrocnemius (MG) activation during the stance phase, as well as peak dorsiflexion angle (Dfmax) and peak tibialis anterior (TA) activation during the swing phase, were retained for analysis. In addition, a coactivation index and a plantarflexor spasticity index were calculated for both the stance and the swing phase, and plantarflexor passive stiffness was evaluated on an isokinetic dynamometer. The results showed that Mmax on the paretic and non-paretic sides were both reduced compared with control values at natural speed. This reduction was combined to a low MG activation (paresis) on the paretic side. On the non-paretic side, the reduced plantarflexor moment was related to excessive coactivation levels. The swing phase Dfmax tended to be reduced (not significantly) on the paretic side of the patients compared with control values. This reduction was neither associated with excessive antagonist coactivation nor to plantarflexor hyperactive stretch reflexes, but rather to an increased plantarflexor passive stiffness. In some of the patients, however, an increased TA activation that overcame the plantarflexor passive stiffness allowed for normal DFmax values. The functional consequences of the disturbed mechanisms of motor control observed in both the paretic and non-paretic sides are discussed.

Early and Intensive Treadmill Locomotor Training for Young Children with Cerebral Palsy: A Feasibility Study

This feasibility study describes the development and application of a new intensive treadmill locomotor training program for young children with cerebral palsy (CP). The premise is that early, intensive, and task-specific locomotor training initiated even before independent walking is attained will promote improved locomotor skills. Four children, three girls and one boy, with spastic cerebral palsy (age range: 1.7–2.3 years) received a combination of conventional therapy and treadmill training four times per week for four months. To enable treadmill locomotor training, a customized treadmill capable of very low speeds and with several safety features, including a harness that could also be used for weight support, was custom built. Change in locomotor performance was evaluated with three clinical measures: the Gross Motor Function Measure (GMFM), a gait videographic test and the Supported Walker Ambulation Performance Scale (SWAPS). In addition, a full laboratory gait analysis was performed at baseline and at two and four months posttherapy. The results confirm the feasibility of early and intensive treadmill locomotor training in young children with CP even before independent walking is attained. Gait spatiotemporal parameters and the GMFM total score did not reveal changes observed in the video records by trained observers while laboratory gait evaluations were confounded by the poor locomotor capacity, especially at baseline. The GMFM D and E subscore and the SWAPS, were more sensitive to changes in the supported locomotor status and may be more appropriate than the GMFM total score for future studies requiring the matching of children who are nonindependent walkers. The results of this study pave the way for additional work on the SWAPS or for future efficacy trials using treadmills.

The Role of Technology in Task-Oriented Training in Persons with Subacute Stroke: A Randomized Controlled Trial:

This trial compares the effects of task-oriented physical therapy (PT) provided with and without the use of rehabilitation technology on locomotor recovery in 63 persons with subacute stroke. Participants in the experimental (EXP) group used a treadmill, a Kinetron isokinetic exerciser, and a limb-load monitor, whereas those in the control (CTL) group did not while engaging in PT 1 h per day, 5 days per week for 2 months. Locomotor recovery was assessed by clinical (gait speed, Fugl Meyer motor leg and arm subscores, the Balance Scale, the Timed Up and Go, and the Barthel ambulation subscore) and laboratory outcomes (gait kinematics and kinetics) pre- and posttherapy and 3 months later. Within groups, gait speed (P < 0.01) and all secondary measures improved posttherapy (P < 0.01-0.05), and improvements in clinical measures were maintained at follow-up, but there was no difference between groups (P > 0.05). When the groups were pooled, the increase in gait speed was associated (r = 0.52, P = 0.003) with an increase in ankle power generation of the affected leg. The results demonstrate that the efficacy of the task-oriented approach is not dependent on rehabilitation technology.

Anticipatory locomotor control for obstacle avoidance in mid-childhood aged children

The present work explored the anticipatory locomotor adjustments during obstacle avoidance by eight children aged 7--9 years. Analyses involved kinematic, kinetic and muscle mechanical power patterns at each lower limb joint, as well as electromyographic data from five muscles. The children demonstrated adult-like limb displacements and general dynamic strategies for obstacle clearance. However, when normalized to body mass, amplitudes of certain muscle power bursts related to anticipatory locomotor adjustments were decreased from those reported in the literature for adults, and an absence of the usual antagonistic knee extensor power burst at the end of the stance phase was frequently observed. The data suggest that the expression of anticipatory locomotor adjustments is still maturing during mid-childhood.

Impaired viscoelastic behaviour of spastic plantarflexors during passive stretch at different velocities.

OBJECTIVE: The aim of this study was to evaluate the effect of velocity on non-reflexly induced resistive torque (RT) responses of the spastic plantarflexors (PFs) of subjects with spinal cord injuries. DESIGN: Descriptive study, transversal. BACKGROUND: In spastic muscles, non-reflex changes such as increased muscle stiffness, contractures and atrophy have been reported. These changes probably alter muscle tensile properties and viscoelastic behaviour. METHODS: Six subjects with chronic (1-3 yr) spinal cord injuries (SCI) and 12 normal controls (CTLs) participated in this study. Passive ankle dorsiflexions (DFs), ranging from -35 degrees to 5 degrees of DF, were randomly imposed at 5 degrees /s, 10 degrees /s, 20 degrees /s, 40 degrees /s, 60 degrees /s, 120 degrees /s and 180 degrees /s using an isokinetic dynamometer (Kin-Com(TM)). Unwanted muscle activity was detected using surface electrodes on the soleus and tibialis anterior muscles. RESULTS: The results show first that RT rose with increasing velocity; the RT increment reached statistical (analysis of variance (ANOVA); Scheffé post-hoc procedure) significance (P < 0.01) at a lower velocity for the CTLs (40 degrees /s) group than for the SCI group (60 degrees /s). Second, significantly (t-test; P < 0.001) larger net increments of RT (RT at each velocity minus RT at 5 degrees /s) were found for the CTLs at 180 degrees /s than for the SCI group whose RT plateaued at 60 degrees /s. Finally, whereas the RT-velocity relationship was linear (r = 0.94) in the CTLs, that of the SCI group followed a power regression model (r = 0.85). CONCLUSIONS: These results show that the spastic PFs of the subjects with SCIs have an impaired velocity-sensitive behaviour, especially at high velocities of stretch where greater resistance is expected.

Factors related to physical activity in adults with cerebral palsy may differ for walkers and nonwalkers.

Maltais DB, Dumas F, Boucher N, Richards CL: Factors related to physical activity in adults with cerebral palsy may differ for walkers and nonwalkers. Objective:To explore what factors besides walking ability, e.g., additional health problems or complications, general health, and sociodemographic status, may be related to physical activity in adults with cerebral palsy. Design:We administered a questionnaire regarding sociodemographic and health-related factors of potential relevance to physical activity to 66 men (20–41 yrs) and 66 women (18–39 yrs) with various types of cerebral palsy. Data were analyzed using logistic regression. Results:Use of walking as the primary means of self-transport (walking ability) was associated with a higher odds of being physically active (odds ratio = 3.75; P = 0.002). Among those who could walk, being younger and having a positive perception of health were also associated with a higher odds of being active (odds ratios of 2.6 and 3.0, respectively). This was not true among nonwalkers. For individuals who walked, inactivity was associated with an increase in the severity (during the past 3 yrs) of several additional health problems or complications. For the nonwalkers, inactivity was most clearly associated with perceived range-of-motion limitations. Conclusions:Among adults with cerebral palsy, the ability to walk, as expected, is associated with being physically active. The factors additionally related to physical activity differ between walkers and nonwalkers.

The influence of selected personal and environmental factors on leisure activities in adults with cerebral palsy.

Purpose. This study examined the influence of selected personal and environmental factors on leisure participation in adults with cerebral palsy (CP). Methods. A group of 145 adults with CP (18–41 years old, 51% male) responded to questionnaires regarding 1) socio-demographic and health factors, 2) life habits (Life-H: short version 3.1) and 3) the environment (Measure of the Quality of the Environment: version 2.0). A χ2 statistic (p < 0.05) estimated the association between 1) socio-demographic and health factors and the environment and 2) the level of leisure activity participation. Results. Most participants (mean age = 28 years) lived with their parents. Leisure activities were their principal occupation. Mobility and participation were positively associated. The environment (e.g. accompanying services, adapted transport, cultural services and computers) facilitated leisure for those with a high or moderate participation level. Individuals with low participation perceived the environment as having no influence. Conclusions. Adults with CP who are more mobile participate more in leisure activities. A positive perception of the environment (facilitating leisure participation) likely reflects the individuals ability to benefit from the environment, whereas a neutral view of the environment may reflect the fact that other factors, such as mobility limitations, are of greater relevance to leisure participation.

Supported Walker Ambulation Performance Scale (swaps): Development of an Outcome Measure of Locomotor Status in Children with Cerebral Palsy

In a recent study on gait training in young children with disabilities, gait velocity and the Gross Motor Function Measure (GMFM) failed to identify changes in locomotor status that could be discerned by trained observers from video records. This led to the development of a clinical measure that would be sensitive to changes in the period preceding the onset of independent gait. The first part of this paper describes the development of the SWAPS (Supported Walker Ambulation Performance Scale), and the second part presents the results from a preliminary testing of its psychometric properties. Three experts were asked to determine the criteria they would use to determine changes in the walking performance of nine children with spastic cerebral palsy. After examining two series of video records taken at four-month intervals, the SWAPS was proposed. It consists of four dimensions: A) support, B) posture, C) quality of steps, and D) quantity of steps. These four dimensions are weighted so that support is worth 40% and the other three dimensions 20% each of the total score (100%). Each dimension is scored on a four-point Likert scale. The interrater reliability of the SWAPS was studied by having four physiotherapists score video records of the walking performance of the nine children. The intraclass correlation coefficient calculated for the total SWAPS score was 0.95, indicating a high-interrater reproducibility. Construct validity was also studied by correlating the SWAPS scores to the Gross Motor Function Measure (GMFM). A Spearman p of 0.68 computed between the SWAPS and GMFM scores indicates a good relationship between the performance measured by the two scales. There are limitations to the present study: the development of the scale was made a posteriori using data recorded before its development in a small convenience sample, and the same sample of subjects was used for both the development and the testing of the scale. Despite these limitations, the present results are encouraging, and valuable information can be drawn from this preliminary study. Suggestions to improve the scale in future investigations are discussed.

Measuring steady-state oxygen uptake during the 6-min walk test in adults with cerebral palsy: feasibility and construct validity.

This study evaluated the feasibility of measuring steady-state oxygen uptake (V[Combining Dot Above]O2) during the 6-min walk test (6MWT) in adults with cerebral palsy (CP) who walk without support and whether there is construct validity for net 6MWT V[Combining Dot Above]O2 as a measure of their walking ability. Cardiorespiratory variables were assessed at rest and during the 6MWT in 15, independently ambulatory adults, 21–41 years old, with CP. The Gross Motor Function Measure dimensions D and E (GMFM-D and GMFM-E) quantified walking-related skills. Steady-state V[Combining Dot Above]O2 was achieved during the 6MWT. After controlling for body mass and speed, the net 6MWT V[Combining Dot Above]O2 was strongly related to GMFM-D (r=−0.58, &rgr;=0.03) and GMFM-E scores (r=−0.66, &rgr;=0.007). We conclude that for young adults with CP who walk without support, it is feasible to measure steady-state V[Combining Dot Above]O2 during the 6MWT and that the net 6MWT V[Combining Dot Above]O2 has construct validity as a measure of walking ability.