Kim Jones

Motor imagery ability in patients with traumatic brain injury.

OBJECTIVE To assess motor imagery (MI) ability in patients with moderate to severe traumatic brain injury (TBI). DESIGN Prospective, cohort study. SETTING University hospital rehabilitation unit. PARTICIPANTS Patients with traumatic brain injury (mean coma duration, 18d) undergoing rehabilitation (n=20) and healthy controls (n=17) matched for age and education level. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES The vividness of MI was assessed using a revised version of the Movement Imagery Questionnaire-Revised second version (MIQ-RS); the temporal features were assessed using the time-dependent motor imagery (TDMI) screening test, the temporal congruence test, and a walking trajectory imagery test; and the accuracy of MI was assessed using a mental rotation test. RESULTS The MIQ-RS revealed a decrease of MI vividness in the TBI group. An increasing number of stepping movements was observed with increasing time periods in both groups during the TDMI screening test. The TBI group performed a significantly smaller number of imagery movements in the same movement time. The temporal congruence test revealed a significant correlation between imagery and actual stepping time in both groups. The walking trajectory test revealed an increase of the imagery and actual walking time with increasing path length in both groups, but the ratio of imaginary walking over actual walking time was significantly greater than 1 in the TBI group. Results of the hand mental rotation test indicated significant effects of rotation angles on imagery movement times in both groups, but rotation time was significantly slower in the TBI group. CONCLUSIONS Our patients with TBI demonstrated a relatively preserved MI ability indicating that MI could be used to aid rehabilitation and subsequent functional recovery.

The Effect of Simulating Weight Gain on the Energy Cost of Walking in Unimpaired Children and Children With Cerebral Palsy

OBJECTIVE To examine the effect of simulating weight gain on the energy cost of walking in children with cerebral palsy (CP) compared with unimpaired children. DESIGN Repeated measures, matched subjects, controlled. SETTING University hospital clinical gait and movement analysis laboratory. PARTICIPANTS Children (n=42) with CP and unimpaired children (n=42). INTERVENTIONS Addition of 10% of body mass in weight belt. MAIN OUTCOME MEASURES Energy cost of walking parameters consisting of walking speed, Physiological Cost Index, Total Heart Beat Index, oxygen uptake (VO2), gross oxygen cost, nondimensional net oxygen cost, and net oxygen cost with speed normalized to height were measured by using a breath-by-breath gas analysis system (K4b2) and a light beam timing gate system arranged around a figure 8 track. Two walking trials were performed in random order, with and the other without wearing a weighted belt. RESULTS Children with CP and their unimpaired counterparts responded in fundamentally different ways to weight gain. The unimpaired population maintained speed and VO2 but the children with CP trended toward a drop in their speed and an increase in their VO2. The oxygen consumption of children with CP showed a greater dependence on mass than the unimpaired group (P=.043). CONCLUSIONS An increase of a relatively small percentage in body mass began to significantly impact the energy cost of walking in children with CP. This result highlights the need for weight control to sustain the level of functional walking in these children.

Energy cost of walking: Solving the paradox of steady state in the presence of variable walking speed

Measurement of the energy cost of walking in children with cerebral palsy is used for baseline and outcome assessment. However, such testing relies on the establishment of steady state that is deemed present when oxygen consumption is stable. This is often assumed when walking speed is constant but in practice, speed can and does vary naturally. Whilst constant speed is achievable on a treadmill, this is often impractical clinically, thus rendering an energy cost test to an element of subjectivity. This paper attempts to address this issue by presenting a new method for calculating energy cost of walking that automatically applies a mathematically defined threshold for steady state within a (non-treadmill) walking trial and then strips out all of the non-steady state events within that trial. The method is compared with a generic approach that does not remove non-steady state data but rather uses an average value over a complete walking trial as is often used in the clinical environment. Both methods were applied to the calculation of several energy cost of walking parameters of self-selected walking speed in a cohort of unimpaired subjects and children with cerebral palsy. The results revealed that both methods were strongly correlated for each parameter but showed systematic significant differences. It is suggested that these differences are introduced by the rejection of non-steady state data that would otherwise have incorrectly been incorporated into the calculation of the energy cost of walking indices during self-selected walking with its inherent speed variation.

The clinical relevance of selecting resting data at different points in an energy cost of walking test in cerebral palsy

Aim  Energy cost of walking (ECOW) is defined as ‘walking oxygen consumption minus resting oxygen consumption divided by speed’, where ‘resting’ data can be obtained either at the start or cessation of a test. This study aimed to ascertain when resting data should be taken during an ECOW test in children with cerebral palsy (CP).