Perceiving limb position in normal and abnormal control: An equilibrium point perspective

Ipsilateral lower limb motor performance and its association with gait after stroke

BACKGROUND AND PURPOSE

Motor deficits of the ipsilateral lower limb could occur after stroke and may be associated with walking performance. This study aimed to determine whether the accuracy and movement path of targeted movement in the ipsilateral lower limb would be impaired in the chronic stage of stroke and whether this impairment would contribution to gait.

METHODS

Twenty adults with chronic stroke and 20 age-matched controls went through Mini Mental Status Examination (MMSE), and a series of sensorimotor tests. The targeted movement tasks were to place the big toe ipsilateral to the lesion at an external visual target (EXT) or a proprioceptive target (PRO, contralateral big toe) with eyes open (EO) or closed (EC) in a seated position. A motion analysis system was used to obtain the data for the calculation of error distance, deviation from a straight path, and peak toe-height during the targeted movement tasks and gait velocity, step length, step width and step length symmetry of the lower limb ipsilateral to the brain lesion during walking.

RESULTS

The stroke group had significantly lower MMSE and poorer visual acuity on the ipsilateral side, but did not differ in age or other sensorimotor functions when compared to the controls. For the targeted movement performance, only the deviation in PRO-EC showed significant between-group differences (p = 0.02). Toe-height in both EXT-EO and in PRO-EO was a significant predictor of step length (R2 = 0.294, p = 0.026) and step length symmetry (R2 = 0.359, p = 0.014), respectively.

DISCUSSION AND CONCLUSIONS

The performance of ipsilateral lower limb targeted movement could be impaired after stroke and was associated with step length and its symmetry. The training of ipsilateral targeted movement with unseen proprioceptive target may be considered in stroke rehabilitation.

A sensorimotor approach to the training of manual actions in children with developmental coordination disorder

Developmental coordination disorder affects a relatively large proportion (5%-6%) of the childhood population. Severity of the disorder varies but there is a great need for therapeutic intervention. We propose a method for the training of manual actions in children with developmental coordination disorder. Our solution is achieved by applying haptic virtual reality technology to attack the difficulties that children with developmental coordination disorder evidence. Our results show that children with developmental coordination disorder are able to learn complex motor skills if proper training methods are employed. These findings conflict with reports of impaired motor learning in developmental coordination disorder because of underactivation of cerebellar and parietal networks.

Children with spastic hemiplegia are equally able as controls in maintaining a precise percentage of maximum force without visually monitoring their performance

In this study the hypothesis was tested that children with spastic hemiplegia rely more on externally guided visual feedback when trying to keep force constant with their affected hand (AH) as compared to their non-affected hand (NAH) and as compared to controls. An isometric force task in which a cursor had to be moved to a visually specified target that disappeared half way the task, was performed by 19 children with cerebral palsy (CP), spastic hemiplegia, aged between 5 and 16 years and an aged matched control group. It was found that the absolute deterioration of performance after withdrawal of target visualization did differ between AH, NAH and controls. The absolute error was smaller and the variability was larger in the hemiplegic hand. However, the normalized force error and co-efficient of variation increased similarly between groups. Furthermore, power spectrum density analysis of the force signal showed that both hands in both groups had a similar loss in the energy in the 2-3 Hz range when target visualization was removed. These results suggest that CP children are equally able to produce stable force without visually monitoring their performance than children without CP, provided they are allowed to operate within their own force range.

A longitudinal study of motor ability and kinaesthetic acuity in young children at risk of developmental coordination disorder

Several studies have linked poor kinaesthetic ability with poor motor coordination in school-aged children. However, few studies have investigated kinaesthesis in younger children. The aim of this study was to determine if preschool aged children who have been identified as at risk of developing developmental coordination disorder (DCD) have poorer kinaesthetic ability than matched controls. Kinaesthetic ability and performance IQ were examined in a group of children aged between 4 and 5 years. Following individual assessment of 291 children, 31 were identified as at risk of DCD at this age. One year later, 30 of these children were retested, and 23 were still found to be at risk. These children were matched on verbal IQ, age and sex with control children and their performance compared on the kinaesthetic acuity test (KAT) [D.J. Livesey and N.A. Parkes, Aust. J. Psychol., 47 (1995) 160] and three subtests of the WPPSI-R performance IQ (D. Wechsler, Manual for the Wechsler preschool and primary scale of intelligence--revised, Psychological Corporation, New York, 1989). Both the KAT and the performance subtest scores were found to be significantly poorer in the children at risk of DCD. Follow-up testing one year later showed that both groups improved their kinaesthetic acuity score although the control children remained significantly better than the children with poor motor coordination.