Visual guidance of interceptive actions in children with spastic unilateral cerebral palsy is influenced by the side of the lesion

Differences in somatosensory processing due to dominant hemispheric motor impairment in cerebral palsy

Background

Although cerebral palsy (CP) is usually defined as a group of permanent motor disorders due to non-progressive disturbances in the developing fetal or infant brain, recent research has shown that CP individuals are also characterized by altered somatosensory perception, increased pain and abnormal activation of cortical somatosensory areas. The present study was aimed to examine hemispheric differences on somatosensory brain processing in individuals with bilateral CP and lateralized motor impairments compared with healthy controls. Nine CP individuals with left-dominant motor impairments (LMI) (age range 5–28 yrs), nine CP individuals with right-dominant motor impairments (RMI) (age range 7–29 yrs), and 12 healthy controls (age range 5–30 yrs) participated in the study. Proprioception, touch and pain thresholds, as well as somatosensory evoked potentials (SEP) elicited by tactile stimulation of right and left lips and thumbs were compared.

Results

Pain sensitivity was higher, and lip stimulation elicited greater beta power and more symmetrical SEP amplitudes in individuals with CP than in healthy controls. In addition, although there was no significant differences between individuals with RMI and LMI on pain or touch sensitivity, lip and thumb stimulation elicited smaller beta power and more symmetrical SEP amplitudes in individuals with LMI than with RMI.

Conclusions

Our data revealed that brain processing of somatosensory stimulation was abnormal in CP individuals. Moreover, this processing was different depending if they presented right- or left-dominant motor impairments, suggesting that different mechanisms of sensorimotor reorganization should be involved in CP depending on dominant side of motor impairment.

Upper limb activity in children with unilateral spastic cerebral palsy: the role of vision in movement strategies

This article reviews the capacity of children with unilateral spastic cerebral palsy (USCP) to (re)organize the available degrees of freedom and to use visual information in interceptive actions during motion with either the impaired or the less-impaired hand. Atypical reaching movements, such as increased trunk movement or slower wrist velocity, are considered adaptive coordination patterns that are the result of a change in the constraints. It is argued that manipulation of the task context facilitates children with USCP to enhance performance. For example, when reducing the time available to intercept a ball, the children are found to exceed their usual maximum walking speed and to increase range of motion of the elbow. In addition, the children appear to rely on a visual information strategy similar to typically developing children ('bearing angle'), although more variability is observed when using the impaired arm. The implications for interventions are, it should be recognized, that these children adapt to the impairment by reorganizing the movement system and that this process can be influenced by changing the task context. Attention should be paid to the importance of using correct visual cues for initiation and guidance of interceptive actions, which may be provoked by using external visual triggers.

Gaze behaviour during interception in children with spastic unilateral cerebral palsy

Anticipatory gaze behaviour during interceptive movements was investigated in children with Spastic Unilateral Cerebral Palsy (SUCP), and related to the side of the intracerebral lesion. Five children with lesions of the right hemisphere (RHL) and five children with lesions of the left hemisphere (LHL) had to walk towards and intercept a ball that moved perpendicular to the walking path. Interception accuracy and gaze patterns were measured in a no-occlusion and occlusion condition, in which the ball was occluded from view for half of its trajectory. There was a clear support for a relationship between gaze behaviour and success in interception performance, with some evidence for the presence of anticipatory gaze behaviour. There were also differences in gaze behaviour between children with RHL and children with LHL that might be related to planning, but these did not affect interception accuracy. It is concluded that gaze behaviour during interceptive movements is anticipatory, and at least partly dependent on the lesional side.