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Impaired grip-lift synergy in children with unilateral brain lesions
H Forssberg1, A C Eliasson, C Redon-Zouitenn
1Department of Woman and Child Health, Karolinska Institute, Stockholm, Sweden. hansf@child.ks.se
Insights
Children with unilateral brain lesions often show abnormal grip-lift synergy, impacting their manual dexterity. This study links impaired force coordination patterns to lesion location and size in spastic hemiplegia.
Area of Science:
- Neuroscience
- Pediatrics
- Motor Control
Background:
- Children with spastic hemiplegia exhibit reduced dexterity in their affected limb.
- Understanding the neural basis of motor control deficits is crucial for effective intervention.
Purpose of the Study:
- To investigate the relationship between the force co-ordination pattern during precision grip and manual dexterity in children with unilateral brain lesions.
- To explore the correlation between this force co-ordination pattern and the location/size of brain lesions.
Main Methods:
- Assessed force co-ordination during precision grip using a specialized object to monitor fingertip forces.
- Evaluated hand function through neurological examination, functional hand-grips, and dexterity tests.
- Identified brain lesions using ultrasound and MRI scans.
Main Results:
- Most children with unilateral brain lesions displayed immature or pathological force co-ordination patterns, deviating from the typical grip-lift synergy.
- A significant correlation was found between the developmental level of grip-lift synergy and impaired manual dexterity.
- Grip-lift synergy correlated with lesion extent in the contralateral cortex, white matter, and basal ganglia, but not isolated cortical lesions.
Conclusions:
- Proper development of the force co-ordination pattern (grip-lift synergy) is essential for skilled hand function in children.
- Neural control of precision grip involves parallel and distributed systems, with basal ganglia playing a key role in circuit formation.
- Compensation for perinatal lesions in motor areas is possible, but extensive lesions limit this capacity.
Abstract:
Children with spastic hemiplegia have impaired dexterity in the affected extremity. The purpose of the present study was to investigate whether the force co-ordination pattern during precision grip in 13 children between 4 and 10 years of age with predominant unilateral brain lesions is related to manual dexterity and to the location and size of the brain lesion. The force co-ordination pattern was investigated by means of a specially designed object that monitored the isometric fingertip forces applied to the contact surfaces during precision grip. Hand function was measured by means of neurological examination, functional hand-grips and dexterity. Brain lesions were identified by series of ultrasound and MRI scans. Normally, the fingertip forces are applied to the object in the initial phase of the lift in an invariant force co-ordination pattern (i.e. grip-lift synergy), in which the grip and load forces are initiated simultaneously and increase in parallel with unimodal force rate trajectories. A majority of children with unilateral brain lesions had not developed the force co-ordination pattern typical for their age, but produced an immature or a pathological pattern. The developmental level of the grip-lift synergy was determined and quantified according to criteria derived from earlier studies on normally developed children. There was a clear relationship between the developmental level of the grip-lift synergy and impaired dexterity, indicating that proper development of the force co-ordination pattern is important for skilled hand function. The grip-lift synergy correlated with the total extent of lesions in the contralateral cortex and white matter and with lesions in the thalamus/basal ganglia, while no correlation was found for isolated cortical lesions. The results suggest that the neural circuits involved in the control of the precision grip are organized in a parallel and distributed system in the hemispheres, and that the basal ganglia are important during the formation of these circuits. Perinatal lesions in specific cortical motor areas may be compensated for by circuits elsewhere in the grip-lift motor system, while large lesions exclude this possibility.