TY - JOUR
T1 - Grip force control during object manipulation in cerebral stroke
AU - Hermsdörfer, J.
AU - Hagl, E.
AU - Nowak, D. A.
AU - Marquardt, C.
PY - 2003/5/1
Y1 - 2003/5/1
N2 - Objective: To analyze impairments of manipulative grip force control in patients with chronic cerebral stroke and relate deficits to more elementary aspects of force and grip control. Methods: Nineteen chronic stroke patients with fine motor deficits after unilateral cerebral lesions were examined when performing 3 manipulative tasks consisting of stationary holding, transport, and vertical cyclic movements of an instrumented object. Technical sensors measured the grip force used to stabilize the object in the hand and the object accelerations, from which the dynamic loads were calculated. Results: Many patients produced exaggerated grip forces with their affected hand in all types of manipulations. The amount of finger displacement in a grip perturbation task emerged as a highly sensitive measure for predicting the force increases. Measures of grip strength and maximum speed of force changes could not account for the impairments with comparable accuracy. In addition to force economy, the precision of the coupling between grip and load forces was impaired. However, no temporal delays were typically observed between the grip and load force profiles during cyclic movements. Conclusions: Impaired sensibility and sensorimotor processing, evident by delayed reactions in the perturbation task, lead to an excessive increase of the safety margin between the actual grip force and the minimum force necessary to prevent object slipping. In addition to grip force scaling, cortical sensorimotor areas are responsible for smoothly and precisely adjusting grip forces to loads according to predictions about movement-induced loads and sensory experiences. However, the basic feedforward mechanism of grip force control by internal models appears to be preserved, and thus may not be a cortical but rather a subcortical or cerebellar function, as has been suggested previously.
AB - Objective: To analyze impairments of manipulative grip force control in patients with chronic cerebral stroke and relate deficits to more elementary aspects of force and grip control. Methods: Nineteen chronic stroke patients with fine motor deficits after unilateral cerebral lesions were examined when performing 3 manipulative tasks consisting of stationary holding, transport, and vertical cyclic movements of an instrumented object. Technical sensors measured the grip force used to stabilize the object in the hand and the object accelerations, from which the dynamic loads were calculated. Results: Many patients produced exaggerated grip forces with their affected hand in all types of manipulations. The amount of finger displacement in a grip perturbation task emerged as a highly sensitive measure for predicting the force increases. Measures of grip strength and maximum speed of force changes could not account for the impairments with comparable accuracy. In addition to force economy, the precision of the coupling between grip and load forces was impaired. However, no temporal delays were typically observed between the grip and load force profiles during cyclic movements. Conclusions: Impaired sensibility and sensorimotor processing, evident by delayed reactions in the perturbation task, lead to an excessive increase of the safety margin between the actual grip force and the minimum force necessary to prevent object slipping. In addition to grip force scaling, cortical sensorimotor areas are responsible for smoothly and precisely adjusting grip forces to loads according to predictions about movement-induced loads and sensory experiences. However, the basic feedforward mechanism of grip force control by internal models appears to be preserved, and thus may not be a cortical but rather a subcortical or cerebellar function, as has been suggested previously.
KW - Fine motor deficits
KW - Grip force control
KW - Object manipulation
KW - Sensorimotor integration
KW - Stroke
UR - http://www.scopus.com/inward/record.url?scp=0038398959&partnerID=8YFLogxK
U2 - 10.1016/S1388-2457(03)00042-7
DO - 10.1016/S1388-2457(03)00042-7
M3 - Article
C2 - 12738439
AN - SCOPUS:0038398959
SN - 1388-2457
VL - 114
SP - 915
EP - 929
JO - Clinical Neurophysiology
JF - Clinical Neurophysiology
IS - 5
ER -