Deficits in grasp versus reach during acute hemiparesis (original) (raw)
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Relationships between sensorimotor impairments and reaching deficits in acute hemiparesis
Neurorehabilitation and neural repair, 2006
To determine the relationships between sensorimotor impairments and upper extremity reaching performance during the acute phase of stroke and to determine which, if any, measures of sensorimotor impairment can predict variance in reaching performance during this phase. Sensorimotor impairments of upper extremity (UE) strength, active range of motion, isolated movement control, light touch sensation, joint position sense, spasticity, and shoulder pain were evaluated in a group of 46 individuals with acute hemiparesis (mean time since insult = 9.2 days). Subjects performed a reaching task to a target placed on their affected side. Three-dimensional kinematic analyses were used to assess reaching speed, accuracy, and efficiency. Forward stepwise multiple linear regression analyses were used to determine which impairment was the best predictor of variance in reaching performance. Measures of UE strength predicted the largest proportion of variance in the speed, accuracy, and efficiency ...
Experimental Brain Research, 2006
Upper extremity (UE) hemiparesis results in decreased movement speed and impaired coordination leading to functional limitations and disability. The effects of UE hemiparesis on bilateral functional reaching have not been studied even though most activities of daily living are bilateral tasks. We examined the characteristics of bilateral simultaneous (SIM-B) and bilateral sequential paretic-lead (SEQ-P) and nonparetic-lead (SEQ-NP) functional reaching tasks at preferred and fast speeds. Sixteen patients with chronic hemiparesis completed three bilateral reaching tasks as fast as possible. A subset of eight participants attempted to complete the tasks at both preferred and fastest possible speeds. Paretic (P) and nonparetic (NP) arms were not different from each other in movement time (MT) or peak velocity in the SIM-B condition. MT and peak velocity differed between the two arms during both SEQ tasks. P MT was shorter and NP MT longer in the SIM-B task compared to SEQ-P and SEQ-NP. The P arm MT was the shortest when moving with the NP arm in a simultaneous task compared to both P and NP lead sequential movements. Despite hemiparesis, the two arms demonstrate a temporal coupling when moving simultaneously. When attempting to move at fastest speed, P arm MT time is better when reaching before or with the NP arm than when reaching after the NP arm showing coupling to the NP limb and increased speed of movement. These coupling effects support the rationale for bilateral arm training for individuals with UE hemiparesis.
Target-dependent differences between free and constrained arm movements in chronic hemiparesis
Experimental Brain Research, 2004
This study compares the kinematic and kinetic characteristics of constrained and free upper limb movements in eight subjects with chronic hemiparesis. Movements of the dominant and nondominant limbs were also examined in five control subjects. Rapid movements were performed in the horizontal plane from a central starting point to five targets located to require various combinations of flexion/extension rotations at the elbow and shoulder. Support of the upper limb against gravity loading was provided either by a low-friction air-bearing apparatus (constrained condition) or by voluntary generation of abduction and external rotation torques at the shoulder (free condition). Data analysis focused on the peak joint torques generated during the acceleratory phase of movement, and on the net change in joint angles at the elbow and shoulder. We found that movement parameters were broadly invariant with support condition for either limb of control subjects, as well as for the nonparetic limb of hemiparetic subjects. In contrast, support condition had a target-dependent effect on movements of the paretic limb. Relative to the constrained condition, peak torques for free arm movements were significantly reduced for distal targets requiring elbow extension and/or shoulder flexion torques. However, peak elbow flexion and shoulder extension joint torques for proximal targets were relatively unaffected by support condition. Of perhaps more functional importance, free movements were characterized by a target-dependent restriction in the hand's work area that reflected a reduced range of active elbow extension, relative to constrained movements. The targetdependent effects of support condition on movements of the paretic limb are consistent with the existence of abnormal constraints on muscle activation patterns in subjects with chronic hemiparesis, namely an abnormal linkage between activation of the elbow flexors and shoulder extensors, abductors, and external rotators.
Compensation for distal impairments of grasping in adults with hemiparesis
Experimental Brain Research, 2004
Previous studies have shown that patients with arm and hand paresis following stroke recruit an additional degree of freedom (the trunk) to transport the hand during reaching and use alternative strategies for grasping. The few studies of grasping parameters of the impaired hand have been case studies mainly focusing on describing grasping in the presence of particular impairments such as hemi-neglect or optic ataxia and have not focussed on the role of the trunk in prehension. We hypothesized that the trunk movement not only ensures the transport of the hand to the object, but it also assists in orienting the hand for grasping when distal deficits are present. Nineteen patients with chronic hemiparesis and seven healthy subjects participated in the study. Patients had sustained a stroke of non-traumatic origin 6-82 months previously (31 ±22 months) and had mild or moderate to severe arm paresis. Using a whole hand grasp, subjects reached and grasped a cylinder (35 mm) that was placed sagittally (T1) or at a 45°angle to the sagittal midline in the ipsilateral workspace (T2), both at about 90% arm's length (10 trials per target). Eight infrared emitting diodes were placed on bony landmarks of the hand, arm and trunk and kinematic data were recorded by an optical motion analysis system (Optotrak) for 2-5 s at 120 Hz. Hand position and orientation were recorded by a Fastrack Polhemus system.
Motor Planning in Chronic Upper-Limb Hemiparesis: Evidence from Movement-Related Potentials
PloS one, 2012
Background: Chronic hemiplegia is a common long-term consequence of stroke, and subsequent motor recovery is often incomplete. Neurophysiological studies have focused on motor execution deficits in relatively high functioning patients. Much less is known about the influence exerted by processes related to motor preparation, particularly in patients with poor motor recovery.
Use of the trunk for reaching targets placed within and beyond the reach in adult hemiparesis
Experimental Brain Research, 2002
Multijoint movements such as reaching are impaired after brain lesions involving sensorimotor areas and pathways. However, the mechanisms by which such lesions affect motor control are not fully understood. Direct effects of the lesion may be partly compensated by both the system's redundancy and its plasticity. Indeed stroke patients with limited arm movement can reach objects placed within the reach of the arm by using a compensatory strategy involving trunk recruitment. A similar strategy is observed in healthy individuals reaching for objects placed beyond the reach of the arm. Determining the control mechanism(s) governing this compensatory strategy in stroke patients was the goal of this study. Kinematics of reaching movements in hemiparetic and healthy participants to targets placed within and beyond the length of the arm were analysed. Targets were placed sagittally in front of the midline of the body. Two targets (targets 1 and 2) were within reaching distance defined as the length of the stretched arm from axilla to wrist crease. Two others were beyond arm's reach so that one required a forward trunk inclination (target 3) and the other required body raising to a semi-standing position (target 4). Healthy participants used minimal trunk displacement for reaches to targets 1 and 2. For reaches to targets 3 and 4, trunk displacement increased with target distance. Whenever the trunk was involved, there was a stereotyped sequential recruitment of the arm and trunk in that the trunk began moving simultaneously with or before the hand and stopped moving after the end of hand movement. This suggested that the control system predicts that the trunk movement will be needed to extend the reach and includes the trunk, in an anticipatory way, into the reach. In contrast, most hemiparetic participants recruited their trunk for reaches to all four targets, even those placed close to the body. Similar to healthy individuals, the sequence of hand and trunk recruitment was stereotyped, suggesting that temporal planning aspects of the motor program underlying movement coordination were relatively unaffected. In contrast to healthy participants, the contribution of the trunk movement to the endpoint displacement was substantially higher in the hemiparetic group and occurred earlier in the reach. It is suggested that the target distance at which the trunk is integrated into the movement to extend the reach of the arm is attained around the limit of arm extension and that this limit is reduced in hemiparetic individuals.
The coordination of reaching and grasping in spastic hemiparesis
Human Movement Science, 2000
The kinematics and intrinsic dynamics of reaching and grasping movements in six subjects with spastic hemiparesis were studied. Movements were performed with both hands together as well as with each hand in isolation, and two target widths were used. As expected, large manual asymmetries existed in unimanual task performance. These asymmetries were more pronounced for grasping than for reaching, which was a consequence of the fact that in grasping the impaired hand stayed longer at zero velocity before lifting the object. This implies diculties coordinating the more distal movement component (hand and ®ngers). In addition, the impaired hand attained the movement goal with a (1) decreased angular range of motion of the joints and (2) an increased trunk involvement. With respect to the intrinsic dynamics, intra-and inter-limb coupling was studied by evaluating cross-correlations of position±time functions joint pairs. In eector space the displacement of the wrist and ipsilateral shoulder were correlated, and in joint-angle space the elbow extension±shoulder¯exion angle pair and the elbow extension±shoulder elevation angle pair were analysed. It was found that despite tight couplings between the dierent pairs, the couping strengths for the impaired limb were consistently lower. This was caused by fragmentation of the movement, mainly due to a large shoulder involvement at the start of the movement concurrent with little or no elbow extension. It is concluded that fragmentation of the movement, operationalised by the (B. Steenbergen). 0167-9457/00/$ -see front matter Ó 2000 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 -9 4 5 7 ( 0 0 ) 0 0 0 0 6 -3 value of the cross-correlation between joint pairs is an essential variable by which the level of recovery of function can be captured. It was further shown that the unimpaired hand mimicked' the impaired hand on a number of movement characteristics under bimanual responding. The impaired hand did not change its style of movement organisation among uni-and bimanual movement responding. It is argued that the apparent stability of the impaired hand can only be sustained at the cost of a decreased¯exibility. Finally, inter-limb coupling, assessed by means of cross-correlations of the tangential velocity pro®les of both hands, was shown to be high during the course of movement. Ó