Deficits in grasp versus reach during acute hemiparesis

Abstract

We studied how acute hemiparesis affects the ability to perform purposeful movements of proximal versus distal upper extremity segments. Given the gradient of corticospinal input to the spinal motoneuron pools, we postulated that movement performance requiring distal segment control (grasping) should be more impaired than movement performance requiring proximal segment control (reaching) in people with hemiparesis. We tested subjects with acute hemiparesis and control subjects performing reach and reach-to-grasp movements. Three characteristics of movement performance were quantified for each movement: speed, accuracy, and efficiency. For the reach, we calculated peak wrist velocity, endpoint error, and reach path ratio. For the grasp, we calculated peak aperture rate, aperture at touch, and aperture path ratio. To evaluate the relative deficits in reaching versus grasping, performance measures were converted to z-scores using control group means and standard deviations. For both the movements, movement times were longer and performance was more variable in the hemiparetic group compared to the control group. Hemiparetic z-scores indicated that relative deficits in movement speed were small in the two movements, with deficits in grasp being slightly greater than deficits in reach. Relative deficits in accuracy showed a trend for being larger in the reach compared to the grasp, but this difference did not reach statistical significance. In contrast, relative deficits in efficiency were larger in the grasp compared to the reach, with reaching efficiency near the range of normal performance. When considering data across all three movement characteristics, the ability to perform a purposeful movement with the distal segments was not clearly more disrupted than the ability to perform a purposeful movement with the proximal segments in people with acute hemiparesis.

Quantitative assessment based on kinematic measures of functional impairments during upper extremity movements: A review

“…However, one study has shown that this metric couldn't be robust against noise or other factors, proposing an analysis of the movement smoothness based on the Fourier Transform (Balasubramanian et al, 2012a). The accuracy during a movement has been analyzed along the trajectory of the hand (Colombo et al, 2008;Zoilo et al, 2011) or around the target in reaching and grasping movements (Lang et al, 2005). The classification of the metrics into different groups related with quality or movement characteristics (Figs.…”

“…Lang defined an efficient movement as the movement that moves directly to the target without extraneous or abnormal trajectories (Lang etal.,2005). This metric has been frequently used in literature during reaching movements (Cacho et al, 2011;Jaspers et al, 2011;Kamper et al, 2002;Lang et al, 2005;Merlo et al, 2013;Van der Heide et al, 2005;Wagner et al, 2008). The reaching movement in healthy people is a highly stereotypic and coordinated movement consisting of a well-executing arm trajectory (Rand et al, 2000).…”

“…The reaching movement in healthy people is a highly stereotypic and coordinated movement consisting of a well-executing arm trajectory (Rand et al, 2000). The theoretical movement trajectory was considered the straight line between the starting point and the target location (Butler et al, 2010;Cacho et al, 2011;Culmer et al, 2009;Jaspers et al, 2011;Kamper et al, 2002;Lang et al, 2005Lang et al, , 2006Merlo et al, 2013;Van der Heide et al, 2005). So a metric result closed to 1 is representative of a healthy pattern (Colombo et al, 2008).…”

“…2a) as the end-point error around the target placement. This metric was computed as the maximum distance from the index finger to the target location at the end of the movement (Lang et al, 2005). Target error was analyzed mostly in point to point or reach and grasp movements.…”

“…Target error was analyzed mostly in point to point or reach and grasp movements. This metric was called end-point error (Lang et al, 2005) in literature.…”