Impaired Grip Force Modulation in the Ipsilesional Hand after Unilateral Middle Cerebral Artery Stroke

Abstract

Understanding grasping control after stroke is important for relearning motor skills. The authors examined 10 individuals (5 males; 5 females; ages 32-86) with chronic unilateral middle cerebral artery (MCA) stroke (4 right lesions; 6 left lesions) when lifting a novel test object using skilled precision grip with their ipsilesional ("unaffected") hand compared to healthy controls (n = 14; 6 males; 8 females; ages 19-86). All subjects possessed normal range of motion, cutaneous sensation, and proprioception in the hand tested and had no apraxia or cognitive deficits. Subjects lifted the object 10 times at each object weight (260 g, 500 g, 780 g) using a moderately paced self-selected lifting speed. The normal horizontal ("grip") force and vertical tangential ("lift") force were separately measured at the thumb and index finger. Regardless of the object weight or stroke location, the stroke group generated greater grip forces at liftoff of the object (> or =39%; P < or = 0.05) and across the dynamic (P < or = 0.05) and static portions (P < or = 0.05) of the lifts compared to the healthy group. Peak lift forces were equivalent between groups, suggesting accurate load force information processing occurred. These results warrant further investigation of altered sensorimotor processing or compensatory biomechanical strategies that may lead to inaccurate grip force execution after strokes.

Force control of quadriceps muscle is bilaterally impaired in subacute stroke

“…Impaired isometric strength and force control in the lessaffected knee extensors are consistent with previously reported bilateral changes after stroke (31,34,36,43,47,58,66). Several factors may contribute to impaired motor function of the less-affected limbs, including hemispheric lateralization for the executed tasks and hemispheric asymmetry (36) or evolving maladaptive changes in the intact hemisphere (38).…”

Deficits of reach-to-grasp coordination following stroke: Comparison of instructed and natural movements

“…Patients with a unilateral left hemisphere stroke (LHS) and elderly controls used their non-dominant, left (ipsilesional) hand to grasp and move an object once in context L, which represents a typical laboratory task, and once in context E, which was modeled after many activities of everyday life. The current data confirm that kinematics and dynamics of reach-to-grasp movements strongly differ between contexts (Bock and Baak, 2013;Bock and Steinberg, 2012;Bock and Züll, 2013), that ipsilesional movements of non-apraxic patients with LHS are impaired (Quaney et al, 2005;Sunderland et al, 1999;Winstein and Pohl, 1995;Goodale, 1988), and that the deficient coordination between the transport and the grasp component is an essential aspect of this impairment (Lang et al, 2005;Nowak et al, 2007aNowak et al, , 2007b.…”

Ipsilateral motor dysfunction from unilateral stroke: implications for the functional neuroanatomy of hemiparesis

“…Functional imaging studies show that complex motor tasks requiring motor planning, integration of sensorimotor information and attention to sequencing are associated with bi-hemispheral activity 27 – 30. In general, more complex unilateral motor tasks such as the 9HPT induce greater bilateral task related activity than do simple tasks31 – 33 and, indeed, with the exception of an older study by Colebatch and Gandevia which identified a reduction in strength in the ipsilateral hand in 14 subacute-to-chronic stroke patients,4 most other behavioural studies have identified post-stroke ipsilateral deficits in complex functions—target directed movements of the hand and foot,5 abnormal anticipated grip forces when lifting novel test objects,34 step tracking deficits in the wrist8 and slowing on the 9HPT7 and grooved pegboard test 35. Among the studies that measured ipsilateral hand function over time, Jones et al , who assessed eight patients with unilateral stroke at six time points starting from day 11 and ending at 12 months post stroke,11 found persistently impaired reaction time, impairment of steadiness and tracking on visuomotor tasks in the ipsilateral hand but no ipsilateral weakness.…”