Hand coordination following capsular stroke

Abstract

Motor outcome following stroke of the internal capsule is variable and its determinants are poorly understood. While many patients fully regain their abilities, recovery of motor functions remains incomplete in others. We analysed functional motor tasks of the upper limb to determine the pattern of focal disability after a small infarct of the internal capsule ('pure motor stroke') in the chronic stage (mean 2.4 years after stroke) with kinematic recordings of a reaching-to-grasp movement, with a quantitative analysis of the precision grip, and with clinical rating scales. The location of the lesions within the posterior limb of the internal capsule (PLIC) in 18 patients was determined from neuroimages obtained in the acute stage (5-20 days after the insult). Involvement of the PLIC was assessed at the level of the basal ganglia, approximately 8 mm above the anterior commissure-posterior commissure level. The distance between the posterior edge of the internal capsule and the centre of gravity of the lesion was determined. Chronic disabilities affected dextrous movements, while paresis was mild and sensitivity for light touch or passive finger flexion was almost normal. For both the reaching-to-grasp movement and the precision grip paradigm, the slowness of movement or force development was confined to the phases when grip formation and stabilization occur, while the onset of hand transport and of the vertical lifting force were not delayed. Grip forces were increased. We observed a close correlation between posterior location within the PLIC and the altered measures of timing and precision grip force. The more posterior the acute lesion was located within the PLIC, the more pronounced were the chronic motor deficits, as seen both in the quantitative measures and in the rating scales. The present study demonstrates for the first time that the amount and quality of chronic motor deficits of dextrous movements are related to a simple measure drawn from routine neuroimaging in the acute stage in patients with capsular stroke. The poor motor outcome in lesions involving the most posterior parts of the PLIC could be due to the condensed organization of corticofugal projections and the density of pyramidal fibres from the primary motor cortex in this subsector. Even small infarcts of this strategic area can disrupt many of the projections from the motor cortices and could thereby limit recovery strategies between homolateral motor representations.

Compensatory role of the cortico-rubro-spinal tract in motor recovery after stroke

“…Due to the topographic organization of corticospinal tracts, 36 stroke patients with lesions in the posterior limb of the internal capsule are more severely impaired with respect to the function of their upper extremities the more posterior the lesion is localized. 37 Our data support this finding and demonstrate that also lesions not restricted to the internal capsule or the primary motor cortex appear to alter those fibers originating in M1 more thoroughly than fibers originating from PMd and SMA in patients who were severely affected in the acute phase after stroke (figure e-1). Furthermore, we found a more pronounced decrease of FA values in the PT than in aMF, indicating that the PT might be more prone to degenerative processes than aMF after ischemic lesions.…”

Corticospinal Dysgenesis and Upper-Limb Deficits in Congenital Hemiplegia: A Diffusion Tensor Imaging Study

“…In monkeys, after an early corticospinal tract lesion, whereas the power grip is preserved, the precision grip between the thumb and index finger remains permanently impaired. 1,2 Along the same lines, in humans, a correlation has been found between corticospinal tract degeneration and the severity of motor deficits in both adult stroke [3][4][5] and congenital hemiplegia (CH). 6,7 In most studies, corticospinal tract degeneration has classically been quantified by measuring the cross-sectional area of the cerebral peduncles in the mesencephalon on T1-weighted MRI.…”

Effects of Motor Training on the Recovery of Manual Dexterity After Primary Motor Cortex Lesion in Macaque Monkeys

“…Although motor recovery has also been investigated in human patients Schieber 2003, 2004;Wade et al 1983;Wenzelburger et al 2005), experimental animal studies are important to understand the recovery process after induction of irreversible lesions in specific brain regions. Among brain functions, the recovery of dexterous hand function, a characteristic of some primate species such as humans, apes, and Old World monkeys (Courtine et al 2007;Lemon and Griffiths 2005), has been investigated in detail because it is important for human quality of life, as in the making and using of tools.…”