Cortical disconnection of the ipsilesional primary motor cortex is associated with gait speed and upper extremity motor impairment in chronic left hemispheric stroke

Abstract

Advances in neuroimaging have enabled the mapping of white matter connections across the entire brain, allowing for a more thorough examination of the extent of white matter disconnection after stroke. To assess how cortical disconnection contributes to motor impairments, we examined the relationship between structural brain connectivity and upper and lower extremity motor function in individuals with chronic stroke. Forty-three participants [mean age: 59.7 (611.2) years; time poststroke: 64.4 (658.8) months] underwent clinical motor assessments and MRI scanning. Nonparametric correlation analyses were performed to examine the relationship between structural connectivity amid a subsection of the motor network and upper/lower extremity motor function. Standard multiple linear regression analyses were performed to examine the relationship between cortical necrosis and disconnection of three main cortical areas of motor control [primary motor cortex (M1), premotor cortex (PMC), and supplementary motor area (SMA)] and motor function. Anatomical connectivity between ipsilesional M1/SMA and the (1) cerebral peduncle, (2) thalamus, and (3) red nucleus were significantly correlated with upper and lower extremity motor performance (P 0.003). M1-M1 interhemispheric connectivity was also significantly correlated with gross manual dexterity of the affected upper extremity (P 5 0.001). Regression models with M1 lesion load and M1 disconnection (adjusted for time poststroke) explained a significant amount of variance in upper extremity motor performance (R 2 5 0.36-0.46) and gait speed (R 2 5 0.46), with M1 disconnection an independent predictor of motor performance. Cortical disconnection, especially of ipsilesional M1, could significantly contribute to variability seen in locomotor and upper extremity motor function and recovery in chronic stroke. Hum Brain Mapp 39:120-132, 2018.V C 2017 Wiley Periodicals, Inc.

Brain networks and their relevance for stroke rehabilitation

“…Greater damage to the CST is robustly associated with more severe motor impairment in acute and chronic phases as well as with less improvement, as shown in multiple convergent studies (Stinear et al, 2007, Kim et al, 2015, Schulz et al, 2015b, Ramsey et al, 2017, Peters et al,2018. More recent studies have additionally demonstrated that severe damage to the CST seems to be a main factor leading to a particularly poor pattern of motor improvement with severe chronic impairment (Byblow et al, 2015, Feng et al, 2015, Buch et al, 2016b, Guggisberg et al, 2017.…”

“…First steps in this direction have been achieved in the motor domain. Structural connectivity analyses could show that secondary motor areas like SMA and PMd and their spinal descending fibres are associated with residual function in chronic stroke patients (Schulz et al, 2012, Peters et al, 2018. Additional to the relevance of the CST, intrahemispheric parieto-frontal cortico-cortical connections of the lesioned hemisphere between the IPS and the PMv and between PMv and M1 are associated with residual motor function in the chronic stage of recovery (Schulz et al, 2015b).…”

Proprioception and motor performance after stroke: An examination of diffusion properties in sensory and motor pathways

“…Additionally, our findings are in agreement with Lindenberg et al (2010) who reported that diffusivity changes were present in chronic stroke subjects with motor deficits even if the lesion did not directly overlap the tract. They, and others, suggest that such findings are consistent with remote changes in the motor network, possibly due to diaschisis (Peters et al, 2018;Seitz Rüdiger et al, 1999;Thomas et al, 2005).…”

Comparison of Brain Hemodynamic Responses to Forward versus Backward Walking among People Post-Stroke

“…Furthermore, Saver et al (1999) documented how the size of the lesion plays a role in motor recovery as well (Saver et al, 1999). Researchers report how reductions in gait speed and motor functioning of the upper extremities are associated with the severity of the ipsilesional hemisphere among people post-stroke (Peters et al, 2017). Likewise, associations between the damage in the brain and asymmetric gait patterns for people post-stroke have been documented (Alexander et al, 2009).…”