Abstract
Background. Poststroke, the ipsilesional upper limb shows slight but substantial and long-term motor deficits.
Objective.
To define brain activation patterns during a gross motor
flexion/extension task of the ipsilesional elbow early poststroke before
and after rehabilitation, in relation to the corresponding kinematic
characteristics at each time point.
Method. Simultaneous analysis
of kinematic features (amplitude, frequency, smoothness, and trajectory
of movement) and of corresponding functional magnetic resonance imaging
activations (block-design). A total of 21 persons with subacute initial
severe stroke (Fugl-Meyer score <30/66) participated twice: within
the first 2 months poststroke (V0) and after 6 weeks of rehabilitation
(V1). Results at both time points were compared with activation patterns
and kinematics of 13 healthy controls.
Results. Compared with controls (a) movements of the ipsilesional upper-limb poststroke were smaller (V0 + V1) and less smooth (V0 + V1) and (b)
participants poststroke showed additional recruitment of the
contralesional middle temporal gyrus (V0) and rolandic opercularis
involved in movement visualization (V0 + V1), whereas they lacked
activation of the supramarginal gyrus (V0 + V1). Over time, participants
poststroke showed an extended activation of the contralesional
sensorimotor cortex at V0.
Conclusion. Movements of the
ipsilesional upper limb within an initially severe stroke group were not
only atypical in motor outcome, but seemed to be controlled
differently. Together the observed changes pointed toward an overall
disturbance of the bihemispheric motor network poststroke, marked by (a) a possible despecialization of the nondamaged hemisphere and (b) the employment of alternative control strategies to ensure optimal task execution.
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