An exploratory study of the influence of posture and hand task on corticomotor excitability of upper extremity muscles after stroke

Publication date: Available online 25 January 2017
Source:Archives of Physical Medicine and Rehabilitation
Author(s): Caroline IE. Renner, Sophia Hanna, Ricarda Ludwig, Balazs Lukats, Horst Hummelsheim
ObjectiveTo explore the interaction between postural stability and hand task on the corticospinal excitability (CE) of upper extremity muscles and how it is affected by lesion location.DesignCross-sectional explorative survey. Setting: inpatient rehabilitation centerParticipantsNeurologically healthy subjects (volunteer sample, n=36) and patients with stroke (convenience sample, mean time since stroke=45 days), stratified according to lesion location: pure subcortical strokes (n=25), strokes with cortical involvement (n=20). Interventions: Not applicable.Main outcome measuresMotor-evoked potentials were recorded simultaneously from the first dorsal interosseus muscle (FDI) and biceps brachii (BB) during rest, low and forceful activation of the FDI in four different postural positions (supine, sitting, sitting unsupported and standing) and compared.ResultsPosture modulated CE of FDI and BB during performance of a motor task but not at rest. The influence of postural position on CE of FDI depended on force demand and lesion location: the control and subcortical stroke group demonstrated significantly higher CE of FDI when performing the forceful task in a supine or stable sitting position, respectively, compared to standing. In contrast, cortical strokes exhibited significantly higher CE of FDI when performing the low force task in a stable sitting position compared to standing.ConclusionPosture influences CE of FDI and BB in healthy subjects and patients with stroke differentially depending on hand task but not at rest. A stable sitting posture increased excitability of FDI in patients with stroke. These findings imply that hand rehabilitation protocols may be influenced by posture.



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