Locomotor circumvention strategies are altered by stroke: II. Postural Coordination

Background: locomotor strategies for obstacle circumvention require appropriate postural coordination that depends on sensorimotor integration within the central nervous system. it is not known how these strategies are affected by a stroke. the objective of this study was to contrast postural coordination strategies used for obstacle circumvention between post-stroke participants (n = 12) and healthy controls (n = 12). methods: participants walked towards a target in a virtual environment (11 × 8 m room) with cylindrical obstacles that were stationary or approaching from head-on,or diagonally 30° left/right. results: two stepping strategies for obstacle circumvention were identified: 1) side step: increase in step width by the foot ipsilateral to the side of circumvention; 2) cross step: decrease in step width by the foot contralateral to the side of circumvention. the side step strategy was favoured by post-stroke individuals in circumventing stationary and head-on approaching obstacles. in circumventing diagonally approaching obstacles,healthy controls generally veered opposite to obstacle approach (>60% trials),whereas the majority of post-stroke participants (7/12) veered to the same side of obstacle approach (vsame). post-stroke participants who veered to the opposite side (vopp,5/12) were more independent and faster ambulators who favoured the side step strategy in circumventing obstacles approaching from the paretic side and cross step strategy for obstacles approaching from the non-paretic side. vsame participants generally favoured the side step strategy for both diagonal approaches. segmental rotation amplitudes and latencies were largest in the vsame group,and significantly greater in post-stroke participants than controls for all obstacle conditions. all participants initiated circumvention with the feet followed by the pelvis and thorax,demonstrating a caudal-rostral sequence of reorientation. conclusion: postural coordination strategies for obstacle circumvention were altered post stroke,depending on the residual or restored functional abilities. segmental re-orientations are also affected by the motion and direction of obstacle. © 2017 the author(s).