Locomotor Recovery in Spinal Cord Injury: Insights Beyond Walking Speed and Distance

Abstract

Recovery of locomotor function after incomplete spinal cord injury (iSCI) is clinically assessed through walking speed and distance, while improvements in these measures might not be in line with a normalization of gait quality and are, on their own, insensitive at revealing potential mechanisms underlying recovery. The objective of this study was to relate changes of gait parameters to the recovery of walking speed while distinguishing between parameters that rather reflect speed improvements from factors contributing to overall recovery. Kinematic data of 16 iSCI subjects were repeatedly recorded during in-patient rehabilitation. The responsiveness of gait parameters to walking speed was assessed by linear regression. Principal component analysis (PCA) was applied on the multivariate data across time to identify factors that contribute to recovery after iSCI. Parameters of gait cycle and movement dynamics were both responsive and closely related to the recovery of walking speed, which increased by 96%. Multivariate analysis revealed specific gait parameters (intralimb shape normality and consistency) that, although less related to speed increments, loaded highly on principal component one (PC1) (58.6%) explaining the highest proportion of variance (i.e., recovery of outcome over time). Interestingly, measures of hip, knee, and ankle range of motion showed varying degrees of responsiveness (from very high to very low) while not contributing to gait recovery as revealed by PCA. The conjunct application of two analysis methods distinguishes gait parameters that simply reflect increased walking speed from parameters that actually contribute to gait recovery in iSCI. This distinction may be of value for the evaluation of interventions for locomotor recovery.

Overground walking patterns after chronic incomplete spinal cord injury show distinct response patterns to unloading

“…Once altered following CNS injury however, the coupling of segments has proven remarkably resilient to change. In iSCI patients, for instance, Awai and Curt [ 12 ] reported unchanged intralimb walking pattern shapes in iSCI patients throughout their rehabilitation, despite increases in walking speed and reductions in intralimb variability. Similarly, Tepavac and Field-Fote [ 51 ] reported improved consistency, yet no systematic change of shape in intralimb coupling following peroneal stimulation coupled with training in 14 iSCI patients.…”

“…Compared to the extensive gains observed in animals however, the functional improvements in humans remain limited [ 10 ]. This is attributed to various factors, including species-specific anatomy and neurophysiology [ 11 ], low sensitivity of outcome measures [ 12 ] and suboptimal dosing/timing of the intervention [ 13 ]. In coherence with the concept of exploiting the neuroplasticity of residual circuits, it is established that training must be task-specific, active and tailored to the individual patient’s capacity [ 5 ].…”

The kinematic recovery process of rhesus monkeys after spinal cord injury

“…Previous research evaluated motor function recovery after SCI in various aspects, including general hindlimb motor performance [ 26 ], intra-limb coordination [ 1 , 2 ], inter-limb coordination [ 7 ], and control hierarchy [ 12 ]. While several research studies have focused on general hindlimb performance, studies based on different control hierarchies have enabled the sensitive reflection of different performances of different hindlimb parts.…”

“…PC1 scores were averaged at each time point and illustrated in a bar graph. Factor loadings with greater correlation were extracted (the absolute value of factor loading was larger than 0.75 [ 2 ]); from these, the most representative parameters were sequentially selected and illustrated in a bar graph.…”

Improvements in skilled walking associated with kinematic adaptations in people with spinal cord injury

“…Rehabilitation and exercise training programs are important for individuals with spinal cord injury (SCI), not only to promote mobility, but also for minimizing the effects of secondary complications and improving quality of life [1–4]. Following motor-incomplete SCI (m-iSCI), individuals have reduced muscle strength [5, 6], inadequate range of motion [7] and impaired inter-joint coordination [8, 9], all factors that likely contribute to the increased falls-risk [10] and limited community ambulation in this population [11, 12]. Gait rehabilitation strategies for people with m-iSCI have been built upon principles of providing appropriate (walking-related) afferent feedback to central locomotor circuits (‘pattern generators’) within the spinal cord [13–16].…”