Acquisition of a precision walking skill and the impact of proprioceptive deficits in people with motor-incomplete spinal cord injury

Upper extremity effort during the sit-to-stand task in able-bodied and in individuals with spinal cord injury: A preliminary study

OBJECTIVE

To investigate the association between the presence of spinal cord injury (SCI) on biomechanical variables by comparing individuals with SCI and able-bodied individuals during the sit-to-stand (STS) task assisted by a walker device. Specifically, we compared the upper-extremity joint angles and moments, trunk forward tilt angle, vertical forces of the instrumented walker, and ground reaction forces between groups.

DESIGN

Case-control study.

SETTING

Department of Orthopedics and Traumatology, UNICAMP-Brazil.

PARTICIPANTS

Six individuals with SCI and fourteen able-bodied individuals.

MAIN OUTCOME MEASURES

Kinematics and kinetics of the shoulder, elbow, and wrist joints; trunk forward tilt angle, vertical walker forces, and ground reaction forces (GRF) were analyzed during the STS task in two phases: before and after the seat-off event.

RESULTS

A higher peak elbow flexion angle and higher vertical walker forces were observed before the seat-off, whereas the lower peak vertical GRF was found, after the seat-off, in the SCI group compared with the control group.

CONCLUSIONS

SCI affects kinematics and kinetics variables during the STS task compared to able-bodied controls. Individuals with SCI adopted different standing-up strategies that affected the distribution of the forces in the upper and lower extremities of the human body.

Postoperative Recovery of Gait Function at Early Phase Is Delayed in Patients with Spinal Tumors with Impairment of the Joint Position Sense in the Big Toe: A Retrospective Cohort Study

Introduction

We investigated the effect of preoperative joint position sense in the big toe on the postoperative recovery of gait function after spinal tumor surgery.

Methods

Seventy-three patients with spinal tumors who underwent surgery at our hospital between 2014 and 2019 and could be followed for at least 6 months after surgery were included. The patients were divided into the cervical spinal (41 cases) and thoracic spinal (32 cases) groups according to the localization of the tumor. These groups were further classified into an Impaired group (cervical spinal, 34 cases; thoracic spinal, 19 cases) and an Intact group (cervical spinal, 7 cases; thoracic spinal, 13 cases) according to the presence or absence of preoperative joint position sense in the big toe. The amount of change in ambulatory function from the preoperative period to 3 and 6 months postoperatively was compared between the Impaired and Intact groups within each tumor localization category.

Results

Impaired preoperative joint position sense in the big toe in patients undergoing thoracic spinal tumor surgery delayed the recovery of gait function in the early postoperative period.

Conclusions

In patients with thoracic spinal tumor surgery, the absence of preoperative joint position sense in the big toe delayed the recovery of postoperative gait function.

Somatosensory Information in Skilled Motor Performance: A Narrative Review

Historically, research aimed at improving motor performance has largely focused on the neural processes involved in motor execution due to their role in muscle activation. However, accompanying somatosensory and proprioceptive sensory information is also vitally involved in performing motor skills. Here we review research from interdisciplinary fields to provide a description for how somatosensation informs the successful performance of motor skills as well as emphasize the need for careful selection of study methods to isolate the neural processes involved in somatosensory perception. We also discuss upcoming strategies of intervention that have been used to improve performance via somatosensory targets. We believe that a greater appreciation for somatosensation's role in motor learning and control will enable researchers and practitioners to develop and apply methods for the enhancement of human performance that will benefit clinical, healthy, and elite populations alike.

The effects of lower extremity deep sensory impairments on walking capability in patients with incomplete cervical spinal cord injury

Objective: To analyze the impact of lower extremity deep sensory impairment on the walking capability of patients with incomplete cervical spinal cord injury.Design: Retrospective cohort study.Setting: Spinal Injuries Center, Fukuoka, Japan.Participants: Patients with incomplete cervical spinal cord injury who were transferred to the Spinal Injuries Center within 2 weeks of injury and whose progress was monitored for 6 months postinjury were included. Sixty-three patients with a lower extremity motor score of 42 points or more were enrolled. They were divided into lower extremity deep sensory impairment (16 patients) and normal (47 patients) groups, and their walking capability was compared.Interventions: Not applicable.Outcome Measures: Upper and lower extremity motor scores, the presence or absence of deep sensation impairment, and walking capability indices at 6 months postinjury were evaluated.Results: The deep sensory impairment group performed significantly worse than the normal group across items in the Walking Index for Spinal Cord Injury II and in the indoor and outdoor mobility items of the Spinal Cord Independence Measure III. Indoor and outdoor mobility independence levels decreased further in the lower extremity deep sensory impairment group than in the normal group.Conclusions: The presence of lower extremity deep sensation impairments was an important factor affecting the achievement of independent walking capabilities in patients with incomplete cervical spinal cord injury. Hence, when patients with incomplete cervical spinal cord injury undergo walking training, not only their lower extremity muscle strength but also their level of deep sensation impairment must be evaluated.

Multisite Transcutaneous Spinal Stimulation for Walking and Autonomic Recovery in Motor-Incomplete Tetraplegia: A Single-Subject Design

OBJECTIVE

This study investigated the effect of cervical and lumbar transcutaneous spinal cord stimulation (tSCS) combined with intensive training to improve walking and autonomic function after chronic spinal cord injury (SCI).

METHODS

Two 64-year-old men with chronic motor incomplete cervical SCI participated in this single-subject design study. They each underwent 2 months of intensive locomotor training and 2 months of multisite cervical and lumbosacral tSCS paired with intensive locomotor training.

RESULTS

The improvement in 6-Minute Walk Test distance after 2 months of tSCS with intensive training was threefold greater than after locomotor training alone. Both participants improved balance ability measured by the Berg Balance Scale and increased their ability to engage in daily home exercises. Gait analysis demonstrated increased step length for each individual. Both participants experienced improved sensation and bowel function, and 1 participant eliminated the need for intermittent catheterization after the stimulation phase of the study.

CONCLUSION

These results suggest that noninvasive spinal cord stimulation might promote recovery of locomotor and autonomic functions beyond traditional gait training in people with chronic incomplete cervical SCI.

IMPACT

Multisite transcutaneous spinal stimulation may induce neuroplasticity of the spinal networks and confer functional benefits following chronic cervical SCI.

Ankle proprioception during gait in individuals with incomplete spinal cord injury

INTRODUCTION

Proprioception is known to be affected after a spinal cord injury (SCI). However, it is currently assessed during simple tasks that do not reflect activities of daily living. To better understand how proprioception affects movement, assessing it during a functional sensorimotor task such as walking is therefore of primary importance. Therefore, the objectives of this study were as follows: (a) measure the protocol reliability of a new robotic test in nondisabled controls; (b) evaluate the effect nonlesion-related factors such as sex, age, pain, and gait speed on ankle proprioception; and (c) assess ankle proprioception during walking in individuals with SCI.

METHODS

In the current study, ankle proprioception was assessed during gait in individuals with an incomplete spinal cord injury (iSCI; n = 15) using an electrohydraulic robotized ankle-foot orthosis (rAFO). Ankle proprioceptive threshold was quantified as the participants' ability to detect torque perturbations of varied amplitude applied during swing by the rAFO. In addition, test-retest reliability and the potential effect of nonlesion-related factors (sex, age, pain, and gait speed) were evaluated in nondisabled (ND; n = 65) participants.

RESULTS

During gait, individuals with iSCI had a 53% poorer proprioceptive threshold than ND controls (p < .05). Test-retest reliability was good (ICC = 0.78), and only gait speed affected proprioceptive threshold (p = .018).

CONCLUSION

This study is the first to show that ankle proprioception assessed during gait is impaired in individuals with an iSCI. The developed test can now be used to better characterize proprioception in population with other neurological conditions and has potential to maximize functional recovery during gait training in those populations.

Providing low-dimensional feedback of a high-dimensional movement allows for improved performance of a skilled walking task

Learning a skilled movement often requires changing multiple dimensions of movement in a coordinated manner. Serial training is one common approach to learning a new movement pattern, where each feature is learned in isolation from the others. Once one feature is learned, we move on to the next. However, when learning a complex movement pattern, serial training is not only laborious but can also be ineffective. Often, movement features are linked such that they cannot simply be added together as we progress through training. Thus, the ability to learn multiple features in parallel could make training faster and more effective. When using visual feedback as the tool for changing movement, however, such parallel training may increase the attentional load of training and impair performance. Here, we developed a novel visual feedback system that uses principal component analysis to weight four features of movement to create a simple one-dimensional 'summary' of performance. We used this feedback to teach healthy, young participants a modified walking pattern and compared their performance to those who received four concurrent streams of visual information to learn the same goal walking pattern. We demonstrated that those who used the principal component-based visual feedback improved their performance faster and to a greater extent compared to those who received concurrent feedback of all features. These results suggest that our novel principal component-based visual feedback provides a method for altering multiple features of movement toward a prescribed goal in an intuitive, low-dimensional manner.

The sensorimotor effects of a lower limb proprioception training intervention in individuals with a spinal cord injury

Proprioception is critical for movement control. After a spinal cord injury (SCI), individuals not only experience paralysis but may also experience proprioceptive deficits, further confounding motor recovery. The objective of this study was to test the effects of a robotic-based proprioception training protocol on lower limb proprioceptive sense in people with incomplete SCI. A secondary objective was to assess whether the effects of training transferred to a precision stepping task in people with motor-incomplete SCI. Participants with chronic incomplete SCI and able-bodied controls underwent a 2-day proprioceptive training protocol using the Lokomat robotic exoskeleton. The training involved positioning the test leg to various positions and participants were asked to report whether they felt their heel position (end-point position) was higher or lower compared with a reference position. Feedback was provided after each trial to help participants learn strategies that could help them discern different positions of their foot. Changes in end-point position as well as knee joint position sense were assessed pre- and posttraining. We also assessed the effects of proprioception training on the performance of a precision stepping task in people with motor-incomplete SCI. Following training, there were significant improvements in end-point and knee joint position sense in both groups. The magnitude of improvement was related to pretraining (baseline) proprioceptive sense, indicating that those who initially had better lower limb position sense showed greater changes. Participants also showed improvements in performance of a precision stepping task.

NEW & NOTEWORTHY We show that it is possible to alter proprioceptive sense in people with incomplete SCI using a passive proprioception training protocol combined with feedback. Improvements in proprioceptive sense transferred from end-point to joint position sense and also to an untrained precision stepping task.