Impaired limb shortening following stroke: what's in a name?

BackgroundDifficulty advancing the paretic limb during the swing phase of gait is a prominent manifestation of walking dysfunction following stroke. This clinically observable sign, frequently referred to as 'foot drop', ostensibly results from dorsiflexor weakness.ObjectiveHere we investigated the extent to which hip, knee, and ankle motions contribute to impaired paretic limb advancement. We hypothesized that neither: 1) minimal toe clearance and maximal limb shortening during swing nor, 2) the pattern of multiple joint contributions to toe clearance and limb shortening would differ between post-stroke and non-disabled control groups.MethodsWe studied 16 individuals post-stroke during overground walking at self-selected speed and nine non-disabled controls who walked at matched speeds using 3D motion analysis.ResultsNo differences were detected with respect to the ankle dorsiflexion contribution to toe clearance post-stroke. Rather, hip flexion had a greater relative influence, while the knee flexion influence on producing toe clearance was reduced.ConclusionsSimilarity in the ankle dorsiflexion, but differences in the hip and knee, contributions to toe clearance between groups argues strongly against dorsiflexion dysfunction as the fundamental impairment of limb advancement post-stroke. Marked reversal in the roles of hip and knee flexion indicates disruption of inter-joint coordination, which most likely results from impairment of the dynamic contribution to knee flexion by the gastrocnemius muscle in preparation for swing. These findings suggest the need to reconsider the notion of foot drop in persons post-stroke. Redirecting the focus of rehabilitation and restoration of hemiparetic walking dysfunction appropriately, towards contributory neuromechanical impairments, will improve outcomes and reduce disability

A functional electrical stimulation system for human walking inspired by reflexive control principles

This study presents an innovative multichannel functional electrical stimulation gait-assist system which employs a well-established purely reflexive control algorithm, previously tested in a series of bipedal walking robots. In these robots, ground contact information was used to activate motors in the legs, generating a gait cycle similar to that of humans. Rather than developing a sophisticated closed-loop functional electrical stimulation control strategy for stepping, we have instead utilised our simple reflexive model where muscle activation is induced through transfer functions which translate sensory signals, predominantly ground contact information, into motor actions. The functionality of the functional electrical stimulation system was tested by analysis of the gait function of seven healthy volunteers during functional electrical stimulation–assisted treadmill walking compared to unassisted walking. The results demonstrated that the system was successful in synchronising muscle activation throughout the gait cycle and was able to promote functional hip and ankle movements. Overall, the study demonstrates the potential of human-inspired robotic systems in the design of assistive devices for bipedal walking

Reinforced Feedback in Virtual Environment for Plantar Flexor Poststroke Spasticity Reduction and Gait Function Improvement

Background. Ankle spasticity is a frequent phenomenon that limits functionality in poststroke patients. Objectives. Our aim was to determine if there was decreased spasticity in the ankle plantar flex (PF) muscles in the plegic lower extremity (LE) and improvement of gait function in stroke patients after traditional rehabilitation (TR) in combination with virtual reality with reinforced feedback, which is termed "reinforced feedback virtual environment" (RFVE). Methods. The evaluation, before and after treatment, of 10 hemiparetic patients was performed using the Modified Ashworth Scale (MAS), Functional Ambulatory Category (FAC), and Functional Independence Measure (FIM). The intervention consisted of 1 hour/day of TR plus 1 hour/day of RFVE (5 days/week for 3 weeks; 15 sessions in total). Results. The MAS and FAC reached statistical significance (P<0.05). The changes in the FIM did not reach statistical significance (P=0.066). The analysis between the ischemic and haemorrhagic patients showed significant differences in favour of the haemorrhagic group in the FIM scale. A significant correlation between the FAC and the months after the stroke was established (P=-0.711). Indeed, patients who most increased their score on the FAC at the end of treatment were those who started the treatment earliest after stroke. Conclusions. The combined treatment of TR and RFVE showed encouraging results regarding the reduction of spasticity and improvement of gait function. An early commencement of the treatment seems to be ideal, and future research should increase the sample size and assessment tools

Motor control-based assessment of therapy effects in individuals post-stroke: implications for prediction of response and subject-specific modifications

Producing a coordinated motion such as walking is, at its root, the result of healthy communication pathways between the central nervous system and the musculoskeletal system. The central nervous system produces an electrical signal responsible for the excitation of a muscle, and the musculoskeletal system contains the necessary equipment for producing a movement-driving force to achieve a desired motion. Motor control refers to the ability an individual has to produce a desired motion, and the complexity of motor control is a mathematical concept stemming from how the electrical signals from the central nervous system translate to muscle activations. Exercising a high-level complexity of motor control is critical to producing a smooth motion. However, the occurrence of a sudden, detrimental neurological event like a stroke damages these connecting pathways between these two systems, and the result is a motion that is uncoordinated and energy-inefficient due to diminished motor control complexity. Stroke is a leading cause of disability with nearly 800,000 stroke victims each year in the U.S. alone, amounting to an estimated cost of $45.5B. Impaired mobility following a stroke is a widespread effect, with more than half of survivors over the age of 65 affected in this way, and up to 80% of survivors at some point experiencing hemiparesis during post-stroke recovery. As such, given the importance of independent mobility for quality of life, improving gait mechanics and mobility of stroke survivors has been the goal of rehabilitation efforts for decades. In this work, we mold together the forefronts of statistics and computational physics-based modeling to obtain insight and information about post-stroke hemiparetic gait mechanics and what drives them that would otherwise be unavailable. We expand upon previous work to quantify motor control complexity as it relates to the health of the neuromuscular system and analyze the effect of a specific therapy on motor control of individuals post-stroke. Secondly, we aim to develop a predictive model to conclude whether an individual will respond to the therapy based on kinematic and dynamic features from pre-therapy recordings. Lastly, we will determine how to individually tailor this therapy in order to achieve maximum improvement in motor control complexity in order to improve gait mechanics in individuals post-stroke

Smart Protocols for Physical Therapy of Foot Drop Based on Functional Electrical Stimulation: A Case Study

Functional electrical stimulation (FES) is used for treating foot drop by delivering electrical pulses to the anterior tibialis muscle during the swing phase of gait. This treatment requires that a patient can walk, which is mostly possible in the later phases of rehabilitation. In the early phase of recovery, the therapy conventionally consists of stretching exercises, and less commonly of FES delivered cyclically. Nevertheless, both approaches minimize patient engagement, which is inconsistent with recent findings that the full rehabilitation potential could be achieved by an active psycho-physical engagement of the patient during physical therapy. Following this notion, we proposed smart protocols whereby the patient sits and ankle movements are FES-induced by self-control. In six smart protocols, movements of the paretic ankle were governed by the non-paretic ankle with different control strategies, while in the seventh voluntary movements of the paretic ankle were used for stimulation triggering. One stroke survivor in the acute phase of recovery participated in the study. During the therapy, the patient’s voluntary ankle range of motion increased and reached the value of normal gait after 15 sessions. Statistical analysis did not reveal the differences between the protocols in FES-induced movements.The APC was funded by Lund University Librar

Rehabilitation of gait after stroke: a review towards a top-down approach

This document provides a review of the techniques and therapies used in gait rehabilitation after stroke. It also examines the possible benefits of including assistive robotic devices and brain-computer interfaces in this field, according to a top-down approach, in which rehabilitation is driven by neural plasticity

After Stroke Movement Impairments: A Review of Current Technologies for Rehabilitation

This chapter presents a review of the rehabilitation technologies for people who have suffered a stroke, comparing and analyzing the impact that these technologies have on their recovery in the short and long term. The problematic is presented, and motor impairments for upper and lower limbs are characterized. The goal of this chapter is to show novel trends and research for the assistance and treatment of motor impairment caused by strokes

The Challenges of Implementing Functional Electrical Stimulation Cycling in a Patient with Hemiparesis following Stroke: A Case Report

Background: Strokes are the most common cause of severe disability in the United States. Functional electrical stimulation (FES) cycling may be used as an intervention to decrease disability post-stroke, though there is conflicting evidence among the existing studies exploring its use. The purpose of this case study is to describe the use of FES cycling in order to decrease residual disability post-stroke, as well as the challenges of implementing this intervention in the inpatient rehabilitation setting. Case Description: The patient was a 75 year-old female who presented to inpatient rehabilitation with a sub-acute ischemic right posterior cerebral artery stroke. The patient demonstrated severe left hemiparesis, left homonymous hemianopsia resulting in left neglect, as well as impairments in sensation, balance, and functional mobility. Interventions consisted of use of an FES bicycle at a low dosage, balance activities, left attention tasks, sensory reeducation, strengthening, and education. Outcomes: The patient’s length of stay was 24 days. During this period, she demonstrated a 22-point increase in the Functional Independence Measure score from initial evaluation to discharge. The patient also demonstrated an increase in postural control as demonstrated by a five-point increase in her Postural Assessment Scale for Stroke score. Discussion: Though the patient made significant improvements in postural control and required much less assistance with mobility, she continued to demonstrate severe deficits at discharge that prevented her from returning home independently. Patient complexity, time constraints, scheduling difficulties, and reimbursement issues represented challenges of regular implementation of FES cycling, resulting in dosage at a level lower than is recommended. While current research is conflicting, FES cycling at an appropriate volume may be beneficial in reducing disability in sub-acute stroke survivors

Systematic Literature Review of AbobotulinumtoxinA in Clinical Trials for Lower Limb Spasticity

AbstractTo elucidate clinical trial efficacy, safety, and dosing practices of AbobotulinumtoxinA (ABO) treatment in adult patients with lower limb spasticity.A systematic literature review was performed to identify randomized controlled trials of ABO in the treatment of adult lower limb spasticity.Of the 295 records identified, 6 primary publications evaluated ABO for the management of lower limb spasticity of various etiologies and were evaluated. Total ABO doses ranged between 500 and 2000 U for lower limb spasticity, depending on the muscles injected. All studies in lower limb spasticity showed statistically significant reduction in muscle tone based on Modified Ashworth Scale of ABO versus placebo. Significant effects on active movement and pain were demonstrated albeit less consistently. ABO was generally well tolerated across the individual studies; most adverse events reported were considered unrelated to treatment. Treatment-related adverse events included but not limited to fatigue, local pain at injection site, hypertonia, dry mouth, weakness of the noninjected muscle, abnormal gait, and urinary tract infection.These data from 6 randomized clinical studies provide the beginnings of an evidence base for the use of ABO to reduce lower limb spasticity. Ongoing studies in this area will add to this evidence base