Rehabilitation of Ambulatory Limitations

There are several traditional and nontraditional strategies available for the rehabilitation of ambulatory limitations in adults with central neurologic disorders. Traditional strategies may include therapies such as exercise training and conventional gait training. Nontraditional rehabilitation strategies typically involve advanced therapeutic technologies or devices. We describe several ambulatory rehabilitation strategies providing advantages, disadvantages, and common applications of these modalities. Feasibility, cost effectiveness, accessibility, and training specificity of the various modalities are also compared. Rehabilitation strategies should be selected based on the specific ambulatory impairments and rehabilitation needs of each patient.

Key points

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A variety of tools and techniques are available for the rehabilitation of ambulatory impairments in adults with central neurologic disorders.
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These strategies can be described as traditional and nontraditional.
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Each strategy has particular advantages and disadvantages with respect to feasibility, cost effectiveness, accessibility, and training specificity.
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The various rehabilitation strategies should be considered complementary rather than exclusive.
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Rehabilitation strategies should be selected using an individualized approach.

Introduction

Rehabilitation has been defined by the World Health Organization as “a proactive and goal-oriented activity to restore function and/or to maximize remaining function to bring about the highest possible level of independence, physically, psychologically, socially and economically.” The rehabilitation process ideally involves a multidisciplinary team of professionals to promote recovery in physical, psychological, and social domains. Rehabilitation represents a particularly important strategy for the treatment of ambulatory limitations in adults who have central neurologic disorders. For certain neurologic populations, rehabilitation strategies may be the only effective mode of therapy to improve or maintain functional abilities. Deficits contributing to ambulatory limitations in adults with central neurologic disorders commonly include impaired walking speed and spatial and temporal parameters of gait, balance, lower extremity strength, and tone (spasticity) ; consequently, these targets are often the focus of ambulatory rehabilitation strategies. Individuals with neurologic diseases have unique clinical presentations and courses, and, as such, rehabilitation strategies should be prescribed based on the specific needs and deficits experienced by each patient.

Despite the importance of ambulatory rehabilitation for individuals with central neurologic disorders, there are several limitations of the current literature in this field. Common limitations include small sample sizes, lack of appropriate controls, substantial patient heterogeneity, lack of long-term interventions and follow-up, and inconsistent or insufficient outcomes for evaluating ambulation in individuals with neurologic impairment. The assessment of ambulatory rehabilitation strategies has typically included outcomes of walking velocity, walking endurance, spatial and temporal gait parameters, or clinical examination. Importantly, the inclusion of real-life measures of ambulation (ie, pedometers and accelerometers) and patient-reported experiences of walking impairment have been increasingly included as outcomes in the evaluation of ambulatory limitations.

Several strategies are currently available for the rehabilitation of ambulatory limitations in adults with central neurologic disorders that can be described as traditional or nontraditional rehabilitation. In general, traditional rehabilitation strategies are those that involve passive or active movements or exercises, whereas nontraditional therapies involve the use of advanced therapeutic technologies or devices. This article describes and evaluates the most common traditional and nontraditional therapies available for ambulatory rehabilitation in adults with central nervous system (CNS) disorders such as stroke, spinal cord injury (SCI), multiple sclerosis (MS), and Parkinson’s disease (PD). Traditional rehabilitation strategies that will be explored include exercise training and conventional gait training. Nontraditional rehabilitation strategies that will be explored include functional electrical stimulation (FES), recumbent stepper training, body weight–supported treadmill training (BWSTT), and the ZeroG overground gait and balance training system. The advantages, disadvantages, and applications of each of these rehabilitation modalities are discussed. Rehabilitation is also often used in conjunction with other interventions for ambulation (eg, fitting and training to the use of an assistive device or orthosis, medical or surgical treatments for spasticity). Such an approach is often considered standard of care or best practice, and, as a consequence, there is little evidence showing the specific benefits of rehabilitation strategies in terms of the overall efficacy, safety, and acceptability of other interventions. We will, therefore, mostly focus our review on the effects of rehabilitation techniques when used alone.

Introduction

Rehabilitation has been defined by the World Health Organization as “a proactive and goal-oriented activity to restore function and/or to maximize remaining function to bring about the highest possible level of independence, physically, psychologically, socially and economically.” The rehabilitation process ideally involves a multidisciplinary team of professionals to promote recovery in physical, psychological, and social domains. Rehabilitation represents a particularly important strategy for the treatment of ambulatory limitations in adults who have central neurologic disorders. For certain neurologic populations, rehabilitation strategies may be the only effective mode of therapy to improve or maintain functional abilities. Deficits contributing to ambulatory limitations in adults with central neurologic disorders commonly include impaired walking speed and spatial and temporal parameters of gait, balance, lower extremity strength, and tone (spasticity) ; consequently, these targets are often the focus of ambulatory rehabilitation strategies. Individuals with neurologic diseases have unique clinical presentations and courses, and, as such, rehabilitation strategies should be prescribed based on the specific needs and deficits experienced by each patient.

Despite the importance of ambulatory rehabilitation for individuals with central neurologic disorders, there are several limitations of the current literature in this field. Common limitations include small sample sizes, lack of appropriate controls, substantial patient heterogeneity, lack of long-term interventions and follow-up, and inconsistent or insufficient outcomes for evaluating ambulation in individuals with neurologic impairment. The assessment of ambulatory rehabilitation strategies has typically included outcomes of walking velocity, walking endurance, spatial and temporal gait parameters, or clinical examination. Importantly, the inclusion of real-life measures of ambulation (ie, pedometers and accelerometers) and patient-reported experiences of walking impairment have been increasingly included as outcomes in the evaluation of ambulatory limitations.

Several strategies are currently available for the rehabilitation of ambulatory limitations in adults with central neurologic disorders that can be described as traditional or nontraditional rehabilitation. In general, traditional rehabilitation strategies are those that involve passive or active movements or exercises, whereas nontraditional therapies involve the use of advanced therapeutic technologies or devices. This article describes and evaluates the most common traditional and nontraditional therapies available for ambulatory rehabilitation in adults with central nervous system (CNS) disorders such as stroke, spinal cord injury (SCI), multiple sclerosis (MS), and Parkinson’s disease (PD). Traditional rehabilitation strategies that will be explored include exercise training and conventional gait training. Nontraditional rehabilitation strategies that will be explored include functional electrical stimulation (FES), recumbent stepper training, body weight–supported treadmill training (BWSTT), and the ZeroG overground gait and balance training system. The advantages, disadvantages, and applications of each of these rehabilitation modalities are discussed. Rehabilitation is also often used in conjunction with other interventions for ambulation (eg, fitting and training to the use of an assistive device or orthosis, medical or surgical treatments for spasticity). Such an approach is often considered standard of care or best practice, and, as a consequence, there is little evidence showing the specific benefits of rehabilitation strategies in terms of the overall efficacy, safety, and acceptability of other interventions. We will, therefore, mostly focus our review on the effects of rehabilitation techniques when used alone.

Traditional rehabilitation in adults with central neurologic conditions

Exercise Training

Exercise training has been widely administered as a rehabilitation strategy in adults with CNS disorders including stroke, SCI, MS, and PD. The forms of exercise training that have been most commonly prescribed and that will be considered in this article include aerobic training and progressive resistance training, either alone or in combination. Traditional aerobic exercise training modalities used for individuals with neurologic diseases include treadmill walking, leg cycling ergometry, arm ergometry, and aquatic exercise. Resistance training regimes typically include weight machines, free weights, body weight exercises, cable pulleys, or elastic bands. Both of these exercise forms have been used successfully in the MS population to improve ambulatory outcomes. For example, 8 weeks of leg cycling ergometry (60 minutes, 3 sessions per week) at a moderate-to-strong intensity resulted in significant improvements in aerobic capacity, walking speed, and walking endurance in adults with MS. Similarly, 12 weeks of lower extremity progressive resistance training resulted in lower limb strength gains and improved walking speed, endurance, and functional task performance in patients with MS.

Traditional aerobic and resistance exercise can also be combined or enhanced with other techniques, such as biofeedback. For instance, biofeedback cycling provides patients with visual information regarding input from each individual leg allowing for the monitoring and correction of cycling asymmetries during training. Correcting cycling asymmetries during exercise may translate into improvements in ambulation. Using this type of intervention, 6 sessions of leg pedaling exercise with biofeedback resulted in improved cycling asymmetry and improvement in walking speed and gait asymmetry in a case series of 3 chronic stroke patients.

Physiologic deconditioning, or the loss of aerobic capacity and muscular strength, is common among adults with neurologic diseases. This loss of physical fitness may, in turn, limit ambulatory capacity. Correctly prescribed exercise training is expected to improve aerobic endurance and muscular strength. As described in the aforementioned training studies, the training-induced improvements in aerobic and muscular performance may also translate into meaningful benefits on ambulation.

There are several advantages to exercise training as a rehabilitation strategy. Exercise training is cost effective compared with many other modalities and generally available in most community settings. A combined program of aerobic and resistance training may also result in several health and fitness benefits, such as improved bone health, body composition, and comorbid disease risk profile. The disadvantage of this modality is that it is generally not task specific to ambulation, with the exception of treadmill walking. Exercise training, however, may be used in combination with other task-specific rehabilitation techniques to improve cardiovascular endurance and muscular capacity, which may act synergistically to improve ambulation. Finally, for individuals with severe mobility limitations, traditional aerobic and resistance training equipment is often not physically accessible.

Conventional Gait Training

Conventional gait training is one of the most commonly used forms of rehabilitation for adults with CNS disorders and may include techniques such as overground walking and movement training; balance, coordination, and range of motion exercises; and active and passive stretching. The variety of techniques used in conventional gait training results in a targeted rehabilitation approach that can be specific to the gait impairments of each patient. Conventional gait training strategies are typically delivered by trained personnel, such as physical therapists, occupational therapists, or exercise professionals. With practice, some strategies may be undertaken outside of the clinical setting, particularly for patients who are capable of independent ambulation. Conventional gait training strategies have been used in patients with stroke, SCI, MS, and PD. For example, a 6-week (3 sessions/week) physical or occupational therapist-supervised program involved practice of 10 walking-related tasks (ie, forward and backward walking, stepping, kicking, balancing, and sitting-to-standing transitions) in patients with chronic stroke. Patients were further encouraged to practice at-home walking. This training program resulted in improvements in walking speed and distance compared with participants who were involved in seated upper extremity functional task training.

Conventional gait training techniques may also be supplemented with adjunct therapies, such as rhythmic auditory stimulation (RAS). RAS is described as a neurologic music therapy technique that targets gait dysfunction through the use of rhythmic timing cues. RAS has been used in patients with several neurologic diseases and often in addition to conventional gait-training techniques. For instance, patients with PD were involved in 6 weeks of stepping training with or without the use of RAS. Compared with stepping practice alone, stepping with RAS resulted in superior improvements on functional gait and balance outcomes, and the effects were more long lasting after the intervention period. This highlights the importance of considering alternative and combined therapies when treating ambulatory impairments.

There are several important benefits to conventional gait training. Conventional gait training is task specific in that it allows patients the opportunity to practice walking and movement-related tasks. Unlike other strategies, training can be tailored to the specific gait deficits experienced by each patient because of the multifaceted rehabilitation approach. Conventional gait training is generally more cost effective than nontraditional rehabilitation strategies involving specialized equipment. Adjunct therapies such as RAS can also be incorporated to enhance outcomes. Unfortunately, the feasibility of conventional gait training may be limited for patients with severe mobility impairment, although likely not to the same extent as exercise training. This modality also requires expertise from specialized personnel, which may only be available at clinical rehabilitation centers.

Nontraditional rehabilitation in adults with central neurologic conditions

Functional Electrical Stimulation

FES is a technique that delivers brief electrical pulses to muscles or peripheral nerves in patients with CNS disorders with the goal of improving function. To date, FES has been used in various populations, particularly in stroke survivors and individuals with SCI, to facilitate ambulatory function and improve muscle strength. The earliest uses of FES in the stroke population was to improve or correct foot drop (through peroneal nerve stimulation), but later studies tended to explore the broader utility of FES to improve specific aspects of walking performance in stroke survivors, such as gait kinematics, muscle spasticity, and muscle strength. There is good evidence that FES is effective in improving gait speed in individuals after stroke, although it may provide more of an orthotic as opposed to therapeutic benefit (ie, the improvements may not necessarily be maintained when the FES is removed). The strongest evidence for a benefit of FES to improve ambulation after stroke is when it is combined with other gait retraining strategies. In the SCI population, FES-assisted walking has been used as both an orthotic aid (for complete or incomplete paraplegics) and as a therapeutic modality to improve gait in people with incomplete SCI. To date, FES-assisted walking therapy has not been found to be superior to other ambulatory training interventions (eg, BWSTT, overground walking training) in people with chronic incomplete SCI, although greater benefits may be seen with combined approaches. Further information about the use of FES after stroke and SCI can be found elsewhere in this issue.

Potential advantages to FES-assisted walking training include the ability to promote active movement of limb segments (as opposed to immobilization of joints and limb segments with traditional orthoses), thereby, decreasing the risk of nonuse muscle atrophy and range of motion limitations, relative safety and ease of use, and the potential to promote CNS plasticity through repetitive afferent feedback from the muscle contraction and limb motion generated by the stimulation. However, limitations of FES-assisted walking training should also be considered. First, this rehabilitation technique can only be applied in individuals with intact lower motoneurons and viable peripheral nerves (and neuromuscular junctions) to the lower limb musculature. Second, clinically available systems of FES-assisted walking cannot stimulate the hip flexors directly; thus, any hip flexion during walking has to be initiated voluntarily by the patient. Third, the muscles stimulated through FES experience rapid fatigue because the larger-diameter (and more fatigable) nerve fibers are most easily stimulated by surface electrodes, which significantly limits the length of time that FES-assisted walking can be performed. Finally, the electrical current excites both motor and sensory nerves and may be painful to some individuals, especially those with preserved sensation.

Recumbent Stepper Training

Recumbent stepper training allows patients to step against graded resistive forces from a supported seated position ( Fig. 1 ). Coupled arm levers and foot pedals move in a bilateral reciprocal manner, which results in movement of the lower and upper extremities. The coupled upper and lower body training system allows for compensation of upper or lower extremity weakness in a self-driven manner in that all movement is patient initiated. Additional features of the recumbent stepper can include adjustable arm levers, rotating seat, large foot pedals with exterior edges, foot and arm strapping, and leg stabilizers, which make this piece of equipment accessible and adaptable for persons with varying degrees of disability. To date, the effects of recumbent stepper training in adults with neurologic diseases have only been examined by 2 research groups: one in patients with stroke and the other in patients with PD. Patients with PD who participated in 10–12 weeks of 3 weekly sessions (30 minutes per session) of recumbent stepper training experienced improvements in walking speed and step length, although there was no change in the severity of disability. Further trials in a variety of neurologic disease populations are necessary to determine the potential of recumbent stepper training as a tool for the rehabilitation of ambulatory limitations.

Recumbent stepper training may target ambulatory deficits through several different mechanisms. The full-body aerobic training stimulus may result in improvements in aerobic and muscular performance, similar to traditional exercise training. In sedentary adults, recumbent stepper training has been found to improve peak aerobic capacity and strength and endurance of both upper and lower extremity muscles. Improved aerobic endurance and muscle strength may, in turn, improve ambulatory performance, although this requires further investigation in specific neurologic populations. The stepping motion of recumbent stepper training has also been shown to have a similar, although less complex, neuromuscular activation pattern to walking, suggesting specificity of this training modality to ambulation; however, the joint kinematics of recumbent stepping are different than those involved in walking.

Compared with most nontraditional rehabilitation modalities, recumbent stepper training is cost effective and simple to operate. This modality could be easily implemented in community and home settings. The accessibility and adapted accessories available for this piece of equipment make it applicable to individuals with varying disability levels. The self-driven nature of the modality also allows for all work to be conducted by the patient rather than requiring substantial assistance from therapists or devices, likely resulting in greater overall effort by the patient. The main disadvantage of this system is that it is less specific to ambulation than other nontraditional rehabilitation techniques. The movement is also restricted to stepping and would not allow participants to practice other ambulatory movements, such as balancing or transferring tasks.

Body Weight–Supported Treadmill Training

BWSTT consists of a motorized treadmill with an overhead counterbalancing system attached to a supportive harness ( Fig. 2 ). Using the support harness, patients are suspended over the treadmill with a certain amount of their body weight off-loaded by the counterbalancing system. This system allows patients with neurologic impairment and limited mobility to practice walking in an upright position without the risk of falling. The initial amount of body weight support required is selected to allow patients to maintain an upright torso and to prevent knee buckling while standing. When necessary, movement of the lower extremities can be facilitated through therapist assistance or robotic assistance. Typically, therapist-assisted training involves 2 trainers positioned one at each lower limb to guide the patient through the proper walking kinematics. An additional therapist can be positioned behind the patient to assist in weight shifting and stabilization when necessary. Robotic-assisted gait training involves the use of a motorized orthosis, which is attached to the patients’ lower extremities. The gait orthosis assists patients in moving their lower limbs through proper gait cycle motions and is controlled by a computerized system. Studies of BWSTT have been conducted with patients with SCI, stroke, MS, and PD and have evaluated both therapist-assisted and robotic-assisted training regimes. For example, patients with PD participated in 12 sessions (45 minutes per session) of robotic-assisted gait training or physiotherapy involving conventional gait training and active joint mobilization. Robot-assisted gait training was superior to conventional physiotherapy on outcomes of walking speed, walking endurance, and some spatiotemporal gait parameters.