Learning a high-precision locomotor task in patients with Parkinson's disease

Avoiding Virtual Obstacles During Treadmill Gait in Parkinson's Disease

Falls often occur due to spontaneous loss of balance, but tripping over an obstacle during gait is also a frequent cause of falls (Sheldon, 1960; Stolze et al., 2004). Obstacle avoidance requires that appropriate modifications of the ongoing cyclical movement be initiated and completed in time. We evaluated the available response time to avoid a virtual obstacle in 26 Parkinson’s disease (PD) patients (in the off-medication state) and 26 controls (18 elderly and 8 young), using a virtual obstacle avoidance task during visually cued treadmill walking. To maintain a stable baseline of stride length and visual attention, participants stepped on virtual “stepping stones” projected onto a treadmill belt. Treadmill speed and stepping stone spacing were matched to overground walking (speed and stride length) for each individual. Unpredictably, a stepping stone changed color, indicating that it was an obstacle. Participants were instructed to try to step short to avoid the obstacle. By using an obstacle that appeared at a precise instant, this task probed the time interval required for processing new information and implementing gait cycle modifications. Probability of successful avoidance of an obstacle was strongly associated with the time of obstacle appearance, with earlier-appearing obstacles being more easily avoided. Age was positively correlated (p < 0.001) with the time required to successfully avoid obstacles. Nonetheless, the PD group required significantly more time than controls (p = 0.001) to achieve equivalent obstacle-avoidance success rates after accounting for the effect of age. Slowing of gait adaptability could contribute to high fall risk in elderly and PD. Possible mechanisms may include disturbances in motor planning, movement execution, or disordered response inhibition.

Treadmill training with additional body load: Effects on the gait of people with Parkinson's disease

Aim:

The aim of this study was to assess the effects of treadmill walking training with additional body load on the gait of people with moderate Parkinson's disease.

Methods:

Nine people with Parkinson's disease (Hoehn and Yahr Scale 2–3) and gait disturbance participated in this study. This study was an A1–B–A2 single-case. Phases A1 and A2 included 6 weeks of gait training on a treadmill with a 10% increase of normal body mass. Phase B included 6 weeks of conventional physical therapy (control condition). Measurements included ground reaction forces, spatiotemporal and kinematic variables during walking on the ground at baseline and after each phase.

Findings:

A significant increase in propulsive forces, stride length, speed, and maximum hip extension during stance were observed after the training programme. No changes in joint range of motion of ankle, knee, and hip were observed.

Conclusions:

Treadmill training with additional body load was associated with an improvement in important variables for the maintenance of a functional gait, and it is a promising alternative to optimise the rehabilitation process together with conventional physical therapy. However, further studies are needed.

Influence of visual feedback sampling on obstacle crossing behavior in people with Parkinson's disease

The purpose of the current study was to investigate the role of visual information on gait control in people with Parkinson's disease as they crossed over obstacles. Twelve healthy individuals, and 12 patients with mild to moderate Parkinson's disease, walked at their preferred speeds along a walkway and stepped over obstacles of varying heights (ankle height or half-knee height), under three visual sampling conditions: dynamic (normal lighting), static (static visual samples, similar to stroboscopic lighting), and voluntary visual sampling. Subjects wore liquid crystal glasses for visual manipulation. In the static visual sampling condition only, the patients with Parkinson's disease made contact with the obstacle more often than did the control subjects. In the successful trials, the patients increased their crossing step width in the static visual sampling condition as compared to the dynamic and voluntary visual sampling conditions; the control group maintained the same step width for all visual sampling conditions. The patients showed lower horizontal mean velocity values during obstacle crossing than did the controls. The patients with Parkinson's disease were more dependent on optic flow information for successful task and postural stability than were the control subjects. Bradykinesia influenced obstacle crossing in the patients with Parkinson's disease.

Gait disorders

This chapter deals with the neuronal mechanisms underlying impaired gait. The aim is, first, a better understanding of the underlying pathophysiology and, second, the selection of an adequate treatment. One of the first symptoms of a lesion within the central motor system perceived by patients is a movement disorder, which is most characteristic during locomotion, e.g. in patients suffering spasticity after stroke or a spinal cord injury or Parkinson disease. By the recording and analysis of electrophysiological and biomechanical signals during a movement, the significance of impaired reflex behavior or muscle tone and its contribution to the movement disorder can reliably be assessed. Adequate treatment should not be restricted to the correction of an isolated clinical sign but should be based on the mechanisms underlying the movement disorder that impairs the patient. Therapy should be directed toward functional training, which takes advantage of the plasticity of the nervous system. In the future a combination of repair and functional training will further improve the mobility of disabled patients.

Postural instability and gait impairment during obstacle crossing in Parkinson's disease

OBJECTIVE

To examine whether Parkinson's disease (PD) affects gait behavior and stability while walking over an obstacle.

DESIGN

Parallel group comparisons were completed in which participants completed 5 trials of normal walking and 5 trials of obstacle crossing while gait kinematics and kinetics were collected.

SETTING

University biomechanics laboratory.

PARTICIPANTS

Individuals with PD (n=10) and age- and sex-matched healthy older adults (n=10).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Gait parameters, obstacle clearance parameters, and center of mass motion were calculated during normal walking and obstacle crossing.

RESULTS

Results revealed that decrements in gait performance in individuals with PD were amplified during obstacle crossing, suggesting that due to disease-related degradation, individuals with PD chose a more conservative strategy for obstacle crossing. Moreover, an increased duration of single limb support (18% increase), a decrease in anteroposterior range of motion (20% decrease), and an increase in mediolateral range of motion (36% increase, though not significant) coupled with the reduction in the distance between the center of pressure and center of mass (mean of 21% decrease across toe-off and heel strike) and increase in margin of stability (31% increase at toe-off and 71% increase at heel strike) may suggest that deficits in muscle strength and balance may contribute to this impairment.

CONCLUSIONS

Persons with PD alter their behavior to reduce the mechanical demands and increase dynamic stability during obstacle avoidance tasks.

Partial dopamine depletion in MPTP-treated mice differentially altered motor skill learning and action control

Recent findings suggest that the neurotransmitter dopamine (DA) system plays a role in motor control and the acquisition of habits and skills. However, isolating DA-mediated motor learning from motor performance remains challenging as most studies include often severely DA-depleted mice. Using the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), we investigated the effect of various degrees of DA-depletion in mice on three tests of motor behaviors: the accelerating rotarod, wire suspension and pole tests. Three protocols were performed to decrease DA synthesis to various extents: 4 injections (i.p.) of 9 mg/kg in 1 day; 4 injections (i.p.) of 15 mg/kg in 1 day; or 5 injections (s.c.) of 30 mg/kg in 5 days. Severity of DA-depletion was assessed by the evaluation of tyrosine hydroxylase (TH) and dopamine transporter levels in the striatum using the Western blot technique. Mice were gathered into four different groups according their TH levels: mild, moderate, marked and severe. In these mice, the general motor abilities such as coordination, motion speed and muscular strength were relatively intact whereas impaired acquisition of skilled behavior occurred in mice with marked and severe reduction in TH levels. Marked and severely DA-depleted mice exhibited lower scores within the first trials of the first training day as well as a much slower progression in the following days on the accelerating rotarod. Based on these results, we conclude that the learning of a skilled behavior is more vulnerable to DA depletion than the DA-mediated control of motor activity.

Quadrupedal coordination of bipedal gait: implications for movement disorders

During recent years, evidence has come up that bipedal locomotion is based on a quadrupedal limb coordination. A task-dependent neuronal coupling of upper and lower limbs allows one to involve the arms during gait but to uncouple this connection during voluntarily guided arm/hand movements. Hence, despite the evolution of a strong cortico-spinal control of hand/arm movements in humans, a quadrupedal limb coordination persists during locomotion. This has consequences for the limb coordination in movement disorders such as in Parkinson's disease (PD) and after stroke. In patients suffering PD, the quadrupedal coordination of gait is basically preserved. The activation of upper limb muscles during locomotion is strong, similar as in age-matched healthy subjects although arm swing is reduced. This suggests a contribution of biomechanical constraints to immobility. In post-stroke subjects a close interactions between unaffected and affected sides with an impaired processing of afferent input takes place. An afferent volley applied to a leg nerve of the unaffected leg leads to a normal reflex activation of proximal arm muscles of both sides. In contrast, when the nerve of the affected leg was stimulated, neither on the affected nor in the unaffected arm muscles EMG responses appear. Muscle activation on the affected arm becomes normalized by influences of the unaffected side during locomotion. These observations have consequences for the rehabilitation of patients suffering movement disorders.

Effects of obstacle height on obstacle crossing in mild Parkinson's disease

The aim of this study was to compare the locomotor behavior of people with Parkinson's disease (PD) and healthy older adults during obstacle negotiation, both in the approaching and crossing phases. Twelve people with idiopathic PD, with mild to moderate disease, and 12 healthy individuals (CG) walked across an 8m pathway for three obstacle conditions: no obstacle, low obstacle and high obstacle. Each performed five trials for each obstacle condition. Performance was more disturbed for the high obstacle than the low obstacle. During the approach phase, people with PD demonstrated shorter stride length (F(1,22)=8.55, P=0.008) and greater stride duration (F(1,22)=7.371, P=0.013) than controls. Those with PD also increased their stance phase durations (F(1,22)=7.426, P=0.012) for both obstacle conditions, while the CG maintained comparable step durations for all conditions. For the crossing phase, people with PD demonstrated shorter step length (F(1,22)=9.699, P=0.005) over the obstacle. Leading limbs were closer to the obstacle, before and after crossing. Thus PD hypokinesia compromises the approach and crossing phases of obstacle negotiation.

Obstacle crossing in people with Parkinson's disease: foot clearance and spatiotemporal deficits

This study investigates the effects of Parkinson's disease (PD) on foot trajectories and spatiotemporal gait adaptations when approaching and stepping over a ground-based obstacle. Twenty people with mild-moderate PD and 20 age and sex matched controls walked 10 steps at their preferred speed along a walkway and stepped over an obstacle (height 10% of leg length × 600 mm × 10 mm). Control participants also performed trials at the same speed and step length as their matched PD participant. People with PD approached and stepped over the obstacle slower and with smaller steps, but had a similar foot clearance. Those with PD were also more likely to step on the obstacle because they did not place their foot close enough to the front of the obstacle before crossing it to accommodate for their reduced step length. During the lead limb crossing step, people with PD increased their step width, whereas controls maintained a narrow step width. These findings indicate that people with PD have difficulty lengthening their step over the obstacle rather than increasing foot height. Increasing step width is a possible compensation strategy used to overcome postural instability during obstacle crossing in those with PD.

Training of walking skills overground and on the treadmill: case series on individuals with incomplete spinal cord injury

BACKGROUND AND PURPOSE

Walking in the home and community is an important goal for individuals with incomplete spinal cord injury (iSCI). Walking in the community requires various skills, such as negotiating curbs, doors, and uneven terrain. This case report describes the use of a method to retrain walking overground that is intensive, variable, and relevant to daily walking (skill training). The aims of this case series were to determine the effectiveness of skill training in a small group of people with iSCI and to compare skill training with body-weight-supported treadmill training (BWSTT) in the same individuals.

CASE DESCRIPTION

Four individuals who were a median of 2.7 years (interquartile range [IQR]=12.8) after iSCI participated in alternating phases of intervention, each 3 months long. All patients started with BWSTT. Two patients subsequently engaged in skill training while the other 2 patients engaged in BWSTT, after which a third phase of intervention (opposite to the second) was repeated.

OUTCOMES

The Modified Emory Functional Ambulation Profile, the 10-Meter Walk Test, the 6-Minute Walk Test, the Berg Balance Scale, and the Activities-specific Balance Confidence Scale were administered before training, monthly throughout training, and 3 months after training.

DISCUSSION

Overall improvements in walking speed met or exceeded the minimal clinically important difference for individuals with iSCI (> or = 0.05 m/s), particularly during the skill training phase (skill training: median=0.09 m/s, IQR=0.13; BWSTT: median=0.01 m/s, IQR=0.07). Walking endurance, obstacle clearance, and stair climbing also improved with both types of intervention. Three of the 4 patients had retained their gains at follow-up (retention of walking speed: median=92%, IQR=63%). Thus, the findings suggest that skill training was effective in this small group of individuals.

Treadmill training for the treatment of gait disturbances in people with Parkinson's disease: a mini-review

This report reviews recent investigations of the effects of treadmill training (TT) on the gait of patients with Parkinson's disease. A literature search identified 14 relevant studies. Three studies reported on the immediate effects of TT; over-ground walking improved (e.g., increased speed and stride length) after one treadmill session. Effects persisted even 15 min later. Eleven longer-term trials demonstrated feasibility, safety and efficacy, reporting positive benefits in gait speed, stride length and other measures such as disease severity (e.g., Unified Parkinson's Disease Rating Scale) and health-related quality of life, even several weeks after cessation of the TT. Long-term carryover effects also raise the possibility that TT may elicit positive neural plastic changes. While encouraging, the work to date is preliminary; none of the identified studies received a quality rating of Gold or level Ia. Additional high quality randomized controlled studies are needed before TT can be recommended with evidence-based support.

Locomotion in Parkinson's disease: neuronal coupling of upper and lower limbs

Quadrupedal limb coordination during human walking was recently shown to be upregulated during obstacle stepping. An anticipatory activity of coupled cervico-thoraco-lumbar interneuronal circuits is followed by an appropriate executory activation of leg and arm muscles during task performance. This mechanism was studied in subjects with Parkinson's disease and age-matched controls walking on a treadmill with a randomly approaching obstacle. Spinal reflex (SR) responses, evoked by tibial nerve stimulation during mid-stance, were present in all arm and leg muscles investigated. They were larger before execution of obstacle avoidance compared with normal steps in both subject groups. The performance of obstacle stepping was slightly worse in Parkinson's disease than in control subjects. The anticipatory SR in the arm muscles prior to normal and obstacle steps was larger in Parkinson's disease compared with age-matched subjects, but smaller in the tibialis anterior. The arm and leg muscle activation was stronger during obstacle compared with normal swing but did not differ between Parkinson's disease and age-matched subjects. These observations indicate that quadrupedal limb coordination is basically preserved in Parkinson's disease subjects. Our data are consistent with the proposal that in Parkinson's disease subjects the enhanced anticipatory spinal neuronal activity (reflected in the SR) in the arm muscles is required to achieve an appropriate muscle activation for the automatic control of body equilibrium during the performance of the task. In the tibialis anterior the SR is attenuated presumably because of a stronger voluntary (i.e. cortical) control of leg movements.

Six weeks of intensive treadmill training improves gait and quality of life in patients with Parkinson's disease: a pilot study

OBJECTIVE

To evaluate the effects of 6 weeks of intensive treadmill training on gait rhythmicity, functional mobility, and quality of life (QOL) in patients with Parkinson's disease (PD).

DESIGN

An open-label, before-after pilot study.

SETTING

Outpatient movement disorders clinic.

PARTICIPANTS

Nine patients with PD who were able to ambulate independently and were not demented. Mean age was 70+/-6.8 years. Patients had mild to moderate PD (Hoehn and Yahr stage range, 1.5-3).

INTERVENTIONS

Patients walked on a treadmill for 30 minutes during each training session, 4 training sessions a week, for 6 weeks. Once a week, usual overground walking speed was re-evaluated and the treadmill speed was adjusted accordingly.

MAIN OUTCOME MEASURES

The 39-item Parkinson's Disease Questionnaire (PDQ-39), motor part of the Unified Parkinson's Disease Rating Scale (UPDRS), gait speed, stride time variability, swing time variability, and the Short Physical Performance Battery (SPPB).

RESULTS

A comparison of the measures taken before and after the treadmill intervention indicates general improvement. QOL, as measured by the PDQ-39, was reduced (improved) from 32 to 22 (P<.014). Parkinsonian symptoms, as measured by the UPDRS, decreased (improved) from 29 to 22 (P<.043). Usual gait speed increased from 1.11 to 1.26 m/s (P<.014). Swing time variability was lower (better) in all but one patient, changing from 3.0% to 2.3% (P<.06). Scores on the SPPB also improved (P<.008). Interestingly, many of the improvements persisted even 4 weeks later.

CONCLUSIONS

These results show the potential to enhance gait rhythmicity in patients with PD and suggest that a progressive and intensive treadmill training program can be used to minimize impairments in gait, reduce fall risk, and increase QOL in these patients.

Locomotor training in people with Parkinson disease

The purpose of this article is to consider the role of the physical therapist in locomotor training for people with Parkinson disease. The ways in which disease progression, medication status, environmental conditions, individual factors, and the goals of locomotor tasks contribute to clinical decision making are explored. Using the International Classification of Functioning, Disability and Health, gait training will be considered in relation to impairments of body structure and function, activity limitations, and participation restrictions in people who are newly diagnosed through to those with end-stage disease. Based on the principles of neural adaptation and clinical research findings, practical suggestions are made on how to provide the most efficient and effective physical therapy services at different stages of Parkinson disease.