The effects of auditory startle and nonstartle stimuli on step initiation in Parkinson's disease.

BACKGROUND: Auditory external cues enhance step initiation in Parkinson's disease (PD) patients. We wanted to explore whether a startle reaction has a comparable effect on step initiation in PD. METHODS: Thirteen PD patients and 13 aged-matched controls participated in this study. Electromyography pattern and onset toe-off time during a step initiation task were recorded in response to three different stimuli: a visual imperative stimulus; visual stimulus simultaneous with a nonstartle auditory stimulus and with a startle auditory stimulus. RESULTS: In all subjects, onset of tibialis anterior was faster in the startle auditory condition, compared with the nonstartle auditory condition. However, in the patient group, there was no difference in onset of soleus and toe-off between the startle and nonstartle conditions. CONCLUSIONS: Startle reaction in PD patients demonstrates a disordered coupling between the anticipatory postural adjustments that initiate the weight shift and the movement to initiate toe-off during step initiation.

Postural Stability and Cognitive Performance of Subjects With Parkinson's Disease During a Dual-Task in an Upright Stance.

BACKGROUND: The reviewed studies on center of pressure (COP) displacement in Parkinson's disease (PD) subjects show important methodological differences and contradictory results with regard to healthy subjects. The dual-task paradigm method has been used to examine cognitive prioritization strategies to control concurrent postural and cognitive tasks. The motor requirements, such as pronouncing words, involved in the cognitive tasks used in double-task conditions could be related to the heterogeneity of the results. RESEARCH OBJECTIVE: To compare postural sway and cognitive performance in subjects with PD and controls using a dual-task paradigm with a cognitive task free of motor demands. We tried to examine the prioritization strategy of PD patients regarding healthy adults to control for concurrent postural and cognitive tasks. MATERIALS AND METHODS: 25 subjects with PD and 20 healthy controls carried out a postural task under both single-task and dual-task conditions. The postural task was to stand as still as possible, with eyes first open and then closed. The dual-task condition added a concurrent cognitive task based on phoneme monitoring. COP displacement variables and cognitive performance were compared between the groups and within-subject factors were also examined. RESULTS: PD participants showed higher COP displacement results than the controls. All participants shortened the mean sway radius in dual-task conditions compared with single-task conditions; only healthy subjects presented less transversal COP sway in dual-task conditions than in single-task conditions. The cognitive performance of PD patients on a phoneme monitoring task worsened when they carried it out while maintaining balance in a standing position compared to sitting. The opposite effect occurred in control subjects. CONCLUSION: This study confirms the negative influence of Parkinson's disease on the control of standing stability, increasing the COP sway amplitude. The attentional demands of a postural task, such as standing balance, may be greater in PD patients than in healthy subjects. This would affect the performance of patients during dual-task conditions to be able to control a postural task while performing other cognitive tasks. In these conditions, cognitive performance would be negatively affected. These results suggest that subjects with PD, at least during initial disease stages, prioritize postural control over other concurrent tasks, as is also seen in healthy subjects.

Effect of Treadmill Walking on Leg Muscle Activation in Parkinson's Disease.

Treadmills are often used as rehabilitation devices to improve gait in Parkinson's disease (PD). Kinematic differences between treadmill and overground gait have been reported. However, electromyographic (EMG) patterns during treadmill and overground walking have not been systematically compared. The aim of this study was to assess the effects of treadmill gait on the magnitude of the EMG activity of the lower limb muscles in PD. We measured EMG activity of the tibialis anterior, gastrocnemius medialis, vastus lateralis, and biceps femoris of nine individuals with PD and nine healthy matched controls. Comparisons between walking overground with walking on a treadmill and with walking with a treadmill simulator were carried out. The treadmill simulator is a device that simulates treadmill conditions with the exception of the belt. Our results have shown that treadmill walking is associated with several EMG differences compared with overground walking. The key finding of the study is that coactivation of the thigh muscles was significantly decreased (37%; p = 0.008) in PD subjects when walking on the treadmill in comparison with overground walking. The changes observed in the coactivation level may be related to the belt movement, since no changes were reported during walking with the treadmill simulator. Understanding the differences between treadmill and overground gait as well as the mechanisms that result in improvement of gait disturbances may optimize rehabilitative protocols for patients with PD.

A Therapeutic Exercise Program Improves Pain and Physical Dimension of Health-Related Quality of Life in Young Adults: A Randomized Controlled Trial.

OBJECTIVE: The aim of this study was to evaluate the effects of an exercise therapy program on pain and physical dimension of health-related quality of life for young adults with musculoskeletal pain. DESIGN: This is a randomized controlled single-blind trial. Fifty-seven subjects (58% women) were randomly assigned to experimental [n = 28, 21.4 (2.9) yrs] and control [n = 29, 21.0 (4.2) yrs] groups. The experimental group participated in a 9-wk stabilization exercise therapy program, 60 mins/wk, whereas the control group did not exercise, with a preintervention and postintervention assessment. Primary outcome was Physical Component Summary of SF-36. Secondary outcomes were Nordic Musculoskeletal Questionnaire, Visual Analogue Scale, Oswestry Disability Index, Neck Disability Index, and Trunk Flexor Endurance Test. The Shapiro-Wilk, independent t test or Mann-Whitney U test, X, or Fisher's exact test were used for statistical analysis. RESULTS: After intervention, the experimental group improved by 3.2 (4.5) points on the Physical Component Summary (P = 0.01), decreased prevalence of low back pain in the last month (P = 0.02) and cervical disability (P = 0.02), and increased flexor trunk endurance (P = 0.005). CONCLUSIONS: This study confirmed that a 9-wk progressive exercise therapy program can improve physical health and reduce the prevalence of cervical disability and low back pain in the last month in young adults with musculoskeletal pain.

Acute kinematic and neurophysiological effects of treadmill and overground walking in Parkinson's disease.

BACKGROUND: The use of the treadmill as a gait rehabilitation tool has provided novel options for treatment of gait impairments in Parkinson's Disease (PD). However, the neural mechanisms underlying these therapeutic effects in PD remain unknown and whether any therapeutic effects from treadmill training can be reproduced on overground walking. OBJECTIVE: To examine the immediate short-term effects of a single session of treadmill and overground walking on gait, spinal and corticospinal parameters in PD.METHODSPD participants (N = 15) were evaluated in two separate sessions under two walking conditions: walking over a treadmill and walking overground. Overground walking performance, the Soleus H-reflex, Reciprocal Ia-Inhibition, Intracortical Facilitation (ICF) and Short Intracortical Inhibition (SICI), were evaluated before and after each condition. RESULTS: Gait speed and stride length improved in post-treadmill compared with pre-treadmill. No significant changes in these gait parameters were found for the pre vs. post-overground condition. ICF values and Hmax/Mmax ratio decreased after, compared with before, the two walking conditions. CONCLUSIONS: Treadmill walking, but not overground walking, lead to an improvement in the stride length and gait speed in the PD patients without evidence of different modulation on spinal and corticospinal parameters.

Treadmill walking in Parkinson's disease patients: adaptation and generalization effect.

We examined the adaptation and generalization effect of one familiarization treadmill walking session on gait in patients with Parkinson's disease (PD) with different degrees of disease severity. Eight moderate PD patients (Hoehn and Yahr stage 2-2.5), eight advanced PD patients (Hoehn and Yahr 3), and eight matched control subjects participated in this study. Subjects first walked overground on a 10-m walkway at a self-selected speed (pretreadmill). They then performed a 20-min treadmill training session, followed by three trials of overground walking (Post1, Post2, Post3). Cadence, step length, speed, and coefficient of variation of stride time (CV) were recorded. During the treadmill session the advanced PD patients significantly decreased their cadence (t = 3.9, P

Transcranial magnetic stimulation over dorsolateral prefrontal cortex in Parkinson's disease.

OBJECTIVE: Several studies have shown that repetitive transcranial magnetic stimulation (rTMS) over the dorsolateral prefrontal cortex (DLPFC) is effective in the treatment of depression in patients with Parkinson disease (PD). However, since research into the effect of this type of rTMS regime on motor function is limited, we studied the effect of rTMS over the DLPFC on the motor functions in PD patients. METHODS: Thirteen patients were randomly assigned into 2 groups, one receiving real-rTMS (90% of resting motor threshold, 10 Hz, 450 pulses-day for 10 consecutive days) over the DLPFC contralateral to the more affected side, and the other group receiving sham-rTMS. Assessment included a clinical motor evaluation using part III of the Unified Parkinson's Disease Rating Scale (UPDRS), and several motor tasks. The UPDRS was applied before and after 10 days of rTMS. Finger tapping, reach movement, grip movement and gait were measured in each session before and after the rTMS over the 10 day period. RESULTS: Statistical analysis (ANOVA for repeated measures; group *day *side *rTMS) only showed a significant effect for finger tapping, reach movement and gait for the factor day. No significant change was reported for the UPDRS in any group. CONCLUSIONS: Application of rTMS over the DLPFC as a 10 day course had no significant effect on motor functions and clinical motor status, and the improvement in performance of motor tasks can be attributed to the effects of practice. SIGNIFICANCE: rTMS over the DLPFC did not lead to any motor improvement in PD patients.

Treadmill Walking Combined With Anodal Transcranial Direct Current Stimulation in Parkinson Disease: A Pilot Study of Kinematic and Neurophysiological Effects.

OBJECTIVE: We tested the hypothesis that combining treadmill walking with transcranial direct current stimulation (tDCS) enhances the gait improvements associated with treadmill walking in Parkinson disease. We explored the effects of these combined methodologies on corticospinal parameters. DESIGN: Eighteen participants with Parkinson disease were evaluated under the following three conditions: treadmill walking alone (treadmill), treadmill walking combined with anodal tDCS (AtDCS+treadmill) delivered over the motor cortex, and treadmill walking combined with sham stimulation (StDCS+treadmill). Overground walking performance, soleus H-reflex, reciprocal Ia inhibition from the tibialis anterior to the soleus muscle, intracortical facilitation, and short intracortical inhibition of the tibialis anterior muscle, were measured before and after each treadmill condition. The soleus H-reflex and walking performance on the treadmill were also evaluated. RESULTS: All treadmill conditions improved walking performance and modulated spinal and corticospinal parameters in a similar way. However, AtDCS+treadmill lead to a different modulation of reciprocal Ia inhibition in comparison with the other treadmill conditions. CONCLUSIONS: A single session combining treadmill walking and anodal tDCS delivered over the motor cortex resulted in a specific modulation of the reciprocal Ia inhibition from the tibialis anterior to the soleus muscle. However, this acute effect did not result in improvements of gait parameters associated with treadmill walking in Parkinson disease.

Gait Pattern and Cognitive Performance During Treadmill Walking in Parkinson Disease.

OBJECTIVE: The aim of this study was to explore whether attentional demands are involved in gait improvements in Parkinson disease (PD) patients when they walk on a treadmill. DESIGN: Nineteen individuals with idiopathic PD and 19 age-matched healthy controls participated in this study. Participants walked on a treadmill and on overground under single task (walk only) and dual task (walk performing a simultaneous cognitive task) conditions. The dual-task paradigm was used to reveal the attention allocation behavior. Gait pattern and cognitive performance was measured. RESULTS: The PD group showed reduced gait variability when walking on a treadmill in comparison with overground. However, this reduction did not deteriorate during the dual task. Moreover, there were no differences in the cognitive performance between treadmill and overground walking. CONCLUSIONS: This study does not support the proposition attentional resource allocation as a possible mechanism for the treadmill-associated gait improvements observed in PD.

Spatiotemporal parameters of gait during treadmill and overground walking in Parkinson's disease.

Despite the increasing number of studies that have examined the therapeutic effect of treadmill training programs in Parkinson's disease (PD), there has been little research to evaluate the modifications of gait induced by treadmill walking. We investigated spatiotemporal differences between treadmill and overground walking in patients with PD. PD patients significantly increased their step length and step height; and reduced their cadence, step width and step width variability on the treadmill in comparison with walking overground. PD patients are able to attenuate their short shuffling steps when walking on a treadmill.

Treadmill training improves overground walking economy in Parkinson's disease: a randomized, controlled pilot study.

Gait disturbances are one of the principal and most incapacitating symptoms of Parkinson's disease (PD). In addition, walking economy is impaired in PD patients and could contribute to excess fatigue in this population. An important number of studies have shown that treadmill training can improve kinematic parameters in PD patients. However, the effects of treadmill and overground walking on the walking economy remain unknown. The goal of this study was to explore the walking economy changes in response to a treadmill and an overground training program, as well as the differences in the walking economy during treadmill and overground walking. Twenty-two mild PD patients were randomly assigned to a treadmill or overground training group. The training program consisted of 5 weeks (3 sessions/week). We evaluated the energy expenditure of overground walking, before and after each of the training programs. The energy expenditure of treadmill walking (before the program) was also evaluated. The treadmill, but not the overground training program, lead to an improvement in the walking economy (the rate of oxygen consumed per distance during overground walking at a preferred speed) in PD patients. In addition, walking on a treadmill required more energy expenditure compared with overground walking at the same speed. This study provides evidence that in mild PD patients, treadmill training is more beneficial compared with that of walking overground, leading to a greater improvement in the walking economy. This finding is of clinical importance for the therapeutic administration of exercise in PD.

The effect of alternating and biphasic currents on humans' wound healing: a literature review.

Although different types of currents, including bidirectional currents, have been used to promote healing, there is neither a summary about their effects nor consensus on best parameters to be used. The aim of this article is to provide an overview of current evidence on the effectiveness of bidirectional electrical stimulation on wound healing in accordance with the parameters used. Relevant articles were selected following a search of Medline, Cochrane, Embase, CINAHL, and PEDro for English, Spanish, Portuguese, Italian, or French articles published between 1980 and 2011. Ten trials and four case-series were found that deal with pressure ulcers, diabetic ulcers, venous ulcers, skin flaps, and amputation. Eight trials were of low-quality. Five of ten controlled trials found a statistically significant difference on wound healing, and another four trials found positive trends. Both of the two skin flap trials, one of two diabetic trials, and two of five pressure ulcer trials found a significant difference in bidirectional stimulated groups. Both TENS and NMES types of currents were used, but many parameters were not specified. In general, bidirectional currents appear to increase wound healing rates and reduce size of wounds, above all in skin flaps. However, there is a lack of well-designed studies on biphasic and alternating stimulation, and there is a need for improvement in description of parameters and in uniformity of nomenclature.

The effects of startle and non-startle auditory stimuli on wrist flexion movement in Parkinson's disease.

Startle stimuli lead to shorter reaction times in control subjects and Parkinson's disease (PD) patients. However, non-startle stimuli also enhance movement initiation in PD. We wanted to examine whether a startle-triggered movement would retain similar kinematic and EMG-related characteristics compared to one induced by a non-startle external cue in PD patients. In this study we investigated the electromyography pattern and the reaction time during a wrist flexion movement in response to three different stimuli: a visual imperative stimulus; visual stimulus simultaneous with a non-startle auditory stimulus and with a startle auditory stimulus. Ten PD patients and ten aged matched controls participated in this study. The reaction times were faster for startle and non-startle stimuli in comparison with the visual imperative stimulus, in both patients and control subjects. The startle cue induced a faster reaction than the non-startle cue. The electromyography pattern remained unchanged across the conditions. The results suggest that the startle reaction effect for upper limb movements are unimpaired in PD patients and has different characteristics than the effect of non-startle stimuli.

How does the treadmill affect gait in Parkinson's disease?

Parkinson's disease (PD) is clinically characterized by symptoms of akinesia, rigidity, and resting tremor, which are related to a dopaminergic deficiency of the nigrostriatal pathway. Disorders of gait are common symptoms of PD that affect the quality of life in these patients. One of the main focuses of physical rehabilitation in PD is to improve the gait deficits in the patients. In the last decade, a small number of studies have investigated the use of the treadmill for the rehabilitation of gait in PD patients. Although, the results of these studies are promising, the mechanisms underlying the therapeutic effect of the treadmill in PD are still largely unknown. This paper reviews 10 years of investigation of treadmill training in PD, focusing on the possible mechanisms involved in the therapeutic effect of the treadmill. Understanding these mechanisms may improve the prescription and design of physical therapy programs for PD patients.

Mechanisms involved in treadmill walking improvements in Parkinson's disease.

Patients with Parkinson's disease (PD) improve gait after treadmill training and while they are walking over the treadmill. However, the mechanisms of these improvements have not been addressed. We designed a treadmill simulator without a belt that could move on a walkway in a constant speed, in order to explore the mechanism underlying treadmill walking improvements in PD. All subjects were tested in three different sessions (treadmill, simulator(assisted) and simulator(not assisted)). In each session, subjects first walked overground and then walked using the treadmill or simulator with the hands over the handrails (simulator(assisted)) or with the hands free (simulator(not assisted)). Step length, cadence, double support time, swing time, support time and the coefficient of variation (CV) of step time and double support time were recorded. Over the treadmill PD patients increased their step length and reduced significantly their cadence and CV of double support time in comparison with overground walking. In the simulator(assisted) condition PD patients reduced significantly the CV of double support time in comparison with overground walking. With the simulator(not assisted) both groups decreased their step length and increased their cadence and CV of double support time, compared with walking overground. These findings suggest that the step length improvement observed in PD patients, walking over a treadmill, is due to the proprioceptive information generated by the belt movement, since no improvement was reported when patients using a treadmill simulator.