Evaluation of Motor and Cognitive Performance in People with Parkinson's Disease Using Instrumented Trail-Making Test.

INTRODUCTION: Parkinson's disease (PD) progressively impairs motor and cognitive performance. The current tools to detect decline in motor and cognitive functioning are often impractical for busy clinics and home settings. To address the gap, we designed an instrumented trail-making task (iTMT) based on a wearable sensor (worn on the shin) with interactive game-based software installed on a tablet. The iTMT test includes reaching to 5 indexed circles, a combination of numbers (1-3) and letters (A&B) randomly positioned inside target circles, in a sequential order, which virtually appears on a screen kept in front of the participants, by rotating one's ankle joint while standing and holding a chair for safety. By measuring time to complete iTMT task (iTMT time), iTMT enables quantifying cognitive-motor performance. PURPOSE: This study's objective is to examine the feasibility of iTMT to detect early cognitive-motor decline in PDs. METHOD: Three groups of volunteers, including 14 cognitively normal (CN) older adults, 14 PDs, and 11 mild cognitive impaireds (MCI), were recruited. Participants completed MoCA, 20 m walking test, and 3 trials of iTMT. RESULTS: All participants enabled to complete iTMT with <3 min, indicating high feasibility. The average iTMT time for CN-Older, PD, and MCI participants were 20.9 ± 0.9 s, 32.3 ± 2.4 s, and 40.9 ± 4.5 s, respectively. After adjusting for age and education level, pairwise comparison suggested large effect sizes for iTMT between CN-older versus PD (Cohen's d = 1.7, p = 0.024) and CN-older versus MCI (d = 1.57, p < 0.01). Significant correlations were observed when comparing iTMT time with the gait speed (r = -0.4, p = 0.011) and MoCA score (r = -0.56, p < 0.01). CONCLUSION: This study demonstrated the feasibility and early results supporting the potential application of iTMT to determine cognitive-motor and distinguishing individuals with MCI and PD from CN-older adults. Future studies are warranted to test the ability of iTMT to track its subtle changes over time.

Robot-assisted gait training for patients with hemiparesis due to stroke.

Robot-assisted devices are becoming a popular alternative to manual facilitation in stroke rehabilitation. These devices have the potential to reduce therapist burden and treatment costs; however, their effectiveness in terms of functional recovery remains in question. This pilot study compared the outcomes of a stroke rehabilitation program that incorporates robot-assisted gait training (RAGT) with a more traditional therapy program that does not. Twenty hemiparetic stroke patients were recruited at a rehabilitation hospital in Houston, Texas, and were randomly assigned to 2 groups. The control group (n = 10) received 24 1-hour sessions of conventional physical therapy, whereas the RAGT group (n = 10) received 24 1-hour sessions of conventional physical therapy combined with RAGT on a treadmill. Gait function was assessed before and after treatment by an 8-m walk test, a 3-minute walk test, and the Tinetti balance assessment. Both groups showed significant improvement in all 3 outcome measures following treatment (P < .05), but there was no difference between groups. It is concluded that RAGT may provide improvements in balance and gait comparable with conventional physical therapy. A larger multicenter trial is required to investigate the effectiveness of RAGT in hemiparetic stroke.

The influence of dopaminergic medication on balance automaticity in Parkinson's disease.

BACKGROUND: Studies have shown that dual-task standing balance in Parkinson's disease (PD) is significantly diminished. Additionally, it is well accepted that dopaminergic medication improves dynamic balance (Berg Balance Scale, mini-BESTest), but standing balance (force platform posturography) may suffer. What remains unknown is how dopaminergic medication influences standing balance automaticity in PD. RESEARCH QUESTION: Does dopaminergic medication improve standing balance automaticity during a phoneme monitoring dual-task in PD? METHODS: This was a cross-sectional study. Sixteen subjects with PD completed single- and dual-task standing with eyes open and eyes closed for 3 min each in off and on medication states. 95% confidence ellipse area, anterior-posterior sway velocity, medial-lateral sway velocity, and integrated time to boundary were calculated. Data were analyzed with a repeated measures ANOVA. RESULTS: Dopaminergic medication significantly increased ellipse area (p = 0.002) and decreased the performance on the secondary task (p = 0.004). Different eyes conditions (open vs. closed) significantly increased both sway velocities (anterior-posterior = p < 0.001, medial-lateral = p < 0.001), and increased integrated time to boundary (p < 0.001). There were also task by eyes condition interaction effects for anterior-posterior velocity and integrated time to boundary (p = 0.015 and p = 0.009, respectively). Increases in sway velocity and integrated time to boundary seen in the eyes condition and interaction effects are traditionally interpreted as poorer balance performance. However, in the context of stability/maneuverability tradeoff, the changes may indicate an increase in freedom of movement instead of a decrease in stability. SIGNIFICANCE: The data did not support a medication-induced improvement in automaticity, as measured by significant medication by task interactions. An alternate interpretation for medication-induced balance changes in PD includes an increase in maneuverability without sacrificing stability after taking dopaminergic medication.

The influence of dopaminergic medication on gait automaticity in Parkinson's disease.

Dual-tasking studies have shown that gait automaticity in Parkinson's disease (PD) is significantly diminished. Additionally, it's well accepted that dopaminergic medication improves single-task gait. But, how dopaminergic medication influences gait automaticity in PD has not been sufficiently understood. This study was a cross-sectional design, where sixteen subjects with PD completed single- and dual-task walking for 3 min off and on medication. Gait velocity, cadence, and stride length were measured. Kinematic variables included mean, maximum, and SD angles of bilateral hip, knee, and shoulder joints. Data were analyzed with a repeated measures ANOVA and a linear mixed effects repeated measures model. Dopaminergic medication significantly increased gait velocity (p = 0.007) and stride length (p = 0.046). After controlling for gait velocity, several kinematic variables were also improved with medication. Despite medication state, dual-tasking significantly interfered with cadence (p = 0.042), stride length (p < 0.001), and some kinematic measures. Dopaminergic medication mostly increased the hip and knee joint angles, while dual-tasking primarily decreased the hip joint angles on the less PD-affected side. There was no significant interaction between medication status and task condition. The significant differences in dual-tasking between off- and on-medication states indicates that motor improvements from taking medications improved dual-tasking. However, the lack of significant interactions and secondary task effects does not support a medication-induced improvement in automaticity.

Rehabilitation of reaching and grasping function in severe hemiplegic patients using functional electrical stimulation therapy.

OBJECTIVE: The aim of this study was to establish the efficacy of a therapeutic intervention based on functional electrical stimulation (FES) therapy to improve reaching and grasping function after severe hemiplegia due to stroke. METHODS: A total of 21 subjects with acute stroke were randomized into 2 groups, FES plus conventional occupational and physiotherapy (FES group) or only conventional therapy (control group) 5 days a week for 12 to 16 weeks. A third group of 7 subjects with chronic hemiplegia (at least 5 months poststroke) received only FES therapy (chronic group) and pre-post training changes were compared. FES was applied to proximal and then distal muscle groups during specific motor tasks. At baseline and at the end of treatment, grasping function was assessed using the Rehabilitation Engineering Laboratory Hand Function Test, along with more standard measures of rehabilitation outcome. RESULTS: The FES group improved significantly more than the control group in terms of object manipulation, palmar grip torque, pinch grip pulling force, Barthel Index, Upper Extremity Fugl-Meyer scores, and Upper Extremity Chedoke-McMaster Stages of Motor Recovery. The chronic stroke subjects demonstrated improvements in most categories, but the changes were not statistically significant. CONCLUSIONS: FES therapy with upper extremity training may be an efficacious intervention in the rehabilitation of reaching and grasping function during acute stroke rehabilitation.

The effect of random modulation of functional electrical stimulation parameters on muscle fatigue.

Muscle contractions induced by functional electrical stimulation (FES) tend to result in rapid muscle fatigue, which greatly limits activities such as FES-assisted standing and walking. It was hypothesized that muscle fatigue caused by FES could be reduced by randomly modulating parameters of the electrical stimulus. Seven paraplegic subjects participated in this study. While subjects were seated, FES was applied to quadriceps and tibialis anterior muscles bilaterally using surface electrodes. The isometric force was measured, and the time for the force to drop by 3 dB (fatigue time) and the normalized force-time integral (FTI) were determined. Four different modes of FES were applied in random order: constant stimulation, randomized frequency (mean 40 Hz), randomized current amplitude, and randomized pulsewidth (mean 250 micros). In randomized trials, stimulation parameters were stochastically modulated every 100 ms in a range of +/-15% using a uniform probability distribution. There was no significant difference between the fatigue time measurements for the four modes of stimulation. There was also no significant difference in the FTI measurements. Therefore, our particular method of stochastic modulation of the stimulation parameters, which involved moderate (15%) variations updated every 100 ms and centered around 40 Hz, appeared to have no effect on muscle fatigue. There was a strong correlation between maximum force measurements and stimulation order, which was not apparent in the fatigue time or FTI measurements. It was concluded that a 10-min rest period between stimulation trials was insufficient to allow full recovery of muscle strength.

Validity and reliability of two protocols for measuring Reachable Workspace Volume in able-bodied and stroke subjects.

BACKGROUND: Researchers are measuring Reachable Workspace Volume (RWV) to assess the effects of various interventions on impaired upper extremity function. These measurement protocols have not been validated. OBJECTIVE: Assess the validity and reliability of two RWV protocols. METHODS: Fifteen able-bodied subjects and eight stroke subjects participated. Two RWV protocols (POLES and PLANES) were completed and compared with hemi-spheric volume estimations using the average reach in the Modified Functional Reach Test (MFRT). RWV, based on the movement of a single hand marker, was calculated using a 3D motion analysis system (Vicon, Centennial, CO, USA). Intraclass correlation coefficients (ICC) represented reliability, Pearson's linear correlation coefficient (r) between RWVs and MFRT represented validity, and p < 0.05 represented significant differences between the volumes. RESULTS: For the able-bodied subjects, the POLES protocol had excellent validity and excellent reliability, the PLANES protocol had good validity and excellent reliability, and both RWVs were significantly larger than estimated MFRT volume. In the stroke subjects, both protocols had good validity, excellent reliability, and RWVs which were significantly smaller than the estimated MFRT volume. CONCLUSIONS: Both measurement protocols provided valid and reliable measures of RWV. MFRT may underestimate RWV in able-bodied subjects, and overestimate RWV in stroke subjects.

A comprehensive three-dimensional dynamic model of the human head and trunk for estimating lumbar and cervical joint torques and forces from upper body kinematics.

Linked-segment representations of human body dynamics have been used extensively in biomechanics, ergonomics, and rehabilitation research to systemize thinking, make predictions, and suggest novel experiments. In the scope of upper body biomechanics, these models play an even more essential role as the human spine dynamics are difficult to study in vivo. No study exists to date, however, that specifically disseminates the technical details of a comprehensive three-dimensional model of the upper body for the purpose of estimating spinal joint torques and forces for a wide range of scenarios. Consequently, researchers are still bound to develop and implement their own models. Therefore, the objective of this study was to design a dynamic model of the upper body that can comprehensively estimate spinal joint torques and forces from upper body kinematics. The proposed three-dimensional model focuses on the actions of the lumbar and cervical vertebrae and consists of five lumbar segments (L1 to L5), the thorax, six cervical segments (C2 to C7), and the head. Additionally, the model: (1) is flexible regarding the kinematic nature of the spinal joints (free, constrained, or fixed); (2) incorporates all geometric and mass-inertia parameters from a single, high-resolution source; and (3) can be feasibly implemented via different inverse dynamics formulations. To demonstrate its practicality, the model was finally employed to estimate the lumbar and cervical joint torques during perturbed sitting using experimental motion data. Considering the growing importance of mathematical predictions, the developed model should become an important resource for researchers in different fields.

A complete, non-lumped, and verifiable set of upper body segment parameters for three-dimensional dynamic modeling.

Dynamic models of the human trunk have been extensively used to investigate the biomechanics of lower back pain and postural instability in different populations. Despite their diverse applications, previous models rely on intrinsic upper body segment parameters (UBSP), e.g., each segment's mass-inertia characteristics. However, a comprehensive UBSP set allowing state-of-the-art, three-dimensional (3D) dynamic modeling does not exist to date. Therefore, our objective was to establish a UBSP set of all vertebral trunk segments that is accurate and complete. Based on high-resolution, transverse color images, anatomical structures of the Male Visible Human (MVH) were digitally reconstructed via commercial software. Subsequently, we identified the 3D spinal joint and 3D center of mass coordinates, the mass, and the moment of inertia tensor for 24 vertebral trunk segments and 4 upper limb segments (two segments per arm). Since the MVH images are public domain, the parameters are uniquely verifiable and expandable to also include lower limb parameters. To demonstrate the UBSP set's practicality, the parameters were finally implemented in a previously proposed inverse dynamics model of the upper body. Our findings reveal that an accurate and complete UBSP set has been obtained that will be beneficial to (1) systemize thinking in postural control studies; (2) quantify the effect of impact forces on the head and trunk (e.g., during whiplash); (3) suggest population-specific experiments based on theoretical insights into trunk dynamics (e.g., regarding lower back pain); or (4) assess the feasibility of new surgical techniques (e.g., spinal fusion) and neuroprostheses (e.g., after spinal cord injury).

Responses of the trunk to multidirectional perturbations during unsupported sitting in normal adults.

Understanding how the human body responds to unexpected force perturbations during quiet sitting is important to the science of motor behavior and the design of neuroprostheses for sitting posture. In this study, the performance characteristics of the neck and trunk in healthy individuals were assessed by measuring the kinematic responses to sudden, unexpected force perturbations applied to the thorax. Perturbations were applied in eight horizontal directions. It was hypothesized that displacement of the trunk, settling time and steady-state error would increase when the perturbation direction was diagonal (i.e., anterior-lateral or posterior-lateral) due to the increased complexity of asymmetrical muscle responses. Perturbation forces were applied manually. The neck and trunk responded in a synchronized manner in which all joints achieved peak displacement simultaneously then returned directly to equilibrium. Displacement in the direction of perturbation and perpendicular to the direction of perturbation were both significantly greater in response to diagonal perturbations (p<.001). The center of mass returned to equilibrium in 3.64±1.42 s after the onset of perturbation. Our results suggest that the trunk sometimes behaves like an underdamped oscillator and is not controlled by simple stiffness when subjected to loads of approximately 200 N. The results of this study are intended to be used to develop a neuroprosthesis for artificial control of trunk stability in individuals with spinal cord injury.

Postural reactions of the trunk muscles to multi-directional perturbations in sitting.

BACKGROUND: The dynamic role of the trunk musculature, with respect to stability, has not been fully explored to date. The purpose of this study was, using a transient and multi-directional perturbation, to: (1) quantify the tonic level of activity in the superficial trunk musculature prior to any perturbation; (2) quantify the phasic activity in those same muscles following application of a transient, horizontally directed load; and (3) quantify the direction-dependent behavior of this phasic response. METHODS: Twelve healthy individuals were perturbed during sitting via a chest harness in eight horizontal directions. Surface electromyograms were measured bilaterally from the abdominal (rectus abdominis, internal and external obliques) and back musculature (thoracic and lumbar erector spinae) to determine the tonic muscle activity prior to perturbation, and the phasic response following perturbation. A descriptive model was used to characterize the relationship between the phasic response of the muscles due to perturbation and the pulling direction. FINDINGS: Tonic activity in the trunk musculature in upright sitting is low, but still above resting levels by at about 1-3% of the MVC for the abdominal muscles, and 4-6% for the back muscles. Each trunk muscle also showed a direction-specific, phasic activation in response to perturbation, above these tonic levels of activation. This phasic activation was accurately modeled using a descriptive model for each muscle. INTERPRETATION: The obtained muscle activation level and the identified descriptive model will be applied in the design of a closed-loop controller for functional electrical stimulation.

Neuroprosthesis for retraining reaching and grasping functions in severe hemiplegic patients.

During the course of rehabilitation hemiplegic patients who have Chedoke McMaster Stages of Motor Recovery scores 4 and 5 measured three weeks after onset of stroke often improve their arm and hand function to the point that they can later use it in the activities of daily living (ADL) (1). These patients can be considered to have mild arm and hand paralysis since they can grasp objects and manipulate them with minor restrictions in the range of movement and force. On the other hand, hemiplegic patients who have Chedoke McMaster Stages of Motor Recovery scores 1 and 2 measured three weeks after onset of stroke, during the course of rehabilitation seldom improve their arm and hand function, and when they do, the improvements are not sufficient to allow these patients to use the arm and hand in ADL (1). These patients can be also described as patients who have severe arm and hand paralysis. Patients with severe arm and hand paralysis cannot move their arm and hand voluntarily at all or have very limited voluntary movements that cannot be used to carry out ADL. In recent years a variety of treatments such as constraint induced therapy, functional electrical therapy, biofeedback therapy, and robotics assisted therapies, were proposed which main objective is to improve reaching and grasping functions in subjects with unilateral arm paralysis. These therapies have shown encouraging results in patients with mild arm and hand paralysis. However, the efficacy of these therapies was limited when they were applied to patients with severe arm and hand paralysis. This article describes a new rehabilitation technique that can improve both reaching and grasping functions in hemiplegic patients with severe unilateral arm paralysis. A neuroprosthesis that applies surface electrical stimulation technology was used to retrain hemiplegic patients who had severe arm and hand paralysis to reach and grasp. The neuroprosthesis was applied both to acute and long-term hemiplegic patients. Patients who were treated with the neuroprosthesis were compared to those patients who were administered only standard physiotherapy and occupational therapy appropriate for hemiplegic patients with unilateral upper extremity paralysis (controls). The treated and control patients had approximately the same time allocated for arm and hand therapy. After the treatment program was completed, the patients treated with the neuroprosthesis significantly improved their reaching and grasping functions and were able to use them in ADL. However, the majority of the control patients did not improve their arm and hand functions significantly and were not able to use them in ADL.