Postural perturbations induced by a moving virtual environment are reduced in persons with brain injury when gripping a mobile object.

BACKGROUND AND PURPOSE: Gripping a mobile (unfixed) object increases standing postural stability in healthy individuals. We tested whether the same strategy is effective for stabilizing upright posture perturbed by a moving environment (virtual perturbation) in participants with traumatic brain injury (TBI). METHODS: Fifteen participants with mild-to-moderate postural deficits after TBI and a comparison group of 15 age-matched healthy subjects participated in the study. Participants stood for 1 minute in front of a large screen with a projected three-dimensional image of a boat; for 30 seconds the boat remained stationary (no visual stimulation condition), and for 30 seconds the boat rocked on the water at a speed of 15°/s (visual stimulation condition). The visual stimulation was applied in pseudorandom order (during either the first or second half of the 1-minute trial). To analyze postural stability, the displacement and velocity of the center of mass in the sagittal and frontal planes were compared between groups and across 4 experimental conditions, including standing with/without visual stimulation and with/without gripping a 300-g object (short wooden stick) in the dominant hand. RESULTS: Participants with TBI showed greater instability under all experimental conditions. The visual stimulation significantly increased postural oscillations in the sagittal plane by 35% to 63% across groups. Gripping a stick significantly reduced the stimulation-induced instability in the sagittal plane by 19% to 29%, although not to the level of the no-stimulation condition in either group. CONCLUSION: The stabilizing effect of gripping an external object in participants with TBI was confirmed. A possibility of using this effect as a balance aid strategy requires further investigation.

Feasibility of using the NewGait assistive device for correcting gait deviations in individuals with various neurological disorders: Case study.

PURPOSE: Impaired gait is one of the earliest, most devastating, and long-lasting symptoms associated with neurological disorders. This study tested the feasibility of wearing the NewGait rehabilitative device in individuals with gait impairments due to the most common neurological disorders. METHODS: Seven participants with gait impairments due to strokes, Multiple Sclerosis, peripheral neuropathies, Cerebral Palsy (CP) and Parkinson's Disease (PD) were included in the study. Their walking with and without wearing the NewGait was analyzed and compared using the Vicon T160 system for motion analysis. Gait velocity, step length, foot clearance, lateral displacement of the Center of Mass, gait deviation and symmetry indexes were compared using two standard deviation band method for each participant. RESULTS: Participants subjectively assessed the NewGait as a comfortable device to wear and showed immediate gait improvements to varying degrees. Most improvements were observed in participants with muscle weakness due to peripheral neuropathies, stroke, MS, and CP. These participants improved their foot clearance, gait velocity, and step length. Participants with cerebellar stroke and PD increased their gait stability. All participants demonstrated a reduction in composite gait deviation indexes. Not all gait parameters, though, showed immediate changes. CONCLUSION: The results suggest that the NewGait rehabilitative device is feasible and useful for correcting gait impairments caused by neurological deficits. Participants may need to wear this device for longer periods of time in order to achieve long lasting changes in the gait pattern, rather than an immediate correction.

The NewGait Rehabilitative Device Corrects Gait Deviations in Individuals With Foot Drop.

The purpose of this quasiexperimental study was to test the effects of wearing the NewGait rehabilitative device on walking abilities in individuals with foot drop. The study involved 16 participants with foot drops caused by stroke (11 participants), multiple sclerosis (one participant), and peripheral neuropathies (four individuals). During a single testing session, participants walked 12 m at their self-selected speed in four experimental conditions: walking without any orthotic device; walking while wearing a regular plastic posterior leaf ankle foot orthosis (AFO); walking with the NewGait device assisting ankle dorsiflexion only; and walking with the NewGait device assisting the hip, knee, and ankle joint motions. Body motions during walking were recorded using a 3D system for motion analysis and analyzed with a set of spatiotemporal and kinematic parameters and a gait decomposition index. The gait decomposition index indicated sagittal interjoint coordination in the three joint pairs (hip-knee, knee-ankle, and hip-ankle) of the paretic (foot drop) leg during walking and was validated in a previous study. Overall, wearing all three orthotic devices improved the gait velocity, ankle dorsiflexion, and foot clearance compared to gait trials in which no assistive devices were used. However, wearing the AFO significantly restricted the plantarflexion range of motion and decreased interjoint coordination as measured by joint decomposition. In contrast, the NewGait device altered the ankle plantarflexion motions but also increased coordinated movement (reduced the decomposition) in most lower-extremity joint pairs and conditions. Therefore, the NewGait rehabilitative device can be considered superior to a regular AFO in correcting gait deviations caused by foot drop.

Bilateral coupling facilitates recovery of rhythmical movements from perturbation in healthy and post-stroke subjects.

The paretic arm of subjects with stroke has a decreased ability to quickly adapt to and recover from perturbations during rhythmical arm swinging. We investigated whether bilateral coupling in the synchronous motion of two arms may facilitate the restoration of rhythmical movement of the paretic arm in subjects with chronic hemiparesis due to stroke. While standing, stroke and age-matched healthy (control) subjects swung one or both arms synchronously at ~0.8 Hz from the shoulder joints. In randomly selected cycles, one arm was transiently arrested by an electromagnetic device when moving forward or backward. In the control group, bilateral swinging resumed faster than unilateral swinging regardless of which arm was perturbed. In the stroke group, this effect was observed only when the perturbation was applied to the paretic arm, suggesting that the motion of the non-paretic arm accelerated the recovery from perturbation of the paretic arm. In addition, bilateral swinging resumed after reduced anterior-posterior excursions of both arms in stroke subjects. Results confirm previous findings that bilateral swinging is normally guided by central changes in the referent configuration of the two arms that function as a single unit. As a consequence, both arms cooperate in recovery from perturbation of motion applied to one arm. Results also suggest that stroke-related brain damage alters the symmetry of bilateral interaction, resulting in deficits of inter-manual cooperative action. The involvement of the non-paretic arm could be beneficial for the recovery of swinging of both arms and may also facilitate movements of the paretic arm in certain tasks.

Does use of a virtual environment change reaching while standing in patients with traumatic brain injury?

BACKGROUND: Although numerous virtual reality applications have been developed for sensorimotor retraining in neurologically impaired individuals, it is unclear whether the virtual environment (VE) changes motor performance, especially in patients with brain injuries. To address this question, the movement characteristics of forward arm reaches during standing were compared in physical and virtual environments, presented at different viewing angles. METHODS: Fifteen patients with traumatic brain injuries (TBI) and 15 sex- and age-matched healthy individuals performed virtual reaches in a computer-generated courtyard with a flower-topped hedge. The hedge was projected on a flat screen and viewed in 3D format in 1 of 3 angles: 10° above horizon (resembling a real-world viewing angle), 50° above horizon, or 90° above horizon (directly overhead). Participants were instructed to reach with their dominant hand avatar and to touch the farthest flower possible without losing their balance or stepping. Virtual reaches were compared with reaches-to-point to a target in an equivalent physical environment. A set of kinematic parameters was used. RESULTS: Reaches by patients with TBI were characterized by shorter distances, lower peak velocities, and smaller postural displacements than reaches by control individuals. All participants reached ~9% farther in the VE presented at a 50° angle than they did in the physical environment. Arm displacement in the more natural 10° angle VE was reduced by the same 9-10% compared to physical reaches. Virtual reaches had smaller velocity peaks and took longer than physical reaches. CONCLUSION: The results suggest that visual perception in the VE differs from real-world perception and the performance of functional tasks (e.g., reaching while standing) can be changed in TBI patients, depending on the viewing angle. Accordingly, the viewing angle is a critical parameter that should be adjusted carefully to achieve maximal therapeutic effect during practice in the VE.

Development of a 3D immersive videogame to improve arm-postural coordination in patients with TBI.

BACKGROUND: Traumatic brain injury (TBI) disrupts the central and executive mechanisms of arm(s) and postural (trunk and legs) coordination. To address these issues, we developed a 3D immersive videogame--Octopus. The game was developed using the basic principles of videogame design and previous experience of using videogames for rehabilitation of patients with acquired brain injuries. Unlike many other custom-designed virtual environments, Octopus included an actual gaming component with a system of multiple rewards, making the game challenging, competitive, motivating and fun. Effect of a short-term practice with the Octopus game on arm-postural coordination in patients with TBI was tested. METHODS: The game was developed using WorldViz Vizard software, integrated with the Qualysis system for motion analysis. Avatars of the participant's hands precisely reproducing the real-time kinematic patterns were synchronized with the simulated environment, presented in the first person 3D view on an 82-inch DLP screen. 13 individuals with mild-to-moderate manifestations of TBI participated in the study. While standing in front of the screen, the participants interacted with a computer-generated environment by popping bubbles blown by the Octopus. The bubbles followed a specific trajectory. Interception of the bubbles with the left or right hand avatar allowed flexible use of the postural segments for balance maintenance and arm transport. All participants practiced ten 90-s gaming trials during a single session, followed by a retention test. Arm-postural coordination was analysed using principal component analysis. RESULTS: As a result of the short-term practice, the participants improved in game performance, arm movement time, and precision. Improvements were achieved mostly by adapting efficient arm-postural coordination strategies. Of the 13 participants, 10 showed an immediate increase in arm forward reach and single-leg stance time. CONCLUSION: These results support the feasibility of using the custom-made 3D game for retraining of arm-postural coordination disrupted as a result of TBI.

Reductions in Kinematics from Brassieres with Varying Breast Support.

Given the abundance of brassieres, manufacturers, and investigations of bras, it remains unclear whether the continued development of bras will provide many additional improvements in support. This study measured performance of sport bras including 4 popular bras and a new style bra at reducing breast motion during five common exercises. Bras demonstrated varying effectiveness and consistency across exercises at reducing undesirable breast motion, (hereafter referred to as kinematics). The new style bra significantly reduced vertical breast displacement and acceleration more consistently than other bras. When significant differences between bras were detected, the newer bra provided 31% greater reduction in vertical displacements and accelerations on average than other bras. Lateral reductions were smaller, less significant and no differences between bras were detected. When participants evaluated bras in terms of performance and ease of use, the newer bra was rated better than other bras by nearly a two to one ratio. There were no differences in how the bras felt, or in terms of pain and discomfort. Correlations between participant comfort and reductions in kinematics were weak and inconsistent. Results suggest continued bra development is possible in order to reduce undesirable motion especially in terms of reducing lateral motion. Additional investigation is required to examine the mechanistic reasons why bras improve comfort and potentially performance.

New approach for evaluating the effectiveness of whole-body magnetic field therapy in the rehabilitation of patients with lumbar discectomy.

OBJECTIVE: Magnetic field therapy involves the application of low-intensity magnetic fields (1-3.5 mT) to a patient's whole body. The purpose of this study was to assess the effectiveness of whole-body magnetic field (WBMF) therapy in the early rehabilitation of patients after lumbar discectomy. METHODS: A convenience sample of 73 patients who underwent lumbar discectomy within 1 month previously participated in the study. All patients were randomly assigned to one of two groups and received either a course of conventional rehabilitation (control group) or conventional rehabilitation together with 10 sessions of WBMF therapy (WBMF group). Participants were evaluated before and after the rehabilitation course by using the Visual Analog Scale for Pain (VAS) and thermal infrared imaging. The latter was used to detect pathological changes in temperature (hyperthermia and thermal asymmetry) of the surface of the skin overlying the lumbar spine and lower extremities. RESULTS: The VAS score of the WBMF group decreased from 6.2 ± 0.3 cm before to 3.2 ± 0.2 cm after rehabilitation (p< 0.01), compared to 6.1 ± 0.4 cm before to 4.3 ± 0.2 cm after rehabilitation for the control group (p< 0.05). Reduction of the area of lumbar hyperthermia was observed in 88% of WBMF and 35% of control group patients. CONCLUSIONS: When combined with conventional rehabilitation, WBMF therapy was effective in reducing lumbar pain, temperature, and, possibly, inflammation. Results of this study will be used for designing a large-scale clinical trial.

Effects of Navigated Repetitive Transcranial Magnetic Stimulation After Stroke.

PURPOSE: The purpose of this study was to test the effects of navigated repetitive transcranial magnetic stimulation, delivered in different modes, on motor impairments and functional limitations after stroke. METHODS: The study sample included 42 patients (58.5 ± 10.7 years; 26 males) who experienced a single unilateral stroke (1-12 months previously) in the area of the middle cerebral artery. Patients completed a course of conventional rehabilitation, together with 10 sessions of navigated repetitive transcranial magnetic stimulation or sham stimulation. Stimulation was scheduled five times a week over two consecutive weeks in an inpatient clinical setting. Patients were randomly assigned to one of four groups and received sham stimulation (n = 10), low-frequency (1-Hz) stimulation of the nonaffected hemisphere (n = 11), high-frequency (10-Hz) stimulation of the affected hemisphere (n = 13), or sequential combination of low- and high-frequency stimulations (n = 8). Participants were evaluated before and after stimulation with clinical tests, including the arm and hand section of the Fugl-Meyer Assessment Scale, modified Ashworth Scale of Muscle Spasticity, and Barthel Index of Activities of Daily Living. RESULTS: Participants in the three groups receiving navigated repetitive transcranial magnetic stimulation showed improvements in arm and hand functions on the Fugl-Meyer Stroke Assessment Scale. Ashworth Scale of Muscle Spasticity and Barthel Index scores were significantly reduced in groups receiving low- or high-frequency stimulation alone. CONCLUSIONS: Including navigated repetitive transcranial magnetic stimulation in a conventional rehabilitation program positively influenced motor and functional recovery in study participants, demonstrating the clinical potential of the method. The results of this study will be used for designing a large-scale clinical trial.

Decomposition of postural movements in individuals with mild TBI while reaching to intercept a moving virtual target.

The study analyzed postural and arm movement coordinations in patients with traumatic brain injury (TBI) while standing and reaching for a target moving in a 3D virtual environment. Thirteen individuals with mild TBI and 13 height, sex, and age-matched healthy control individuals were involved. While standing in front of the screen, the participants interacted with the projected environment by reaching for virtual targets. Coordination was analyzed as the percentage of reach-to-intercept cycle time during which their movement toward the target was decomposed with 0% indicating simultaneous motion in three planes or 100% indicating motion in one or two planes only. Decomposition was calculated for the postural movements (DIp), arm movements (DIa), and arm-postural coordination (DIa-p). The latter index represented the percentage of reach-to-intercept cycle time during which either the posture or arm moved alone. DIp and DIa-p were larger in the TBI group compared to the control group (p < 0.01). In the TBI group, DIp and DIa-p correlated negatively with postural stability (r = - 0.71 and r = - 0.60; p < 0.01). Results suggest that individuals with TBI decompose postural and arm-postural coordinations during a reach-to-intercept task. This may be either a result of impaired postural control or an effort to compensate for instability. These abnormalities should be taken into consideration while planning physical therapy programs for individuals after brain injury.

Enhanced arm swing alters interlimb coordination during overground walking in individuals with traumatic brain injury.

The current study investigated interlimb coordination in individuals with traumatic brain injury (TBI) during overground walking. The study involved 10 participants with coordination, balance, and gait abnormalities post-TBI, as well as 10 sex- and age-matched healthy control individuals. Participants walked 12m under two experimental conditions: 1) at self-selected comfortable walking speeds; and 2) with instructions to increase the amplitude and out-of-phase coordination of arm swinging. The gait was assessed with a set of spatiotemporal and kinematic parameters including the gait velocity, step length and width, double support time, lateral displacement of the center of mass, the amplitude of horizontal trunk rotation, and angular motions at shoulder and hip joints in sagittal plane. Interlimb coordination (coupling) was analyzed as the relative phase angles between the left and right shoulders, hips, and contralateral shoulders and hips, with an ideal out-of-phase coupling of 180° and ideal in-phase coupling of 0°. The TBI group showed much less interlimb coupling of the above pairs of joint motions than the control group. When participants were required to increase and synchronize arm swinging, coupling between shoulder and hip motions was significantly improved in both groups. Enhanced arm swinging was associated with greater hip and shoulder motion amplitudes, and greater step length. No other significant changes in spatiotemporal or kinematic gait characteristics were found in either group. The results suggest that arm swinging may be a gait parameter that, if controlled properly, can improve interlimb coordination during overground walking in patients with TBI.

Physical therapy for correcting postural and coordination deficits in patients with mild-to-moderate traumatic brain injury.

The purpose of this study was to test the effects of a conventional exercise program designed for correcting postural and coordination abnormalities in patients with mild-to-moderate traumatic brain injury (TBI). Using principles of motor learning applied to functional exercise training, exercises were performed while lying, sitting, standing and walking, with the goal of improving intra- and inter-limb coordination in the upper and lower extremities, postural stability and gait pattern. Twenty-two participants with TBI-related deficits received therapy in a supervised outpatient clinic. Therapy included 20 sessions, each approximately 55 to 60 min in duration, scheduled four to five times a week over four consecutive weeks. Each participant was evaluated with a battery of clinical tests at baseline and immediately after therapy. Upon completion of the therapy, participants improved static and dynamic postural stability and gait, evaluated with the Berg Balance Scale (from 45.2 ± 5.9 to 49.2 ± 4.2 points) and the Functional Gait Assessment (from 22.8 ± 4.1 to 26.9 ± 3.4 points). They also reduced truncal, upper and lower extremity ataxia, evaluated with the Ataxia Scale (from 7.3 ± 4.5 to 5.9 ± 4.2 points). Results will be used to refine the current version of the exercise therapy, which focused on whole body coordination and balance, and to design a large-scale clinical trial establishing effectiveness of this intervention and for comparison with other forms of therapy.

Postural stabilization by gripping a stick with different force levels.

Hand contact with a stationary surface reduces postural sway in healthy individuals even when the level of force applied is mechanically insufficient. To make this phenomenon more applicable to a real-life situation, where a stationary support is not available, a mobile stick was used to measure and control grip force. The effect of a supra-postural task of stick gripping on stability was tested in 18 healthy individuals during quiet standing, standing in semi-tandem, and with eyes closed. Subjects stood either holding no haptic stick, or gripping with one of six force levels ranging from 1 to 9N and a self-selected force in the same range. The path length and velocity of the center of pressure (COP) were measured and compared within and between experimental conditions. Gripping the stick reduced the COP path length and velocity by up to 23% and 25%, respectively, and postural stability was increased at all force levels, including self-selected. The results confirmed the stabilizing effects of gripping an external portable object regardless of the amount of force applied. This knowledge may be useful for counseling people on prevention of stability loss in real life situations where balance is challenged.

Challenging stability limits in old and young individuals with a functional reaching task.

OBJECTIVES: The aim of this study was to evaluate the extent to which adding a challenge to a reach test would increase the limit of stability (LOS) in young and old individuals. DESIGN: While standing on a force plate, with infrared markers on bony landmarks for motion analysis, 15 old (mean [SD], 70 [7] yrs old) and 15 young (mean [SD], 24 [2] yrs old) participants completed the modified functional reach test, in which they were asked to touch the farthest target possible in a series. They were then challenged to touch additional targets (functional reach challenge test) until they lost balance. RESULTS: The young participants reached farther than the old participants on both the modified functional reach and functional reach challenge tests (P = 0.005 and P = 0.003), but no group differences were found in absolute distance gains seen with the addition of the challenge. The participants in both groups displaced the center of pressure farther and used 10% more of their anatomic stability allowance in the functional reach challenge test than in the modified functional reach test. The young participants increased the LOS from 80.5% to 90.9% of their anatomic allowance, whereas the old participants increased theirs from 72.1% to 82.8%. CONCLUSIONS: The challenge improved reaching and LOS similarly in the young and old participants, but the old participants used smaller absolute percentages of LOS. Knowing the flexibility of LOS is useful for rehabilitation practitioners in assessing balance and designing therapeutic exercises that challenge stability during performance of functional arm movements and train individuals to use their LOS safely.

Cognitive ability predicts motor learning on a virtual reality game in patients with TBI.

BACKGROUND: Virtual reality games and simulations have been utilized successfully for motor rehabilitation of individuals with traumatic brain injury (TBI). Little is known, however, how TBI-related cognitive decline affects learning of motor tasks in virtual environments. OBJECTIVE: To fill this gap, we examined learning within a virtual reality game involving various reaching motions in 14 patients with TBI and 15 healthy individuals with different cognitive abilities. METHODS: All participants practiced ten 90-second gaming trials to assess various aspects of motor learning. Cognitive abilities were assessed with a battery of tests including measures of memory, executive functioning, and visuospatial ability. RESULTS: Overall, participants with TBI showed both reduced performance and a slower learning rate in the virtual reality game compared to healthy individuals. Numerous correlations between overall performance and several of the cognitive ability domains were revealed for both the patient and control groups, with the best predictor being overall cognitive ability. CONCLUSIONS: The results may provide a starting point for rehabilitation programs regarding which cognitive domains interact with motor learning.

A pointing task to improve reaching performance in older adults.

OBJECTIVE: The objective of this study was to evaluate whether adding a pointing task would influence functional reach test performance in younger and older adults. DESIGN: While standing on a force plate, 20 older (73 ± 8 yrs) and 20 younger (23 ± 1 yrs) adults were randomly administered a modification of the functional reach test and the functional point test. Functional pointing involved reaching and pointing at the farthest possible target in a series of 1.27-cm colored craft pom-poms attached at 2.54-cm intervals on a yardstick. RESULTS: Both older adults (P = 0.001) and younger adults (P = 0.043) reached farther using the functional point test. Older adults also increased their anterior center of pressure displacement with this test (P = 0.037). CONCLUSIONS: The addition of a pointing task can make the original clinical test more functional and increase reaching distance in both older and younger adults. Further research is needed to determine whether functional pointing challenges subjects' stability limits more than the traditional test does and offers greater sensitivity in the evaluation of functional balance and fall risk.

Central resetting of neuromuscular steady states may underlie rhythmical arm movements.

Changing the steady-state configuration of the body or its segments may be an important function of central pattern generators for locomotion and other rhythmical movements. Thereby, muscle activation, forces, and movement may emerge following a natural tendency of the neuromuscular system to achieve the current steady-state configuration. To verify that transitions between different steady states occur during rhythmical movements, we asked standing subjects to swing one or both arms synchronously or reciprocally at approximately 0.8 Hz from the shoulder joints. In randomly selected cycles, one arm was transiently arrested by an electromagnetic device. Swinging resumed after some delay and phase resetting. During bilateral swinging, the nonperturbed arm often stopped before resuming swinging at a position that was close to either the extreme forward or the extreme backward arm position observed before the perturbation. Oscillations usually resumed when both arms arrived at similar extreme positions when a synchronous bilateral pattern was initially produced or at the opposite positions if the initial pattern was reciprocal. Results suggest that a central generator controls both arms as a coherent unit by producing transitions between its steady state (equilibrium) positions. By controlling these positions, the system may define the spatial boundaries of movement. At these positions, the system may halt the oscillations, resume them at a new phase (as observed in the present study), or initiate a new motor action. Our findings are relevant to locomotion and suggest that walking may also be generated by transitions between several equilibrium configurations of the body, possibly accomplished by modulation and gating of proprioceptive reflexes.

Disruption of coordination between arm, trunk, and center of pressure displacement in patients with hemiparesis.

To determine how arm movements influence postural sway in the upright position after stroke, interactions between arm, trunk, and center of pressure (CoP) displacements in the sagittal direction were investigated in participants with hemiparesis and healthy subjects. Participants swung both arms sagittally in either of 2 directions (in-phase, anti-phase) and at 2 speeds (preferred, fast) while standing on separate force plates. Variables measured included amplitude and frequency of arm swinging, shoulder and trunk range of motion, CoP displacements under each foot and of the whole body, and the relationships between the arm, trunk, and CoP displacements. CoP displacements under the non-paretic leg were greater than those under the paretic leg, which may in part be related to the larger amplitude of swinging of the non-paretic arm. CoP displacements under each foot were not related to arm swinging during in-phase swinging at the preferred speed in healthy subjects. When speed of arm swinging was increased, however, the CoP moved in a direction opposite to the arm movement. In contrast, in individuals with hemiparesis, CoPs and arms moved in the same direction for both speeds. During anti-phase swinging in healthy subjects, the trunk counterbalanced the arm movements, while in participants with hemiparesis, the trunk moved with the affected arm. Results show that stroke resulted in abnormal patterns of arm-trunk-CoP interactions that may be related to a greater involvement of the trunk in arm transport, an altered pattern of coordination between arm and CoP displacements, and an impaired ability of the damaged nervous system to adapt postural synergies to changes in movement velocity.