A spatiotemporal analysis of gait freezing and the impact of pedunculopontine nucleus stimulation

Gait freezing is an episodic arrest of locomotion due to an inability to take normal steps. Pedunculopontine nucleus stimulation is an emerging therapy proposed to improve gait freezing, even where refractory to medication. However, the efficacy and precise effects of pedunculopontine nucleus stimulation on Parkinsonian gait disturbance are not established. The clinical application of this new therapy is controversial and it is unknown if bilateral stimulation is more effective than unilateral. Here, in a double-blinded study using objective spatiotemporal gait analysis, we assessed the impact of unilateral and bilateral pedunculopontine nucleus stimulation on triggered episodes of gait freezing and on background deficits of unconstrained gait in Parkinson’s disease. Under experimental conditions, while OFF medication, Parkinsonian patients with severe gait freezing implanted with pedunculopontine nucleus stimulators below the pontomesencephalic junction were assessed during three conditions; off stimulation, unilateral stimulation and bilateral stimulation. Results were compared to Parkinsonian patients without gait freezing matched for disease severity and healthy controls. Pedunculopontine nucleus stimulation improved objective measures of gait freezing, with bilateral stimulation more effective than unilateral. During unconstrained walking, Parkinsonian patients who experience gait freezing had reduced step length and increased step length variability compared to patients without gait freezing; however, these deficits were unchanged by pedunculopontine nucleus stimulation. Chronic pedunculopontine nucleus stimulation improved Freezing of Gait Questionnaire scores, reflecting a reduction of the freezing encountered in patients’ usual environments and medication states. This study provides objective, double-blinded evidence that in a specific subgroup of Parkinsonian patients, stimulation of a caudal pedunculopontine nucleus region selectively improves gait freezing but not background deficits in step length. Bilateral stimulation was more effective than unilateral

A Physical Exercise Program Using Music-supported Video-based Training in Older Adults in Nursing Homes Suffering from Dementia: A Feasibility Study

BACKGROUND: Motivation towards an exercise program is higher in a small group setting in comparison to individual therapy. Due to attentional problems, group exercises are difficult for people with Alzheimer disease (AD). This study evaluates the feasibility of a music-supported video-based group exercise program in older adults suffering from AD. METHODS: Five participants with moderate AD were recruited from a nursing home. A progressive physical exercise program using a video-based training with musical accompaniment was performed and digitally recorded to investigate the adherence and performed accuracy of the exercises. RESULTS: The overall participation during the exercises was 84.1%. The quality of the performance was for all exercises above the cut-off scores. CONCLUSION: A music-supported video-based group exercise program is feasible in persons with AD. The participants were motivated and the expectations towards the program increased over time. Music seemed an important factor for attention in participants with AD

Center of mass trajectories during turning in patients with Parkinson's disease with and without freezing of gait

BACKGROUND: Despite the strong relationship between freezing of gait (FOG) and turning in Parkinson's disease (PD), few studies have addressed specific postural characteristics during turning that might contribute to freezing. METHODS: Thirty participants with PD (16 freezers, 14 non-freezers) (all tested OFF medication) and 14 healthy controls walked 5 meters and turned 180° in a 3D gait laboratory. COM behavior was analyzed during four turning quadrants of 40° between 10° and 170° pelvic rotation and during 40° before actual FOG episodes. These pre-FOG segments were compared with similar turning sections in turns of freezers without FOG. Outcome parameters were turn time, COM distance, COM velocity, step width and the medial- and anterior COM position. RESULTS: Turn time was increased in freezers compared to non-freezers (p=.000). No differences were found regarding COM distance and velocity during turning quadrants between groups and between freezers' pre-FOG segments and similar turning segments without FOG. Medial COM deviation was reduced in PD patients compared to controls (p=.004), but no differences were found between freezers and non-freezers. In turns with freezing, turn time increased (p=.005) and step width decreased (p=.025) pre-FOG. Freezers also showed a less medial (p=.020) and more anterior (p=.016) COM position pre-FOG compared to turning sections without FOG. CONCLUSIONS: Our results revealed no subgroup differences in COM behavior during uninterrupted turning. However, we found a reduced medial deviation, a forward COM shift and a decreased step width in freezers just before FOG episodes. These abnormalities may play a causal role, as they could hamper stability and fluent weight shifting necessary for continued stepping during turning.publisher: Elsevier articletitle: Center of mass trajectories during turning in patients with Parkinson's disease with and without freezing of gait journaltitle: Gait & Posture articlelink: http://dx.doi.org/10.1016/j.gaitpost.2015.10.021 content_type: article copyright: Copyright © 2015 Elsevier B.V. All rights reserved.status: publishe

Unilateral Auditory Cueing to Improve Freezing During Turning in Parkinson's Disease

Objective: To investigate the effect of unilateral cueing on turning and freezing of gait (FOG) in Parkinson’s disease and explore the impact of disease dominance on these effects. Background: Freezers (FRs) increase their cadence during turning compared to non-freezers (nFRs)1 which can result in FOG. Cueing at -10% of preferred cadence can improve normal gait in FR2, but the influence on turning remains unknown. Methods: 12 FR and 11 nFR were matched for age, leg length, disease severity, duration and amount of disease-asymmetry. Patients were asked to turn 180° left and right during baseline-condition. They were then randomly exposed to cueing of the disease-dominant and non-dominant side (calculated by UPDRS-score differences) at -10% of preferred stride frequency. After removing the cues, gait tests were repeated to determine the carry-over effects of cues. Turn duration, number of steps, cadence and amount of FOG-trials were registered by an 8 camera VICON 3D motion analysis system for each turn side and condition. ANOVA for repeated measures was used to analyze the data. The influence of cueing on FOG was calculated using Chi-square statistics. Results: 4 FRs froze during baseline testing, resulting in 14 FOG-trials. No FOG occurred during cueing (p<0.01). During the carry-over trials after cueing, 14 FOG-trials were found. After removing the FOG-trials from the data, FRs took longer, used more steps and had a higher cadence to complete the turn compared to nFRs. During cueing, both groups decreased their cadence (p<0.01) and overall more steps were needed to turn to the disease-dominant side (p<0.05). However, a turn*condition*group effect was found for turn duration (p<0.05) This indicated that NFRs turned more efficiently in response to cueing, by reducing their cadence within the same turn duration in all conditions. In contrast, FRs benefited only from cueing, when cueing the disease dominant side while turning towards that side. Conclusion: Unilateral cueing reduces the occurrence of FOG during turning, but this effect is not maintained when the cues are taken away. Although FRs and nFRs had comparable disease characteristics, only nFRs benefit from adjusting their cadence to the slower cueing pace to both turning sides. FRs respond selectively to cueing, indicating that cueing the disease-dominant side when turning towards the same side is effective only. 1. Spildooren J et al. Mov Disord. Submitted. 2. Willems AM et al. Disability and rehabilitation. 2006status: publishe

Turning behavior in patients with Parkinson's disease with and without freezing of gait

Objective: To evaluate 1) the difference in turning behavior between freezers (FRs) and non-freezers (n-FRs) and 2) to explore possible predictors of turning behavior. Background: Turning is the most important trigger for Freezing Of Gait (FOG) in Parkinson Disease (PD) but why this is so, is presently unknown. Methods: 16 patients with PD (7 FRs and 9 n-FRs) during the off-period of the medication cycle and 10 age-matched controls were asked to walk straight ahead and to make a right 180° turn at an infrared reflective marker placed on the floor. An 8 camera VICON 3D motion analysis system was used to determine the amount of steps, turn duration and frequency of freezing episodes. The FOG questionnaire, UPDRSIII, Timed UP and Go test (with and without dual task) and the SCOPA-test of cognition were administered in the on-period. Results: No significant differences were found between FRs and n-FRs for age, Hoehn &Yahr stage and UPDRSIII scores. Freezing was provoked in 4 out of 7 FRs during turning and only in one FR when walking straight. FRs needed significantly more steps than controls and n-FRs to complete the turn (15.5 vs. 5.6 and 6.1 steps respectively, p<0.05) and tended to have a longer turn duration (12.4 vs. 3.2 and 3.7 seconds respectively, p=0.085). However, similar results were found for walking straight (average number of steps was 10.1 vs. 5.8 and 6.8 steps respectively, p<0.05 and average turn duration 5.1 vs. 2.6 and 3.3 seconds, p<0.05). Turn duration was significantly correlated with number of steps and duration to walk 3m in a straight line, and the FOG questionnaire (R=.96, .97 and .75 respectively). Similar correlations were found for the amount of steps during turning (R= .96, .93 and .82, respectively). No correlations were found between turning behavior and UPDRSIII, SCOPA-COG and differences between the TUG with and without a dual task. Conclusions: Turning behavior in FRs shows an abnormally high number of steps, FOG episodes and increased duration. However, turning seems highly dependent on patient’s performance during straight-line walking and patient’s reported freezing severity, but can not be explained by disease severity or mental function. Further research on turning and freezing should control for parameters of normal walking performance.status: publishe

Head-pelvis coupling is increased during turning in patients with Parkinson's disease and freezing of gait

Turning is the most important trigger for freezing of gait (FOG). The aim of this study was to investigate the relationship between impaired head-pelvis rotation during turning and FOG. Head, trunk, and pelvic rotation were measured at onset and throughout a 180-degree turn in 13 freezers and 14 nonfreezers (OFF medication). We also studied 14 controls at preferred and slow speed to investigate the influence of turn velocity on axial rotation. Location and duration of FOG episodes were defined during the turn. At turning onset, head rotation preceded thorax and pelvic rotation in all groups, but this craniocaudal sequence disappeared when FOG occurred. Maximum head-pelvis separation was significantly greater in controls, compared to freezers and nonfreezers (35.4 versus 25.7 and 27.3 degrees; P < 0.01), but this finding was speed dependent. Timing of maximum head-pelvis separation was delayed in freezers, compared to nonfreezers and controls, irrespective of turn velocity. This delay was correlated with increased neck rigidity (R = 0.62; P = 0.02) and worsened during FOG trials. FOG occurred more often at the end of the turn, when difference in rotation velocity between head and pelvis was greatest. Even after controlling for speed and disease severity, turning in freezers was characterized by delayed head rotation and a closer coupling between head and pelvis, especially in turns where FOG occurred. These changes may be attributed to delayed preparation for the change in walking direction and, as such, contribute to FOG

Influence of cueing and an attentional strategy on freezing of gait in Parkinson disease during turning

Background and Purpose: Individuals with Parkinson disease exhibit decreased axial head-pelvis rotation. Consequently, they turn more en bloc than healthy controls, which may contribute to freezing during turning. We wanted to understand the influence of auditory cueing and an attentional strategy on turning and how this related to freezing of gait (FOG). Methods: Fifteen participants with Parkinson disease and FOG were asked to turn 180° during baseline condition, unilateral cueing, and an attentional strategy prompting to start the turn with head rotation first. FOG occurrence, axial rotation, center of mass (COM) deviation, knee-flexion amplitude, and total turn velocity were measured using 3D motion analysis while off-medication. Normal reference values were obtained from 14 age-matched controls. Results: Thirty-nine FOG episodes occurred in 5 participants. FOG occurred in 52.8% of baseline trials compared with 34.6% of trials using the head-first strategy, and 3.8% of the auditory cueing trials. During the head first strategy, the initiation of head, trunk, and pelvic rotation as well as the head-pelvis separation resembled turning patterns of healthy controls, but the COM shift to the inside of the turn was exaggerated. By contrast, during cueing, turning became more en bloc, with decreased head-pelvis separation and knee-flexion amplitude. Discussion and Conclusions: Cueing reduced FOG but did not correct axial movement deficits. The head-first strategy improved head-pelvis dissociation but had only limited effects on FOG. These results suggest that axial and COM deviation impairments are not directly related to FOG but may rather indicate a compensatory mechanism. Cueing reinforced the en-bloc movement and might as such help prevent FOG by triggering an alternative neural mechanism for movement generation

Cognitive aspects of freezing of gait in Parkinson's disease: a challenge for rehabilitation

Freezing of gait (FOG) is a very disabling symptom affecting up to half of the patients with Parkinson's disease (PD). Evidence is accumulating that FOG is caused by a complex interplay between motor, cognitive and affective factors, rather than being a pure motor phenomenon. In the current paper, we review the evidence on the specific role of cognitive factors in FOG. Results from behavioral studies show that patients with FOG experience impairments in executive functioning and response selection which predict that motor learning may be compromised. Brain imaging studies strengthen the neural basis of a potential association between FOG and cognitive impairment, but do not clarify whether it is a primary or secondary determinant of FOG. A FOG-related reduction of cognitive resources implies that adaptation of rehabilitation interventions is indicated for patients with FOG to promote the consolidation of learning.status: publishe

Conflict and freezing of gait in Parkinson's disease: support for a response control deficit

We investigated response activation and suppression processes in Parkinson's disease patients with freezing of gait (FOG). Fourteen freezers, 14 nonfreezers, and 14 matched healthy controls performed the attention network task (ANT) and the Stroop task. The former task has more stimulus-response overlap and is expected to elicit stronger irrelevant response activation, requiring more inhibition. Congruency effects were used as a general measure of conflict resolution. Supplementary reaction time (RT) distribution analyses were utilized to calculate conditional accuracy functions (CAFs) and delta plots to measure response activation and suppression processes. In agreement with previous research, freezers showed a general conflict resolution deficit compared with nonfreezers and healthy controls. Moreover, CAFs pointed to a strong initial incorrect response activation in FOG. As expected, conflict resolution impairment was only apparent in the ANT, and not in the Stroop task. These results suggest an imbalance between automatic and controlled processes in FOG, leading to a breakdown in both motor and cognitive response control.status: publishe