Effect of Dual Tasking and Levodopa-induced Dyskinesia on Postural Sway in People with Parkinson\u27s Disease

Parkinson\u27s disease (PD) is a neurodegenerative disorder that results in motor impairments such as gait and balance deficits. Levodopa is one of the most effective drugs in treating the slowness of movement in individuals with PD. However, the long-term use of levodopa in treating PD often causes undesirable involuntary and uncontrollable movements, known as levodopa-induced dyskinesia (LID). LID is a known cause of increased postural sway. Yet, the relative contribution of the body segments often affected by dyskinesia to postural sway is unknown. We aimed to investigate the contribution of different body segments to postural sway in PD for individuals with and without LID. We collected postural sway of the head, trunk, and lumbar segments in 26 people with PD. Each participant performed a postural sway task in single and cognitive dual-task conditions while ON and OFF levodopa. Our data demonstrated that postural sway ratios were increased during dual-task and ON levodopa. We found up to 2.5x and 2x increase in sway at the head compared to the trunk and lumbar, respectively, in individuals with LID compared to those without LID. These findings suggest a lack of inhibitory control prominent in the superior segment (head) of individuals with LID in PD

Gait Asymmetry in People With Parkinson’s Disease Is Linked to Reduced Integrity of Callosal Sensorimotor Regions

Background: Individuals with Parkinson’s disease (PD) often manifest significant temporal and spatial asymmetries of the lower extremities during gait, which significantly contribute to mobility impairments. While the neural mechanisms underlying mobility asymmetries within this population remain poorly understood, recent evidence points to altered microstructural integrity of white matter fiber tracts within the corpus callosum as potentially playing a substantial role. Objectives: The purpose of this study was to quantify spatial and temporal gait asymmetries as well as transcallosal microstructural integrity of white matter fiber tracts connecting the primary and secondary sensorimotor cortices in people with PD and age-matched control participants. Methods: Spatial and temporal gait asymmetry in the levodopa off state was assessed using an instrumented walkway. On the next day, diffusion-weighted images were collected to assess white matter microstructural integrity in transcallosal fibers connecting the homologous sensorimotor cortical regions. Results: People with PD exhibited significantly more temporal and spatial gait asymmetry than healthy control subjects. Furthermore, people with PD had significantly reduced white matter microstructural integrity of transcallosal fibers connecting homologous regions of the pre-supplementary motor and supplementary motor areas (SMAs), but not the primary motor or somatosensory cortices. Finally, reduced transcallosal fiber tract integrity of the pre-SMA and S1 was associated with greater step length asymmetry in people with PD. Conclusion: People with PD showed increased step length asymmetries and decreased microstructural integrity of callosal white matter tracts connecting the higher-order sensorimotor cortices (pre-SMA and SMA). The strong association between gait asymmetries and corpus collosum integrity, supports the hypothesis that reduced transcallosal structural connectivity is a significant mechanism underlying gait asymmetries in people with PD

Freezing of gait associated with a corpus callosum lesion

Freezing of gait (FoG) is a debilitating feature of Parkinson’s disease and other parkinsonian disorders. This case demonstrates a variant of freezing of gait in a non-parkinsonian patient with a lesion of the anterior corpus callosum. The freezing improved with increased upper extremity sensory input, suggesting that compensatory circuits for use of somatosensory inputs from the arms to postural and locomotor centers were intact

Frontal plane roll-over analysis of prosthetic feet

In prosthetic walking mediolateral balance is compromised due to the lack of active ankle control, by moments of force, in the prosthetic limb. Active control is reduced to the hip strategy, and passive mechanical stability depends on the curvature of the prosthetic foot under load. Mediolateral roll-over curvatures of prosthetic feet are largely unknown. In this study we determined the mediolateral roll-over characteristics of various prosthetic feet and foot-shoe combinations. Characteristics were determined by means of an inverted pendulum-like apparatus. The relationship between the centre of pressure (CoP) and the shank angle was measured and converted to roll-over shape and effective radius of curvature. Further, hysteresis (i.e., lagging in CoP displacement due to material compliance or slip) at vertical shank angle was determined from the hysteresis curve. Passive mechanical stability varied widely, though all measured foot-shoe combinations were relatively compliant. Mediolateral motion of the CoP ranged between 4 mm and 40 mm, thereby remaining well within each foot's physical width. Derived roll-over radii of curvature are also small, with an average of 102 mm. Hysteresis ranges between 20% and 115% of total CoP displacement and becomes more pronounced when adding a shoe. This may be due to slipping of the foot core in its cosmetic cover, or the foot in the shoe. Slip may be disadvantageous for balance control by limiting mediolateral travel of the CoP. It may therefore be clinically relevant to eliminate mediolateral slip in prosthetic foot design

Associations between mobility, cognition and callosal integrity in people with parkinsonism

Falls in people with parkinsonism are likely related to both motor and cognitive impairments. In addition to idiopathic Parkinson\u27s disease (PD), some older adults have lower body parkinsonism (a frontal gait disorder), characterized by impaired lower extremity balance and gait as well as cognition, but without tremor or rigidity. Neuroimaging during virtual gait suggests that interhemispheric, prefrontal cortex communication may be involved in locomotion, but contributions of neuroanatomy connecting these regions to objective measures of gait in people with parkinsonism remains unknown. Our objectives were to compare the integrity of fiber tracts connecting prefrontal and sensorimotor cortical regions via the corpus callosum in people with two types of parkinsonism and an age-matched control group and to relate integrity of these callosal fibers with clinical and objective measures of mobility and cognition. We recruited 10 patients with frontal gait disorders, 10 patients with idiopathic PD and 10 age-matched healthy control participants. Participants underwent cognitive and mobility testing as well as diffusion weighted magnetic resonance imaging to quantify white matter microstructural integrity of interhemispheric fiber tracts. People with frontal gait disorders displayed poorer cognitive performance and a slower, wider-based gait compared to subjects with PD and age-matched control subjects. Despite a widespread network of reduced white matter integrity in people with frontal gait disorders, gait and cognitive deficits were solely related to interhemispheric circuitry employing the genu of the corpus callosum. Current results highlight the importance of prefrontal interhemispheric communication for lower extremity control in neurological patients with cognitive dysfunction

Effect of Bout Length on Gait Measures in People with and without Parkinson’s Disease during Daily Life

Although the use of wearable technology to characterize gait disorders in daily life is increasing, there is no consensus on which specific gait bout length should be used to characterize gait. Clinical trialists using daily life gait quality as study outcomes need to understand how gait bout length affects the sensitivity and specificity of measures to discriminate pathological gait as well as the reliability of gait measures across gait bout lengths. We investigated whether Parkinson’s disease (PD) affects how gait characteristics change as bout length changes, and how gait bout length affects the reliability and discriminative ability of gait measures to identify gait impairments in people with PD compared to neurotypical Old Adults (OA). We recruited 29 people with PD and 20 neurotypical OA of similar age for this study. Subjects wore 3 inertial sensors, one on each foot and one over the lumbar spine all day, for 7 days. To investigate which gait bout lengths should be included to extract gait measures, we determined the range of gait bout lengths available across all subjects. To investigate if the effect of bout length on each gait measure is similar or not between subjects with PD and OA, we used a growth curve analysis. For reliability and discriminative ability of each gait measure as a function of gait bout length, we used the intraclass correlation coefficient (ICC) and area under the curve (AUC), respectively. Ninety percent of subjects walked with a bout length of less than 53 strides during the week, and the majority (\u3e50%) of gait bouts consisted of less than 12 strides. Although bout length affected all gait measures, the effects depended on the specific measure and sometimes differed for PD versus OA. Specifically, people with PD did not increase/decrease cadence and swing duration with bout length in the same way as OA. ICC and AUC characteristics tended to be larger for shorter than longer gait bouts. Our findings suggest that PD interferes with the scaling of cadence and swing duration with gait bout length. Whereas control subjects gradually increased cadence and decreased swing duration as bout length increased, participants with PD started with higher than normal cadence and shorter than normal stride duration for the smallest bouts, and cadence and stride duration changed little as bout length increased, so differences between PD and OA disappeared for the longer bout lengths. Gait measures extracted from shorter bouts are more common, more reliable, and more discriminative, suggesting that shorter gait bouts should be used to extract potential digital biomarkers for people with PD

Laboratory versus daily life gait characteristics in patients with multiple sclerosis, Parkinson’s disease, and matched controls

Background and purpose Recent findings suggest that a gait assessment at a discrete moment in a clinic or laboratory setting may not reflect functional, everyday mobility. As a step towards better understanding gait during daily life in neurological populations, we compared gait measures that best discriminated people with multiple sclerosis (MS) and people with Parkinson’s Disease (PD) from their respective, age-matched, healthy control subjects (MS-Ctl, PD-Ctl) in laboratory tests versus a week of daily life monitoring. Methods We recruited 15 people with MS (age mean ± SD: 49 ± 10 years), 16 MS-Ctl (45 ± 11 years), 16 people with idiopathic PD (71 ± 5 years), and 15 PD-Ctl (69 ± 7 years). Subjects wore 3 inertial sensors (one each foot and lower back) in the laboratory followed by 7 days during daily life. Mann–Whitney U test and area under the curve (AUC) compared differences between PD and PD-Ctl, and between MS and MS-Ctl in the laboratory and in daily life. Results Participants wore sensors for 60–68 h in daily life. Measures that best discriminated gait characteristics in people with MS and PD from their respective control groups were different between the laboratory gait test and a week of daily life. Specifically, the toe-off angle best discriminated MS versus MS-Ctl in the laboratory (AUC [95% CI] = 0.80 [0.63–0.96]) whereas gait speed in daily life (AUC = 0.84 [0.69–1.00]). In contrast, the lumbar coronal range of motion best discriminated PD versus PD-Ctl in the laboratory (AUC = 0.78 [0.59–0.96]) whereas foot-strike angle in daily life (AUC = 0.84 [0.70–0.98]). AUCs were larger in daily life compared to the laboratory. Conclusions Larger AUC for daily life gait measures compared to the laboratory gait measures suggest that daily life monitoring may be more sensitive to impairments from neurological disease, but each neurological disease may require different gait outcome measures

Measuring freezing of gait during daily-life: an open-source, wearable sensors approach

Background Although a growing number of studies focus on the measurement and detection of freezing of gait (FoG) in laboratory settings, only a few studies have attempted to measure FoG during daily life with body-worn sensors. Here, we presented a novel algorithm to detect FoG in a group of people with Parkinson’s disease (PD) in the laboratory (Study I) and extended the algorithm in a second cohort of people with PD at home during daily life (Study II). Methods In Study I, we described of our novel FoG detection algorithm based on five inertial sensors attached to the feet, shins and lumbar region while walking in 40 participants with PD. We compared the performance of the algorithm with two expert clinical raters who scored the number of FoG episodes from video recordings of walking and turning based on duration of the episodes: very short (\u3c 1 s), short (2–5 s), and long (\u3e 5 s). In Study II, a different cohort of 48 people with PD (with and without FoG) wore 3 wearable sensors on their feet and lumbar region for 7 days. Our primary outcome measures for freezing were the % time spent freezing and its variability. Results We showed moderate to good agreement in the number of FoG episodes detected in the laboratory (Study I) between clinical raters and the algorithm (if wearable sensors were placed on the feet) for short and long FoG episodes, but not for very short FoG episodes. When extending this methodology to unsupervised home monitoring (Study II), we found that percent time spent freezing and the variability of time spent freezing differentiated between people with and without FoG (p \u3c 0.05), and that short FoG episodes account for 69% of the total FoG episodes. Conclusion Our findings showed that objective measures of freezing in PD using inertial sensors on the feet in the laboratory are matching well with clinical scores. Although results found during daily life are promising, they need to be validated. Objective measures of FoG with wearable technology during community-living would be useful for managing this distressing feature of mobility disability in PD