Carolin Curtze

Levodopa Is a Double-Edged Sword for Balance and Gait in People With Parkinson's Disease

The effects of levodopa on balance and gait function in people with Parkinsons disease (PD) is controversial. This study compared the relative responsiveness to l‐dopa on six domains of balance and gait: postural sway in stance; gait pace; dynamic stability; gait initiation; arm swing; and turning in people with mild and severe PD, with and without dyskinesia.

Comparative roll-over analysis of prosthetic feet

A prosthetic foot is a key element of a prosthetic leg, literally forming the basis for a stable and efficient amputee gait. We determined the roll-over characteristics of a broad range of prosthetic feet and examined the effect of a variety of shoes on these characteristics. The body weight of a person acting on a prosthetic foot during roll-over was emulated by means of an inverted pendulum-like apparatus. Parameters measured were the effective radius of curvature, the forward travel of the center of pressure, and the instantaneous radius of curvature of the prosthetic feet. Finally, we discuss how these parameters relate to amputee gait.

Effects of lower limb amputation on the mental rotation of feet

What happens to the mental representation of our body when the actual anatomy of our body changes? We asked 18 able-bodied controls, 18 patients with a lower limb amputation and a patient with rotationplasty to perform a laterality judgment task. They were shown illustrations of feet in different orientations which they had to classify as left or right limb. This laterality recognition task, originally introduced by Parsons in Cognit Psychol 19:178–241, (1987), is known to elicit implicit mental rotation of the subject’s own body part. However, it can also be solved by mental transformation of the visual stimuli. Despite the anatomical changes in the body periphery of the amputees and of the rotationplasty patient, no differences in their ability to identify illustrations of their affected versus contralateral limb were found, while the group of able-bodied controls showed clear laterality effects. These findings are discussed in the context of various strategies for mental rotation versus the maintenance of an intact prototypical body structural description.

The relative contributions of the prosthetic and sound limb to balance control in unilateral transtibial amputees

In unilateral transtibial amputees maintenance of standing balance is compromised due to the lack of active ankle control in the prosthetic limb. The purpose of this study is to disentangle the contribution of the prosthetic and sound limb to balance control following waist-pull perturbations. We compared the contribution of the hip and ankle joints to balance control of 15 unilateral transtibial amputees and 13 able-bodied controls after been externally perturbed through release of a pulling force. Perturbations were applied in four different directions. Outcome measure was the proportion of joint moment integrated over time generated by the hip and ankle joints in order to restore static stability after perturbation. Analyses revealed that perturbations in backward/forward direction were recovered mainly by the ankle strategy. The amputees compensated for the absence of active ankle control in the prosthetic limb by increasing the ankle moment in the sound limb. Interestingly, the passive properties of the prosthetic foot contributed to balance control, which has important implications for prosthetic fitting and standing stability in lower limb amputees. Amputees and controls resisted perturbations in medio-lateral direction by generating the necessary hip moments. Finally, these findings are discussed with respect to prosthetic design and rehabilitation processes.

Balance recovery after an evoked forward fall in unilateral transtibial amputees

Falls are a common and potentially dangerous event, especially in amputees. In this study, we compared the mechanisms of balance recovery of 17 unilateral transtibial amputees and 17 matched able-bodied controls after being released from a forward-inclined orientation of 10%. Kinematic analysis revealed statistically significant differences in response time and knee flexion at heel-strike between both groups. However, there were no statistically significant differences in step length of the leading and trailing limb, swing time of the leading limb, and maximal knee flexion during swing. In the amputees, we found spatial and temporal differences when recovering with the sound versus prosthetic limb first. When leading with the prosthetic limb, they responded faster and also the interval between heel-strike of the leading and trailing limb was shorter. Furthermore, amputees made a longer step and showed less knee flexion at heel-strike when leading with the prosthetic limb. Interestingly, amputees as a group had no specific limb preference, prosthetic or sound, to recover after a forward fall, despite the asymmetry in their locomotor system. Analyses of dynamic stability (extrapolated center of mass) revealed that the amputees were equally efficient in recovering from an impending fall as controls, irrespective whether they lead with their prosthetic or sound limb. We suggest that in amputee rehabilitation, balance recovery after a fall should be trained with both sides, as this can increase confidence in fall-prone situations.

The Narrow Ridge Balance Test: A measure for one-leg lateral balance control

The assessment of balance capacity for people with widely different balance abilities is an important issue in clinical practice. We propose the narrow ridge balance test as a sensitive tool to assess one-leg balance capacity. In this test, participants are asked to perform single-leg stance on ridges of gradually decreasing width (100, 80, 60, 40, 20, 10, and 4mm). An outcome measure was developed, base on time in balance in relation to the gradually decreasing ridge width. To evaluate the sensitivity and discriminating power of the test, we applied it to two groups of participants, a group of young participants (age 20-30 years) and group of healthy elderly participants (age 60-80 years). The test showed to sensitively differentiate between the two groups, showing lower scores for the elderly. Furthermore, the test appeared to identify large within-group differences. A special feature of this setup is that the difficulty of the test increases with the balance capacity of the participant. In this way, each participant is exposed to the maximally challenging task, and a broader variety of balance control mechanisms come into play. Finally, the outcome score of the new test was contrasted to conventional measures of standing balance, showing good agreement.

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 Parkinsons 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.

Determining asymmetry of roll-over shapes in prosthetic walking.

How does the inherent asymmetry of the locomotor system in people with lower-limb amputation affect the ankle-foot roll-over shape of prosthetic walking? In a single-case design, we evaluated the walking patterns of six people with lower-limb amputation (3 transtibial and 3 transfemoral) and three matched nondisabled controls. We analyzed the walking patterns in terms of roll-over characteristics and spatial and temporal factors. We determined the level of asymmetry by roll-over shape comparison (root-mean-square distance) as well as differences in radius of curvature. In addition, we calculated ratios to determine spatial and temporal asymmetries and described different aspects of asymmetry of roll-over shapes. All participants showed some level of asymmetry in roll-over shape, even the nondisabled controls. Furthermore, we found good intralimb reproducibility for the group as a whole. With respect to spatial and temporal factors, the participants with transtibial amputation had a quite symmetrical gait pattern, while the gait in the participants with transfemoral amputation was more asymmetrical. The individual ankle-foot roll-over shapes provide additional insight into the marked individual adjustments occurring during the stance phase of the nondisabled limb. The two methods we present are suitable for determining asymmetry of roll-over shapes; both methods should be used complementarily.

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.

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.