The Relationship Between Ankle Proprioception and Functional Mobility in People With Parkinson's Disease: A Cross-Sectional Study

Effects of Physical Therapy on Ankle Proprioception and Postural Control in People with Parkinson's: A Semi-experimental Clinical Trial

BackgroundProprioceptive sensory integration is impaired in people with Parkinson's (PwP), affecting control of the posture.ObjectiveThe goal of this study was to examine the effects of proprioceptive exercises on improvement of the ankle proprioception acuity, functional mobility, postural control, and quality of life of PwP.MethodsSixteen PwP participated in this semi-experimental clinical trial to receive proprioceptive exercises over 10 weeks. Ankle kinesthesia and repositioning acuity, four square step test, center of pressure-related balance metrics, and PDQ-39 questionnaire were measured.ResultsAnkle kinesthesia in plantarflexion is improved after the exercises (p = 0.033). Four square step test time was significantly decreased (∼780 ms) after proprioceptive exercises (p = 0.008). Significant decreases in closed eyes postural metrics of the center of pressure's maximum excursion (p = 0.008), maximum velocity (p = 0.035), total mean velocity (p = 0.004), range (p = 0.002), and variability (p = 0.002) indicated reduced instabilities. Significant correlations between the proprioception and postural metrics in closed eyes standing before the exercises were vanished to corroborate the role of improved proprioception in boosted postural control. PDQ-39 scores was also significantly decreased after the exercises (p = 0.021).ConclusionsProprioceptive exercises over 10 weeks improved proprioception in people with Parkinson's that caused reduced postural instabilities and consequently increased their quality of life.

Development of a 3D active movement extent discrimination apparatus for testing proprioception at the ankle joint with inversion movements made in plantarflexion

Proprioception plays an important role in joint stability, and ankle sprains usually happen involving plantarflexion, internal rotation, and inversion. However, ankle 3D movement proprioception has never been measured in weight-bearing. Accordingly, the active 3-dimensional movement extent discrimination apparatus (AMEDA-3D) was developed and its reliability and validity were investigated. A total of 58 subjects volunteered for this trial, with 12 subjects with chronic ankle instability (CAI) and 12 healthy controls in the test-retest reliability study. There were 17 subjects with CAI and 17 healthy controls in the validity study. An intraclass correlation coefficient (ICC) and Minimum Detectable Change at the 90% confidence interval (MDC90) were computed. AMEDA-3D scores were analysed by independent samples t-tests, and Youden's index was used to calculate the optimal AMEDA-3D cut-off for discriminating individuals with CAI. Pearson's correlation analysis was used to explore the relationship between AMEDA-3D scores and Y Balance Test (YBT), Time In Balance Test (TIB), and Cumberland Ankle Instability Tool (CAIT) scores. The main results were as follows: (1) The ICC(3,1) value of AMEDA-3D scores was 0.817 (95% CI = 0.452-0.945) in CAI subjects. (2) The AMEDA-3D proprioceptive area under the curve score used to discriminate CAI subjects from healthy controls was 0.778, with a sensitivity of 94% and a specificity of 82%. (3) AMEDA-3D proprioceptive scores were moderately correlated with CAIT scores (r = 0.58 and p < 0.001), YBT (r = 0.47 and p = 0.005), and TIB (r = 0.68 and p < 0.001). Our findings suggest that the AMEDA-3D tool shows good reliability and validity for clinical assessment of proprioceptive deficits associated with CAI. Improved ankle 3D motor proprioception may positively impact subjects' balance control, self-rated symptoms, and function.

A Novel Kinematic Gait Parameter-Based Vibrotactile Cue for Freezing of Gait Mitigation Among Parkinson's Patients: A Pilot Study

Auditory and visual cues have been efficacious in laboratory-based freezing of gait (FoG) mitigation in Parkinson's disease (PD). However, real-life applications of these cues are restricted due to inconvenience to the users. Closed-loop vibrotactile cues based on temporal gait events have overcome the shortcomings of auditory and visual cueing. However, kinematic gait parameter-driven vibrotactile cueing has not been explored yet. Kinematic gait parameter-driven cueing is more effective than temporal cueing, according to FoG pathophysiology studies. Therefore, we developed and pilot-tested a novel cueing scheme in which the foot-to-ground angle at heel strike (FGA_HS) is estimated using indigenous instrumented shoes to drive vibrotactile cueing. Ten PD freezers underwent a 6-meter timed walk test in the off-medication state with and without the cue and after medication without the cue. The proposed system potentially mitigated FoG, quantified by a reduction in the ratio of time spent freezing to the total walking time and the number of FoGs. The FoG mitigation potential of the cue was further supported by increased anteroposterior center of pressure progression and FGA_HS. With a future comprehensive validation in a larger number of participants, the novel cue could likely be used in practice and commercialized.

A Robotic Device for Measuring Human Ankle Motion Sense

Proprioceptive signals about ankle motion are essential for the control of balance and gait. However, objective, accurate methods for testing ankle motion sense in clinical settings are not established. This study presents a fast and accurate method to assess human ankle motion sense acuity. A one degree-of-freedom (DOF) robotic device was used to passively rotate the ankle under controlled conditions and applied a psychophysical forced-choice paradigm. Twenty healthy participants were recruited for study participation. Within a trial, participants experienced one of three reference velocities (10°/s, 15°/s, and 20°/s), and a smaller comparison velocity. Subsequently, they verbally indicated which of the two movements was faster. As outcome measures, a just-noticeable-difference (JND) threshold and interval of uncertainty (IU) were derived from the psychometric stimulus-response difference function for each participant. Our data show that mean JND threshold increased almost linearly from 0.53°/s at the 10°/s reference to 1.6°/s at 20°/s ( ). Perceptual uncertainty increased similarly (median IU = 0.33°/s at 10°/s and 0.97°/s at 20°/s; ). Both measures were strongly correlated ( r s = 0.70). This implies that the bias of the human ankle motion sense is approximately 5 - 8% of the experienced movement velocity. We demonstrate that this robot-aided test produces quantitative data on human ankle motion sense acuity. It provides a useful addition to the current measures of ankle proprioceptive function.

Ankle Inversion Proprioception Impairment in Persons with Chronic Ankle Instability Is Task-Specific

While investigators have often compared ankle proprioception between groups with and without chronic ankle instability (CAI), findings have been inconsistent. Possibly this is because ankle proprioceptive impairment in this population is task-specific. Thus, we aimed to compare ankle inversion proprioception in individuals with and without CAI in two task conditions: (i) when standing (not challenging) and (ii) when on a step-down landing (minimally-challenging). Ankle inversion proprioception was measured in both conditions for 38 recreational sport player volunteers with CAI (n = 19) and without CAI (n = 19). We used the Active Movement Extent Discrimination Apparatus (AMEDA) for the standing condition and the Ankle Inversion Discrimination Apparatus-Landing (AIDAL) for step-down landing. From analysis of variance (ANOVA) tests, CAI and non-CAI participants performed equally well on the AMEDA when standing; but the CAI group performed significantly worse than the non-CAI group on the AIDAL step-down landing task (p = 0.03). Within the non-CAI group, the AIDAL proprioceptive scores, as area under the receiver operating characteristics curve (AUC), were significantly higher than their AMEDA AUC scores (p = 0.03), while there was no significant difference between AIDAL and AMEDA AUC scores in the CAI group. Cumberland Ankle Instability Tool CAIT scores were significantly correlated with AIDAL scores (Spearman's rho = 0.391, p = 0.015), but not with the AMEDA scores; and there was no significant correlation between the AIDAL and AMEDA scores. Thus, an ankle inversion proprioceptive deficit was evident for persons with CAI on the step-down AIDAL, and in a dose-response way, but not evident on the standing AMEDA, suggesting that ankle proprioceptive impairment is task-specific. Selected proprioceptive tests must present some minimal degree of challenge to the ankle joint in a functional task in order to differentiate CAI from non-CAI participants.

Association between Severity of Freezing of Gait and Turning Characteristics in People with Parkinson's Disease

For people with Parkinson's disease (PD) with freezing of gait (FOG) (freezers), symptoms mainly exhibit as unilateral motor impairments that may cause difficulty during postural transitions such as turning during daily activities. We investigated the turning characteristics that distinguished freezers among people with PD and analyzed the association between the New Freezing of Gait Questionnaire (NFOGQ) scores and the gait characteristics according to the turning direction for the affected limbs of freezers. The study recruited 57 people with PD (27 freezers, 30 non-freezers). All experiments measured the maximum 180° turning task with the "Off" medication state. Results revealed that the outer ankle range of motion in the direction of the inner step of the more affected limb (IMA) was identified to distinguish freezers and non-freezers (R_N² = 0.735). In addition, higher NFOGQ scores were associated with a more significant anteroposterior root mean square distance of the center of mass in the IMA direction and a greater inner stance phase in the outer step of the more affected limb (OMA) direction; explanatory power was 50.1%. Assessing the maximum speed and turning direction is useful for evaluating the differences in turning characteristics between freezers and non-freezers, which can help define freezers more accurately.

Assessing bilateral ankle proprioceptive acuity in stroke survivors: An exploratory study

Background

Bilateral proprioception deficits were reported in stroke survivors. However, whether bilateral proprioception deficits exist in the ankle joint after stroke was unclear. Ankle proprioception is a significant predictor of balance dysfunction after stroke, and previous studies to date are lacking appropriate evaluation methods.

Objectives

We want to determine whether the active movement extent discrimination apparatus (AMEDA) is a reliable tool for assessing ankle proprioceptive acuity in stroke survivors and the presence of deficits in ankle proprioception on the affected and unaffected sides in patients after stroke.

Methods

Bilateral ankle proprioception was assessed in 20 stroke patients and 20 age-matched healthy controls using AMEDA. Test-retest reliability was assessed using the intraclass correlation coefficient (ICC).

Results

The ICC in the affected and unaffected sides was 0.713 and 0.74, respectively. Analysis of variance revealed significant deficits in ankle proprioception in subacute stroke survivors vs. healthy controls (F = 2.719, p = 0.045). However, there were no significant differences in proprioception acuity scores between the affected and unaffected sides in patients after stroke (F = 1.14, p = 0.331).

Conclusions

Stroke survivors had bilateral deficits in ankle proprioceptive acuity during active movements compared with age-matched healthy controls, underscoring the need to evaluate these deficits on both sides of the body and develop effective sensorimotor rehabilitation methods for this patient population. The AMEDA can reliably determine bilateral ankle proprioceptive acuity in stroke survivors.

Deep brain stimulation in the subthalamic nuclei alters postural alignment and adaptation in Parkinson's disease

Parkinson’s disease (PD) can produce postural abnormalities of the standing body position such as kyphosis. We investigated the effects of PD, deep brain stimulation (DBS) in the subthalamic nucleus (STN), vision and adaptation on body position in a well-defined group of patients with PD in quiet standing and during balance perturbations. Ten patients with PD and 25 young and 17 old control participants were recruited. Body position was measured with 3D motion tracking of the ankle, knee, hip, shoulder and head. By taking the ankle as reference, we mapped the position of the joints during quiet standing and balance perturbations through repeated calf muscle vibration. We did this to explore the effect of PD, DBS in the STN, and vision on the motor learning process of adaptation in response to the repeated stimulus. We found that patients with PD adopt a different body position with DBS ON vs. DBS OFF, to young and old controls, and with eyes open vs. eyes closed. There was an altered body position in PD with greater flexion of the head, shoulder and knee (p≤0.042) and a posterior position of the hip with DBS OFF (p≤0.014). With DBS ON, body position was brought more in line with the position taken by control participants but there was still evidence of greater flexion at the head, shoulder and knee. The amplitude of movement during the vibration period decreased in controls at all measured sites with eyes open and closed (except at the head in old controls with eyes open) showing adaptation which contrasted the weaker adaptive responses in patients with PD. Our findings suggest that alterations of posture and greater forward leaning with repeated calf vibration, are independent from reduced movement amplitude changes. DBS in the STN can significantly improve body position in PD although the effects are not completely reversed. Patients with PD maintain adaptive capabilities by leaning further forward and reducing movement amplitude despite their kyphotic posture.

The Cost of Gait Slowness: Can Persons with Parkinson's Disease Save Energy by Walking Faster?

BACKGROUND

Gait slowing is a common feature of Parkinson's disease (PD). Many therapies aim to improve gait speed in persons with PD, but goals are often imprecise. How fast should each patient walk? And how do persons with PD benefit from walking faster? There is an important need to understand how walking speed affects fundamental aspects of gait-including energy cost and stability-that could guide individualized therapy decisions in persons with PD.

OBJECTIVE

We investigated how changes in walking speed affected energy cost and spatiotemporal gait parameters in persons with PD. We compared these effects between dopaminergic medication states and to those observed in age-matched control participants.

METHODS

Twelve persons with PD and twelve control participants performed treadmill walking trials spanning at least five different speeds (seven speeds were desired, but not all participants could walk at the fastest speeds). Persons with PD participated in two walking sessions on separate days (once while optimally medicated, once after 12-hour withdrawal from dopaminergic medication). We measured kinematic and metabolic data across all trials.

RESULTS

Persons with PD significantly reduced energy cost by walking faster than their preferred speeds. This held true across medication conditions and was not observed in control participants. The patient-specific walking speeds that reduced energy cost did not significantly affect gait variability metrics (used as proxies for gait stability).

CONCLUSION

The gait slowing that occurs with PD results in energetically suboptimal walking. Rehabilitation strategies that target patient-specific increases in walking speed could result in a less effortful gait.