Postural control and freezing of gait in Parkinson's disease

Adaptations to Postural Perturbations in Patients With Freezing of Gait

Introduction: Freezing of gait (FOG) is a powerful determinant of falls in Parkinson's disease (PD). Automatic postural reactions serve as a protective strategy to prevent falling after perturbations. However, differences in automatic postural reactions between patients with and without FOG in response to perturbation are at present unclear. Therefore, the present study aimed to compare the response patterns and neuromuscular control between PD patients with and without FOG and healthy controls (HCs) after postural perturbations.

Methods: 28 PD patients (15 FOG+, 13 FOG−) and 22 HCs were included. Participants stood on a moveable platform while random perturbations were imposed. The first anterior platform translation was retained for analysis. Center of pressure (CoP) and center of mass (CoM) trajectories and trunk, knee and ankle angles were compared between the three groups using the Statistical Parametric Mapping technique, allowing to capture changes in time. In addition, muscle activation of lower leg muscles was measured using EMG.

Results: At baseline, FOG+ stood with more trunk flexion than HCs (p = 0.005), a result not found in FOG−. Following a perturbation, FOG+ reacted with increased trunk extension (p = 0.004) in comparison to HCs, a pattern not observed in FOG−. The CoM showed greater backward displacement in FOG− and FOG+ (p = 0.008, p = 0.027). Both FOG+ and FOG− showed increased co-activation of agonist and antagonist muscles compared to HCs (p = 0.010), with no differences between FOG+ and FOG−.

Conclusions: Automatic postural reactions after a sudden perturbation are similar between PD subgroups with and without FOG but different from HCs. Reactive postural control, largely regulated by brain stem centers, seems to be modulated by different mechanisms than those governing freezing of gait. Greater differences in initial stance position, enhanced by joint stiffening, could however underlie maladaptive postural responses and increase susceptibility for balance loss in FOG+ compared to FOG−.

Evaluation of the effects of sensorimotor exercise on physical and psychological parameters in breast cancer patients undergoing neurotoxic chemotherapy

INTRODUCTION

Breast cancer is the most common cancer disease of women in industrialized countries. Neurotoxic chemotherapy drugs are known to harm peripheral nerves and cause a chemotherapy-induced peripheral neuropathy (CIPN). CIPN is one of the most common adverse events associated with Paclitaxel chemotherapy and may remain present long after the termination of chemotherapy. Thus, it reduces the patients' quality of life (QoL) both during chemotherapy and onwards, and can impose a danger on breast cancer survivors due to an increased risk of falling and fall-related injuries.

METHODS

The aim of this randomized-controlled trial (RCT) (n = 36) (IG: intervention group, n = 17) (CG: control group, n = 19) was to determine whether sensorimotor exercises have a positive effect on physical and psychological parameters in breast cancer patients undergoing neurotoxic chemotherapy (Paclitaxel).

RESULTS

As a result, we were able to show significant improvements in postural stability in monopedal stance [left leg 16.17 ± 3.67 vs. 21.55 ± 5.33 (p < 0.001) and right leg 15.14 ± 2.30 vs. 20.85 ± 5.05 (p < 0.001)] and in bipedal stance [T1 vs. T0, - 0.49 (IG) vs. + 1.14 (CG) p = 0.039].

DISCUSSION

These results in posturography correlate with the clinical presentation with intervention group patients scoring significantly better on the Fullerton Advanced Balance Scale [37.71 ± 2.73 vs. 34.47 ± 3.98 (p = 0.004)]. Moderate strength training successfully prevented a strength loss in the IG that was remarkable in the CG (- 1.60 vs. 0.60, p = 0.029). Concerning the psychological parameters assessed via EORTC- and MFI-questionnaires, no significant improvements were found.

CONCLUSION

Future studies should focus on the correlation of clinical and posturometry findings and subjective QOL such as the long-term-development of CIPN.

Motor Subtypes of Parkinson's Disease Can Be Identified by Frequency Component of Postural Stability

Parkinson’s disease (PD) can be divided into two subtypes based on clinical features—namely tremor dominant (TD) and postural instability and gait difficulty (PIGD). This categorization is important at the early stage of PD, since identifying the subtypes can help to predict the clinical progression of the disease. Accordingly, correctly diagnosing subtypes is critical in initiating appropriate early interventions and tracking the progression of the disease. However, as the disease progresses, it becomes increasingly difficult to further distinguish those attributes that are relevant to the subtypes. In this study, we investigated whether a method using the standing center of pressure (COP) time series data can separate two subtypes of PD by looking at the frequency component of COP (i.e., COP position and speed). Thirty-six participants diagnosed with PD were evaluated, with their bare feet on the force platform, and were instructed to stand upright with their arms by their sides for 20 s (with their eyes open and closed), which is consistent with the traditional COP measures. Fast Fourier transform (FFT) and wavelet transform (WT) were performed to distinguish between the motor subtypes using the COP measures. The TD group exhibited larger amplitudes at the frequency range of 3–7 Hz when compared to the PIGD group. Both the FFT and WT methods were able to differentiate the subtypes. COP time series information can be used to differentiate between the two motor subtypes of PD, using the frequency component of postural stability.

Spatial and temporal analysis center of pressure displacement during adolescence: Clinical implications of developmental changes

This study aimed to provide insight into the development of postural control abilities in youth. A total of 276 typically developing adolescents (155 males, 121 females) with a mean age of 13.23 years (range of 7.11-18.80) were recruited for participation. Subjects performed two-minute quiet standing trials in bipedal stance on a force plate. Center of pressure (COP) trajectories were quantified using Sample Entropy (SampEn) in the anterior-posterior direction (SampEn-AP), SampEn in the medial-lateral direction (SampEn-ML), and Path Length (PL) measures. Three separate linear regression analyses were conducted to predict the relationship between age and each of the response variables after adjusting for individuals' physical characteristics. Linear regression models showed an inverse relationship between age and entropy measures after adjusting for body mass index. Results indicated that chronological age was predictive of entropy and path length patterns. Specifically, older adolescents exhibited center of pressure displacement (smaller path length) and less complex, more regular center of pressure displacement patterns (lower SampEn-AP and SampEn-ML values) compared to the younger children. These findings support prior studies suggesting that developmental changes in postural control abilities may continue throughout adolescence and into adulthood.

Instrumental or Physical-Exercise Rehabilitation of Balance Improves Both Balance and Gait in Parkinson's Disease

We hypothesised that rehabilitation specifically addressing balance in Parkinson's disease patients might improve not only balance but locomotion as well. Two balance-training protocols (standing on a moving platform and traditional balance exercises) were assessed by assigning patients to two groups (Platform, n = 15, and Exercises, n = 17). The platform moved periodically in the anteroposterior, laterolateral, and oblique direction, with and without vision in different trials. Balance exercises were based on the Otago Exercise Program. Both platform and exercise sessions were administered from easy to difficult. Outcome measures were (a) balancing behaviour, assessed by both Index of Stability (IS) on platform and Mini-BESTest, and (b) gait, assessed by both baropodometry and Timed Up and Go (TUG) test. Falls Efficacy Scale-International (FES-I) and Parkinson's Disease Questionnaire (PDQ-8) were administered. Both groups exhibited better balance control, as assessed both by IS and by Mini-BESTest. Gait speed at baropodometry also improved in both groups, while TUG was less sensitive to improvement. Scores of FES-I and PDQ-8 showed a marginal improvement. A four-week treatment featuring no gait training but focused on challenging balance tasks produces considerable gait enhancement in mildly to moderately affected patients. Walking problems in PD depend on postural instability and are successfully relieved by appropriate balance rehabilitation. This trial is registered with ClinicalTrials.gov NCT03314597.

Are Hypometric Anticipatory Postural Adjustments Contributing to Freezing of Gait in Parkinson's Disease?

Introduction: This study aims at investigating whether impaired anticipatory postural adjustments (APA) during gait initiation contribute to the occurrence of freezing of gait (FOG) or whether altered APAs compensate for FOG in Parkinson’s disease (PD).

Methods: Gait initiation after 30 s quiet stance was analyzed without and with a cognitive dual task (DT) in 33 PD subjects with FOG (PD+FOG), 30 PD subjects without FOG (PD-FOG), and 32 healthy controls (HC). APAs were characterized with inertial sensors and muscle activity of the tensor fasciae latae (TFL), gastrocnemius, and tibialis anterior was captured with electromyography recordings. Nine trials (of 190) were associated with start hesitation/FOG and analyzed separately.

Results: PD+FOG and PD-FOG did not differ in disease duration, disease severity, age, or gender. PD+FOG had significantly smaller medio-lateral (ML) and anterio-posterior APAs compared to PD-FOG (DT, p < 0.05). PD+FOG had more co-contraction of left and right TFL during APAs compared to PD-FOG (p < 0.01). Within the PD+FOG, the ML size of APA (DT) was positively correlated with the severity of FOG history (NFOG-Q), with larger APAs associated with worse FOG (rho = 0.477, p = 0.025). ML APAs were larger during trials with observed FOG compared to trials of PD+FOG without FOG.

Conclusions: People with PD who have a history of FOG have smaller ML APAs (weight shifting) during gait initiation compared to PD-FOG and HC. However, start hesitation (FOG) is not caused by an inability to sufficiently displace the center of mass toward the stance leg because APAs were larger during trials with observed FOG. We speculate that reducing the acceleration of the body center of mass with hip abductor co-contraction for APAs might be a compensatory strategy in PD+FOG, to address postural control deficits and enable step initiation.

Low to moderate relationships between gait and postural responses in Parkinson disease

OBJECTIVE

To evaluate the relationship between spatiotemporal parameters of forward and backward gait and quality of compensatory stepping responses in forward and backward directions in people with Parkinson's disease with and without freezing of gait.

DESIGN

Cross-sectional analysis.

SUBJECTS

A total of 111 individuals with mild to moderate Parkinson's disease.

METHODS

Forward and backward gait velocity and step length were evaluated using a GAITRite walkway. Forward and backward postural responses were evaluated using items from the Mini Balance Evaluation Systems Test and the Movement Disorders Society Unified Parkinson Disease Rating Scale motor subsection. Relationships between gait and postural responses were examined for the full sample and for sub-groups with and without freezing of gait.

RESULTS

There were significant (p < 0.05) low to moderate correlations between postural responses and gait overall. Correlations were similar in the freezer and non-freezer sub-groups. Freezers performed worse than non-freezers on all gait parameters and backward postural response items (p < 0.05).

CONCLUSION

Low to moderate relationships between gait and postural responses indicate the complexity of postural control and the potential involvement of different neural circuitry across these tasks. Better understanding of the relationships between gait and postural deficits in Parkinson's disease may inform the future development of targeted interventions to address these impairments.

CHANGES IN INSTABILITY AND IRREGULARITY OF THE ELDERLY DUE TO DIFFERENT BALANCE ABILITY

Older adults with a balance-related neurological disease or who have experienced previous falling incidents tend to show increase in instability and changes in irregularity of postural control. This study analyzed the impact of differences in balance ability on the instability and irregularity of postural control in older adults without neurological disease and previous fall experiences. The 49 subjects were older adults aged 65 years and above who did not have neurological disease and prior falling incidents during the previous year. The subjects were classified into two groups of 27 healthy (Berg score [Formula: see text]) and 22 balance-impaired older adults (Berg score [Formula: see text]) according to the Berg balance scale. Each subject was asked to hold in the standing position with eyes closed and with eyes open for one minute. Postural sway was measured along with acceleration using an inertial sensor attached to the subject’s waist. The measured postural sway was calculated using linear measures (95% confidence ellipse area, root mean square) that represented instability and nonlinear measures (sample, multi-scale and composite multi-scale entropy) that represented irregularity. All linear measures showed an increase in the average value in the balance-impaired older adult group’ as well as significant differences between the two groups, whereas the nonlinear measures did not show any differences. These findings indicated that differences in instability were not necessarily accompanied by irregularity changes, and the similarities in irregularity were assumed to be the result of the postural control mechanisms of the subjects without neurological diseases and prior fall incidents being similar to those of subjects with physical injuries.

Bicycling suppresses abnormal beta synchrony in the Parkinsonian basal ganglia

OBJECTIVE

Freezing of gait is a poorly understood symptom of Parkinson disease, and can severely disrupt the locomotion of affected patients. However, bicycling ability remains surprisingly unaffected in most patients suffering from freezing, suggesting functional differences in the motor network. The purpose of this study was to characterize and contrast the oscillatory dynamics underlying bicycling and walking in the basal ganglia.

METHODS

We present the first local field potential recordings directly comparing bicycling and walking in Parkinson disease patients with electrodes implanted in the subthalamic nuclei for deep brain stimulation. Low (13-22Hz) and high (23-35Hz) beta power changes were analyzed in 22 subthalamic nuclei from 13 Parkinson disease patients (57.5 ± 5.9 years old, 4 female). The study group consisted of 5 patients with and 8 patients without freezing of gait.

RESULTS

In patients without freezing of gait, both bicycling and walking led to a suppression of subthalamic beta power (13-35Hz), and this suppression was stronger for bicycling. Freezers showed a similar pattern in general. Superimposed on this pattern, however, we observed a movement-induced, narrowband power increase around 18Hz, which was evident even in the absence of freezing.

INTERPRETATION

These results indicate that bicycling facilitates overall suppression of beta power. Furthermore, movement leads to exaggerated synchronization in the low beta band specifically within the basal ganglia of patients susceptible to freezing. Abnormal ∼18Hz oscillations are implicated in the pathophysiology of freezing of gait, and suppressing them may form a key strategy in developing potential therapies. Ann Neurol 2017;82:592-601.

Investigation of Anticipatory Postural Adjustments during One-Leg Stance Using Inertial Sensors: Evidence from Subjects with Parkinsonism

The One-Leg Stance (OLS) test is a widely adopted tool for the clinical assessment of balance in the elderly and in subjects with neurological disorders. It was previously showed that the ability to control anticipatory postural adjustments (APAs) prior to lifting one leg is significantly impaired by idiopathic Parkinson’s disease (iPD). However, it is not known how APAs are affected by other types of parkinsonism, such as frontal gait disorders (FGD). In this study, an instrumented OLS test based on wearable inertial sensors is proposed to investigate both the initial anticipatory phase and the subsequent unipedal balance. The sensitivity and the validity of the test have been evaluated. Twenty-five subjects with iPD presenting freezing of gait (FOG), 33 with iPD without FOG, 13 with FGD, and 32 healthy elderly controls were recruited. All subjects wore three inertial sensors positioned on the posterior trunk (L4–L5), and on the left and right frontal face of the tibias. Participants were asked to lift a foot and stand on a single leg as long as possible with eyes open, as proposed by the mini-BESTest. Temporal parameters and trunk acceleration were extracted from sensors and compared among groups. The results showed that, regarding the anticipatory phase, the peak of mediolateral trunk acceleration was significantly reduced compared to healthy controls (p < 0.05) in subjects with iPD with and without FOG, but not in FGD group (p = 0.151). Regarding the balance phase duration, a significant shortening was found in the three parkinsonian groups compared to controls (p < 0.001). Moreover, balance was significantly longer (p < 0.001) in iPD subjects without FOG compared to subjects with FGD and iPD subjects presenting FOG. Strong correlations between balance duration extracted by sensors and clinical mini-BESTest scores were found (ρ > 0.74), demonstrating the method’s validity. Our findings support the validity of the proposed method for assessing the OLS test and its sensitivity in distinguishing among the tested groups. The instrumented test discriminated between healthy controls and people with parkinsonism and among the three groups with parkinsonism. The objective characterization of the initial anticipatory phase represents an interesting improvement compared to most clinical OLS tests.

Anticipatory Postural Adjustment During Self-Initiated, Cued, and Compensatory Stepping in Healthy Older Adults and Patients With Parkinson Disease

OBJECTIVE

To characterize anticipatory postural adjustments (APAs) across a variety of step initiation tasks in people with Parkinson disease (PD) and healthy subjects.

DESIGN

Cross-sectional study. Step initiation was analyzed during self-initiated gait, perceptual cued gait, and compensatory forward stepping after platform perturbation. People with PD were assessed on and off levodopa.

SETTING

University research laboratory.

PARTICIPANTS

People (N=31) with PD (n=19) and healthy aged-matched subjects (n=12).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Mediolateral (ML) size of APAs (calculated from center of pressure recordings), step kinematics, and body alignment.

RESULTS

With respect to self-initiated gait, the ML size of APAs was significantly larger during the cued condition and significantly smaller during the compensatory condition (P<.001). Healthy subjects and patients with PD did not differ in body alignment during the stance phase prior to stepping. No significant group effect was found for ML size of APAs between healthy subjects and patients with PD. However, the reduction in APA size from cued to compensatory stepping was significantly less pronounced in PD off medication compared with healthy subjects, as indicated by a significant group by condition interaction effect (P<.01). No significant differences were found comparing patients with PD on and off medications.

CONCLUSIONS

Specific stepping conditions had a significant effect on the preparation and execution of step initiation. Therefore, APA size should be interpreted with respect to the specific stepping condition. Across-task changes in people with PD were less pronounced compared with healthy subjects. Antiparkinsonian medication did not significantly improve step initiation in this mildly affected PD cohort.

Clinical balance scales indicate worse postural control in people with Parkinson's disease who exhibit freezing of gait compared to those who do not: A meta-analysis

Postural instability and freezing of gait (FOG) are key features of Parkinson's disease (PD) that are closely related to falls. Uncovering the postural control differences between individuals with and without FOG contributes to our understanding of the relationship between these phenomena. The objective of this meta-analysis was to investigate whether postural control deficits, as detected by clinical balance scales, were more apparent in FOG+ compared to FOG-. Furthermore, we aimed to identify whether different scales were equally sensitive to detect postural control deficits and whether medication affected postural control differentially in each subgroup. Relevant articles were identified via five electronic databases. We performed a meta-analysis on nine studies which reported clinical balance scale scores in 249 freezers and 321 non-freezers. Methodological analysis showed that in 5/9 studies disease duration differed between subgroups. Despite this drawback, postural control was found to be significantly worse in FOG+ compared to FOG-. All included clinical balance scales were found to be sufficiently sensitive to detect the postural control differences. Levodopa did not differentially affect postural control (p=0.21), as in both medication states FOG+ had worse postural stability than FOG-. However, this finding warrants a cautious interpretation given the limitations of the studies included. From subscore analysis, we found that reactive and dynamic postural control were the most affected postural control systems in FOG+. We conclude that our findings provide important evidence for pronounced postural instability in individuals with FOG, which can be easily picked up with clinical evaluation tools. Posturographic measures in well-matched subgroups are needed to highlight the exact nature of these deficits.

Dual task interference on postural sway, postural transitions and gait in people with Parkinson's disease and freezing of gait

Freezing of gait (FoG) is associated with less automatic gait and more impaired cognition, balance and postural transitions compared to people with PD who do not have FoG. However, it is unknown whether dual-task cost during postural sway, postural transitions (such as gait initiation and turning), and gait are more in subjects with Parkinson's disease (PD) who have freezing of gait (FoG+) compared to those who do not have FoG (FoG-). Here, we hypothesized that the effects of a cognitive dual task on postural sway, postural transitions and gait would be larger in FoG+ than FoG-. Thirty FoG- and 24 FoG+ performed an Instrumented Stand and Walk test in OFF medication state, with and without a secondary cognitive task (serial subtraction by 3s). Measures of postural sway, gait initiation, turning, and walking were extracted using body-worn inertial sensors. FoG+ showed significantly larger dual task cost than FoG- for several gait metrics, but not during postural sway or postural transitions. During walking, FoG+ exhibited a larger dual task cost than FoG- resulting in shorter stride length and slower stride velocity. During standing, FoG+ showed a larger postural sway compared to FoG- and during gait initiation, FoG+, but not FoG-, showed a longer first step duration during the dual-task condition compared to single-task condition (interaction effect, p=0.04). During turning, both groups showed a slower turn peak speed in the dual-task condition compared to single task condition. These findings partly support our hypothesis that dual task cost on walking is greater in FoG+ than FoG-.

Body Posture, Postural Stability, and Metabolic Age in Patients with Parkinson's Disease

BACKGROUND

The study aims to analyze the relationship between body posture and composition, as well as postural stability in Parkinson's disease patients.

MATERIAL AND METHODS

32 people were evaluated. The study was conducted in the Laboratory of Posturology at Jan Kochanowski University in Kielce (Poland). Body posture was examined using the optoelectronic body posture Formetric Diers Method III 4D. Postural stability was evaluated using the Biodex Balance System platform. Body composition was assessed with the method of bioelectrical impedance analysis using the Tanita MC 780 MA analyzer.

RESULTS

11 patients (34.37%) had hyperkyphosis, 10 (31.25%) hyperlordosis, and 3 (9.37%) hyperkyphosis-hyperlordosis posture. Scoliosis (>10°) was observed in 28 (87.5%) subjects, whereas 4 (12.5%) presented scoliotic body posture (1-9°). In the examined population, all parameters of postural stability were within normal limits.

CONCLUSIONS

A significant positive correlation was observed between surface rotation (°), General Stability Index (r = 0.4075, p = 0.0206), and Anteroposterior Stability Index (r = 0.3819, p = 0.0310). There was also a significant positive correlation between surface rotation (+max) (°), General Stability Index (r = 0.3526, p = 0.0206), and Anteroposterior Stability Index (r = 0.3873, p = 0.0285). Metabolic age also presented a significant positive correlation between metabolic age and General Stability Index (r = 0.4057, p = 0.0212), as well as Anteroposterior Stability Index (r = 0.3507, p = 0.0490).

Falling Direction can Predict the Mechanism of Recurrent Falls in Advanced Parkinson's Disease

Falls are a common and disabling symptom in patients with Parkinson’s disease (PD). For prevention, it is important to understand the pathophysiology of falls in PD patients, but the predictors for the possible mechanisms underlying such falls have not been clearly elucidated. In this prospective observational study, we investigated the implications of falling direction to predict the mechanisms of recurrent falls in PD patients. We enrolled 62 recurrent fallers with PD and divided them into two groups according to the main falling directions: 45 PD fallers who fell forward (forward fallers), and 17 PD fallers who fell in the other directions (non-forward fallers). Although there was no difference in demographic data, parkinsonism, or frontal lobe function, forward fallers showed more severe falls and tended to fall during walking or turning, while non-forward fallers usually fell during sitting/standing or turning. Additionally, forward fallers revealed higher score on a freezing of gait (FOG) questionnaire. Logistic regression analysis demonstrated that FOG was associated with falling forward, while balance impairment, akinetic-rigid subtype, and neuropsychiatric symptoms were associated with falling into the other directions. Our results indicate that FOG and balance impairment are two major mechanisms for recurrent falling in PD patients, and falling direction is an important predictor for these mechanisms.

Impact of Cognitive Loading on Postural Control in Parkinson's Disease With Freezing of Gait

Objective:To assess standing balance in Parkinson’s disease (PD) patients with and without freezing of gait (FOG) during cognitive loading. Method:A balance assessment with cognitive loading, reading (RE) and counting backward (CB), was performed by the Nintendo Wii Fit in 60 PD patients (Hoehn and Yahr stages 1-3) at Thammasat University Hospital, Thailand. The participants were grouped into FOG and non-FOG according to the Freezing of Gait–Questionnaire (FOG-Q) scores. The center of pressure (CoP) in terms of path length (PL), sway area (SA), root mean square (RMS), medio-lateral (ML), and antero-posterior (AP) were analyzed. Results:Significant increases of PL were observed in both groups of PD patients during cognitive loading (p < .001). Meanwhile, the increased differences of PL during cognitive loading in PD-FOG were larger than in PD-non-FOG. The ML displacement during counting backward was significantly increased in PD-FOG (p = .012). Conclusion:Cognitive loading influenced standing balance and postural sway of PD patients. The effects were more prominent in PD-FOG. These findings represent the interactions between cognitive function, postural control, and FOG in PD.

Freezing of gait in Parkinson's disease: from pathophysiology to emerging therapies

Freezing of gait (FOG) is 'an episodic inability to generate effective stepping in the absence of any known cause other than parkinsonism or high level gait disorders'. FOG is one of the most disabling symptoms in Parkinson's disease, especially in its more advanced stages. Early recognition is important as FOG is related to higher fall risk and poorer prognosis. Although specific treatments are still elusive, there have been recent advances in the development of new therapeutic approaches. The aim of this review is to present the latest knowledge regarding the phenomenology, pathogenesis, diagnostic assessment and conventional treatment of FOG in Parkinson's disease. A review of the evidence supporting noninvasive brain stimulation will follow to highlight the potential of these strategies.