PARKINSON'S DISEASE PATIENTS WITH DOMINANT HEMIBODY AFFECTED BY THE DISEASE RELY MORE ON VISION TO MAINTAIN UPRIGHT POSTURAL CONTROL

Does the side of onset influence symptom severity in Parkinson's disease? A systematic review and meta-analysis

Parkinson's disease (PD) is a neurodegenerative movement disorder characterized by motor symptoms that initially manifest unilaterally. Whilst some studies indicate that right-side onset is associated with greater symptom severity, others report no differences between right-side and left-side onset patients. The present meta-analysis was thus designed to reconcile inconsistencies in the literature and determine whether side of onset affects PD symptom severity. Following the PRISMA guidelines 1013 studies were initially identified in database and grey literature searches; following title and abstract, and full text, screening 34 studies met the stringent inclusion criteria (n = 2210). Results of the random-effects meta-analysis indicated no difference in symptom severity between PD patients with left-side (n = 1104) and right-side (n = 1106) onset. As such, the meta-analysis suggests that the side of onset should not be used to predict symptom trajectory or to formulate prognoses for PD patients. The current meta-analysis was the first to focus on the relationship between the side of onset and symptom severity in PD. However, the studies included were limited by the common exclusion of left-handed participants. Future research would benefit from exploring other factors that may influence symptom severity and disease progression in PD, such as asymmetric loss of nigrostriatal dopaminergic neurons.

Pupillary Response to Postural Demand in Parkinson's Disease

Background: Individuals with Parkinson’s disease (PD) may need to spend more mental and physical effort (i.e., cognitive workload) to maintain postural control. Pupillary response reflects cognitive workload during postural control tasks in healthy controls but has not been investigated as a measure of postural demand in PD.

Objectives: To compare pupillary response during increased postural demand using vision occlusion and dual tasking between individuals with PD and healthy controls.

Methods: Thirty-three individuals with PD and thirty-five healthy controls were recruited. The four conditions lasted 60 s and involved single balance task with eyes open; single balance task with eyes occluded; dual task with eyes open; dual task with eyes occluded. The dual task comprised the Auditory Stroop test. Pupillary response was recorded using an eye tracker. The balance was assessed by using a force plate. Two-way Repeated Measures ANOVA and LSD post-hoc tests were employed to compare pupillary response and Center of Pressure (CoP) displacement across the four conditions and between individuals with PD and healthy controls.

Results: Pupillary response was higher in individuals with PD compared to healthy controls (p = 0.009) and increased with more challenging postural conditions in both groups (p < 0.001). The post-hoc analysis demonstrated increased pupillary response in the single balance eyes occluded (p < 0.001), dual task eyes open (p = 0.01), and dual task eyes occluded (p < 0.001) conditions compared to single task eyes open condition.

Conclusion: Overall, the PD group had increased pupillary response with increased postural demand compared to the healthy controls. In the future, pupillary response can be a potential tool to understand the neurophysiological underpinnings of falls risk in the PD population.

Reliability and Validity of Pupillary Response During Dual-Task Balance in Parkinson Disease

OBJECTIVE

To investigate the reliability and validity of pupillary response during dual-task balance conditions in individuals with Parkinson disease (PD).

DESIGN

Cross-sectional study.

SETTING

University of Kansas Medical Center Parkinson's Disease and Movement Disorder Center.

PARTICIPANTS

Participants (N=68) included individuals with PD (n=33) and healthy controls (n=35).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Pupillary response was the main outcome measure that was measured during the following conditions: single-task balance eyes open, single-task balance eyes occluded, dual-task eyes open, and dual-task eyes occluded. After each condition, the National Aeronautics and Space Administration-Task Load Index (NASA-TLX) was administered to assess self-reported cognitive workload. To examine the test-retest reliability of the pupillary response, the conditions were administered twice for each individual within 2 hours. Intraclass correlation coefficients (ICC) were used to analyze the test-retest reliability of pupillary response in each condition for both groups. Pearson's r correlation was used to assess the convergent validity of pupillary response against the NASA-TLX.

RESULTS

The test-retest reliability was excellent for both groups in almost all conditions (ICC>0.75). There were no correlations between pupillary response and the NASA-TLX. However, increased mental demand (a subitem of the NASA-TLX) significantly correlated with increased pupillary response in individuals with PD (r=0.38; P=.03).

CONCLUSIONS

Pupillary response showed excellent test-retest reliability and validity during dual-task balance for individuals with PD and healthy controls. Overall, these results suggest that pupillary response represents a stable index of cognitive workload during dual-task balance in individuals with PD.

Abnormal Spontaneous Brain Activity in Left-Onset Parkinson Disease: A Resting-State Functional MRI Study

Objective: Motor asymmetry is characteristic in Parkinson disease (PD). This phenomenon is originated from uneven degeneration of bilateral substantia nigra. However, this asymmetry may not restrict to substantia nigra or striatum. We aimed to determine the effect of asymmetry on spontaneous brain activity across the whole brain. Methods: We consecutively recruited 71 patients with PD, as well as 35 healthy controls, and collected relevant demographic, clinical, and neuropsychological information. The PD patients were divided into two groups according to the side of motor symptom onset. All the participants underwent resting-state functional magnetic resonance imaging, and spontaneous brain activity was assessed using amplitude of low-frequency fluctuation (ALFF). The associations between areas showing significant group differences and various clinical and neuropsychological measures were analyzed. Results: Finally, the data of 30 PD patients with left-onset (LPD), 27 PD patients with right-onset (RPD), and 32 healthy controls were obtained. The three groups had similar age and gender ratios. Our results demonstrated that LPD patients had increased ALFF in the left inferior temporal gyrus and decreased ALFF in bilateral thalamus and cerebellum anterior lobes than the control group. The value of ALFF of the left inferior temporal gyrus was correlated with motor function, and ALFF value of the thalamus was associated with cognition. Comparisons between LPD and RPD patients and between RPD patients and the controls did not yield significant difference. Conclusions: The present study provides new insights into the distinct characteristics of spontaneous brain activity in LPD, which may be associated with motor and cognitive function.

Comparing Balance Performance on Force Platform Measures in Individuals with Parkinson's Disease and Healthy Adults

Introduction

Postural instability is a known contributing factor to balance dysfunction and increased fall risk in those with Parkinson's disease (PD). Computerized posturography employing a force platform system provides objective, quantitative assessments of postural control impairments. This study examines balance performance as measured by force platform (FP) tests in persons with PD compared to age-matched healthy adults. Secondarily, we examine if these FP measures provide diagnostic and clinically meaningful information about the underlying balance impairments in the PD population.

Methods

Participants-42 individuals with PD (Hoehn and Yahr stage = 2.33 ± 0.77) and 55 age-matched healthy adults-were assessed on three standardized balance measures on a computerized force platform system. Between groups, comparisons of FP performance were analyzed using independent t-test. Within the group, comparisons for the PD cohort were analyzed using ANOVA for comparing disease stage and Mann-Whitney U test for PD subtypes.

Results

The PD cohort demonstrated significantly greater postural instability on the sensory organization test (SOT) measures (P=0.013, CI-95% = 1.286 to 10.37) and slower movement velocity on the limits of stability (LOS) test (P=0.001, CI-95% = 0.597 to 1.595) than the healthy cohort, suggesting that these tests were sensitive to detect sensory integration and voluntary postural control deficits in the PD cohort. Within the PD group, the SOT differentiated between H&Y stages 1-3. The motor control test (MCT) detected changes in reactive postural control mainly in later disease stages. All three FP tests distinguished between PD subtypes, with the Posture Gait Instability subtype demonstrating poorer balance performance than Tremor Dominant subtype.

Conclusion

These findings suggest FP measures provide clinically meaningful, diagnostic information in the examination of balance impairments in individuals with PD. FP measures may inform clinicians regarding intrinsic balance deficits and guide them in designing targeted balance interventions to reduce fall risk in persons with PD.

Romberg ratio coefficient in quiet stance and postural control in Parkinson's disease

The aim of this study was to determine the function of visual afference in postural control in Parkinson patients. We enrolled 29 patients and 30 healthy controls. The stabilometry test was performed for posture and balance and Romberg ratio coefficients were calculated. In addition, the Berg Balance Scale and the 6-Minute Walking Test were administered to assess balance and functional exercise capacity; the Unified Parkinson's Disease Rating Scale was used to determine the stage of the disease; and the Short Form (SF)-36 Health Survey was given to collect information on quality of life.

RESULTS

significantly longer Center of Pressure (CoP) sway lengths were observed in the parkinson group. The Romberg index for CoP length of sway in parkinson patients was 94.3 ± 19.3%, versus 147.4 ± 120.6% for the control group. (p = 0.025).

CONCLUSION

Parkinson patients use the increase in CoP sway length and ellipse area to stabilize their balance and sight does not facilitate static postural control as in healthy subjects.

Postural instability in subjects with parkinson’s disease undergoing different sensory pitfalls

Purpose. Previous research has reported postural instability in subjects with Parkinson’s disease (PD). However, there are still doubts about the effect of sensory stimuli on one’s balance. In this study, we further investigated the stabilometric measures of individuals with PD, analysing the impact of different sensory stimuli on the outcomes. Methods. The total of 26 participants (13 with PD and 13 matched control peers) were submitted to 8 sensorimotor dynamics differing in relation to support base (30 cm vs. 10 cm, feet in parallel vs. feet in semi-tandem position), contact surface (foam vs. no foam), and visual conditions (eyes open vs. eyes closed). The measures used to assess one’s balance were body position in space, area of support base, and velocity of postural control. The variables involved the anterior-posterior and the mediolateral axes. Participants with PD were evaluated during the off medication state. Mann-Whitney U test and Friedman’s test were applied to carry out inter- and intra-group comparisons. Significance was set at 5%. Results. Cross-sectional analyses illustrated that tasks with sensory pitfalls impacted postural stability to a larger extent in PD subjects. The differences were found in anterior-posterior body position, area of support base, anterior-posterior velocity, and mediolateral velocity. Complementary analyses confirmed considerable instability on balance when support bases were small and visual information was absent (p < 0.05). Conclusions. The current results confirm worse postural stability response in subjects with PD and highlight that the interference of the sensory pitfalls is notable when individuals are off medication.