Persistence of Basal Ganglia Oscillatory Activity During Tremor Attenuation by Movement in Parkinson's Disease Patients.

BACKGROUND: One of the characteristics of parkinsonian tremor is that its amplitude decreases with movement. Current models suggest an interaction between basal ganglia (BG) and cerebello-thalamo-cortical circuits in parkinsonian tremor pathophysiology. OBJECTIVE: We aimed to correlate central oscillation in the BG with electromyographic activity during re-emergent tremor in order to detect changes in BG oscillatory activity when tremor is attenuated by movement. METHODS: We performed a prospective, observational study on consecutive parkinsonian patients who underwent deep brain stimulation surgery and presented re-emergent tremor. Coherence analysis between subthalamic nucleus/globus pallidus internus (STN/GPi) tremorous activity measured by microrecording (MER) and electromyogram (EMG) from flexor and extensor wrist muscles during rest, posture, and re-emergent tremor pause was performed during surgery. The statistical significance level of the MER-EMG coherence was determined using surrogate data analysis, and the directionality of information transfer between BG and muscle was performed using entropy transfer analysis. RESULTS: We analyzed 148 MERs with tremor-like activity from 6 patients which were evaluated against the simultaneous EMGs, resulting in 296 correlations. Of these, 26 presented a significant level of coherence at tremor frequency, throughout rest and posture, with a complete EMG stop in between. During the pause, all recordings showed sustained MER peaks at tremor frequency (±1.5 Hz). Information flows preferentially from BG to muscle during rest and posture, with a loss of directionality during the pause. CONCLUSIONS: Our results suggest that oscillatory activity in STN/GPi functionally linked to tremor sustains firing frequency during re-emergent tremor pause, thus suggesting no direct role of the BG circuit on tremor attenuation due to voluntary movements. © 2024 International Parkinson and Movement Disorder Society.

Genetic Testing in Parkinson's Disease.

Genetic testing for persons with Parkinson's disease is becoming increasingly common. Significant gains have been made regarding genetic testing methods, and testing is becoming more readily available in clinical, research, and direct-to-consumer settings. Although the potential utility of clinical testing is expanding, there are currently no proven gene-targeted therapies, but clinical trials are underway. Furthermore, genetic testing practices vary widely, as do knowledge and attitudes of relevant stakeholders. The specter of testing mandates financial, ethical, and physician engagement, and there is a need for guidelines to help navigate the myriad of challenges. However, to develop guidelines, gaps and controversies need to be clearly identified and analyzed. To this end, we first reviewed recent literature and subsequently identified gaps and controversies, some of which were partially addressed in the literature, but many of which are not well delineated or researched. Key gaps and controversies include: (1) Is genetic testing appropriate in symptomatic and asymptomatic individuals without medical actionability? (2) How, if at all, should testing vary based on ethnicity? (3) What are the long-term outcomes of consumer- and research-based genetic testing in presymptomatic PD? (4) What resources are needed for clinical genetic testing, and how is this impacted by models of care and cost-benefit considerations? Addressing these issues will help facilitate the development of consensus and guidelines regarding the approach and access to genetic testing and counseling. This is also needed to guide a multidisciplinary approach that accounts for cultural, geographic, and socioeconomic factors in developing testing guidelines. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

International Genetic Testing and Counseling Practices for Parkinson's Disease.

BACKGROUND: There is growing clinical and research utilization of genetic testing in Parkinson's disease (PD), including direct-to-consumer testing. OBJECTIVES: The aim is to determine the international landscape of genetic testing in PD to inform future worldwide recommendations. METHODS: A web-based survey assessing current practices, concerns, and barriers to genetic testing and counseling was administered to the International Parkinson and Movement Disorders Society membership. RESULTS: Common hurdles across sites included cost and access to genetic testing, and counseling, as well as education on genetic counseling. Region-dependent differences in access to and availability of testing and counseling were most notable in Africa. High-income countries also demonstrated heterogeneity, with European nations more likely to have genetic testing covered through insurance than Pan-American and Asian countries. CONCLUSIONS: This survey highlights not only diversity of barriers in different regions but also the shared and highly actionable needs for improved education and access to genetic counseling and testing for PD worldwide. © 2023 International Parkinson and Movement Disorder Society.

Clinical correlates of fear of falling in progressive supranuclear palsy and multiple system atrophy.

BACKGROUND AND PURPOSE: Clinical correlates of fear of falling (FoF) are scarcely studied in patients with progressive supranuclear palsy (PSP) and multiple system atrophy (MSA). This study was undertaken to evaluate the clinical correlates of FoF in PSP and MSA. METHODS: This cross-sectional study features motor, cognitive, and psychiatric assessment and longitudinal evaluation of falls and FoF at 6-month follow-up. RESULTS: Twenty-one patients with PSP-parkinsonism, 22 patients with MSA (13 parkinsonian type and nine cerebellar type), and 22 healthy controls were evaluated; 76.2% of patients with PSP and 86.4% of patients with MSA had FoF regardless of falls. Berg Balance Scale (p < 0.001), Tinetti Mobility Test (p < 0.01), Beck Anxiety Inventory (p = 0.001), and Beck Depression Inventory-II (p = 0.01) correlated with FoF in patients with PSP and MSA, whereas Timed Up and Go test (p = 0.01) and Starkstein Apathy Scale correlated only in MSA (p = 0.04). CONCLUSIONS: Mobility, balance, and gait performance as well as anxiety and depression in PSP and MSA, and apathy in MSA, were determinants of FoF. These findings underline the importance of a multidisciplinary approach to FoF in neurodegenerative atypical parkinsonism.

Motor assessment of patients with multiple system atrophy: underuse of the Unified Multiple System Atrophy Rating Scale (UMSARS).

PURPOSE: Despite the availability of the Unified Multiple System Atrophy (MSA) Rating Scale (UMSARS) for almost two decades, studies still use scales developed for Parkinson's disease (PD) or ataxia (ATX). Our aim was to evaluate the use of UMSARS (part II, motor) compared to other motor rating scales in patients with MSA. METHODS: A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-compliant literature search was conducted concerning studies of patients with MSA, reporting motor assessment with clinical rating scales, and focusing on the frequency of UMSARS use. RESULTS: We included 261 articles, of which 42.9% did not use UMSARS, but rather scales for PD (59.8%), ATX (24.1%), or both (14.3%). Although UMSARS use increased with time, misuse of PD and ATX scales persists, with no evidence of a decremental trend. CONCLUSIONS: Although higher in observational studies, the misuse of PD and ATX-related scales in MSA patients persists in prospective (planned) trials. Reasons for that must be addressed.

Heart rate variability and falls in Huntington's disease.

PURPOSE: Persons with Huntington's disease (HD) have a high incidence of falls. Autonomic nervous system dysfunction has been reported even in early stages of this disease. To date, there has been no analysis of the relationship between heart rate variability (HRV) and falls in this patient population. The aim of the study reported here was to evaluate the relationship between HRV and falls in persons with HD. METHODS: Huntington's disease patients enrolled in a prospective study on fear of falling and falls were assessed using short-term HRV analyses and blood pressure measures in both the resting and standing states. Time-frequency domains and nonlinear parameters were calculated. Data on falls, the risk of falling (RoF) and disease-specific scales were collected at baseline and at the end of the 6-month follow-up. RESULTS: Of the 24 HD patients who were invited to participate in the study, 20 completed the baseline analysis and 18 completed the 6-month follow-up. At baseline, seven (35%) HD patients reported at least one fall (single fallers) and 13 (65%) reported ≥ 2 falls (recurrent fallers) in the previous 12 months. At baseline, recurrent fallers had lower RMSSD (root mean square of successive RR interval differences) in the resting state (RMSSD-resting), higher LF/HF (low/high frequency) ratio in both states and higher DFA-α1 parameter (detrended fluctuation analyses over the short term) in both states. This association was similar at the 6-month follow-up for recurrent fallers, who showed lower RMSSD-resting and higher LF/HF ratio in the standing state (LF/HF-standing) than single fallers. Significant correlations were found between the number of falls, RMSSD-resting and LF/HF-standing. No differences were found between recurrent and single fallers for any blood pressure measures. CONCLUSIONS: The observed HRV pattern is consistent with a higher sympathetic prevalence associated with a higher RoF. Reduced parasympathetic HRV values in this patient population predict being a recurrent faller at 6 months of follow-up, independently of orthostatic phenomena.

Limitations of the Unified Multiple System Atrophy Rating Scale as outcome measure for clinical trials and a roadmap for improvement.

PURPOSE: The unified multiple system atrophy (MSA) rating scale (UMSARS) was developed almost 20 years ago as a clinical rating scale to capture multiple aspects of the disease. With its widespread use, the shortcomings of the UMSARS as a clinical outcome assessment (COA) have become increasingly apparent. We here summarize the shortcomings of the scale, confirm some of its limitations with data from the Natural History Study of the Synucleinopathies (NHSS), and suggest a framework to develop and validate an improved COA to be used in future clinical trials of disease-modifying drugs in patients with MSA. METHODS: Expert consensus assessment of the limitations of the UMSARS and recommendations for the development and validation of a novel COA for MSA. We used UMSARS data from the ongoing NHSS (ClinicalTrials.gov: NCT01799915) to showcase some of these limitations. RESULTS: The UMSARS in general, and specific items in particular, have limitations to detect change resulting in a ceiling effect. Some items have specific limitations including unclear anchoring descriptions, lack of correlation with disease severity, susceptibility to improve with symptomatic therapies (e.g., orthostatic hypotension, constipation, and bladder dysfunction), and redundancy, among others. CONCLUSIONS: Because of the limitations of the UMSARS, developing and validating an improved COA is a priority. The time is right for academic MSA clinicians together with industry, professional societies, and patient advocacy groups to develop and validate a new COA.

Sensitivity and specificity of different hand positions to assess upper limb rest tremor.

BACKGROUND: Hand position for rest tremor evaluation in PD is not standardized. We evaluated the sensitivity and specificity of different hand positions commonly used to evaluate rest tremor. METHODS: Twenty patients with PD and rest tremor were included as cases and 20 patients with essential tremor without rest tremor as controls. Video and accelerometric recordings were conducted in semiprone, completely prone, and with hands hanging down from armrest positions. Three movement disorder specialists rated tremor in each different position using Movement Disorder Society UPDRS items 3.17 and 3.18. RESULTS: Hands hanging showed the highest amplitude (P = 0.004) and constancy (P = 0.015) scores. Sensitivity and specificity analysis for each position showed the following sensitivity/specificity results: semiprone, 95%/80%; completely prone, 85%/98.33%; and hands hanging, 96.66%/63.33%, respectively. CONCLUSIONS: The hands-hanging position was shown to be the most suitable for evaluating rest tremor amplitude in PD, whereas the completely prone position proved to be more specific to detect rest tremor. The preferred hand position would depend on the purpose of the examination. © 2019 International Parkinson and Movement Disorder Society.

Design and validation of a new instrument to assess fear of falling in Parkinson's disease.

BACKGROUND: Fear of falling may be significantly associated with falls in Parkinson's disease (PD) and may have a negative impact on quality of life. Nevertheless, there are no valid and reliable tools to examine this condition in PD. The objective of this study was to design and determine the psychometric attributes of an instrument to assess fear of falling in PD. METHODS: A prospective 1-year, 2-phase study was conducted to validate the Fear of Falling Scale, a self-assessed instrument for assessing fear of falling in PD. During phase 1, we designed a scale to measure the severity of fear of falling and determine its baseline psychometric characteristics, whereas phase 2 was a 1-year follow-up study to assess the frequency of falls and other clinical factors linked to fear of falling. Convergent and discriminant validity were assessed against the Fear of Falling Measure and the Starkstein Apathy Scale, respectively. RESULTS: The Fear of Falling Scale showed high internal consistency, test-retest reliability, and strong convergent and discriminant validity. There was a significant association between fear of falling score and the presence of both generalized anxiety disorder and major depression, poor balance-related motor ability, increased nonmotor symptoms of PD, more severe impairments in activities of daily living, and increased motor fluctuations. Finally, generalized anxiety disorder was a significant predictor of number of falls during a 12-month follow-up period. CONCLUSIONS: The Fear of Falling Scale is a valid and reliable instrument to assess fear of falling in PD. Fear of falling in PD is associated with specific psychiatric and motor disorders and is significantly related to the performance of balance-related motor functions. © 2019 International Parkinson and Movement Disorder Society.

Motor features in Parkinson's disease with normal olfactory function.

BACKGROUND: Normosmic Parkinson's disease (PD) might be a unique clinical phenotype with a more benign course when compared with hyposmic PD. OBJECTIVE: The objective of this study was to evaluate motor features and the acute levodopa response according to olfactory function. METHODS: A total of 169 de novo PD patients that underwent olfactory testing and acute levodopa challenge for clinical prediction of sustained long-term dopaminergic response were evaluated. RESULTS: The overall frequency of normosmia was 33%. Normosmic PD patients scored nonsignificantly different to hyposmic/anosmic patients on motor scale and on degree of improvement with levodopa. Motor scores at follow-up were comparable among groups. CONCLUSIONS: Normal olfactory function is common in early PD and was not associated with a different motor phenotype when compared with PD patients with olfactory dysfunction. © 2016 International Parkinson and Movement Disorder Society.

Comparison of Olfactory Identification Patterns among Parkinson's Disease Patients from Different Countries.

Olfactory function assessment is an important screening tool and also may differentiate Parkinson's disease (PD) patients from other parkinsonisms, including nondegenerative ones, such as, normal pressure hydrocephalus, vascular, drug induced, or infectious parkinsonism. Several authors in different countries have reported various sets of odors that best differentiate between these conditions. It is debated if distinctive patterns of "restrictive" or "selective" hyposmia in PD may be affected by cultural aspects. To compare the olfactory identification function in PD across different countries, we analyzed Sniffin' Sticks identification task results between 112 PD patients from Argentina and previously reported data of PD patients from Brazil (106 patients), the Netherlands (400 patients), Germany (40 patients), China (110 patients), and Sri Lanka (89 patients). Categorical principal component analysis (CATPCA) was performed to find components reflecting groups of odors similarly perceived across subjects. CATPCA analysis found 2 components for each group which shared 10 out of 16 odors amongst each other. We found that only the shared items of component 2 (orange, mint, banana, garlic, coffee, cloves, and fish) showed uniform results across all of the included countries, whereas variations in component 1 (licorice, turpentine, and apple) were attributed mostly to differences across control groups.

Facial tremors in patients with and without parkinsonism.

Facial (lip and jaw) tremors can be an early sign of Parkinson's disease (PD), essential tremor and other parkinsonisms. Its response to acute dopaminergic therapy and further predictive clinical diagnosis has not been previously addressed. The aim of this study was to evaluate facial tremors response to acute dopaminergic therapy and further predictive value for clinical diagnosis. A retrospective review of medical records from patients with recent onset of facial tremor, with or without parkinsonism, submitted to acute levodopa challenge for clinical prediction of sustained long-term dopaminergic response was conducted. Twenty-eight out of 559 patients (5 %) had facial tremors, which responded to levodopa in 46 % of patients. Facial tremors response to acute levodopa challenge showed 92 % sensitivity and 93 % specificity to predict a final PD diagnosis. In PD patients, facial tremor magnitude of response to levodopa was not different from that of hand rest tremor (p = 0.8). Facial tremors, although infrequent, can be an early sign of PD. Positive response to acute levodopa challenge predicts long-term PD diagnosis.

Olfactory Dysfunction Evaluation Is Not Affected by Comorbid Depression in Parkinson's Disease.

BACKGROUND: Olfactory function assessment is an important screening tool for Parkinson's disease (PD) diagnosis. It is debated whether olfaction is affected by comorbid depression. We assessed the relationship between depression and olfaction in PD and determined whether depression may limit the usefulness of olfactory testing for PD diagnosis. METHODS: Olfaction was evaluated using the Sniffin' Sticks test and the Hyposmia Rating Scale in four groups of subjects: PD patients without depression (n = 30); PD patients with major depression (PDD; n = 30); major depressive disorder (MDD) patients (n = 29); and healthy controls (HCs; n = 30). RESULTS: No differences were found between PD and PDD patients for total Sniffin' Sticks test, threshold, discrimination or identification scores, or in Hyposmia Rating Scale, although both groups differed from HCs and MDD patients (P < 0.05), which, in turn, showed similar olfactory scores. CONCLUSIONS: Lack of differences in olfactory impairment between PD and PDD suggest that depression may not contribute to olfactory dysfunction in PD.

The impact of emotional distress on motor blocks and festination in Parkinson's disease.

Recent studies suggest that depression and anxiety in patients with Parkinson's disease may predispose them to freezing. Although festination is also frequent, the association with emotional disorders has not been examined. The aim of the authors was to clarify the association between freezing and festination with anxiety, depressive disorders, and emotional distress. The authors examined a consecutive series of 95 patients with Parkinson's disease using comprehensive psychiatric assessments and a new instrument specifically designed to assess the severity of freezing, festination, and emotional distress (Motor Blocks and Festination Scale). All patients were assessed with the Motor Blocks and Festination Scale, the Mini International Neuropsychiatric Interview, and scales to measure the severity of mood and anxiety disorders. A linear regression analysis showed that both motor blocks and festination were significantly associated with emotional distress and deficits on activities of daily living. Conversely, there was no significant association between motor blocks or festination and generalized anxiety disorder, panic disorder, agoraphobia, social phobia, or depression. Motor blocks and festination are significantly associated with emotional distress, but no significant associations were found with anxiety or affective disorders.