NIH Toolbox performance of persons with Parkinson's disease according to GBA1 and STN-DBS status

OBJECTIVE

Mutations in the glucocerebrosidase (GBA1) gene and subthalamic nucleus deep brain stimulation (STN-DBS) are independently associated with cognitive dysfunction in persons with Parkinson's disease (PwP). We hypothesized that PwP with both GBA1 mutations and STN-DBS are at greater risk of cognitive dysfunction than PwP with only GBA1 mutations or STN-DBS, or neither. In this study, we determined the pattern of cognitive dysfunction in PwP based on GBA1 mutation status and STN-DBS treatment.

METHODS

PwP who are GBA1 mutation carriers with or without DBS (GBA1+DBS+, GBA1+DBS-), and noncarriers with or without DBS (GBA1-DBS+, GBA1-DBS-) were included. Using the NIH Toolbox, cross-sectional differences in response inhibition, processing speed, and episodic memory were compared using analysis of variance with adjustment for relevant covariates.

RESULTS

Data were available for 9 GBA1+DBS+, 14 GBA1+DBS-, 17 GBA1-DBS+, and 26 GBA1-DBS- PwP. In this cross-sectional study, after adjusting for covariates, we found that performance on the Flanker test (measure of response inhibition) was lower in GBA1+DBS+ PwP compared with GBA1-DBS+ PwP (P = 0.030).

INTERPRETATION

PwP who carry GBA1 mutations and have STN-DBS have greater impaired response inhibition compared with PwP with STN-DBS but without GBA1 mutations. Longitudinal data, including preoperative scores, are required to definitively determine whether GBA1 mutation carriers respond differently to STN-DBS, particularly in the domain of response inhibition.

Unveiling Assessment Gaps in Parkinson's Disease Psychosis: A Scoping Review

BACKGROUND

Parkinson's disease psychosis (PDP) is a multidimensional construct that is challenging to measure. Accurate assessment of PDP requires comprehensive and reliable clinical outcome assessment (COA) measures.

OBJECTIVE

To identify PDP measurement gaps in available COAs currently used in clinical and research settings.

METHODS

We conducted a scoping review using Preferred Reporting Items for Systematic Review and Meta-Analysis Extension for Scoping Reviews (PRISMA-ScR) guidelines. We implemented a three-step search strategy in international databases with keywords related to Parkinson's disease (PD), psychosis, and COA. We analyzed studies using COA to assess PDP, classifying their items according to domains and subdomains.

RESULTS

From 5673 identified studies, we included 628 containing 432 PDP core items from 32 COAs. Among the 32 COAs, 19 were PD-specific, containing 266 items, constructed as clinician-reported outcomes (ClinRO) (148 items), patient-reported outcomes (PRO) (112 items), and observer-reported outcomes (ObsRO) (six items). Across all PD-specific COAs, regardless of structure, 89.4% of the items from 27 COAs focused primarily on assessing PDP symptoms' severity, and only 9.7% of items probed the impact of PDP on a person's daily functioning.

CONCLUSIONS

Symptom-based domains are currently prioritized for measuring the severity of PDP, with limited coverage of the functional impact of PDP on patients' lives. Whereas the International Parkinson and Movement Disorder Society has traditionally developed a "Unified" COA that culls items from prior COAs to form a new one, a new COA will largely need newly developed items if the functional impact of PDP is prioritized. © 2024 International Parkinson and Movement Disorder Society.

Patient With Parkinson Disease and Care Partner Perceptions of Key Domains Affecting Health-Related Quality of Life: Systematic Review

BACKGROUND AND OBJECTIVES

To effectively customize Parkinson disease (PD) programs, it is important to incorporate the "individual's voice" and have a thorough understanding of the symptom priorities of people with PD (PwP) and care partners (CP). In this convergent integrated mixed-method systematic review, we aimed to analyze qualitative and quantitative evidence of PD motor and nonmotor symptoms affecting health-related quality of life (HRQOL) in PwP and CP, comparing priorities across different levels of disease severity.

METHODS

We searched MEDLINE, PsycINFO, Web of Science, Embase, and Scopus; ProQuest Dissertations and Theses Global; and the Michael J. Fox Foundation Data Resources for studies published up to June 29, 2022. We included qualitative, quantitative, and mixed-method studies investigating PD symptom priorities among PwP and CP. We critically appraised eligible studies for methodological quality using the Mixed-Methods Appraisal Tool. Derived terms were mapped and coded according to thematic attribution. Independent syntheses of qualitative and quantitative evidence and transformation of quantitative data into qualitative formats were performed.

RESULTS

Of the 7,716 identified studies, we included 70 that provided qualitative (n = 13), quantitative (n = 53), and mixed (n = 4) evidence. We included 604 mapped terms representing 11 PwP-identified and CP-identified motor and nonmotor symptom categories. Across all PD stages, both PwP and CP considered 5 domains more affecting their HRQOL, namely: "motor functionality," "mood," "cognition," "gait, balance, posture, and falls," and "nighttime sleep disorders." In early disease, PwP and CP considered "mood" the domain that most affected their HRQOL. In advanced PD, PwP considered "pain" the domain that most affects their HRQOL, while CP considered "psychiatric symptoms." The domain "gait, balance, posture, and falls" was equally considered by both PwP and CP as the second domain that most affects their HRQOL in the advanced stage of PD.

DISCUSSION

The ranking of the priority of symptoms is largely shared by PwP and CP, and motor symptom priorities dominate the full disease spectrum. However, the nonmotor symptom priorities shift according to the disease severity stage. Tailored care and research require that providers consider these shifting priorities and incorporate the "individual's voice" into treatment decisions.

A Novel Home-Based Telerehabilitation Program Targeting Fall Prevention in Parkinson Disease: A Preliminary Trial

Background and Objectives

Falls in a person with Parkinson disease (PwP) are frequent, consequential, and only partially prevented by current therapeutic options. Notably, most falls in PwPs occur in the home or its immediate surroundings; however, our current strategies for fall prevention are clinic-centered. The primary objective of this nonrandomized pilot trial was to investigate the feasibility and preliminary efficacy of the novel implementation of home-based PD telerehabilitation (tele-physical/occupational therapy) focusing on fall risk reduction and home-safety modification.

Methods

Persons with mild-to-moderate PD who were identified as being at risk of falls by their movement disorders neurologist were recruited from a tertiary movement disorders clinic. After an initial in-person evaluation by the study physical and occupational therapists, 15 patients with PD (Hoehn and Yahr Stage 2 (n = 8) and Stage 3 (n = 7)) participated in 4 biweekly PT/OT televisits with care partner supervision over the course of 10 weeks. The Goal Attainment Scale (GAS) was implemented to assess progress toward individualized PT/OT goals established at baseline. Outcomes were assessed at the end of the intervention at 10 weeks and at a six-month follow-up.

Results

Participants completed all 120 protocol-defined televisits without dropouts and adverse events. At 10 weeks, mean composite PT and OT-GAS scores showed significant improvement from baseline (PT: p < 0.001, OT: p < 0.008), which continued at 6 months (PT: p < 0.0005, OT: p < 0.0005). Home-modification recommendations made through novel virtual home-safety tours were cumulatively met by participants at 87% at 10 weeks and 91% at 6 months.

Discussion

Home-based telerehabilitation is a promising new strategy toward fall prevention in PD. The GAS has the potential to serve as an effective and patient-driven primary outcome variable for rehabilitation interventions for heterogeneous PwPs to assess progress toward personalized goals.

Trial Registration Information

ClinicalTrial.gov identifier: NCT04600011.

Validation of the Kazakh version of the movement disorder Society-Unified Parkinson's disease rating scale

Background and Purpose

The International Movement Disorder Society revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) is widely used in the assessment of the severity of Parkinson's disease (PD). This study aimed to validate the Kazakh version of the MDS-UPDRS, explore its dimensionality, and compare it to the original English version.

Methods

The validation was conducted in three phases: first, the English version of the MDS-UPDRS was translated into Kazakh and thereafter back-translated into English by two independent teams; second, the Kazakh version underwent a cognitive pretesting; third, the Kazakh version was tested in 360 native Kazakh-speaking PD patients. Both confirmatory and exploratory factor analyses were performed to validate the scale. We calculated the comparative fit index (CFI) for confirmatory factor analysis and used unweighted least squares for exploratory factor analysis.

Results

The CFI was higher than 0.90 for all parts of the scale, thereby meeting the pre-set threshold for the official designation of a validated translation. Exploratory factor analysis also showed that the Kazakh MDS-UPDRS has the analogous factors structure in each part as the English version.

Conclusions

The Kazakh MDS-UPDRS had a consistent overall structure as the English MDS-UPDRS, and it was designated as the official Kazakh MDS-UPDRS, which can reliably be used in the Kazakh-speaking populations. Presently, Kazakhstan stands as the sole country in both Central Asia and Transcaucasia with an MDS-approved translated version of the MDS-UPDRS. We expect that other Central Asian and Transcaucasian countries will embark on the MDS Translation Program for MDS-UPDRS in the near future.

Assessing the Severity of Cervical Dystonia: Ask the Doctor or Ask the Patient?

Background

Assessing disease severity can be performed using either clinician-rated scales (CRS) or patient-rated outcome (PRO) tools. These two measures frequently demonstrate poor correlations.

Objectives

To determine if the correlation between a CRS and PRO for motor features of cervical dystonia (CD) improves by accounting for non-motor features.

Methods

Subjects with CD (N = 209) were evaluated using a CRS (Toronto Western Spasmodic Torticollis Rating Scale, TWSTRS) and a PRO (Cervical Dystonia Impact Profile, CDIP-58).

Results

Linear regression revealed a weak correlation between the two measures, even when considering only the motor subscales of each. The strength of this relationship improved with a regression model that included non-motor symptoms of pain, depression, and disability.

Conclusions

These results argue that the results of motor assessments in a PRO for CD cannot be fully appreciated without simultaneous assessment of non-motor co-morbidities. This conclusion might apply to other disorders, especially those with frequent non-motor co-morbidities.

Understanding visual hallucinations: a new synthesis

Despite decades of research, we do not definitively know how people sometimes see things that are not there. Eight models of complex visual hallucinations have been published since 2000, including Deafferentation, Reality Monitoring, Perception and Attention Deficit, Activation, Input, and Modulation, Hodological, Attentional Networks, Active inference, and Thalamocortical Dysrhythmia Default Mode Network Decoupling. Each was derived from different understandings of brain organisation. To reduce this variability, representatives from each research group agreed an integrated Visual Hallucination Framework that is consistent with current theories of veridical and hallucinatory vision. The Framework delineates cognitive systems relevant to hallucinations. It allows a systematic, consistent, investigation of relationships between the phenomenology of visual hallucinations and changes in underpinning cognitive structures. The episodic nature of hallucinations highlights separate factors associated with the onset, persistence, and end of specific hallucinations suggesting a complex relationship between state and trait markers of hallucination risk. In addition to a harmonised interpretation of existing evidence, the Framework highlights new avenues of research, and potentially, new approaches to treating distressing hallucinations.

The Rush Video-Based Tic Rating Scale-Revised: A Practice-Oriented Revision

Background

The Modified Rush Video-Based Tic Rating Scale (MRVS) is the most widely used video-based scale for assessing tic severity in patients with Tourette syndrome (TS). However, shortcomings of the MRVS, including a lack of clear instructions, a time-consuming recording procedure, and weak correlations with the gold standard for tic assessment, the Yale Global Tic Severity Scale-Total Tic Score (YGTSS-TTS), limits its use in research settings, although video assessments are generally considered objective, reliable, and time-saving measurements.

Objectives

We aimed to revise the MRVS (MRVS-R) to simplify and standardize the assessment procedure and improve the correlation with the YGTSS-TTS.

Methods

We used 102 videos of patients with TS or persistent motor tic disorder filmed according to the MRVS. We compared the tic frequency assessed by MRVS with frequencies according to MRVS-R based on a 5-min (instead of a 10-min) video to investigate whether reducing the recording time leads to significant changes. In addition, we adapted the MRVS to the YGTSS and defined new anchor values for motor and phonic tic frequency based on frequency distributions as assessed in our sample. Finally, we compared the MRVS-R and MRVS regarding psychometric properties and correlation with the YGTSS-TTS.

Results

Cutting video recording time in half did not significantly affect assessments of motor and phonic tic frequencies. Psychometric properties were acceptable. Most important, proposed revisions of the MRVS improved correlation with the YGTSS-TTS.

Conclusions

The MRVS-R is a simplified version of the MRVS with comparable psychometric qualities, but higher correlations with the YGTSS-TTS.

Using Movement Disorder Society Unified Parkinson's Disease Rating Scale Parts 2 and 3 Simultaneously: Combining the Patient Voice with Clinician Ratings

BACKGROUND

Regulatory recommendations favor outcomes combining objective and patient input. The Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS), the most commonly used scale in Parkinson's disease (PD), includes patient and investigator ratings in distinct parts, but original clinimetric analyses failed to confirm the validity of combining parts by simple summing.

OBJECTIVES

The aim was to develop clinimetrically valid constructs for combining patient-reported Part 2 and investigator-rated Part 3 MDS-UPDRS scores.

METHODS

Using 7888 MDS-UPDRS scores, we assessed construct validity of combined Part 2 and Part 3 items using exploratory factor analysis (EFA) and graded item response theory (IRT) with threshold criteria: comparative fit index ≥0.9 (EFA) and discrimination parameters ≥0.65 (IRT).

RESULTS

The direct sum of Parts 2 + 3 failed to meet the threshold for a valid outcome of PD severity (comparative fit index, CFI = 0.855). However, a two-domain construct combining item scores for tremor and non-tremor domains from Parts 2 and 3 confirmed validity, meeting both EFA and IRT criteria as distinct but correlated indices of disease severity (CFI = 0.923; discrimination mean 2.197 ± 0.480 [tremor] and 1.737 ± 0.344 [non-tremor] domains).

CONCLUSIONS

The sum of Parts 2 + 3 is not clinimetrically sound. However, considering tremor and non-tremor items of both Parts 2 and 3 as two outcomes results in a valid summary of PD motor severity that leverages simultaneous patient- and investigator-derived measures. This analytic application addresses regulatory prioritizations and retains the well-validated MDS-UPDRS items. In future interventional trials, we suggest that tremor and non-tremor components of PD motor severity from Parts 2 + 3 be monitored and analyzed to accurately detect objective changes that integrate the patient's voice. © 2023 International Parkinson and Movement Disorder Society.

An open label, non-randomized study assessing a prebiotic fiber intervention in a small cohort of Parkinson's disease participants

A pro-inflammatory intestinal microbiome is characteristic of Parkinson's disease (PD). Prebiotic fibers change the microbiome and this study sought to understand the utility of prebiotic fibers for use in PD patients. The first experiments demonstrate that fermentation of PD patient stool with prebiotic fibers increased the production of beneficial metabolites (short chain fatty acids, SCFA) and changed the microbiota demonstrating the capacity of PD microbiota to respond favorably to prebiotics. Subsequently, an open-label, non-randomized study was conducted in newly diagnosed, non-medicated (n = 10) and treated PD participants (n = 10) wherein the impact of 10 days of prebiotic intervention was evaluated. Outcomes demonstrate that the prebiotic intervention was well tolerated (primary outcome) and safe (secondary outcome) in PD participants and was associated with beneficial biological changes in the microbiota, SCFA, inflammation, and neurofilament light chain. Exploratory analyses indicate effects on clinically relevant outcomes. This proof-of-concept study offers the scientific rationale for placebo-controlled trials using prebiotic fibers in PD patients. ClinicalTrials.gov Identifier: NCT04512599.

It Is as It Was: MDS-UPDRS Part III Scores Cannot Be Combined with Other Parts to Give a Valid Sum

BACKGROUND

Original clinimetric analyses by the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) developers did not confirm the validity of summing the scores of its parts. Recent studies used the summed score of Part III and other parts as efficacy outcomes.

OBJECTIVE

The aim of this study was to establish whether summing scores of MDS-UPDRS parts can be recommended.

METHODS

Using 7466 full MDS-UPDRS scores, we applied two-step factor analysis as in the original article to reassess the validity analysis with the threshold criterion set at comparative fit index ≥0.9.

RESULTS

All comparative fit indexes of any combination including Part III were lower than 0.90.

CONCLUSIONS

Summing Part III MDS-UPDRS scores with other parts is not clinimetrically sound. The MDS-UPDRS is a validated four-part scale with corresponding individual part scores and needs to be used within the limits originally presented. © 2022 International Parkinson and Movement Disorder Society.

Rating Scales for Medication Adherence in Parkinson's Disease: A Systematic Review for Critique and Recommendations

Background

Behaviors interfering with medication adherence (MA) are common and often complex in Parkinson's disease (PD), negatively affecting quality of life and undermining the value of clinical trials. The Clinical Outcome Assessments (COA) Scientific Evaluation Committee of the International Parkinson and Movement Disorder Society (MDS) commissioned the assessment of MA rating scales to recommend the use in PD.

Objective

Critically review the measurement properties of rating scales used to assess MA in PD and to issue recommendations.

Methods

We conducted systematic review across seven databases to identify structured scales to assess MA in PD. Eligible studies were critically appraised for methodological quality using the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) Risk of Bias checklist. Standards for good measurement properties of the selected scales were summarized narratively using the COSMIN, the MDS-COA Committee methodology, the World Health Organization concepts, and the Ascertaining Barriers to Compliance taxonomy. The certainty of the evidence was determined using the modified Grades of Recommendation, Assessment, Development and Evaluation approach with final assessments (highest to lowest) of "Recommended," "Suggested" and "Listed".

Results

Of the nine reviewed scales, none met the designation "Recommended". The Morisky Medication Adherence Scale (MMAS-8); Beliefs Related to Medications Adherence questionnaire, Beliefs about Medication Questionnaire, Medication Adherence Rating Scale, and Satisfaction with Information on Medicines Scale were rated "Suggested".

Conclusions

We suggest further work focusing on resolving the problems of the suggested scales or developing a new scale meeting all required criteria.

Cross-Cultural Differences in Patient Perceptions of Dyskinesia in Parkinson's Disease

BACKGROUND

The prevalence of levodopa-induced dyskinesia (LID) in Parkinson's disease (PD) varies among geographical regions. Cultural differences in patient-based perceptions of LID have not been studied.

OBJECTIVE

We compared patient and clinician evaluations of LID severity across multiple cultures in patients with PD.

METHODS

The data set included the Unified Dyskinesia Rating (UDysRS) scores from 16 language translation programs (3566 patients). We defined the Perception Severity Index (PSI) as the ratio between normalized patient-based subjective ratings (UDysRS Part 1B) and normalized clinician examination (Parts 3 and 4) scores (Part 1B/Parts 3 + 4) and compared the PSI across languages.

RESULTS

The mean PSI for the Chinese language (2.16) was higher than those of all other languages, whereas the ratio for the Korean language (0.73) was lower than those for Japanese, German, Turkish, Greek, Polish, and Finnish languages (corrected P values <0.05).

CONCLUSIONS

Culture, as represented by language, affects the subjective perception of LID and needs to be considered in multinational clinical PD trials on dyskinesia. © 2023 International Parkinson and Movement Disorder Society.

The plight of loneliness in Parkinson's disease: New opportunities

The human phenomenon of loneliness has been increasing in prominence across societies, with precipitous increase since COVID-19, and individuals with Parkinson's disease are not unscathed. Loneliness is of clinical relevance as it is cross-sectionally related to, and longitudinally precedes, mortality and other health risks, including worse motor, cognitive, and behavioral-psychological functioning. Relatively few studies have evaluated loneliness, or associated social experiences, in the context of Parkinson's, but the existing data is provocative. The authors advocate for clinicians' awareness and researchers' investigational focus.

Two faces of the teacher: Comparing editions of Charcot's Leçons du mardi

Jean-Martin Charcot, renowned teacher and clinical neurologist of the nineteenth century, held a unique set of impromptu "show and tell" case presentations that were transcribed as professor-patient dialogues. These lessons, known as the Leçons du mardi, were hand transcribed by his students and published as a limited-edition lithograph in 1887-1888, but reprinted for wider circulation with modifications in 1892, one year before Charcot died. This study highlights several important differences between the two versions of the work, with interpretative commentary on the importance of studying them side by side to more completely understand Charcot, his career, and the development of early clinical neurology.

Fragile X-associated tremor ataxia syndrome rating scale: Revision and content validity using a mixed method approach

Background

The original Fragile X-associated Tremor Ataxia Syndrome Rating Scale (FXTAS-RS) contained 61 items, some requiring modifications to better meet recommendations for patient-focused rating scale development.

Purpose

Provide initial validation of a revised version of the FXTAS-RS for motor signs.

Method

We conducted a two-phase mixed-method approach. In Phase 1, revision, we implemented a Delphi technique identifying pertinent domains/subdomains and developing items through expert consensus. In Phase 2, content validation, we conducted cognitive pretesting assessing comprehensibility, comprehensiveness, and relevance of items to FXTAS motor signs.

Results

After five rounds of Delphi panel and two rounds of cognitive pretesting, the revised version of the FXTAS-RS was established with 18 items covering five domains and 13 subdomains of motor signs. Cognitive pretesting revealed adequate content validity for the assessment of FXTAS motor signs.

Conclusion

The revised FXTAS-RS has been successfully validated for content and it is now ready for large-scale field validation.

Dissecting the Domains of Parkinson's Disease: Insights from Longitudinal Item Response Theory Modeling

BACKGROUND

Longitudinal item response theory (IRT) models previously suggested that the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) motor examination has two salient domains, tremor and nontremor, that progress in time and in response to treatment differently.

OBJECTIVE

Apply longitudinal IRT modeling, separating tremor and nontremor domains, to reanalyze outcomes in the previously published clinical trial (Study of Urate Elevation in Parkinson's Disease, Phase 3) that showed no overall treatment effects.

METHODS

We applied unidimensional and multidimensional longitudinal IRT models to MDS-UPDRS motor examination items in 298 participants with Parkinson's disease from the Study of Urate Elevation in Parkinson's Disease, Phase 3 (placebo vs. inosine) study. We separated 10 tremor items from 23 nontremor items and used Bayesian inference to estimate progression rates and sensitivity to treatment in overall motor severity and tremor and nontremor domains.

RESULTS

The progression rate was faster in the tremor domain than the nontremor domain before levodopa treatment. Inosine treatment had no effect on either domain relative to placebo. Levodopa treatment was associated with greater slowing of progression in the tremor domain than the nontremor domain regardless of inosine exposure. Linear patterns of progression were observed. Despite different domain-specific progression patterns, tremor and nontremor severities at baseline and over time were significantly correlated.

CONCLUSIONS

Longitudinal IRT analysis is a novel statistical method addressing limitations of traditional linear regression approaches. It is particularly useful because it can simultaneously monitor changes in different, but related, domains over time and in response to treatment interventions. We suggest that in neurological diseases with distinct impairment domains, clinical or anatomical, this application may identify patterns of change unappreciated by standard statistical methods. © 2022 International Parkinson and Movement Disorder Society.

Intestinal microbiota and neuroinflammation in Parkinson's disease: At the helm of the gut-brain axis

Emerging data suggest that disrupted intestinal microbiota, or dysbiosis, may be responsible for multiple features of Parkinson's disease (PD), from initiation, to progression, to therapeutic response. We have progressed greatly in our understanding of microbial signatures associated with PD, and have gained important insights into how dysbiosis and intestinal permeability promote neurodegeneration through neuroinflammation and Lewy body formation. These insights underscore the potential of microbiota-directed therapies, which include dietary, pharmacologic, and lifestyle interventions.

Resolving Missing Data from the Movement Disorder Society Unified Parkinson's Disease Rating Scale: Implications for Telemedicine

BACKGROUND

Telemedicine has become standard in clinical care and research during the coronavirus disease 2019 pandemic. Remote administration of Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III (Motor Examination) precludes ratings of all items, because Rigidity and Postural Stability (six scores) require in-person rating.

OBJECTIVE

The objective of this study was to determine imputation accuracy for total-sum and item-specific MDS-UPDRS Motor Examination scores in remote administration.

METHODS

We applied multivariate imputation by chained equations techniques in a cross-sectional dataset where patients had one MDS-UPDRS rating (International Translational Program, n = 8,588) and in a longitudinal dataset where patients had multiple ratings (Rush Program, n = 396). Successful imputation was stringently defined as (1) generalized Lin's concordance correlation coefficient >0.95, reflecting near-perfect agreement between total-sum score with complete data and surrogate score, calculated without patients' actual Rigidity and Postural Stability scores; and (2) perfect agreement for item-level scores for Rigidity and Postural Stability items.

RESULTS

For total-sum score when Rigidity and Postural Stability scores were withdrawn, using one or multiple visits, multivariate imputation by chained equations imputation reached near-perfect agreement with the original total-sum score. However, at the item level, the degree of perfect agreement between the surrogate and actual Rigidity items and Postural Stability scores always fell below threshold.

CONCLUSIONS

The MDS-UPDRS Part III total-sum score, a key clinical outcome in research and in clinical practice, can be accurately imputed without the Rigidity and Postural Stability items that cannot be rated by telemedicine. No formula, however, allows for specific item-level imputation. When Rigidity and Postural Stability item scores are of key clinical or research interest, patients with PD must be scored in person. © 2022 International Parkinson and Movement Disorder Society.

Gut-Brain Communication in Parkinson's Disease: Enteroendocrine Regulation by GLP-1

PURPOSE OF REVIEW

Defective gut-brain communication has recently been proposed as a promoter of neurodegeneration, but mechanisms mediating communication remain elusive. In particular, the Parkinson's disease (PD) phenotype has been associated with both dysbiosis of intestinal microbiota and neuroinflammation. Here, we review recent advances in the PD field that connect these two concepts, providing an explanation based on enteroendocrine signaling from the gut to the brain.

RECENT FINDINGS

There have been several recent accounts highlighting the importance of the microbiota-gut-brain axis in PD. The objective of this review is to discuss the role of the neuroendocrine system in gut-brain communication as it relates to PD pathogenesis, as this system has not been comprehensively considered in prior reviews. The incretin hormone glucagon-like peptide 1 (GLP-1) is secreted by enteroendocrine cells of the intestinal epithelium, and there is evidence that it is neuroprotective in animal models and human subjects with PD. Agonists of GLP-1 receptors used in diabetes appear to be useful for preventing neurodegeneration. New tools and models have enabled us to study regulation of GLP-1 secretion by intestinal microbiota, to understand how this process may be defective in PD, and to develop methods for therapeutically modifying disease development or progression using the enteroendocrine system. GLP-1 secretion by enteroendocrine cells may be a key mediator of neuroprotection in PD, and new findings in this field may offer unique insights into PD pathogenesis and therapeutic strategies.

Parkinson’s Disease Medication Adherence Scale: Conceptualization, Scale Development, and Clinimetric Testing Plan

Background

Medication adherence is a crucial component in the management of patients with chronic diseases needing a long-term pharmacotherapy. Parkinson’s disease (PD) is a chronic, degenerative disease with complex drug treatment that poses challenging barriers to patient adherence. The adoption of best practices of scale development can contribute to generate solid concepts and, in the long run, a more stable knowledge base on the underlying constructs of medication adherence in PD measured by the items of the first scale to be created for this purpose.

Purpose

To present the development process and clinimetric testing plan of the Parkinson’s Disease Medication Adherence Scale (PD-MAS).

Method

We adopted a hybrid approach plan based on the United States Food and Drug Administration and Benson and Clark Guide that will create a patient-reported outcome instrument. We presented an overview of consecutive and interrelated steps, containing a concise description of each one. International research centers from Brazil and United States were initially involved in the planning and implementation of the methodological steps of this study.

Results

We developed a four-phase multimethod approach for the conceptualization and the clinimetric testing plan of the PD-MAS. First, we describe the development process of the conceptual framework of the PD-MAS underpinning the scale construct; second, we formalized the development process of the first version of the PD-MAS from the generation of item pools to the content validation and pre-testing; third, we established the steps for the first pilot testing and revision; fourth, we describe the steps plan for the first pilot testing and revision, to finally describe its clinimetric testing plan and validation.

Conclusion

The overview presentation of the development phases and the clinimetric testing plan of the PD-MAS demonstrate the feasibility of creating an instrument to measure the multidimensional and multifactorial components of the medication adherence process in people with PD.

Hold that pose: capturing cervical dystonia's head deviation severity from video

Objective

Deviated head posture is a defining characteristic of cervical dystonia (CD). Head posture severity is typically quantified with clinical rating scales such as the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). Because clinical rating scales are inherently subjective, they are susceptible to variability that reduces their sensitivity as outcome measures. The variability could be circumvented with methods to measure CD head posture objectively. However, previously used objective methods require specialized equipment and have been limited to studies with a small number of cases. The objective of this study was to evaluate a novel software system—the Computational Motor Objective Rater (CMOR)—to quantify multi‐axis directionality and severity of head posture in CD using only conventional video camera recordings.

Methods

CMOR is based on computer vision and machine learning technology that captures 3D head angle from video. We used CMOR to quantify the axial patterns and severity of predominant head posture in a retrospective, cross‐sectional study of 185 patients with isolated CD recruited from 10 sites in the Dystonia Coalition.

Results

The predominant head posture involved more than one axis in 80.5% of patients and all three axes in 44.4%. CMOR's metrics for head posture severity correlated with severity ratings from movement disorders neurologists using both the TWSTRS‐2 and an adapted version of the Global Dystonia Rating Scale (rho = 0.59–0.68, all p <0.001).

Conclusions

CMOR's convergent validity with clinical rating scales and reliance upon only conventional video recordings supports its future potential for large scale multisite clinical trials.

Validation of the Thai Version of the Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale

Objective

This study aims to validate the Thai translation of the Movement Disorder Society-sponsored revision of the Unified Parkinson’s Disease Rating Scale (MDS-UPDRS).

Methods

The English version was translated into Thai and then back-translated into English. The translated version underwent 2 rounds of cognitive pretesting to assess the ease of comprehension, ease of use and comfort with the scale. Then, it underwent large clinimetric testing.

Results

The Thai version was validated in 354 PD patients. The comparative fit index (CFI) for all four parts of the Thai version of the MDS-UPDRS was 0.93 or greater. Exploratory factor analysis identified isolated item differences in factor structure between the Thai and English versions.

Conclusion

The overall factor structure of the Thai version was consistent with that of the English version based on the high CFIs (all CFI ≥ 0.90). Hence, it can be designated the official Thai version of the MDS-UPDRS.

Head tremor in cervical dystonia: Quantifying severity with computer vision

BACKGROUND

Head tremor (HT) is a common feature of cervical dystonia (CD), usually quantified by subjective observation. Technological developments offer alternatives for measuring HT severity that are objective and amenable to automation.

OBJECTIVES

Our objectives were to develop CMOR (Computational Motor Objective Rater; a computer vision-based software system) to quantify oscillatory and directional aspects of HT from video recordings during a clinical examination and to test its convergent validity with clinical rating scales.

METHODS

For 93 participants with isolated CD and HT enrolled by the Dystonia Coalition, we analyzed video recordings from an examination segment in which participants were instructed to let their head drift to its most comfortable dystonic position. We evaluated peak power, frequency, and directional dominance, and used Spearman's correlation to measure the agreement between CMOR and clinical ratings.

RESULTS

Power averaged 0.90 (SD 1.80) deg²/Hz, and peak frequency 1.95 (SD 0.94) Hz. The dominant HT axis was pitch (antero/retrocollis) for 50%, roll (laterocollis) for 6%, and yaw (torticollis) for 44% of participants. One-sided t-tests showed substantial contributions from the secondary (t = 18.17, p < 0.0001) and tertiary (t = 12.89, p < 0.0001) HT axes. CMOR's HT severity measure positively correlated with the HT item on the Toronto Western Spasmodic Torticollis Rating Scale-2 (Spearman's rho = 0.54, p < 0.001).

CONCLUSIONS

We demonstrate a new objective method to measure HT severity that requires only conventional video recordings, quantifies the complexities of HT in CD, and exhibits convergent validity with clinical severity ratings.

Implementation and Outcomes of a Movement Disorder Society-Sponsored Peer Reviewing Education and Mentoring Program

BACKGROUND

Effective dissemination of scientific results depends on competent peer reviewers. Participating as a reviewer is important for academic advancement, although no formal training in peer review has existed in the movement disorders field.

OBJECTIVES

To report the design, implementation, and outcomes of a Peer Reviewing Education and Mentoring Program.

METHODS

We enrolled 10 participants in a 1-year mentored program with didactic training followed by two peer reviews with feedback from a senior mentor. Outcomes measures were an objective skills assessment and subjective questionnaire.

RESULTS

Participants were diverse in gender, age, and background. All participants were deemed competent reviewers by their mentors upon completion. Objective skills improved after didactic training and self-assessment increased significantly after program completion (19.5 [12-25] to 29 [25-30], P < 0.001).

CONCLUSIONS

This dedicated program helped participants gain competence and confidence in the peer review process. We plan to continue the program while improving educational methods and assessments. © 2022 International Parkinson and Movement Disorder Society.

Parkinson Disease and Subthalamic Nucleus Deep Brain Stimulation: Cognitive Effects in GBA Mutation Carriers

OBJECTIVE

This study was undertaken to compare the rate of change in cognition between glucocerebrosidase (GBA) mutation carriers and noncarriers with and without subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson disease.

METHODS

Clinical and genetic data from 12 datasets were examined. Global cognition was assessed using the Mattis Dementia Rating Scale (MDRS). Subjects were examined for mutations in GBA and categorized as GBA carriers with or without DBS (GBA+DBS+, GBA+DBS-), and noncarriers with or without DBS (GBA-DBS+, GBA-DBS-). GBA mutation carriers were subcategorized according to mutation severity (risk variant, mild, severe). Linear mixed modeling was used to compare rate of change in MDRS scores over time among the groups according to GBA and DBS status and then according to GBA severity and DBS status.

RESULTS

Data were available for 366 subjects (58 GBA+DBS+, 82 GBA+DBS-, 98 GBA-DBS+, and 128 GBA-DBS- subjects), who were longitudinally followed (range = 36-60 months after surgery). Using the MDRS, GBA+DBS+ subjects declined on average 2.02 points/yr more than GBA-DBS- subjects (95% confidence interval [CI] = -2.35 to -1.69), 1.71 points/yr more than GBA+DBS- subjects (95% CI = -2.14 to -1.28), and 1.49 points/yr more than GBA-DBS+ subjects (95% CI = -1.80 to -1.18).

INTERPRETATION

Although not randomized, this composite analysis suggests that the combined effects of GBA mutations and STN-DBS negatively impact cognition. We advise that DBS candidates be screened for GBA mutations as part of the presurgical decision-making process. We advise that GBA mutation carriers be counseled regarding potential risks associated with STN-DBS so that alternative options may be considered. ANN NEUROL 2022;91:424-435.

Validation of the Arabic Version of the Movement Disorder Society-Unified Parkinson's Disease Rating Scale

BACKGROUND

The Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) has become the gold standard for evaluating different domains in Parkinson's disease (PD), and it is commonly used in clinical practice, research, and clinical trials.

OBJECTIVES

The objectives are to validate the Arabic-translated version of the MDS-UPDRS and to assess its factor structure compared with the English version.

METHODS

The study was carried out in three phases: first, the English version of the MDS-UPDRS was translated into Arabic and subsequently back-translated into English by independent translation team; second, cognitive pretesting of selected items was performed; third, the Arabic version was tested in over 400 native Arabic-speaking PD patients. The psychometric properties of the translated version were analyzed using confirmatory factor analysis (CFA) as well as exploratory factor analysis (EFA).

RESULTS

The factor structure of the Arabic version was consistent with that of the English version based on the high CFIs for all four parts of the MDS-UPDRS in the CFA (CFI ≥0.90), confirming its suitability for use in Arabic.

CONCLUSIONS

The Arabic version of the MDS-UPDRS has good construct validity in Arabic-speaking patients with PD and has been thereby designated as an official MDS-UPDRS version. The data collection methodology among Arabic-speaking countries across two continents of Asia and Africa provides a roadmap for validating additional MDS rating scale initiatives and is strong evidence that underserved regions can be energically mobilized to promote efforts that apply to better clinical care, education, and research for PD. © 2022 International Parkinson and Movement Disorder Society.

From null to midline: changes in head posture do not predictably change head tremor in cervical dystonia

Introduction

A common view is that head tremor (HT) in cervical dystonia (CD) decreases when the head assumes an unopposed dystonic posture and increases when the head is held at midline. However, this has not been examined with objective measures in a large, multicenter cohort.

Methods

For 80 participants with CD and HT, we analyzed videos from examination segments in which participants were instructed to 1) let their head drift to its most comfortable position (null point) and then 2) hold their head straight at midline. We used our previously developed Computational Motor Objective Rater (CMOR) to quantify changes in severity, amplitude, and frequency between the two postures.

Results

Although up to 9% of participants had exacerbated HT in midline, across the whole cohort, paired t-tests reveal no significant changes in overall severity (t = -0.23, p = 0.81), amplitude (t = -0.80, p = 0.43), and frequency (t = 1.48, p = 0.14) between the two postures.

Conclusions

When instructed to first let their head drift to its null point and then to hold their head straight at midline, most patient's changes in HT were below the thresholds one would expect from the sensitivity of clinical rating scales. Counter to common clinical impression, CMOR objectively showed that HT does not consistently increase at midline posture in comparison to the null posture.

TikTok Tics: A Pandemic Within a Pandemic

BACKGROUND

TikTok is a social media platform where users create and share videos. During the COVID-19 pandemic, the use of this site greatly expanded. Tic and Tourette syndrome content also increased dramatically along with the number of patients with tics in neurology clinics.

OBJECTIVES

We compared the phenomenology of "TikTok tics" to typical tic disorders. We chose to analyze the most widely viewed videos and therefore focused on the most popular content creators.

METHODS

Videos with the keywords "tic," "Tourette," or "tourettes" were reviewed to identify content creators between March 11, 2020 and March 30, 2021. We performed a quantitative assessment of TikTok tics as well as a descriptive analysis of the entire series of videos of each content creator.

RESULTS

The mean age of the cohort was 18.8 years old, and the majority were women. Unlike the predominance of facial movements in typical tics, arm movements were most frequent. Average tics per minute was 29, and almost all recorded TikTok tics were severe, causing significant disability. Whereas coprolalia and self-injurious behavior are only infrequently encountered in typical tic disorders, they were present in the overwhelming majority of TikTok subjects.

CONCLUSIONS

TikTok tics are distinct from what is typically seen in patients with Tourette syndrome, although share many characteristics with functional tics. We believe this to be an example of mass sociogenic illness, which involves behaviors, emotions, or conditions spreading spontaneously through a group. A modern clinician needs to remain abreast of social media sources as knowledge of media content is essential in managing patients in the current environment.

Novel Approach to Movement Disorder Society-Unified Parkinson's Disease Rating Scale Monitoring in Clinical Trials: Longitudinal Item Response Theory Models

Background

Although nontremor and tremor Part 3 Movement Disorder Society-Unified Parkinson's Disease Rating Scale items measure different impairment domains, their distinct progression and drug responsivity remain unstudied longitudinally. The total score may obscure important time-based and treatment-based changes occurring in the individual domains.

Objective

Using the unique advantages of item response theory (IRT), we developed novel longitudinal unidimensional and multidimensional models to investigate nontremor and tremor changes occurring in an interventional Parkinson's disease (PD) study.

Method

With unidimensional longitudinal IRT, we assessed the 33 Part 3 item data (22 nontremor and 10 tremor items) of 336 patients with early PD from the STEADY-PD III (Safety, Tolerability, and Efficacy Assessment of Isradipine for PD, placebo vs. isradipine) study. With multidimensional longitudinal IRT, we assessed the progression rates over time and treatment (in overall motor severity, nontremor, and tremor domains) using Markov Chain Monte Carlo implemented in Stan.

Results

Regardless of treatment, patients showed significant but different time-based deterioration rates for total motor, nontremor, and tremor scores. Isradipine was associated with additional significant deterioration over placebo in total score and nontremor scores, but not in tremor score. Further highlighting the 2 separate latent domains, nontremor and tremor severity changes were positively but weakly correlated (correlation coefficient, 0.108).

Conclusions

Longitudinal IRT analysis is a novel statistical method highly applicable to PD clinical trials. It addresses limitations of traditional linear regression approaches and previous IRT investigations that either applied cross-sectional IRT models to longitudinal data or failed to estimate all parameters simultaneously. It is particularly useful because it can separate nontremor and tremor changes both over time and in response to treatment interventions.

Rating scales for medication adherence in people living with Parkinson's disease: a systematic review protocol

OBJECTIVE

The objective of the review is to evaluate the measurement properties of rating scales that have been used to assess the components of medication adherence in patients with Parkinson's disease.

INTRODUCTION

Drug therapy is a central strategy in the control of Parkinson's disease symptoms. Measuring behaviors related to medication adherence in patients with Parkinson's disease is vital to understanding the therapeutic response, making it necessary to define which instrument offers the most reliable and valid screening.

INCLUSION CRITERIA

Studies in English and Portuguese using structured rating scales to assess medication adherence in people with Parkinson's disease will be included. Studies including data from patients with different diseases in addition to Parkinson's disease, will be included only if data are clearly available for each disorder covered. Study protocols, letters to the editors, reviews, and studies with clinical judgment scales but no operationally defined anchor points will be excluded.

METHODS

A three-step search strategy will be utilized. Databases that will be utilized are MEDLINE (PubMed), LILACS (BVS Portal), PsycINFO (APA PsycNet), CINAHL (EBSCO), Web of Science (Clarivate Analytics), Embase, and Scopus (Elsevier). The search strategy will be presented using a PRISMA flow diagram. Eligible studies will be critically appraised for methodological quality using the COSMIN Risk of Bias checklist. Criteria for good measurement properties of the selected scales will be summarized narratively using COSMIN, the Movement Disorder Society Rating Scale Program Committee methodology, the World Health Organization concepts, and the ABC taxonomy of medication adherence. The certainty of the evidence will be determined using the modified GRADE.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO (CRD42021211099).

Non-motor phenotypic subgroups in adult-onset idiopathic, isolated, focal cervical dystonia

BACKGROUND

Non-motor symptoms are well established phenotypic components of adult-onset idiopathic, isolated, focal cervical dystonia (AOIFCD). However, improved understanding of their clinical heterogeneity is needed to better target therapeutic intervention. Here, we examine non-motor phenotypic features to identify possible AOIFCD subgroups.

METHODS

Participants diagnosed with AOIFCD were recruited via specialist neurology clinics (dystonia wales: n = 114, dystonia coalition: n = 183). Non-motor assessment included psychiatric symptoms, pain, sleep disturbance, and quality of life, assessed using self-completed questionnaires or face-to-face assessment. Both cohorts were analyzed independently using Cluster, and Bayesian multiple mixed model phenotype analyses to investigate the relationship between non-motor symptoms and determine evidence of phenotypic subgroups.

RESULTS

Independent cluster analysis of the two cohorts suggests two predominant phenotypic subgroups, one consisting of approximately a third of participants in both cohorts, experiencing increased levels of depression, anxiety, sleep impairment, and pain catastrophizing, as well as, decreased quality of life. The Bayesian approach reinforced this with the primary axis, which explained the majority of the variance, in each cohort being associated with psychiatric symptomology, and also sleep impairment and pain catastrophizing in the Dystonia Wales cohort.

CONCLUSIONS

Non-motor symptoms accompanying AOIFCD parse into two predominant phenotypic sub-groups, with differences in psychiatric symptoms, pain catastrophizing, sleep quality, and quality of life. Improved understanding of these symptom groups will enable better targeted pathophysiological investigation and future therapeutic intervention.

Prognostic Modeling of Parkinson's Disease Progression Using Early Longitudinal Patterns of Change

BACKGROUND

Predicting Parkinson's disease (PD) progression may enable better adaptive and targeted treatment planning.

OBJECTIVE

Develop a prognostic model using multiple, easily acquired longitudinal measures to predict temporal clinical progression from Hoehn and Yahr (H&Y) stage 1 or 2 to stage 3 in early PD.

METHODS

Predictive longitudinal measures of PD progression were identified by the joint modeling method. Measures were extracted by multivariate functional principal component analysis methods and used as covariates in Cox proportional hazards models. The optimal model was developed from the Parkinson's Progression Marker Initiative (PPMI) data set and confirmed with external validation from the Longitudinal and Biomarker Study in PD (LABS-PD) study.

RESULTS

The proposed prognostic model with longitudinal information of selected clinical measures showed significant advantages in predicting PD temporal progression in comparison to a model with only baseline information (iAUC = 0.812 vs. 0.743). The modeling results allowed the development of a prognostic index for categorizing PD patients into low, mid, and high risk of progression to HY 3 that is offered to facilitate physician-patient discussion on prognosis.

CONCLUSION

Incorporating longitudinal information of multiple clinical measures significantly enhances predictive performance of prognostic models. Furthermore, the proposed prognostic index enables clinicians to classify patients into different risk groups, which could be adaptively updated as new longitudinal information becomes available. Modeling of this type allows clinicians to utilize observational data sets that inform on disease natural history and specifically, for precision medicine, allows the insertion of a patient's clinical data to calculate prognostic estimates at the individual case level. © 2021 International Parkinson and Movement Disorder Society.

Validation of the Finnish Version of the Unified Dyskinesia Rating Scale

INTRODUCTION

The Unified Dyskinesia Rating Scale (UDysRS) was developed to provide a comprehensive rating tool of dyskinesia in Parkinson's disease (PD). Because dyskinesia therapy trials involve multicenter studies, having a scale that is validated in multiple non-English languages is pivotal to international efforts to treat dyskinesia. The aim of the present study was to organize and perform an independent validation of the UDysRS Finnish version.

METHODS

The UDysRS was translated into Finnish and then back-translated into English using 2 independent teams. Cognitive pretesting was conducted on the Finnish version and required modifications to the structure or wording of the translation. The final Finnish version was administered to 250 PD patients whose native language is Finnish. The data were analyzed to assess the confirmatory factor structure to the Spanish UDysRS (the reference standard). Secondary analyses included an exploratory factor analysis (EFA), independent of the reference standard.

RESULTS

The comparative fit index (CFI), in comparison with the reference standard factor structure, was 0.963 for Finnish. In the EFA, where variability from sample to sample is expected, isolated item differences of factor structure were found between the Finnish and Reference Standard versions of the UDysRS. These subtle differences may relate to differences in sample composition or variations in disease status.

CONCLUSION

The overall factor structure of the Finnish version was consistent with that of the reference standard, and it can be designated as the official version of the UDysRS for Finnish speaking populations.

Attenuated Postprandial GLP-1 Response in Parkinson's Disease

The incretin hormone glucagon-like peptide 1 (GLP-1) has neuroprotective effects in animal models of Parkinson’s disease (PD), and GLP-1 receptor agonists are associated with clinical improvements in human PD patients. GLP-1 is produced and secreted by intestinal L-cells in response to consumption of a meal. Specifically, intestinal microbiota produce short chain fatty acids (SCFA) which, in turn, promote secretion of GLP-1 into the systemic circulation, from which it can enter the brain. Our group and others have reported that PD patients have an altered intestinal microbial community that produces less SCFA compared to age-matched controls. In this report, we demonstrate that PD patients have diminished GLP-1 secretion in response to a meal compared to their household controls. Peak postprandial GLP-1 levels did not correlate with PD disease severity, motor function, or disease duration. These data provide the scientific rationale for future studies designed to elucidate the role of GLP-1 in the pathogenesis of PD and test the potential utility of GLP-1-directed therapies.

Validation of the Polish version of the Unified Dyskinesia Rating Scale (UDysRS)

BACKGROUND

In 2008, the Movement Disorders Society published the Unified Dyskinesia Rating Scale (UDysRS). This has become the established tool for assessing the severity and disability associated with dyskinesia in patients with Parkinson's Disease (PD). We translated and validated the Polish version of the UDysRS, explored its dimensionality, and compared it to the Spanish version, which is the Reference Standard for UDysRS translations.

MATERIAL AND METHODS

The UDysRS was translated into Polish by a team led by JS and GO. The back-translation, completed by colleagues fluent in both Polish and English who were not involved in the original translation, was reviewed and approved by the Executive Committee of the MDS Rating Scales Programme. Then the translated version of the UDysRS underwent cognitive pretesting, and the translation was modified based on the results. The approved version was considered to be the Official Working Document of the Polish UDysRS and was tested on 250 Polish PD patients recruited at movement disorder centres. Data was compared to the Reference Standard used for validating UDysRS translations.

RESULTS

The overall factor structure of the Polish version was consistent with that of the Reference Standard version, as evidenced by the high Confirmatory Fit Index score (CFI = 0.98). The Polish UDysRS was thus confirmed to share a common factor structure with the Reference Standard.

CONCLUSIONS

The Official Polish UDysRS translation is recommended for use in clinical and research settings. Worldwide use of uniform rating measures offers a common ground to study similarities and differences in disease manifestations and progression across cultures.

Head tremor and pain in cervical dystonia

BACKGROUND

Although head tremor (HT) and pain are prevalent in cervical dystonia (CD), their joint relationship to phenotypic features of focal dystonia remains unclear.

OBJECTIVES

We examined how severity of HT and pain are associated with age of CD onset and duration, and whether HT subtypes ("jerky" or "regular") exhibit distinct relationships between severity of HT and pain.

METHODS

The severity of HT and pain were assessed with the Toronto Western Spasmodic Torticollis Rating Scale in retrospective review of 188 CD patients recruited through the Dystonia Coalition.

RESULTS

HT severity was associated with longer CD duration (p < 0.0005), whereas pain severity was associated with younger age at onset (p = 0.043). HT severity and pain severity were not correlated for jerky HT (p = 0.996), but positively correlated for regular HT (p = 0.01).

CONCLUSIONS

The distinct associations of HT and pain with age at onset, disease duration, and HT subtype further characterize the heterogeneity of CD's clinical presentation and suggest similarly heterogeneous underlying mechanisms.