Genome-wide meta-analyses of restless legs syndrome yield insights into genetic architecture, disease biology and risk prediction.

Restless legs syndrome (RLS) affects up to 10% of older adults. Their healthcare is impeded by delayed diagnosis and insufficient treatment. To advance disease prediction and find new entry points for therapy, we performed meta-analyses of genome-wide association studies in 116,647 individuals with RLS (cases) and 1,546,466 controls of European ancestry. The pooled analysis increased the number of risk loci eightfold to 164, including three on chromosome X. Sex-specific meta-analyses revealed largely overlapping genetic predispositions of the sexes (rg = 0.96). Locus annotation prioritized druggable genes such as glutamate receptors 1 and 4, and Mendelian randomization indicated RLS as a causal risk factor for diabetes. Machine learning approaches combining genetic and nongenetic information performed best in risk prediction (area under the curve (AUC) = 0.82-0.91). In summary, we identified targets for drug development and repurposing, prioritized potential causal relationships between RLS and relevant comorbidities and risk factors for follow-up and provided evidence that nonlinear interactions are likely relevant to RLS risk prediction.

A Randomized Phase 2 KINETIC Trial Evaluating SAGE-324/BIIB124 in Individuals with Essential Tremor.

BACKGROUND: SAGE-324/BIIB124 is an investigational positive allosteric modulator of GABAA receptors. OBJECTIVE: KINETIC (NCT04305275), a double-blind, randomized, placebo-controlled, phase 2 study, evaluated SAGE-324/BIIB124 in individuals with essential tremor (ET). METHODS: Individuals aged 18 to 80 years were randomly assigned 1:1 to orally receive 60 mg of SAGE-324/BIIB124 or placebo once daily for 28 days. The primary endpoint was change from baseline in The Essential Tremor Rating Assessment Scale-Performance Subscale (TETRAS-PS) Item 4 (upper-limb tremor) at day 29 with SAGE-324/BIIB124 versus placebo. RESULTS: Between May 2020 and February 2021, 69 U.S. participants were randomly assigned to receive SAGE-324/BIIB124 (n = 34) or placebo (n = 35). There was a significant reduction from baseline in TETRAS-PS Item 4 at day 29 with SAGE-324/BIIB124 versus placebo (least squares mean [standard error]: -2.31 [0.401] vs. -1.24 [0.349], P = 0.0491). The most common treatment-emergent adverse events included somnolence, dizziness, fatigue, and balance disorder. CONCLUSION: These results support further development of SAGE-324/BIIB124 for potential ET treatment. © 2024 Sage Therapeutics, Inc and The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

The Clinician's Tardive Inventory (CTI): A New Clinical Tool for Documenting and Rating Tardive Dyskinesia.

Objective: Current clinician-rated tardive dyskinesia (TD) symptom scales have not addressed the expanding clinical signs and functional impact of TD. The study objective was to develop and test the reliability of a new integrated instrument.Methods: A movement disorder neurologist devised the outline of the rating scale. A Steering Committee (5 neurologists and 2 psychiatrists) provided revisions until consensus was reached. The Clinician's Tardive Inventory (CTI) assesses abnormal movements of the eye/eyelid/face, tongue/mouth, jaw, and limb/trunk; complex movements defined as complicated movements different from simple patterned movements or postures; and vocalizations. The CTI rates frequency of symptoms from 0 to 3 (ranging from absent to constant). Functional impairments, including activities of daily living (ADL), social impairment, symptom distress, and physical harm, are rated 0-3 (ranging from unawareness to severe impact). The CTI underwent interrater and test-retest reliability testing between February and June 2022 based on videos and accompanying vignettes, which were reviewed by 2 movement disorder specialists to determine adequacy. Four clinicians rated each video/vignette. Interrater agreement was analyzed via 2-way random-effects intraclass correlation (ICC), and test-retest agreement was assessed utilizing the Kendall tau-b.Results: Forty-five video/vignettes were assessed for interrater reliability and 16 for test-retest reliability. The most prevalent movements were those of the tongue and mouth (77.8%) and jaw (55.6%). ICCs for movement frequency for anatomic symptoms were as follows: anatomic symptom summary score 0.92, abnormal eye movement 0.89, abnormal tongue/mouth movement 0.91, abnormal jaw movement 0.89, abnormal limb movement 0.76, complex movement 0.87, and abnormal vocalization 0.77; ICCs for functional impairments were as follows: total impairment score 0.92, physical harm 0.82, social embarrassment 0.88, ADLs 0.83, and symptom bother 0.92; Retests were conducted a mean (SD) of 15 (3) days later with correlation coefficients ranging from 0.66 to 0.87.Conclusions: The CTI is a new integrated instrument with proven reliability in assessing TD signs and functional impacts. Future validation study is warranted.

Review of the role of the endogenous opioid and melanocortin systems in the restless legs syndrome.

Restless legs syndrome (RLS) is responsive to opioid, dopaminergic and iron-based treatments. Receptor blocker studies in RLS patients suggest that the therapeutic efficacy of opioids is specific to the opioid receptor and mediated indirectly through the dopaminergic system. An RLS autopsy study reveals decreases in endogenous opioids, ß-endorphin and perhaps Met-enkephalin in the thalamus of RLS patients. A total opioid receptor knock-out (mu, delta and kappa) and a mu-opioid receptor knock-out mouse model of RLS show circadian motor changes akin to RLS and, although both models show sensory changes, the mu-opioid receptor knock mouse shows circadian sensory changes closest to those seen in idiopathic RLS. Both models show changes in striatal dopamine, anaemia and low serum iron. However, only in the total receptor knock-out mouse do we see the decreases in serum ferritin that are normally found in RLS. There are also decreases in serum iron when wild-type mice are administered a mu-opioid receptor blocker. In addition, the mu-opioid receptor knock-out mouse also shows increases in striatal zinc paralleling similar changes in RLS. Adrenocorticotropic hormone and α-melanocyte stimulating hormone are derived from pro-opiomelanocortin as is ß-endorphin. However, they cause RLS-like symptoms and periodic limb movements when injected intraventricularly into rats. These results collectively suggest that an endogenous opioid deficiency is pathogenetic to RLS and that an altered melanocortin system may be causal to RLS as well.

The Self-Administered Screening Questionnaire for Parkinson's Disease-Associated Psychosis (SASPAP).

BACKGROUND: Psychosis is a common manifestation of Parkinson's disease (PD), and a major source of caregiver burden, nursing home placement, and mortality. Psychosis symptoms are often not volunteered during the clinic visit because of embarrassment or lack of insight, and there is no validated screening scale. We compare a new self-administered psychosis screening questionnaire against the Parkinson's Disease Psychosis Scale (PDPS) and physician interview as the gold standard assessments. OBJECTIVE: To create and validate the Self-Administered Screening Questionnaire for PD-Associated Psychosis (SASPAP). METHODS: The questionnaire was developed through a modified Delphi method by a committee of two neurologists, a psychiatrist, a patient, and patient advocate and underwent several rounds of revisions, including patient ß-testing. It was provided by staff at intake to 250 consecutive patients diagnosed with PD, at the Methodist Hospital Movement Disorders Clinic, and separately to their caregivers when available. Later, the PDPS and a general psychosis interview were administered by PD specialists without knowledge of the screening questionnaire responses. RESULTS: Two hundred and fifty consecutive patients with PD (mean age, 68.6 ± 7.0; mean age of PD onset, 62.7 ± 10.5 years; 35.2% female) were included. The screening questionnaire was positive for psychosis (any of the four questions positive) in 33.6% of patients. Compared to the gold standard, the SASPAP sensitivity was 87.8% and the specificity 92.3%. CONCLUSION: This four-question self-administered screening questionnaire for PD psychosis demonstrated high diagnostic accuracy compared with the gold standard assessments and can be self-completed at visit intake. © 2023 International Parkinson and Movement Disorder Society.

IPX203 vs Immediate-Release Carbidopa-Levodopa for the Treatment of Motor Fluctuations in Parkinson Disease: The RISE-PD Randomized Clinical Trial.

Importance: Levodopa has a short half-life and a limited window of opportunity for absorption in the proximal small intestine. IPX203 is an oral, extended-release formulation of carbidopa-levodopa developed to address these limitations. Objective: To assess the efficacy and safety of IPX203 vs immediate-release carbidopa-levodopa in patients with Parkinson disease who are experiencing motor fluctuations. Design, Setting, and Participants: RISE-PD was a 20-week, randomized, double-blind, double-dummy, active-controlled, phase 3 clinical trial. The study was conducted between November 6, 2018, and June 15, 2021, at 105 academic and clinical centers in the US and Europe. Patients with Parkinson disease taking a total daily dose of 400 mg or more of levodopa and experiencing an average of 2.5 hours or more daily off-time were included in the study. A total of 770 patients were screened, 140 were excluded (those taking controlled-release carbidopa-levodopa apart from a single daily bedtime dose, Rytary (Amneal Pharmaceuticals), additional carbidopa or benserazide, or catechol O-methyl transferase inhibitors or who had a history of psychosis within the past 10 years), and 630 were enrolled in the trial. Interventions: Following open-label immediate-release carbidopa-levodopa dose adjustment (3 weeks) and conversion to IPX203 (4 weeks), patients were randomized in a 1:1 ratio to double-blind, double-dummy treatment with immediate-release carbidopa-levodopa or IPX203 for 13 weeks. Main Outcome and Measures: The primary end point was mean change in daily good on-time (ie, on-time without troublesome dyskinesia) from baseline to the end of the double-blind treatment period. Results: A total of 630 patients (mean [SD] age, 66.5 [8.95] years; 396 [62.9%] men) were enrolled, and 506 patients were randomly assigned to receive IPX203 (n = 256) or immediate-release carbidopa-levodopa (n = 250). The study met its primary end point, demonstrating statistically significant improvement in daily good on-time for IPX203 compared to immediate-release carbidopa-levodopa (least squares mean, 0.53 hours; 95% CI, 0.09-0.97; P = .02), with IPX203 dosed a mean 3 times per day vs 5 times per day for immediate-release carbidopa-levodopa. Good on-time per dose increased by 1.55 hours with IPX203 compared to immediate-release carbidopa-levodopa (95% CI, 1.37-1.73; P < .001). IPX203 was well tolerated. The most common adverse events in the double-blind phase (IPX203 vs immediate-release carbidopa-levodopa) were nausea (4.3% vs 0.8%) and anxiety (2.7% vs 0.0%). Conclusions and Relevance: In this study, IPX203 provided more hours of good on-time per day than immediate-release carbidopa-levodopa, even as IPX203 was dosed less frequently. Trial Registration: ClinicalTrials.gov Identifier: NCT03670953.

Task Specific Tremor in Parkinson's Disease Responds to Apomorphine.

Background: Task specific tremor (TST) is a poorly understood entity without any standard treatments, that may subsequently develop tremor during additional tasks, later develop postural/kinetic tremor (essential tremor criteria), and later develop Parkinson's disease. The pathophysiology is not understood as it has features of tremor, dystonia, and parkinsonism. Objectives: To assess response of TST to apomorphine and thus infer pathophysiology. Methods: We administered sublingual apomorphine to 8 patients diagnosed with Parkinson's disease based on clinical criteria and dopamine imaging, who all initially presented with TST and later presented other parkinsonian signs and dopamine imaging deficits. Results: Apomorphine improved TST, which was refractory to oral levodopa and other tremor therapies, in 6/8 subjects. Discussion: These results offer a treatment option for TST, which is usually refractory to other pharmacologic treatments, in patients with other parkinsonian features, and infers a dopaminergic pathophysiology of TST.

Clozapine: Efficacy for Parkinson Disease psychosis in patients refractory to pimavanserin.

Pimavanserin is the only approved drug for Parkinson's disease psychosis (PDP) and is an increasingly used therapy where available. Clozapine has proven efficacy for PDP but is much less commonly used secondary to frequent blood tests to monitor for agranulocytopenia. We identified 27 patients with PDP (72 ± 7.3 years, 11 (41%) female), with an inadequate response to pimavanserin, who subsequently started clozapine. The final mean daily dose of clozapine was 49.5 mg [range 25-100] at night, and mean duration of follow-up was 17 months [range: 2-50 months]. Patients reported clozapine to be markedly effective in 11 (41%), moderately effective in 6 (22%), somewhat effective in 5 (18%). No patient reported that it was ineffective, but 5 (19%) had inadequate follow-up. Clozapine should be considered in pimavanserin refractory psychosis.

Dose Optimization of Apomorphine Sublingual Film for OFF Episodes in Parkinson's Disease: Is the Prophylactic Use of an Antiemetic Necessary?

BACKGROUND: Nausea is common upon initiating dopamine agonists in patients with Parkinson's disease (PD); however, pretreatment with an antiemetic is recommended only when initiating apomorphine formulations. OBJECTIVE: Evaluate the need for prophylactic antiemetic use during dose optimization of apomorphine sublingual film (SL-APO). METHODS: A post hoc analysis of a Phase III study evaluated nausea and vomiting treatment-emergent adverse events in patients with PD who underwent SL-APO dose optimization (10-35 mg; 5-mg increments) to achieve a tolerable FULL ON. Frequencies of nausea and vomiting were described for patients who did versus did not use an antiemetic during dose optimization and by patient subgroups based on extrinsic and intrinsic factors. RESULTS: Overall, 43.7% (196/449) of patients did not use an antiemetic during dose optimization; most of these patients (86.2% [169/196]) achieved an effective and tolerable SL-APO dose. In patients who did not use an antiemetic, nausea (12.2% [24/196]) and vomiting (0.5% [1/196]) were uncommon. An antiemetic was used in 56.3% (253/449) of patients, with 17.0% (43/253) and 2.4% (6/253) experiencing nausea and vomiting, respectively. All events of nausea (14.9% [67/449]) and vomiting (1.6% [7/449]) were of mild-to-moderate severity except for 1 event each. Irrespective of antiemetic use, among patients without baseline dopamine agonist use, nausea and vomiting rates were 25.2% (40/159) and 3.8% (6/159); in those already using dopamine agonists, rates were 9.3% (27/290) and 0.3% (1/290). CONCLUSION: Prophylactic treatment with an antiemetic is not necessary for most patients who initiate SL-APO for the treatment of OFF episodes in PD.

Stroke-related restless legs syndrome: epidemiology, clinical characteristics, and pathophysiology.

Stroke-related restless legs syndrome (RLS) is one of stroke-related sleep disorders, which may be due to de novo RLS after stroke onset or an exacerbation of RLS symptoms after incident stroke. To date, the diagnostic rate of stroke-related RLS is low but it has a significant effect on patients' daily life and functional outcome. This review provides an overview of the epidemiology, clinical characteristics, pathophysiology, and impact on functional outcome of stroke-related RLS.

Exploratory cross-over, trial of augmented RLS with the dopamine receptor 1/5 antagonist ecopipam D1/D5 antagonist ecopipam for augmented RLS.

BACKGROUND: Restless legs syndrome (RLS) is a common condition that initially responds dramatically to dopaminergic therapy. Over time, however, dopaminergics cause augmentation, where symptoms occur earlier and intensify. Animal models suggest this may result from increased dopamine receptor type-1 affinity in the spinal cord. Ecopipam is a potent, specific dopamine-1/5 receptor antagonist. METHODS: We performed a small (N = 10) exploratory placebo controlled, cross-over safety trial of ecopipam (25-100 mg/day) for patients with augmented RLS currently taking dopamine agonists. RESULTS: Ecopipam was well tolerated with sedation being the most common adverse event in drug and placebo. Safety scales and serology data were similar to placebo. The study was not powered to demonstrate efficacy and exploratory efficacy data showed no significant improvement compared to placebo, but RLS diaries, the international RLS rating scale, and clinical global impressions all favored drug. No subject worsened on drug or demonstrated rebound worsening after drug discontinuation. CONCLUSION: Ecopipam was safe and well tolerated in this initial study for RLS. Given the lack of alternate options, larger efficacy studies for augmented RLS, and potentially de novo RLS are justified.

THN 102 for Excessive Daytime Sleepiness Associated with Parkinson's Disease: A Phase 2a Trial.

BACKGROUND: Excessive daytime sleepiness (EDS) is a frequent and disabling symptom of Parkinson's disease (PD) without approved treatment. THN102 is a novel combination drug of modafinil and low-dose flecainide. OBJECTIVE: The aim of this study is to evaluate the safety and efficacy of THN102 in PD patients with EDS. METHODS: The method involved a randomized, double-blind, placebo-controlled, crossover trial testing two doses of THN102 (200 mg/d modafinil with 2 mg/d [200/2] or 18 mg/d flecainide [200/18]) versus placebo; 75 patients were exposed to treatment. The primary endpoint was safety. The primary efficacy outcome was the change in Epworth Sleepiness Scale (ESS) score. RESULTS: Both doses of THN102 were well tolerated. ESS significantly improved with THN102 200/2 (least square means vs. placebo [95% confidence interval, CI]: -1.4 [-2.49; -0.31], P = 0.012) but did not change significantly with the 200/18 dosage. CONCLUSIONS: THN102 was well tolerated and showed a signal of efficacy at the 200/2 dose, supporting further development for the treatment of EDS in PD. © 2021 International Parkinson and Movement Disorder Society.

TETRAS Spirals and Handwriting Samples: Determination of Optimal Scoring Examples.

Background: Spiral drawings and handwriting tasks have long been used to assess the severity of essential tremor, but these motor tasks are somewhat less objective as the rules for scoring are not based on firm objective amplitude-based criteria. Publishing the best examples of each of the possible 0-4 ratings for these items could reduce scoring variance. Methods: 21 members of the Tremor Research Group each rated 94 spirals and 64 handwriting samples using TETRAS scoring criteria. For each sample, the most frequently reported score (mode; maximum of 21) was determined. Ratings not adjacent to the mode were subtracted from the number of mode scores, to calculate a total value. For each of the ratings (0, 1, 1.5, 2, 2.5, 3, 3.5, 4), the samples with the highest total value were selected as best examples. Results: In general, rater agreement was good for spirals but poor for handwriting samples. Nevertheless, examples with excellent agreement were identified for all spiral and handwriting ratings, and are presented. Conclusion: Best examples for scoring spirals and handwritings are needed to reduce the variance of TETRAS scores in clinical trials and clinical practice.

A Multi-center Genome-wide Association Study of Cervical Dystonia.

BACKGROUND: Several monogenic causes for isolated dystonia have been identified, but they collectively account for only a small proportion of cases. Two genome-wide association studies have reported a few potential dystonia risk loci; but conclusions have been limited by small sample sizes, partial coverage of genetic variants, or poor reproducibility. OBJECTIVE: To identify robust genetic variants and loci in a large multicenter cervical dystonia cohort using a genome-wide approach. METHODS: We performed a genome-wide association study using cervical dystonia samples from the Dystonia Coalition. Logistic and linear regressions, including age, sex, and population structure as covariates, were employed to assess variant- and gene-based genetic associations with disease status and age at onset. We also performed a replication study for an identified genome-wide significant signal. RESULTS: After quality control, 919 cervical dystonia patients compared with 1491 controls of European ancestry were included in the analyses. We identified one genome-wide significant variant (rs2219975, chromosome 3, upstream of COL8A1, P-value 3.04 × 10-8 ). The association was not replicated in a newly genotyped sample of 473 cervical dystonia cases and 481 controls. Gene-based analysis identified DENND1A to be significantly associated with cervical dystonia (P-value 1.23 × 10-6 ). One low-frequency variant was associated with lower age-at-onset (16.4 ± 2.9 years, P-value = 3.07 × 10-8 , minor allele frequency = 0.01), located within the GABBR2 gene on chromosome 9 (rs147331823). CONCLUSION: The genetic underpinnings of cervical dystonia are complex and likely consist of multiple distinct variants of small effect sizes. Larger sample sizes may be needed to provide sufficient statistical power to address the presumably multi-genic etiology of cervical dystonia. © 2021 International Parkinson and Movement Disorder Society.

Task Specific Tremor Subsequently Developing into Parkinson's Disease: Case Series.

BACKGROUND: Parkinson's Disease (PD) can present with dystonia or essential tremor but task specific tremor (TST) preceding PD has been only rarely reported. The relationship between TST and PD is unclear. We report a series of 12 patients with TST who later developed PD. CASES: Patients with TST and PD were identified from our database. Records and imaging were reviewed and descriptive statistics presented. Twelve patients were identified. All 11 patients who had TST of arm developed rest tremor ipsilateral to the TST arm. DaTscan showed reduced dopaminergic uptake in all 11 patients who were scanned. The TST improved with STN and VIM DBS (3/12) and partially to dopaminergic medications (N = 3) and trihexyphenidyl (N = 2). CONCLUSION: Rest tremor consistently occurring ipsilateral to TST, positive DaTscan, and partial response to dopaminergic medications but not to ET medications suggests TST is a precursor to PD in this population rather than chance occurrence.

SNCA-Rep1 polymorphism correlates with susceptibility and iron deficiency in restless legs syndrome.

BACKGROUND: Brain iron disequilibrium and dopaminergic dysfunction are key pathophysiological features of Restless Legs Syndrome (RLS). Rep1 polymorphism in the promotor region of SNCA is associated with risk of Parkinson's disease, however its association with RLS and iron status is unclear. OBJECTIVE: To investigate SNCA-Rep1 polymorphism in RLS and its phenotypes. METHODS: We recruited RLS patients as well as age and gender matched healthy controls. Demographic information and clinical features of RLS were recorded. Laboratory examinations were performed to exclude possible secondary causes. RESULTS: 215 RLS patients and 369 healthy controls were included. We found that the Rep1 allele 0 homozygosity significantly decreased RLS risk (OR: 0.345; P < 0.0001, and remained significant after the Bonferroni correction). Phenotypic analysis demonstrated that longer Rep1 alleles were associated with increased susceptibility to iron deficiency (53.0% vs 36.1%, P = 0.017), however had no phenotypic significant effects on age, gender, onset age, duration, RLS family history, severity, laterality, extra body involvement and seasonal fluctuation. Multivariate logistic regression analyses confirmed long Rep1 allele was associated with higher risk of iron deficiency in RLS after adjusting for potential confounding factors. In detail, Rep1 allele 2 homozygosity was prone to a higher risk of peripheral iron deficiency in RLS (OR: 4.550, P = 0.006, remained significant after the Bonferroni correction). CONCLUSION: The SNCA-Rep1 variability modified RLS risk and influenced peripheral iron deficiency in this group of Chinese RLS patients. Rep1 allele 0 homozygosity decreased the risk of RLS, while homozygous allele 2 increased the risk of nonanemic iron deficiency in RLS.

Tremor Research Group Essential Tremor Rating Scale (TETRAS): Assessing Impact of Different Item Instructions and Procedures.

Introduction: The Tremor Research Group Essential Tremor Rating Scale (TETRAS) is a well-validated instrument to assess essential tremor. However, similar to all other tremor rating scales, specific instructions for individual tasks are based mostly on expert opinion and tradition. Several tasks have multiple possible variations that have never been compared to determine if they impact score. Methods: Using blinded, randomized videotapes, a group of tremor experts evaluated multiple ET patients to determine: 1. whether assessments of spirals and writing samples are similar if the rater only sees the end result as opposed to actually watching the task, 2. whether arm tremor ratings (postural and wing-beating) are similar if the subjects hold both hands out concurrently vs. if they only hold one arm out at a time, 3. whether heal to shin tremor scores vary between supine and sitting, and 4. compared cursive vs script writing samples. Results: Intraclass correlation coefficients (ICC) were excellent (>0.95) for all arm assessments. Writing tremor was rated worse if only rating the spiral/writing photos (p < 0.05) rather than also viewing the writing process, arm tremor scores were higher if each arm was rated individually (p < 0.001), heal to shin scores were higher when done sitting (p = 0.01), and cursive writing tended to be rated higher than script (p = 0.08). Discussion: Minor procedure differences when administering the TETRAS can significantly alter results.

Prodromal Markers of Parkinson's Disease in Patients With Essential Tremor.

Background: Essential tremor (ET) is manifested as an isolated syndrome of bilateral upper limb action tremor. Parkinson's disease (PD) is the second most common neurodegenerative disease, with typical motor symptoms of bradykinesia, rigidity, and resting tremor. ET-PD describes the new-onset of PD in ET patients. Recently, numerous studies on epidemiology, genetics, pathology, clinical features, and neuroimaging studies are challenging the idea that ET is an isolated disease, suggesting that patients with ET have the tendency to develop PD. Methods: In this review article, we collected recent findings that reveal prodromal markers of PD in patients with ET. Results: Substantia nigra hyperechogenicity serves as a prodromal marker for predicting the development of PD in patients with ET and provides a reference for therapeutic strategies. Additional potential markers include other neuroimaging, clinical features, heart rate, and genetics, whereas others lack sufficient evidence. Conclusion: In consideration of the limited research of PD in patients with ET, we are still far from revealing the prodromal markers. However, from the existing follow-up studies on ET patients, Substantia nigra hyperechogenicity may enable further exploration of the relationship between ET and PD and the search for pathogenesis-based therapies.