Long-Term Medication Profiles in Parkinson's Disease under Subthalamic Deep Brain Stimulation: A Controlled Study.

BACKGROUND: Subthalamic deep brain stimulation (STN-DBS) reduces antiparkinsonian medications in Parkinson's disease (PD) compared with the preoperative state. Longitudinal and comparative studies on this effect are lacking. OBJECTIVE: To compare longitudinal trajectories of antiparkinsonian medication in STN-DBS treated patients to non-surgically treated control patients. METHODS: We collected retrospective information on antiparkinsonian medication from PD patients that underwent subthalamic DBS between 1999 and 2010 and control PD patients similar in age at onset and baseline, sex-distribution, and comorbidities. RESULTS: In 74 DBS patients levodopa-equivalent daily dose (LEDD) were reduced by 33.9-56.0% in relation to the preoperative baseline over the 14-year observational period. In 61 control patients LEDDs increased over approximately 10 years, causing a significant divergence between groups. The largest difference amongst single drug-classes was observed for dopamine agonists. CONCLUSION: In PD patients, chronic STN-DBS was associated with a lower LEDD compared with control patients over 14 years.

Sex-related differences in the clinical presentation of multiple system atrophy.

PURPOSE: To investigate sex-related differences in the clinical presentation of multiple system atrophy (MSA) through a literature review and an analysis of a retrospective cohort. METHODS: The PubMed database was searched for articles including sex-related information in MSA. In a retrospective Innsbruck cohort, we investigated the baseline to last available follow-up clinical-demographic differences between men and women with MSA in a univariate fashion, followed by multivariable binary regression analysis. RESULTS: The literature search yielded 46 publications with sex-related information in MSA. Most studies found comparable survival rates between the sexes, while some recent reports suggested a potential survival benefit for women, possibly due to initial motor onset and overall less severe autonomic failure compared to men. The retrospective Innsbruck MSA cohort comprised 56 female and 60 male individuals with a comparable median follow-up of 27 months. At baseline, female sex was independently associated with depression (odds ratio [OR] 4.7; p = 0.007) and male sex with severe orthostatic hypotension (OR 5.5; p = 0.016). In addition, at last follow-up, female sex was associated with the intake of central nervous system-active drugs (OR 4.1; p = 0.029), whereas male sex was associated with the presence of supine hypertension (OR 3.0; p = 0.020) and the intake of antihypertensive medications (OR 8.7; p = 0.001). Male sex was also associated with initiation of antihypertensive medications over the observation period (OR 12.4; p = 0.004). CONCLUSION: The available literature and findings of the present study indicate sex-related differences in the clinical presentation of MSA and its evolution over time, highlighting the importance of considering sex in symptom exploration, therapeutic decision-making, and future clinical trial design.

Long-term safety and efficacy of open-label nabilone on sleep and pain in Parkinson´s Disease.

The synthetic tetrahydrocannabinol-analog nabilone improved non-motor symptoms (NMS) in Parkinson's disease (PD) patients in a placebo-controlled, double-blind, parallel-group, randomized withdrawal trial with enriched enrollment (NMS-Nab-study). This was a single-center open-label extension study to assess the long-term safety and efficacy of nabilone for NMS in PD. To be eligible for this study, patients had to be treatment responders during the previous NMS-Nab-trial and complete its double-blind phase without experiencing a drug-related serious/severe/moderate adverse event (AE). Patients were re-introduced to nabilone during an up-titration phase until their overall NMS burden improved. Nabilone was continued for six months with clinic visits every 3 months. Evaluation of AEs was based on self-report and clinical assessment. Twenty-two patients participated in the NMS-Nab2-study (age-median 68.33 y, 52% females, disease duration-median 7.42 y). Nabilone was well tolerated with concentration difficulties as the most common treatment-related AE (possibly/not related n = 1 each). One in two drop-outs discontinued because of an AE for which a prohibited concomitant medication needed to be introduced (night-time sleep problems). Efficacy evaluation showed a significant and lasting improvement in NMS burden according to the CGI-I (79% at V3). Nabilone improved overall sleep (NMSS Domain-2: -8.26 points; 95%CI -13.82 to -2.71; p = 0.004; ES = -0.72), night-time sleep problems (MDS-UPDRS-1.7: -1.42 points; 95 CI -2.16 to -0.68; p = 0.002; ES = -0.92), and overall pain (KPPS Total Score: -8.00 points; 95%CI -15.05 to -0.95; p = 0.046; ES -0.55 and MDS-UPDRS-1.9: -0.74 points; 95%CI -1.21 to -0.26; p = 0.008; ES = -0.74). This study demonstrates continuous long-term safety and efficacy in PD patients responding early to nabilone without intolerable side effects.

Body Composition and Physical Performance 1 Year After COVID-19.

OBJECTIVE: Long-term consequences after COVID-19 include physical complaints, which may impair physical recovery and quality of life. DESIGN: We assessed body composition and physical ability in patients 12 months after COVID-19. Consecutively recruited patients recovering from mild to severe COVID-19 were assessed using bioelectrical impedance analysis, 6-min-walk test, additional scales for physical performance and health-related quality of life. RESULTS: Overall physical recovery was good (i.e., Glasgow Outcome Scale-Extended ≥7 in 96%, Modified Rankin Scale ≤1 in 87%, Eastern Cooperative Oncology Group ≤1 in 99%). Forty-four percent of the 69 patients experienced a significant body mass index increase in the year after COVID-19 (≥1 kg/m 2 ), whereas skeletal muscle mass index was reduced in only 12%. Patients requiring intensive care treatment ( n = 15, 22%) during acute COVID-19 more often had a body mass index increase ( P = 0.002), worse 6-min-walk test-performance ( P = 0.044), and higher body fat mass ( P = 0.030) at the 1-yr follow-up when compared with patients with mild ( n = 22, 32%) and moderate ( n = 32, 46%) acute COVID-19. Body mass index increase was also more frequent in patients who had no professional rehabilitation ( P = 0.014). CONCLUSIONS: Although patients with severe COVID-19 had increased body mass index and body fat and performed worse in physical outcome measures 1 yr after COVID-19, overall physical recovery was satisfying. Translating these findings to variants beyond the Alpha strain of severe acute respiratory syndrome coronavirus 2 virus needs further studies.

Distinct smell and taste disorder phenotype of post-acute COVID-19 sequelae.

PURPOSE: Olfactory dysfunction (OD) commonly accompanies coronavirus disease 2019 (COVID-19). We investigated the kinetics of OD resolution following SARS-CoV-2 infection (wild-type and alpha variant) and its impact on quality of life, physical and mental health. METHODS: OD prevalence was assessed in an ambulatory COVID-19 survey (n = 906, ≥ 90 days follow-up) and an observational cohort of ambulatory and hospitalized individuals (n = 108, 360 days follow-up). Co-occurrence of OD with other symptoms and effects on quality of life, physical and mental health were analyzed by multi-dimensional scaling, association rule mining and semi-supervised clustering. RESULTS: Both in the ambulatory COVID-19 survey study (72%) and the observational ambulatory and hospitalized cohort (41%) self-reported OD was frequent during acute COVID-19. Recovery from self-reported OD was slow (survey: median 28 days, observational cohort: 90 days). By clustering of the survey data, we identified a predominantly young, female, comorbidity-free group of convalescents with persistent OD and taste disorders (median recovery: 90 days) but low frequency of post-acute fatigue, respiratory or neurocognitive symptoms. This smell and taste disorder cluster was characterized by a high rating of physical performance, mental health, and quality of life as compared with convalescents affected by prolonged fatigue or neurocognitive complaints. CONCLUSION: Our results underline the heterogeneity of post-acute COVID-19 sequelae calling for tailored management strategies. The persistent smell and taste disorder phenotype is characterized by good clinical, physical, and mental recovery and may pose a minor challenge for public health. STUDY REGISTRATION: ClinicalTrials.gov: NCT04661462 (survey study), NCT04416100 (observational cohort).

Pimavanserin: A Truly Effective Treatment for Parkinson's Disease Psychosis? A Review of Interventions.

Parkinson's disease (PD) is the second-most common neurodegenerative disorder with a long-term 60% cumulative prevalence of PD psychosis. Medical treatment is limited to few atypical antipsychotic drugs with low affinity to dopamine D2 receptors. In 2016, pimavanserin, a selective 5-HT2A inverse agonist/antagonist, was approved by the US Food and Drug Administration (FDA) as the only treatment for PD psychosis (PDP). This article provides an overview of the epidemiology, pathophysiology, and treatment options for PDP and illuminates the mode of action and therapy options with pimavanserin and the current study data.

α-Synuclein Seed Amplification Assays in the Diagnosis of Synucleinopathies Using Cerebrospinal Fluid-A Systematic Review and Meta-Analysis.

Background: Real-time quaking-induced conversion (RT-QuIC) and protein misfolding cyclic amplification (PMCA) have been developed to detect minute amounts of amyloidogenic proteins via amplification techniques and have been used to detect misfolded α-synuclein (αSyn) aggregates in the cerebrospinal fluid (CSF) and other source materials of patients with Parkinson's Disease and other synucleinopathies. Objectives: The aim of this systematic review and meta-analysis was to evaluate the diagnostic accuracy of αSyn seed amplification assays (αSyn-SAAs), including RT-QuIC and PMCA, using CSF as source material to differentiate synucleinopathies from controls. Methods: The electronic MEDLINE database PubMed was searched for relevant articles published until June 30, 2022. Study quality assessment was performed using the QUADAS-2 toolbox. A random effects bivariate model was exploited for data synthesis. Results: Our systematic review identified 27 eligible studies according to the predefined inclusion criteria, of which 22 were included in the final analysis. Overall, 1855 patients with synucleinopathies and 1378 non-synucleinopathies as control subjects were included in the meta-analysis. The pooled sensitivity and specificity to differentiate synucleinopathies from controls with αSyn-SAA were 0.88 (95% CI, 0.82-0.93) and 0.95 (95% CI, 0.92-0.97), respectively. Evaluating the diagnostic performance of RT-QuIC in a subgroup analysis for the detection of patients with multiple system atrophy the pooled sensitivity decreased to 0.30 (95% CI, 0.11-0.59). Conclusions: While our study clearly demonstrated a high diagnostic performance of RT-QuIC and PMCA for differentiating synucleinopathies with Lewy bodies from controls, results for the diagnosis of multiple system atrophy were less robust.

Temporal Muscle Thickness Correlates with Sarcopenia in Parkinson's Disease.

BACKGROUND: Sarcopenia is characterized by a progressive loss of muscle mass, strength, and function resulting in adverse health outcomes. Current assessment strategies are bothersome and means to simplify the diagnosis are an unmet medical need in Parkinson's disease (PD). OBJECTIVE: To evaluate temporal muscle thickness (TMT) obtained on routine cranial MRI as a surrogate marker of sarcopenia in PD patients. METHODS: We correlated TMT from axial non-contrast-enhanced T1-weighted sequences of MRI close (±12 months) to an outpatient visit including sarcopenia (EWGSOP1, EWGSOP2, SARC-F), frailty (Fried's criteria, clinical frailty scale), and disease characteristics of Parkinson's patients (Hoehn and Yahr-scale, Movement Disorder Society-Unified Parkinson's Disease Rating Scale, quality of life with the Parkinson's Disease Questionnaire-8) assessments. RESULTS: Cranial MRI was available in 32 patients with a mean age of 73.56±5.14 years, mean disease duration of 11.46±5.66 years, and median Hoehn and Yahr stage of 2.5. The mean TMT was 7.49±2.76 (7.15) mm. Mean TMT was significantly associated with sarcopenia (EWGSOP2, p = 0.018; EWGSOP1, p = 0.023) and frailty status (physical phenotype; p = 0.045). Moreover, there were significant moderate to strong correlations between TMT measurement and appendicular skeletal muscle mass index (r: 0.437, p = 0.012), as well as handgrip strength (r: 0.561, p < 0.001). CONCLUSION: Reduced TMT seems to be a promising surrogate marker for sarcopenia (EWGSOP2) and muscle strength in this pilot study in PD patients.

Anti-IgLON5 Disease with Isolated Hemichorea: A Case Report and Review of the Literature.

Background: Anti-IgLON5 disease is an autoimmune encephalopathy with sleep disturbances as a hallmark in the majority of reported cases. Additional clinical symptoms are heterogenous and include movement disorders, bulbar dysfunction, autonomic disorders, and neurocognitive impairment. Case: Here, we report the case of an 87-year-old woman presenting with isolated progressive hemichorea. An extensive diagnostic work-up revealed antibodies against IgLON5 in the serum. Neither history nor polysomnography (PSG) unveiled signs and features of sleep dysfunction typically reported in anti-IgLON5 disease. Literature Review: In an extensive literature review we identified twelve other studies reporting about patients with confirmed anti-IgLON5 disease and chorea as extrapyramidal movement disorder in their clinical phenotype. Subsequently, clinical characteristics of these patients were carefully evaluated. Conclusions: Our results support the diversity of clinical phenotypes in anti-IgLON5 disease, adding isolated hemichorea to the spectrum of presenting symptoms. As sleep-related disorders are often not the leading reason for consultation and only revealed by PSG examination, we suggest that screening for antibodies against IgLON5 should be considered in patients presenting with unexplained movement disorders, including isolated hemichorea.

Nomogram to Predict the Probability of Functional Dependence in Early Parkinson's Disease.

BACKGROUND: Early identification of Parkinson's disease (PD) patients at risk for becoming functionally dependent is important for patient counseling. Several models describing the relationship between predictors and outcome have been reported, however, most of these require computer software for practical use. OBJECTIVE: Here we report the development of a risk nomogram allowing an approximate graphical computation of the risk of becoming functionally dependent in early PD. METHODS: We analyzed data form the Parkinson's Progression Markers Initiative cohort of newly diagnosed PD patients from baseline through the first 5 years of follow-up. Functional dependence was defined as a score < 80 on the Schwab & England Activities of Daily Living scale. A binary logistic model was developed to estimate the risk of functional dependence and based on the results, a nomogram for the prediction of functional dependence was drawn in order to provide an easy-to-use tool in clinical and academic settings as a part of personalized medicine approach to PD treatment. RESULTS: At baseline, three patients and over the five-year follow-up, 85 (22%) out of 395 patients were functionally dependent as scored by the Schwab & England Activities of Daily Living rating scale. The binary logistic model showed that clinical parameters such as MDS-UPDRS I (rater part), MDS-UPDRS II, and MDS-UPDRS axial motor score were significant predictors for functional dependence within 5 years. CONCLUSION: We here provide an easy-to-use tool to estimate the risk of functional dependence in PD patients based on the MDS-UPDRS part I, II and axial motor score.

Different assessment tools to detect sarcopenia in patients with Parkinson's disease.

Introduction: Sarcopenia and Parkinson's disease are closely related diseases of the elderly population leading to progressive disability and nursing-dependent care. Objective: The aim of this study was to estimate the prevalence of sarcopenia in PD patients with three different approaches: (1) the screening tool SARC-F, (2) EWGSOP-1 criteria, and (3) EWGSOP-2 criteria. Moreover, we aimed to evaluate the diagnostic accuracy of the screening tool SARC-F to detect sarcopenia according to the updated EWGSOP-2 criteria. Methods: Eighty-one patients with Parkinson's disease aged 65 years and above were interviewed in a cross-sectional study at a tertiary referral center. All patients were screened with the SARC-F questionnaire and were evaluated for motor and non-motor symptoms, exercise, quality of life, and frailty. Muscle mass was assessed with bioelectrical impedance analysis, handgrip strength with a dynamometer, and gait speed was assessed with the 8-m walk test. EWGSOP-2 criteria were considered the gold standard to diagnose sarcopenia in our study. Results: Eighty-one patients were evaluated (mean age: 73.82; SD 5.30). The prevalence of sarcopenia was 28.4% according to the EWGSOP-2 criteria. The concordance between EWGSOP-2 and EWGSOP-1 was poor (weighted kappa of 0.361[95% 0.164-0.557]). The sensitivity of the SARC-F screening test for detecting sarcopenia was 60.9%. The corresponding AUC in the ROC curve analysis showed 0.598 (0.462, 0.734 CI). The item assessing strength was found to have the highest sensitivity (69.6%). Conclusion: Sarcopenia prevalence in patients with PD in Tirol, Austria is higher with EWGSOP-1 criteria compared to EWGSOP-2 criteria. The sensitivity and specificity of the SARC-F scale to detect sarcopenia in this population are poor.

Cognitive dysfunction 1 year after COVID-19: evidence from eye tracking.

Increasing evidence suggests persistent cognitive dysfunction after COVID-19. In this cross-sectional study, frontal lobe function was assessed 12 months after the acute phase of the disease, using tailored eye tracking assessments. Individuals who recovered from COVID-19 made significantly more errors in all eye tracking tasks compared to age/sex-matched healthy controls. Furthermore, patients who were treated as inpatients performed worse compared to outpatients and controls. Our results show impaired inhibitory cortical control in individuals who recovered from COVID-19. The association between disease severity and its sequelae may contribute to a better understanding of post-COVID-19 cognitive function.

Effects of Nabilone on Sleep Outcomes in Patients with Parkinson's Disease: A Post-hoc Analysis of NMS-Nab Study.

Background: The synthetic tetrahydrocannabinol analogue nabilone improved overall non-motor symptom (NMS) burden in Parkinson's disease (PD) patients in comparison to placebo. Objectives: To characterize the effects of nabilone on different sleep outcomes in PD patients. Methods: We performed a post-hoc analysis of the controlled, double-blind, enriched enrollment randomized withdrawal NMS-Nab study to assess the effects of nabilone on sleep outcomes in study participants who reported clinically-relevant sleep problems (MDS-UPDRS-1.7 ≥ 2 points). Results: After open-label nabilone administration, 77.4% reported no relevant sleep problem. In the withdrawal phase of the trial, the MDS-UPDRS-1.7. and the NMS-Scale Domain 2 (i.e., Sleep/Fatigue) significantly worsened only in PD patients in the placebo group, which was mostly driven by a significant worsening of insomnia (question 5 of the NMS-Scale Domain 2). Conclusions: This post-hoc analysis of the NMS-Nab trial suggests that nabilone has beneficial effects on sleep outcomes in PD patients experiencing sleep problems at baseline.The original trial was registered with ClinicalTrials.gov (NCT03769896, https://clinicaltrials.gov/ct2/show/NCT03769896) and EudraCT (2017-000192-86).

Hospital Admissions of Huntington's Disease Patients in a Huntington's Disease Centre Between 2011 and 2016: A Retrospective Analysis.

Background: Huntington's Disease (HD) is a relentlessly progressive genetic neurodegenerative disorder with characteristic motor, psychiatric, and behavioral abnormalities that inevitably results in severe disability and death. Many patients have multiple hospital admissions during the disease course, but there is limited information which problems lead to hospitalization. Objectives: To assess acute reasons for hospital admissions, discharge routes, and clinical characteristics of HD patients in a retrospective analysis. Methods: We reviewed all medical records of patients with an established diagnosis of Huntington's Disease and hospital admissions between 2011 and 2016 in our local hospital-based database. Results: There were 135 hospital admissions in 53 HD patients during the review period, representing a median of two admissions per patient. Median duration of hospitalization was seven days. The most frequent reason for admission was a worsening of HD motor symptoms (n = 77, 57.0%) such as chorea, parkinsonism, gait problems, falls, and dysphagia. Psychiatric symptoms related to HD were the second most common reason for admission (n = 58, 43.0%). Infections (including aspiration pneumonia) and traumas/surgical procedures were only responsible for 6.7% and 5.9% of admissions, respectively. Emergency admissions were not common (42.2%), and the majority of patients were able to return to their previous residency upon discharge (85.2%, home or nursing home). Recurrent admissions were associated with worse motor function and functional capacity. Conclusions: Worsening of motor and psychiatric symptoms associated with Huntington's Disease were the most common reasons for hospital admissions. Therefore, our data highlight the importance of optimal symptom control in HD patients.

Eye Tracking in Patients with Parkinson's Disease Treated with Nabilone-Results of a Phase II, Placebo-Controlled, Double-Blind, Parallel-Group Pilot Study.

The topic of the therapeutic use of cannabinoids in Parkinson's disease (PD) is broadly discussed and frequently comes up in the outpatient clinic. So far, there are only a few randomized clinical trials assessing the effects of cannabinoids in PD. We are able to demonstrate a reduction in non-motor symptom (NMS) burden after the administration of nabilone. As impairment of attention and working memory have been described earlier as possible side effects, we assess cognitive performance using saccadic paradigms measured by an eye tracker. We do not observe a significant difference in any of the saccadic paradigms between PD patients on placebo versus those treated with nabilone. We, therefore, conclude that top-down inhibitory control is not affected by the tetrahydrocannabinol analogue. Nabilone did not significantly worsen cognitive performance and appears to be safe to use in selected PD patients who suffer from disabling NMS.

Undetected ophthalmological disorders in Parkinson's disease.

BACKGROUND: Ophthalmological disorders are common and frequently disabling for people with Parkinson's disease (PD). However, details on the prevalence, severity and impact of ophthalmological disorders thus far lacking. We aimed to identify PD patients with undetected ophthalmological disorders in a large cross-sectional, observational study. METHODS: We previously delivered a screening questionnaire to detect ophthalmological symptoms (Visual impairment in PD questionnaire; VIPD-Q) to 848 patients. Here, we report on a subgroup of 102 patients who received complete ophthalmological assessment aimed at identifying clinically relevant ophthalmological diseases, which were classified as either vison-threatening or not. Impact on daily life functioning was measured using the visual functioning-25 questionnaire (VFQ-25) and fall frequency. RESULTS: Almost all patients (92%) had one or more clinically relevant ophthalmological disorders. Of those, 77% had a potentially vision-threatening disease, while 34% had a potentially treatable ophthalmological disease which impacted on quality of life. The most prevalent ophthalmological disorders were dry eyes (86%), ocular misalignment (50%) and convergence insufficiency (41%). We found a weak but significant association between clinically relevant ophthalmological diseases and both fall frequency (R2 = 0.15, p = 0.037) and VFQ-25 score (R2 = 0.15, p = 0.02). The VIPD-Q could not correctly identify patients with relevant ophthalmological disorders. CONCLUSIONS: Surprisingly, in our study sample, many participants manifested previously undetected ophthalmological diseases, most of which threatened vision, impacted on daily life functioning and were amenable to treatment. Screening for these ophthalmological disorders using a questionnaire asking about symptoms seems insufficient. Instead, episodic ophthalmological assessments should be considered for PD patients, aiming to identify vision-threatening yet treatable diseases. TRIAL REGISTRATION: Dutch Trial Registration, NL7421.

Neurological outcomes 1 year after COVID-19 diagnosis: A prospective longitudinal cohort study.

BACKGROUND AND PURPOSE: Neurological sequelae from coronavirus disease 2019 (COVID-19) may persist after recovery from acute infection. Here, the aim was to describe the natural history of neurological manifestations over 1 year after COVID-19. METHODS: A prospective, multicentre, longitudinal cohort study in COVID-19 survivors was performed. At a 3-month and 1-year follow-up, patients were assessed for neurological impairments by a neurological examination and a standardized test battery including the assessment of hyposmia (16-item Sniffin' Sticks test), cognitive deficits (Montreal Cognitive Assessment < 26) and mental health (Hospital Anxiety and Depression Scale and Post-traumatic Stress Disorder Checklist 5). RESULTS: Eighty-one patients were evaluated 1 year after COVID-19, out of which 76 (94%) patients completed a 3-month and 1-year follow-up. Patients were 54 (47-64) years old and 59% were male. New and persistent neurological disorders were found in 15% (3 months) and 12% (10/81; 1 year). Symptoms at 1-year follow-up were reported by 48/81 (59%) patients, including fatigue (38%), concentration difficulties (25%), forgetfulness (25%), sleep disturbances (22%), myalgia (17%), limb weakness (17%), headache (16%), impaired sensation (16%) and hyposmia (15%). Neurological examination revealed findings in 52/81 (64%) patients without improvement over time (3 months, 61%, p = 0.230) including objective hyposmia (Sniffin' Sticks test <13; 51%). Cognitive deficits were apparent in 18%, whereas signs of depression, anxiety and post-traumatic stress disorders were found in 6%, 29% and 10% respectively 1 year after infection. These mental and cognitive disorders had not improved after the 3-month follow-up (all p > 0.05). CONCLUSION: Our data indicate that a significant patient number still suffer from neurological sequelae including neuropsychiatric symptoms 1 year after COVID-19 calling for interdisciplinary management of these patients.

Differentiating Parkinson's Disease from Essential Tremor Using Transcranial Sonography: A Systematic Review and Meta-Analysis.

BACKGROUND: Essential tremor (ET) and the tremor of Parkinson's disease (PD) are the most common tremors encountered in clinical practice. Especially in early disease stages, discrimination between the tremors of ET and PD can be challenging. OBJECTIVE: The aim of this study was to evaluate the diagnostic accuracy of transcranial sonography (TCS) of the substantia nigra echogenicity for differential diagnosis of PD versus ET. METHODS: A systematic PubMed search identified 512 studies. Sensitivity and specificity of substantia nigra hyperechogenicity was estimated. Data synthesis was carried applying a random effects bivariate binomial model. To assess study quality and risk of bias, the QUADAS-2 tool was used. RESULTS: Eighteen studies were suitable for analysis including 1,264 PD and 824 ET patients. The meta analysis showed a pooled sensitivity and specificity for TCS in the differential diagnosis of PD versus ET of 84.6% (95% CI, 79.4-88.6%) and 83.9% (95% CI, 78.4-88.2%), respectively. Furthermore, we found nearly similar results in sensitivity and specificity comparing TCS and DaTSCAN in a subgroup-analysis of three studies using both diagnostic tools including 107 patients with PD and 62 patients with ET. The QUADAS-2 toolbox revealed a high risk of bias regarding the methodological quality of patient selection. CONCLUSION: Substantia nigra hyperechogenicity yield high diagnostic accuracy for the discrimination of PD from ET. TCS is a low cost, widely available, non-invasive marker without radiation Therefore, a diagnostic algorithm based on presence or absence of substantia nigra hyperechogenicity is highly warranted.