The Signature of Primary Writing Tremor Is Dystonic.

BACKGROUND: It has been debated for decades whether primary writing tremor is a form of dystonic tremor, a variant of essential tremor, or a separate entity. We wished to test the hypothesis that primary writing tremor and dystonia share a common pathophysiology. OBJECTIVES: The objective of the present study was to investigate the pathophysiological hallmarks of dystonia in patients affected by primary writing tremor. METHODS: Ten patients with idiopathic dystonic tremor syndrome, 7 with primary writing tremor, 10 with essential tremor, and 10 healthy subjects were recruited. They underwent eyeblink classic conditioning, blink recovery cycle, and transcranial magnetic stimulation assessment, including motor-evoked potentials and short- and long-interval intracortical inhibition at baseline. Transcranial magnetic stimulation measures were also recorded after paired-associative plasticity protocol. RESULTS: Primary writing tremor and dystonic tremor syndrome had a similar pattern of electrophysiological abnormalities, consisting of reduced eyeblink classic conditioning learning, reduced blink recovery cycle inhibition, and a lack of effect of paired-associative plasticity on long-interval intracortical inhibition. The latter 2 differ from those obtained in essential tremor and healthy subjects. Although not significant, slightly reduced short-interval intracortical inhibition and a larger effect of paired-associative plasticity in primary writing tremor and dystonic tremor syndrome, compared with essential tremor and healthy subjects, was observed. CONCLUSIONS: Our initial hypothesis of a common pathophysiology between dystonia and primary writing tremor has been confirmed. Primary writing tremor might be considered a form of dystonic tremor. © 2021 International Parkinson and Movement Disorder Society.

Exploratory pilot study of exogenous sustained-release melatonin on nocturia in Parkinson's disease.

INTRODUCTION: Nocturia is one of the commonest non-motor symptoms in Parkinson's disease (PD). Nocturia has evolved from being understood as a symptom of urological disorders or neurogenic bladder dysfunction to being considered as a form of circadian dysregulation. Exogenous melatonin is known to help circadian function and can be an effective strategy for nocturia in PD. METHODS: In this open-label, single-site, exploratory, phase 2 pilot study, adults with PD and nocturia underwent assessments using standardized questionnaires, urodynamics studies and a bladder scan. This was followed by completion of a frequency volume chart (FVC) and 2-week sleep diary. Sustained-release melatonin 2 mg was then administered once-nightly for 6 weeks. A repeat assessment using questionnaires, the FVC and sleep diary was performed whilst on treatment with melatonin. Companion or bed partners filled in sleep questionnaires to assess their sleep during the intervention. RESULTS: Twenty patients (12 males; mean age 68.2 [SD = 7.8] years; mean PD duration 8.0 [±5.5] years) with PD reporting nocturia were included. Administration of melatonin was associated with a significant reduction in the primary outcome bother related to nocturia measured using the International Consultation on Incontinence Questionnaire Nocturia (ICIQ-N) (p = 0.01), number of episodes of nocturia per night (p = 0.013) and average urine volume voided at night (p = 0.013). No serious adverse events were reported. No significant improvement was noted in bed partner sleep scores. CONCLUSIONS: In this preliminary open-label study, administration of sustained-release melatonin 2 mg was found to be safe for clinical use and was associated with significant improvements in night-time frequency and nocturnal voided volumes in PD patients.

Lower urinary tract dysfunction in Parkinsonian syndromes.

PURPOSE OF REVIEW: The aim of this review is to outline the clinical presentation, pathophysiology and evaluation of lower urinary tract (LUT) dysfunction in Parkinson's disease and other parkinsonian syndromes including multiple system atrophy, dementia with Lewy bodies, progressive supranuclear palsy and corticobasal degeneration. RECENT FINDINGS: LUT dysfunction commonly occurs in neurological disorders, including patients with parkinsonian syndromes. The pattern of LUT dysfunction and its severity are variable, depending upon the site of lesion within the neural pathways. Parkinsonian syndromes are broadly divided into Parkinson's disease (PD) and a typical parkinsonian syndromes such as multiple system atrophy (MSA), dementia with Lewy bodies (DLB), progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). Different parkinsonian syndromes have distinct clinical features (e.g. dysautonomia, early dementia, supranuclear gaze palsy, higher cortical signs), and the pattern of LUT dysfunction and its severity can differ. CONCLUSIONS: LUT dysfunction is a common feature in patients with parkinsonian syndromes. Recognising the pattern of LUT dysfunction during the assessment of these patients can help management and possibly facilitate an earlier diagnosis.

Network localization of cervical dystonia based on causal brain lesions.

Cervical dystonia is a neurological disorder characterized by sustained, involuntary movements of the head and neck. Most cases of cervical dystonia are idiopathic, with no obvious cause, yet some cases are acquired, secondary to focal brain lesions. These latter cases are valuable as they establish a causal link between neuroanatomy and resultant symptoms, lending insight into the brain regions causing cervical dystonia and possible treatment targets. However, lesions causing cervical dystonia can occur in multiple different brain locations, leaving localization unclear. Here, we use a technique termed 'lesion network mapping', which uses connectome data from a large cohort of healthy subjects (resting state functional MRI, n = 1000) to test whether lesion locations causing cervical dystonia map to a common brain network. We then test whether this network, derived from brain lesions, is abnormal in patients with idiopathic cervical dystonia (n = 39) versus matched controls (n = 37). A systematic literature search identified 25 cases of lesion-induced cervical dystonia. Lesion locations were heterogeneous, with lesions scattered throughout the cerebellum, brainstem, and basal ganglia. However, these heterogeneous lesion locations were all part of a single functionally connected brain network. Positive connectivity to the cerebellum and negative connectivity to the somatosensory cortex were specific markers for cervical dystonia compared to lesions causing other neurological symptoms. Connectivity with these two regions defined a single brain network that encompassed the heterogeneous lesion locations causing cervical dystonia. These cerebellar and somatosensory regions also showed abnormal connectivity in patients with idiopathic cervical dystonia. Finally, the most effective deep brain stimulation sites for treating dystonia were connected to these same cerebellar and somatosensory regions identified using lesion network mapping. These results lend insight into the causal neuroanatomical substrate of cervical dystonia, demonstrate convergence across idiopathic and acquired dystonia, and identify a network target for dystonia treatment.

Young-onset multiple system atrophy: Clinical and pathological features.

BACKGROUND: The onset of multiple system atrophy (MSA) before age 40 years is referred to as "young-onset MSA." We identified clinical and pathological characteristics that might help with its early diagnosis and distinction from young-onset Parkinson's disease and late-onset MSA. METHODS: We reviewed the available clinical and pathological features in cases that fulfilled consensus criteria for diagnosis of probable MSA or had autopsy confirmed MSA with an onset before age 40 years and compared the clinical features with 16 autopsy confirmed cases with young-onset Parkinson's disease and a large published series of late-onset MSA from the European MSA Study Group. RESULTS: We identified 22 patients with young-onset MSA, 8 of whom had available pathology. The mean age of onset was 36.7 years (standard deviation 2.3). Levodopa-induced dyskinesia was more common, whereas myoclonus and pyramidal signs were less common in young-onset Parkinson's disease when compared with young-onset MSA. Dystonia, levodopa responsiveness, levodopa-induced dyskinesia, and pyramidal signs were more common (P < .05) when compared with the data in late-onset MSA. On postmortem analysis, the minimal-change pathological variant was more common in young-onset MSA (n = 2) than late-onset MSA (P = .045), with a mean survival of 11.1 ± 3.2 years (range 5.5-14.6) in pathologically confirmed cases of young-onset MSA. CONCLUSION: This study has identified useful differences that may improve diagnostic accuracy, help us understand the pathological basis, and assist clinicians with the early diagnosis of young-onset MSA. © 2018 International Parkinson and Movement Disorder Society.

Dystonia: A review.

Dystonia is a hyperkinetic movement disorder characterized by sustained or intermittent muscle contractions that cause abnormal repetitive movements, abnormal postures, or both. The new consensus classifies dystonia into two axes to characterize clinical characteristics, and etiology. This system allows correct identification of isolated and combined forms of dystonia and retains the description of generalized and focal dystonia which is very useful in planning investigations and management. The characterization of dystonia for its better identification and a brief overview of its management are discussed in this article. The treatment options for dystonia include drugs, botulinum toxin and deep brain stimulation surgery.

The CACNA1B R1389H variant is not associated with myoclonus-dystonia in a large European multicentric cohort.

Myoclonus-dystonia (M-D) is a very rare movement disorder, caused in ∼30-50% of cases by mutations in SGCE. The CACNA1B variant c.4166G>A; (p.R1389H) was recently reported as the likely causative mutation in a single 3-generation Dutch pedigree with five subjects affected by a unique dominant M-D syndrome and cardiac arrhythmias. In an attempt to replicate this finding, we assessed by direct sequencing the frequency of CACNA1B c.4166G>A; (p.R1389H) in a cohort of 520 M-D cases, in which SGCE mutations had been previously excluded. A total of 146 cases (28%) had a positive family history of M-D. The frequency of the variant was also assessed in 489 neurologically healthy controls and in publicly available data sets of genetic variation (1000 Genomes, Exome Variant Server and Exome Aggregation Consortium). The variant was detected in a single sporadic case with M-D, but in none of the 146 probands with familial M-D. Overall, the variant was present at comparable frequencies in M-D cases (1 out of 520; 0.19%) and healthy controls (1 out of 489; 0.2%). A similar frequency of the variant was also reported in all publicly available databases. These results do not support a causal association between the CACNA1B c.4166G>A; (p.R1389H) variant and M-D.

Current Opinions and Areas of Consensus on the Role of the Cerebellum in Dystonia.

A role for the cerebellum in causing ataxia, a disorder characterized by uncoordinated movement, is widely accepted. Recent work has suggested that alterations in activity, connectivity, and structure of the cerebellum are also associated with dystonia, a neurological disorder characterized by abnormal and sustained muscle contractions often leading to abnormal maintained postures. In this manuscript, the authors discuss their views on how the cerebellum may play a role in dystonia. The following topics are discussed: The relationships between neuronal/network dysfunctions and motor abnormalities in rodent models of dystonia. Data about brain structure, cerebellar metabolism, cerebellar connections, and noninvasive cerebellar stimulation that support (or not) a role for the cerebellum in human dystonia. Connections between the cerebellum and motor cortical and sub-cortical structures that could support a role for the cerebellum in dystonia. Overall points of consensus include: Neuronal dysfunction originating in the cerebellum can drive dystonic movements in rodent model systems. Imaging and neurophysiological studies in humans suggest that the cerebellum plays a role in the pathophysiology of dystonia, but do not provide conclusive evidence that the cerebellum is the primary or sole neuroanatomical site of origin.

The long-term outcome of orthostatic tremor.

OBJECTIVES: Orthostatic tremor is a rare condition characterised by high-frequency tremor that appears on standing. Although the essential clinical features of orthostatic tremor are well established, little is known about the natural progression of the disorder. We report the long-term outcome based on the largest multicentre cohort of patients with orthostatic tremor. METHODS: Clinical information of 68 patients with clinical and electrophysiological diagnosis of orthostatic tremor and a minimum follow-up of 5 years is presented. RESULTS: There was a clear female preponderance (76.5%) with a mean age of onset at 54 years. Median follow-up was 6 years (range 5-25). On diagnosis, 86.8% of patients presented with isolated orthostatic tremor and 13.2% had additional neurological features. At follow-up, seven patients who initially had isolated orthostatic tremor later developed further neurological signs. A total 79.4% of patients reported worsening of orthostatic tremor symptoms. These patients had significantly longer symptom duration than those without reported worsening (median 15.5 vs 10.5 years, respectively; p=0.005). There was no change in orthostatic tremor frequency over time. Structural imaging was largely unremarkable and dopaminergic neuroimaging (DaTSCAN) was normal in 18/19 cases. Pharmacological treatments were disappointing. Two patients were treated surgically and showed improvement. CONCLUSIONS: Orthostatic tremor is a progressive disorder with increased disability although tremor frequency is unchanged over time. In most cases, orthostatic tremor represents an isolated syndrome. Drug treatments are unsatisfactory but surgery may hold promise.

H-ABC syndrome and DYT4: Variable expressivity or pleiotropy of TUBB4 mutations?

Recently, mutations in the TUBB4A gene have been found to underlie hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC) syndrome, a rare neurodegenerative disorder of infancy and childhood. TUBB4A mutations also have been described as causative of DYT4 ("hereditary whispering dysphonia"). However, in DYT4, brain imaging has been reported to be normal and, therefore, H-ABC syndrome and DYT4 have been construed to be different disorders, despite some phenotypic overlap. Hence, the question of whether these disorders reflect variable expressivity or pleiotropy of TUBB4A mutations has been raised. We report four unrelated patients with imaging findings either partially or totally consistent with H-ABC syndrome, who were found to have TUBB4A mutations. All four subjects had a relatively homogenous phenotype characterized by severe generalized dystonia with superimposed pyramidal and cerebellar signs, and also bulbar involvement leading to complete aphonia and swallowing difficulties, even though one of the cases had an intermediate phenotype between H-ABC syndrome and DYT4. Genetic analysis of the TUBB4A gene showed one previously described and two novel mutations (c.941C>T; p.Ala314Val and c.900G>T; p.Met300Ile) in the exon 4 of the gene. While expanding the genetic spectrum of H-ABC syndrome, we confirm its radiological heterogeneity and demonstrate that phenotypic overlap with DYT4. Moreover, reappraisal of previously reported cases would also argue against pleiotropy of TUBB4A mutations. We therefore suggest that H-ABC and DYT4 belong to a continuous phenotypic spectrum associated with TUBB4A mutations.

Parkinson's disease in GTP cyclohydrolase 1 mutation carriers.

GTP cyclohydrolase 1, encoded by the GCH1 gene, is an essential enzyme for dopamine production in nigrostriatal cells. Loss-of-function mutations in GCH1 result in severe reduction of dopamine synthesis in nigrostriatal cells and are the most common cause of DOPA-responsive dystonia, a rare disease that classically presents in childhood with generalized dystonia and a dramatic long-lasting response to levodopa. We describe clinical, genetic and nigrostriatal dopaminergic imaging ([(123)I]N-ω-fluoropropyl-2ß-carbomethoxy-3ß-(4-iodophenyl) tropane single photon computed tomography) findings of four unrelated pedigrees with DOPA-responsive dystonia in which pathogenic GCH1 variants were identified in family members with adult-onset parkinsonism. Dopamine transporter imaging was abnormal in all parkinsonian patients, indicating Parkinson's disease-like nigrostriatal dopaminergic denervation. We subsequently explored the possibility that pathogenic GCH1 variants could contribute to the risk of developing Parkinson's disease, even in the absence of a family history for DOPA-responsive dystonia. The frequency of GCH1 variants was evaluated in whole-exome sequencing data of 1318 cases with Parkinson's disease and 5935 control subjects. Combining cases and controls, we identified a total of 11 different heterozygous GCH1 variants, all at low frequency. This list includes four pathogenic variants previously associated with DOPA-responsive dystonia (Q110X, V204I, K224R and M230I) and seven of undetermined clinical relevance (Q110E, T112A, A120S, D134G, I154V, R198Q and G217V). The frequency of GCH1 variants was significantly higher (Fisher's exact test P-value 0.0001) in cases (10/1318 = 0.75%) than in controls (6/5935 = 0.1%; odds ratio 7.5; 95% confidence interval 2.4-25.3). Our results show that rare GCH1 variants are associated with an increased risk for Parkinson's disease. These findings expand the clinical and biological relevance of GTP cycloydrolase 1 deficiency, suggesting that it not only leads to biochemical striatal dopamine depletion and DOPA-responsive dystonia, but also predisposes to nigrostriatal cell loss. Further insight into GCH1-associated pathogenetic mechanisms will shed light on the role of dopamine metabolism in nigral degeneration and Parkinson's disease.

Rest and other types of tremor in adult-onset primary dystonia.

INTRODUCTION: Knowledge regarding tremor prevalence and phenomenology in patients with adult-onset primary dystonia is limited. Dystonic tremor is presumably under-reported, and we aimed to assess the prevalence and the clinical correlates of tremor in patients with adult-onset primary dystonia. METHODS: We enrolled 473 consecutive patients with different types of adult-onset primary dystonia. They were assessed for presence of head tremor and arm tremor (rest, postural and kinetic). RESULTS: A total of 262 patients (55.4%) were tremulous: 196 patients presented head tremor, 140 patients presented arm tremor and 98 of them had a combination of head and arm tremor. Of the 140 patients with arm tremor, all presented postural tremor, 103 patients (73.6%) presented also a kinetic component, whereas 57 patients (40.7%) had rest tremor. Rest tremor was unilateral/asymmetric in up to 92.9% of them. Patients with segmental and multifocal dystonia were more likely tremulous than patients with focal dystonia. Dystonic symptoms involving the neck were more frequently observed in patients with head tremor, whereas dystonic symptoms involving the arms were more frequently observed in patients with arm tremor. DISCUSSION: Here we show that tremor is a common feature of patients with adult-onset primary dystonia. It may involve different body segments, with the head being the most commonly affected site. Arm tremor is also frequent (postural>kinetic>rest), occurring in up to one-third of cases. There is a suggestion of a stronger tendency for spread of dystonic features in patients with associated tremor. Dystonic tremor is under-reported and this underscores the importance of careful clinical examination when assessing tremulous patients without overt dystonia.

Patients with scans without evidence of dopaminergic deficit: a long-term follow-up study.

BACKGROUND: We previously reported on a cohort of dystonic tremor and patients with scans without evidence of dopaminergic deficit (SWEDDs). We aim to report the long-term clinical and imaging follow-up of these patients. PATIENTS AND METHODS: Patients with at least 5-year follow-up were included. These patients had an asymmetric arm tremor, a previous diagnosis of Parkinson's disease (PD), and a subsequent normal DaTscan. The imaging and clinical follow-up was done on the clinical basis. RESULTS: Sixteen patients were included. The mean gap between the first and subsequent scans was 5.4 years. Two patients (12.5%) had reduced nigrostriatal uptake on follow-up DaTscan, whereas 14 continued to have normal dopaminergic imaging. CONCLUSION: This is the longest follow up of patients with asymmetric rest tremor and normal DaT scans (SWEDDs) reported to date. We show here that only a minority of them show reduced striatonigral uptake over long term follow up.

The phenotypic spectrum of DYT24 due to ANO3 mutations.

Genes causing primary dystonia are rare. Recently, pathogenic mutations in the anoctamin 3 gene (ANO3) have been identified to cause autosomal dominant craniocervical dystonia and have been assigned to the dystonia locus dystonia-24 (DYT24). Here, we expand on the phenotypic spectrum of DYT24 and provide demonstrative videos. Moreover, tremor recordings were performed, and back-averaged electroencephalography, sensory evoked potentials, and C-reflex studies were carried out in two individuals who carried two different mutations in ANO3. Ten patients from three families are described. The age at onset ranged from early childhood to the forties. Cervical dystonia was the most common site of onset followed by laryngeal dystonia. The characteristic feature in all affected individuals was the presence of tremor, which contrasts DYT24 from the typical DYT6 phenotype. Tremor was the sole initial manifestation in some individuals with ANO3 mutations, leading to misdiagnosis as essential tremor. Electrophysiology in two patients with two different mutations showed co-contraction of antagonist muscles, confirming dystonia, and a 6-Hz arm tremor at rest, which increased in amplitude during action. In one of the studied patients, clinically superimposed myoclonus was observed. The duration of the myoclonus was in the range of 250 msec at about 3 Hz, which is more consistent with subcortical myoclonus. In summary, ANO3 causes a varied phenotype of young-onset or adult-onset craniocervical dystonia with tremor and/or myoclonic jerks. Patients with familial cervical dystonia who also have myoclonus-dystonia as well as patients with prominent tremor and mild dystonia should be tested for ANO3 mutations.

Episodic mandibular tremor in dogs: an idiopathic movement disorder or a manifestation of pain.

OBJECTIVE: Episodic mandibular tremor (EMT), manifested as teeth chattering, is not well described in dogs. The aim of this study was to describe clinical signs, MRI findings, and outcome of dogs with EMT. ANIMALS: 11 dogs retrospectively and 31 dogs in an online survey. METHODS: A retrospective multicenter study of dogs with EMT between 2018 and 2023 and prospective online questionnaire open to owners of pets with teeth chattering. RESULTS: All dogs had rapid and short-lasting (< 1 minute) episodes of EMT in the absence of other neurological signs. Lip smacking occasionally accompanied the tremor in 5 of 11 (45.5%) hospital dog cases. Excitement was a common trigger in 14 of 31 (45.2%) dogs from the survey. Cavalier King Charles Spaniel was the most common breed in both clinical and survey populations. Median age at presentation was 3 years for both hospital cases and the survey dogs. A concurrent medical condition was present in 8 of 11 (72.7%) hospital cases and 20 of 31 (64.5%) survey dogs. In 3 hospital dogs that underwent further investigations, no brain disease was present. CLINICAL RELEVANCE: EMT and its clinical features are presented for the first time, shedding light on a clinical sign that might resemble an idiopathic movement disorder or a manifestation of pain in dogs.

Ethnic Differences in Atypical Parkinsonism-is South Asian PSP Different?

BACKGROUND: Progressive supranuclear palsy (PSP) is a progressive atypical parkinsonian condition that results in severe disability. There are few studies of PSP in patients of non-white European ancestry. OBJECTIVES: We aim to perform deep phenotyping in a South Asian PSP cohort to uncover possible ethnic differences in disease characteristics. METHODS: Consecutive PSP patients had their clinical records reviewed for clinical features operationalized in the Movement Disorder Society (MDS)-PSP diagnostic criteria and relevant investigations, including imaging and genetic tests. Clinical variables were summarized by descriptive statistics and Kaplan-Meier curves were generated for survival analysis. RESULTS: Twenty-seven patients, comprising Indians (78%), Pakistanis (11%) and Sri Lankans (11%) were included. Mean age of symptom onset was 63.8 ± 7.0 years and 22% of patients had an early age of onset (<60 years). The most common presenting symptom was parkinsonism (56%), followed by cognitive dysfunction (37%), falls (33%) and dysarthria (26%). The predominance types at final review were distributed across PSP-RS (67%), PSP-PGF (15%), PSP-P (15%) and PSP-F (4%). Atypical clinical features like cerebellar signs (33%), REM-sleep behavior disorder (RBD) (55%), visual hallucinations (22%), and a family history of parkinsonism (20%) were evident in a proportion of patients. CONCLUSIONS: We present a South Asian cohort of PSP patients with a higher than previously reported percentages of early-onset disease, family history and atypical clinical manifestations. These patients do not fit easily into the PSP phenotypes defined by the current MDS criteria. Dedicated clinicopathological and genetic tests are needed in this population to dissect the pathogenesis of clinically-defined PSP.

Patient and Public Involvement and Engagement in the Development of a Platform Clinical Trial for Parkinson's Disease: An Evaluation Protocol.

Background: Patient and public involvement and engagement (PPIE) in the design of trials is important, as participant experience critically impacts delivery. The Edmond J Safra Accelerating Clinical Trials in PD (EJS ACT-PD) initiative is a UK consortium designing a platform trial for disease modifying therapies in PD. Objective: The integration of PPIE in all aspects of trial design and its evaluation throughout the project. Methods: PwP and care partners were recruited to a PPIE working group (WG) via UK Parkinson's charities, investigator patient groups and participants of a Delphi study on trial design. They are supported by charity representatives, trial delivery experts, researchers and core project team members. PPIE is fully embedded within the consortium's five other WGs and steering group. The group's terms of reference, processes for effective working and PPIE evaluation were co-developed with PPIE contributors. Results: 11 PwP and 4 care partners have supported the PPIE WG and contributed to the development of processes for effective working. A mixed methods research-in-action study is ongoing to evaluate PPIE within the consortium. This includes the Patient Engagement in Research Scale -a quantitative PPIE quality measure; semi-structured interviews -identifying areas for improvement and overall impressions of involvement; process fidelity- recording adherence; project documentation review - identifying impact of PPIE on project outputs. Conclusions: We provide a practical example of PPIE in complex projects. Evaluating feasibility, experiences and impact of PPIE involvement in EJS ACT-PD will inform similar programs on effective strategies. This will help enable future patient-centered research.