Bilateral thalamic changes in anti-NMDAR encephalitis presenting with hemichorea and dystonia and acute transient psychotic disorder

Anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis is one of the most common causes of autoimmune encephalitis. Both movement disorders and neuropsychiatric manifestations are considered core features of anti-NMDAR encephalitis. Strong clinical suspicion, along with NMDAR antibody positivity in paired sample of serum and cerebrospinal fluid, with supportive MRI changes clinch diagnosis in majority. We herein report a case of a middle-aged woman with subacute behavioral abnormalities, which were so severe that forced her to attempt suicide. Hemichorea and dystonia, which appeared later in course, are not previously reported movement disorders in combination in anti-NMDAR encephalitis. Further, magnetic resonance imaging showed bilateral thalamic hyperintensities with diffusion restriction, which are in turn not described in this entity. After amalgamation of history, especially the presence of neuropsychiatric symptoms, clinical features, physical examination, and investigations, the diagnosis of anti-NMDAR encephalitis could be established. Our case not only highlights that the combination of hemichorea and dystonia can be features of anti-NMDAR encephalitis, but adds novelty by bilateral symmetric thalamic changes.

Sex differences in movement disorders

A number of studies reported the possible differences between men and women in movement disorders. Evidence shows that estrogens may have a neuroprotective effect and may modulate the neurodevelopment of the different brain structures. Movement disorders including Parkinson's disease, dementia with Lewy body, Huntington's disease, Tourette's syndrome, and dystonia among others display significant clinical differences between sexes, with structural differences in the dopaminergic pathways between men and women. Here we summarize the most relevant clinical aspects of some of the most common movement disorders, highlighting the differences in disease onset, clinical presentation, therapy, and outcomes. Increased recognition of these differences may help physicians better understand the pathophysiology of these conditions and provide a tailored therapeutic approach.

Hyperkinetic manifestations in superficial siderosis: evidence for pathogenic network disruption

Superficial siderosis (SS) of central nervous system is a rare condition characterized by hemosiderin deposition diffusely involving supratentorial and infratentorial compartments. SS usually manifests with ataxia and sensorineural hearing loss. Basal ganglia are almost always spared by the degenerative process, and movement disorders are only rarely reported. We describe the case of an aged woman with apparently idiopathic SS presenting with cerebellar ataxia, hearing loss, and orofacial dyskinesias. Together with some previously reported patients affected by SS and presenting with dystonic manifestations, our case reinforces the current hypothesis supporting a wide network disruption, rather than a direct basal ganglia damage, as the likely underlying cause of some dystonic syndromes.

Dysfunction of parvalbumin neurons in the cerebellar nuclei produces an action tremor

Essential tremor is a common brain disorder affecting millions of people, yet the neuronal mechanisms underlying this prevalent disease remain elusive. Here, we showed that conditional deletion of synaptotagmin-2, the fastest Ca2+ sensor for synaptic neurotransmitter release, from parvalbumin neurons in mice caused an action tremor syndrome resembling the core symptom of essential tremor patients. Combining brain region-specific and cell type-specific genetic manipulation methods, we found that deletion of synaptotagmin-2 from excitatory parvalbumin-positive neurons in cerebellar nuclei was sufficient to generate an action tremor. The synaptotagmin-2 deletion converted synchronous into asynchronous neurotransmitter release in projections from cerebellar nuclei neurons onto gigantocellular reticular nucleus neurons, which might produce an action tremor by causing signal oscillations during movement. The tremor was rescued by completely blocking synaptic transmission with tetanus toxin in cerebellar nuclei, which also reversed the tremor phenotype in the traditional harmaline-induced essential tremor model. Using a promising animal model for action tremor, our results thus characterized a synaptic circuit mechanism that may underlie the prevalent essential tremor disorder.

IncobotulinumtoxinA for the Treatment of Blepharospasm in Toxin-Naïve Subjects: A Multi-Center, Double-Blind, Randomized, Placebo-Controlled Trial

This study aimed to assess the efficacy/safety of incobotulinumtoxinA (Xeomin^®, Merz Pharmaceuticals GmbH) in botulinum neurotoxin-naïve subjects with blepharospasm. Botulinum neurotoxin-naïve subjects (≥ 12 months without botulinum neurotoxin treatment for blepharospasm) received single-dose incobotulinumtoxinA 50 U, 25 U, or placebo. Subjects were followed for 6-20 weeks (main period). Qualified subjects entered an open-label extension period and received another incobotulinumtoxinA injection (≤ 70 U). The primary efficacy variable was change from baseline in the Jankovic Rating Scale (JRS) severity subscore at the main period of week 6. Other efficacy variables included changes in the Blepharospasm Disability Index score and JRS frequency subscore and sumscore. Adverse events were monitored. Sixty-one subjects were randomized (main period: incobotulinumtoxinA 50 U, n = 19; incobotulinumtoxinA 25 U, n = 22; placebo, n = 20); 39 entered the open-label extension period (9, 14, and 16 subjects from the incobotulinumtoxinA 50 U, incobotulinumtoxinA 25 U, and placebo groups [main period], respectively, changed to open-label extension period dosing). A statistically significantly greater reduction in JRS severity subscore was reported for subjects receiving incobotulinumtoxinA 50 U versus placebo (ANCOVA, least square mean difference: - 1.2, p = 0.0004). Subjects receiving incobotulinumtoxinA experienced improvements in other efficacy variables versus baseline and/or placebo. Sustained clinical improvements and low adverse event rates (22.2-42.1%) were observed. This is the second placebo-controlled, double-blind study that demonstrates favorable efficacy/safety of incobotulinumtoxinA in subjects with blepharospasm. IncobotulinumtoxinA is the first botulinum neurotoxin that could fulfill the American Academy of Neurology criteria for a Level A recommendation for blepharospasm.Trial registration ClinicalTrials.gov identifier, NCT01896895.

Principles of Medical and Surgical Treatment of Cerebral Palsy

Cerebral palsy is the most common cause of childhood motor disability, affecting 2 to 3/1000 children worldwide. Clinical abnormalities in tone, posture, and movement are the result of brain dysgenesis or injury early in life, and impairment varies in type, distribution, and in severity. The underlying brain disorder may also lead to other associated neurologic and systemic impairments. Variability in functional impairments, which can change during development, necessitates an individualized treatment plan. Treatment options are primarily symptomatic and directed toward optimizing independence, function, and/or ease of care-while limiting side effects. New promising disease-preventing and modifying treatments are emerging.

Exposure to the neurotoxin 3-nitropropionic acid in neuronal cells induces unique histone acetylation pattern: Implications for neurodegeneration

Mitochondrial dysfunction is critical for neurodegeneration in movement disorders. Neurotoxicological models recapitulating movement disorder involve mitochondrial damage including inhibition of mitochondrial complexes. Previously, we demonstrated that neurotoxic models of Parkinson's disease and Manganism showed distinct morphological, electrophysiological and molecular profile indicating disease-specific characteristics. In a recent study, we demonstrated that the transcriptomic changes triggered by the neurotoxic mitochondrial complex II inhibitor 3-nitropropionic acid (3-NPA), was significantly different from the profile induced by the neurotoxic mitochondrial complex I inhibitor 1-methyl-4- phenylpyridinium (MPP⁺) and mitochondrial toxin Manganese (Mn). Among the plausible pathways, we surmised that epigenetic mechanisms could contribute to 3-NPA specific transcriptomic profile. To address this, we assessed global and individual lys-specific acetylation profile of Histone H3 and H4 in the 3-NPA neuronal cell model. Our data revealed histone acetylation profile unique to the 3-NPA model that was not noted in the MPP⁺ and Mn models. Among the individual lys, Histone H3K56 showed robust dose and time-dependent hyperacetylation in the 3-NPA model. Chromatin Immunoprecipitation-sequencing (ChIP-seq) revealed that acetylated H3K56 was associated with 13072 chromatin sites, which showed increased occupancy in the transcription start site-promoter site. Acetylated histone H3K56 was associated with 1747 up-regulated and 263 down-regulated genes in the 3-NPA model, which included many up-regulated autophagy and mitophagy genes. Western analysis validated the involvement of PINK1-Parkin dependent mitophagy in the 3-NPA model. We propose that 3-NPA specific chromatin dynamics could contribute to the unique transcriptomic profile with implications for movement disorders.

Structural brain correlates of dementia in Huntington's disease

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Dementia may occur in the early stages of HD and with independence of disease burden.

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More severe posterior-cortical atrophy is associated with dementia in HD.

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Neuropsychological alterations of dementia in HD extends beyond executive dysfunction.

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CAG-independent neuropathological mechanisms may contribute to dementia in HD.

Background

Huntington’s disease (HD) is a fatal genetic neurodegenerative disorder with no effective treatment currently available. Progressive basal ganglia and whole-brain atrophy and concurrent cognitive deterioration are prototypical aspects of HD. However, the specific patterns of brain atrophy underlying cognitive impairment of different severity in HD are poorly understood. The aim of this study was to investigate the specific structural brain correlates of major cognitive deficits in HD and to explore its association with neuropsychological indicators.

Participants

Thirty-five symptomatic early-to-mild HD patients and 15 healthy controls (HC) with available T1-MRI imaging were included in this study.

Methods

In this cross-sectional study, HD patients were classified as patients with (HD-Dem) and without (HD-ND) major cognitive impairment in the range of dementia. This classification was based on previously validated PD-CRS cutoff scores for HD. Differences in brain atrophy across groups were studied by means of grey-matter volume voxel-based morphometry (GMV-VBM) and cortical thickness (Cth). Voxelwise and vertexwise general linear models were used to assess the group comparisons, controlling for the effects of age, sex, education, CAG repeat length and severity of motor symptoms. Clusters surviving p < 0.05 and family-wise error (FWE) correction were considered statistically significant. In order to characterize the impact on cognitive performance of the observed brain differences across groups, GMV and Cth values in the set of significant regions were computed and correlated with specific neuropsychological tests.

Results

All groups had similar sociodemographic profiles, and the HD groups did not significantly differ in terms of CAG repeat length. Compared to HC, both HD groups exhibited significant atrophy in multiple subcortical and parietal brain regions. However, compared to HC and HD-ND groups, HD-Dem patients showed a more prominent pattern of reduced GMV and cortical thinning. Importantly, this thinning was restricted to regions of the parietal-temporal and occipital cortices. Furthermore, these brain alterations were further associated with poorer cognitive performance in tasks assessing frontal-executive and attention domains as well as memory, language and constructional abilities.

Conclusions

Major cognitive impairment in the range of dementia in HD is associated with brain and cognitive alterations exceeding the prototypical frontal-executive deficits commonly recognized in HD. The observed posterior-cortical damage identified by MRI and its association with memory, language, and visuoconstructive dysfunction suggest a strong involvement of extra-striatal atrophy in the onset of severe cognitive dysfunction in HD patients. Critically, major cognitive impairment in this sample was not associated with CAG repeat length, age or education. This finding could support a possible involvement of additional neuropathological mechanisms aggravating cognitive deterioration in HD.

Coronaviruses: a challenge of today and a call for extended human postmortem brain analyses

While there is abounding literature on virus-induced pathology in general and coronavirus in particular, recent evidence accumulates showing distinct and deleterious brain affection. As the respiratory tract connects to the brain without protection of the blood-brain barrier, SARS-CoV-2 might in the early invasive phase attack the cardiorespiratory centres located in the medulla/pons areas, giving rise to disturbances of respiration and cardiac problems. Furthermore, brainstem regions are at risk to lose their functional integrity. Therefore, long-term neurological as well as psychiatric symptomatology and eventual respective disorders cannot be excluded as evidenced from influenza-A triggered post-encephalitic Parkinsonism and HIV-1 triggered AIDS-dementia complex. From the available evidences for coronavirus-induced brain pathology, this review concludes a number of unmet needs for further research strategies like human postmortem brain analyses. SARS-CoV-2 mirroring experimental animal brain studies, characterization of time-dependent and region-dependent spreading behaviours of coronaviruses, enlightening of pathological mechanisms after coronavirus infection using long-term animal models and clinical observations of patients having had COVID-19 infection are calling to develop both protective strategies and drug discoveries to avoid early and late coronavirus-induced functional brain disturbances, symptoms and eventually disorders. To fight SARS-CoV-2, it is an urgent need to enforce clinical, molecular biological, neurochemical and genetic research including brain-related studies on a worldwide harmonized basis.

Long-term clinical outcome of 6-pyruvoyl-tetrahydropterin synthase-deficient patients

INTRODUCTION

6-Pyruvoyl-tetrahydropterin synthase deficiency (PTPSd) is a rare autosomal recessive disorder of synthesis of biogenic amines, which is characterized by variable neurological impairment and hyperphenylalaninemia. We aimed to assess the long-term clinical outcome of this disorder and the factors affecting it.

METHODS

At total of 28 PTPSd patients (aged 19.9 ± 10.9 years) underwent clinical (neurological and psychiatric) and neuropsychological assessment (BRIEF, VABS-II, and IQ). Based on CSF homovanillic (HVA) and 5-hydroxyindolacetic acid (5-HIAA) and pterin concentrations at diagnosis, patients were classified as having either a severe [SF; low level of CSF, HVA, and 5-HIAA with altered neopterin/biopterin (Neo/Bio)] or mild form (MF; normal HVA and 5-HIAA with altered Neo/Bio) of PTPSd.

RESULTS

Approximately 36% of patients had MF PTPSd. At the last examination, 43% of patients had movement disorders (2 MF, 10 SF), 43% of patients had variable degrees of intellectual disability (SF only), 39% met the criteria for a psychiatric disorder (3 MF, 9 SF). Applying a linear regression model, we found that HVA and phenylalanine levels at birth had a significant influence on IQ, BRIEF, and VABS-II variability. Lastly, 5-HIAA further contributed to VABS-II variability. The disease showed a self-limiting clinical course and its treatment, although delayed, is effective in improving the neurological status.

CONCLUSIONS

Neurodevelopmental impairment due to PTPSd shows a self-limiting course. A continuous improvement in the neurological condition has been observed in patients receiving treatment, even when delayed. The severity of brain biogenic amine depletion at diagnosis predicts neurological and psychiatric outcomes.

Distinct perceptive pathways selected with tonic and bursting patterns of thalamic stimulation

BACKGROUND

Novel patterns of electrical stimulation of the brain and spinal cord hold tremendous promise to improve neuromodulation therapies for diverse disorders, including tremor and pain. To date, there are limited numbers of experimental studies in human subjects to help explain how stimulation patterns impact the clinical response, especially with deep brain stimulation. We propose using novel stimulation patterns during electrical stimulation of somatosensory thalamus in awake deep brain stimulation surgeries and hypothesize that stimulation patterns will influence the sensory percept without moving the electrode.

METHODS

In this study of 15 fully awake patients, the threshold of perception as well as perceptual characteristics were compared for tonic (trains of regularly-repeated pulses) and bursting stimulation patterns.

RESULTS

In a majority of subjects, tonic and burst percepts were located in separate, non-overlapping body regions (i.e., face vs. hand) without moving the stimulating electrode (p < 0.001; binomial test). The qualitative features of burst percepts also differed from those of tonic-evoked percepts as burst patterns were less likely to evoke percepts described as tingling (p = 0.013; Fisher's exact test).

CONCLUSIONS

Because somatosensory thalamus is somatotopically organized, percept location can be related to anatomic thalamocortical pathways. Thus, stimulation pattern may provide a mechanism to select for different thalamocortical pathways. This added control could lead to improvements in neuromodulation - such as improved efficacy and side effect attenuation - and may also improve localization for sensory prostheses.

Movement disorder and sensorimotor abnormalities in schizophrenia and other psychoses - European consensus on assessment and perspectives

Over the last three decades, movement disorder as well as sensorimotor and psychomotor functioning in schizophrenia (SZ) and other psychoses has gained greater scientific and clinical relevance as an intrinsic component of the disease process of psychotic illness; this extends to early psychosis prediction, early detection of motor side effects of antipsychotic medication, clinical outcome monitoring, treatment of psychomotor syndromes (e.g. catatonia), and identification of new targets for non-invasive brain stimulation. In 2017, a systematic cooperation between working groups interested in movement disorder and sensorimotor/psychomotor functioning in psychoses was initiated across European universities. As a first step, the members of this group would like to introduce and define the theoretical aspects of the sensorimotor domain in SZ and other psychoses. This consensus paper is based on a synthesis of scientific evidence, good clinical practice and expert opinions that were discussed during recent conferences hosted by national and international psychiatric associations. While reviewing and discussing the recent theoretical and experimental work on neural mechanisms and clinical implications of sensorimotor behavior, we here seek to define the key principles and elements of research on movement disorder and sensorimotor/psychomotor functioning in psychotic illness. Finally, the members of this European group anticipate that this consensus paper will stimulate further multimodal and prospective studies on hypo- and hyperkinetic movement disorders and sensorimotor/psychomotor functioning in SZ and other psychotic disorders.

Movement disorders in ADAR1 disease: Insights from a comprehensive cohort

ADAR1 variants are associated to rare and heterogenous neurological conditions, including Aicardi-Goutières syndrome type 6, bilateral striatal necrosis, and dyschromatosis symmetrica hereditaria. Movement disorders (MDs) commonly occur in ADAR1-related diseases although a complete overview on the phenomenology has not been provided yet. Here, a cohort of 57 patients with ADAR1-related diseases, including 3 unpublished patients and 54 previously reported cases, was reviewed. Data on demographics, clinical features of MDs, genetics and biomarkers were collected and descriptive statistics, group analysis for genotype and logistic regression were run. Manifestations of MD characterized the onset of ADAR1-related disease in 60% of patients. Specifically, dystonia occurred in 39% of cases, even as severe status dystonicus, while prevalence of other MDs was lower. Patients often presented brain lesions (>90%) and progressive disease course (43%), fatal in some cases. Clinical presentation and outcome differed among patients with distinct genotype. This review shows that phenomenology of MDs in ADAR1-related diseases is wide and heterogeneous, although a severe motor syndrome (often characterized by dystonia) secondary to brain lesions represents the most common manifestation. Waiting for future development of disease-modifying treatments, an appropriate symptomatic intervention is crucial for ADAR1 patients. Accordingly, a deeper knowledge of phenomenology is fundamental.

Case report of hyperacute edema and cavitation following deep brain stimulation lead implantation

Background:

Postoperative cerebral edema around a deep brain stimulation (DBS) electrode is an uncommonly reported complication of DBS surgery. The etiology of this remains unknown, and the presentation is highly variable; however, the patients generally report a good outcome.

Case Description:

Here, we report an unusual presentation of postoperative edema in a 66-year-old female who has bilateral dentatorubrothalamic tract (specifically, the ventral intermediate nucleus) DBS for a mixed type tremor disorder. Initial postoperative computed tomography (CT) was unremarkable and the patient was admitted for observation. She declined later on postoperative day (POD) 1 and became lethargic. Stat head CT scan performed revealed marked left-sided peri-lead edema extending into the centrum semiovale with cystic cavitation, and trace right-sided edema. On POD 2, the patient was alert, but with global aphasia, right-sided neglect, and a plegic right upper extremity. Corticosteroids were started and a complete infectious workup was unremarkable. She was intubated and ultimately required a tracheostomy and percutaneous gastrostomy tube. She returned to the clinic 3 months postoperatively completely recovered and ready for battery implantation.

Conclusion:

While this is an unusual presentation of cerebral edema following DBS placement, ultimately, the outcome was good similar to other reported cases. Supportive care and corticosteroids remain the treatment of choice for this phenomenon.

Striatal and nigral muscarinic type 1 and type 4 receptors modulate levodopa-induced dyskinesia and striato-nigral pathway activation in 6-hydroxydopamine hemilesioned rats

Acetylcholine muscarinic receptors (mAChRs) contribute to both the facilitation and inhibition of levodopa-induced dyskinesia operated by striatal cholinergic interneurons, although the receptor subtypes involved remain elusive. Cholinergic afferents from the midbrain also innervate the substantia nigra reticulata, although the role of nigral mAChRs in levodopa-induced dyskinesia is unknown. Here, we investigate whether striatal and nigral M1 and/or M4 mAChRs modulate dyskinesia and the underlying striato-nigral GABAergic pathway activation in 6-hydroxydopamine hemilesioned rats. Reverse microdialysis allowed to deliver the mAChR antagonists telenzepine (M1 subtype preferring), PD-102807 and tropicamide (M4 subtype preferring), as well as the selective M4 mAChR positive allosteric modulator VU0152100 in striatum or substantia nigra, while levodopa was administered systemically. Dyskinetic movements were monitored along with nigral GABA (and glutamate) and striatal glutamate dialysate levels, taken as neurochemical correlates of striato-nigral pathway and cortico-basal ganglia-thalamo-cortical loop activation. We observed that intrastriatal telenzepine, PD-102807 and tropicamide alleviated dyskinesia and inhibited nigral GABA and striatal glutamate release. This was partially replicated by intrastriatal VU0152100. The M2 subtype preferring antagonist AFDX-116, used to elevate striatal acetylcholine levels, blocked the behavioral and neurochemical effects of PD-102807. Intranigral VU0152100 prevented levodopa-induced dyskinesia and its neurochemical correlates whereas PD-102807 was ineffective. These results suggest that striatal, likely postsynaptic, M1 mAChRs facilitate dyskinesia and striato-nigral pathway activation in vivo. Conversely, striatal M4 mAChRs can both facilitate and inhibit dyskinesia, possibly depending on their localization. Potentiation of striatal and nigral M4 mAChR transmission leads to powerful multilevel inhibition of striato-nigral pathway and attenuation of dyskinesia.

Parkin Pleiotropy: Extremely Atypical Phenotypes in Patients With Compound Heterozygous Mutations

Background:

Parkin mutations are suspected in early-onset Parkinson’s disease with early motor complications, and in pedigrees showing an autosomal recessive pattern. Some compound heterozygous mutations can present with various uncommon phenotypes.

Case Report:

Two siblings with the same mutations, one with atypical postural and action tremor, and the other with an axonal motor autonomic neuropathy. A woman with a 45-year history of slowly progressive parkinsonism with no motor complications.

Discussion:

Due to the variability of phenotypes of Parkin mutations, testing should also be warranted in patients with atypical tremor syndromes or axonal polyneuropathy when more common causes have been ruled out.

Highlights:

We report three patients with extremely atypical parkin mutation phenotypes: an atypical tremor syndrome, an axonal motor autonomic neuropathy, and a remarkably slowly progressive parkinsonism. This shows that parkin mutations may present with a highly variable phenotype, and should be considered in patients with such manifestations.

Multiple system atrophy pathology is associated with primary Sjögren's syndrome

BACKGROUND

Our objective was to investigate whether primary Sjögren’s syndrome (pSS) is associated with multiple system atrophy (MSA).

METHODS

We performed a retrospective cohort study assessing (a) rates of MSA in a cohort of patients with pSS and (b) rates of pSS in a cohort of patients with MSA. These data were compared with rates in respective control groups. We additionally reviewed the neuropathologic findings in 2 patients with pSS, cerebellar degeneration, parkinsonism, and autonomic dysfunction.

RESULTS

Our cohort of 308 patients with pSS had a greater incidence of MSA compared with 4 large population-based studies and had a significantly higher prevalence of at least probable MSA (1% vs. 0%, P = 0.02) compared with 776 patients in a control cohort of patients with other autoimmune disorders. Our cohort of 26 autopsy-proven patients with MSA had a significantly higher prevalence of pSS compared with a cohort of 115 patients with other autopsy-proven neurodegenerative disorders (8% vs. 0%, P = 0.03). The 2 patients we described with pSS and progressive neurodegenerative disease showed classic MSA pathology at autopsy.

CONCLUSION

Our findings provide evidence for an association between MSA and pSS that is specific to both pSS, among autoimmune disorders, and MSA, among neurodegenerative disorders. The 2 cases we describe of autopsy-proven MSA support that MSA pathology can explain neurologic disease in a subset of patients with pSS. These findings together support the hypothesis that systemic autoimmune disease plays a role in neurodegeneration.

FUNDING

The Michigan Brain Bank is supported in part through NIH grant P30AG053760.

This single-center retrospective cohort study shows an association between primary Sjogren’s syndrome and multiple system atrophy pathology.

Long-term Safety and Dosing of OnabotulinumtoxinA: A Prospective, Observational Study

BACKGROUND

Although therapeutic treatments are intended to help alleviate symptoms associated with disease, safety must be carefully considered and monitored to confirm continued positive benefit/risk balance. The objective of MOBILITY was to study the long-term safety of onabotulinumtoxinA for treatment of various therapeutic indications.

METHODS

A prospective, multicenter, observational, Phase IV Canadian study in patients treated with onabotulinumtoxinA for a therapeutic indication. Dosing was determined by the participating physician. Adverse events (AEs) were recorded throughout the study.

RESULTS

Patients (n = 1372) with adult focal spasticity, blepharospasm, cerebral palsy, cervical dystonia, hemifacial spasm, hyperhidrosis, or "other" diagnoses were enrolled into the safety cohort. Eighty-three patients (6%) reported 209 AEs; 44 AEs in 24 patients (2%) were considered treatment-related AEs. Seventy-two serious AEs were reported by 38 patients (3%); 10 serious AEs in 5 patients (0.4%) were considered treatment related. Most commonly reported treatment-related AEs were muscular weakness (n = 7/44) and dysphagia (n = 6/44).

CONCLUSIONS

In patients with follow-up for up to six treatments with onabotulinumtoxinA, treatment-related AEs were reported in <2% of the safety population over the course of nearly 5 years. Our findings from MOBILITY provide further evidence that onabotulinumtoxinA treatment is safe for long-term use across a variety of therapeutic indications.

Subthalamic stimulation for cervical dystonia

The globus pallidus internus (GPi) has been the primary target for deep brain stimulation (DBS) to treat severe medication-refractory dystonia. Some patients with primary cervical dystonia do not respond adequately to GPi stimulation. Subthalamic nucleus (STN) DBS may provide an alternative choice for treating this dystonia. In this study, we analysed the effect of bilateral STN DBS on two patients of medically refractory primary cervical dystonia. The severity of the dystonia was measured using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) preoperatively, and 1, 3, 6 and 12 months postoperatively and yearly follow-up was performed. Any change in mental status was recorded using the Mini-Mental State Examination (MMSE) score. Surgery was performed using the Leksell stereotactic system and by fusing CT scan and MR images with neuronavigation and microelectrode recording. Both patients were followed for more than 3 years. STN DBS was well-tolerated by both patients with no adverse effects. The benefit seems to be immediate. The first patient showed 74% improvement, and the second patient showed 84.3% improvement in the overall TWSTRS score. No mental deterioration was observed in either of the cases, as the MMSE score remained unchanged in both patients. A prior bilateral pallidal lesion in the first case did not adversely affect the outcome. This study showed that bilateral STN DBS results in a very significant improvement in cervical dystonia with no mental worsening and suggests that STN DBS may be an alternative to GPi DBS for treating primary cervical dystonia.

Isolated and combined genetic tremor syndromes: a critical appraisal based on the 2018 MDS criteria

The 2018 consensus statement on the classification of tremors proposes a two-axis categorization scheme based on clinical features and etiology. It also defines "isolated" and "combined" tremor syndromes depending on whether tremor is the sole clinical manifestation or is associated with other neurological or systemic signs. This syndromic approach provides a guide to investigate the underlying etiology of tremors, either genetic or acquired. Several genetic defects have been proven to cause tremor disorders, including autosomal dominant and recessive, X-linked, and mitochondrial diseases, as well as chromosomal abnormalities. Furthermore, some tremor syndromes are recognized in individuals with a positive family history, but their genetic confirmation is pending. Although most genetic tremor disorders show a combined clinical picture, there are some distinctive conditions in which tremor may precede the appearance of other neurological signs by years or remain the prominent manifestation throughout the disease course, previously leading to misdiagnosis as essential tremor (ET). Advances in the knowledge of genetically determined tremors may have been hampered by the inclusion of heterogeneous entities in previous studies on ET. The recent classification of tremors therefore aims to provide more consistent clinical data for deconstructing the genetic basis of tremor syndromes in the next-generation and long-read sequencing era. This review outlines the wide spectrum of tremor disorders with defined or presumed genetic etiology, both isolated and combined, unraveling diagnostic clues of these conditions and focusing mainly on ET-like phenotypes. Furthermore, we suggest a phenotype-to-genotype algorithm to support clinicians in identifying tremor syndromes and guiding genetic investigations.

Understanding motor control in health and disease: classic single (n = 1) observations

The field of neuroscience is increasingly dominated by a preferred use of big data, where analysis of large numbers has become an essential area of development. We here draw attention to the importance of smaller numbers, and more specifically, to the historical and continued importance of detailed and judiciously performed studies in single healthy volunteers or single patients with a unique clinical presentation, as an important approach to study normal functions of the nervous system, and to understand the pathophysiology underlying neurological movement disorders. We illustrate this by discussing several historical examples and by summarising Professor John Rothwell's impressive body of work in single-patient studies, highlighting some of his seminal n = 1 studies that have had a great impact on the field. In doing so, we hope to provide a powerful incentive for the next generation of neuroscientists to keep appreciating the value of detailed analyses of single observations.

De novo nose-pinching stereotypy with somnolence: Clues to autoimmune encephalitis

Autoimmune encephalitis (AE) is being increasingly recognized as a cause of new-onset movement disorders. Movement disorders in AE are diverse and range from hyperkinetic conditions such as oromandibular dyskinesias, tremors and chorea to hypokinetic ones such as bradykinesia and parkinsonism. Stereotypies have been described in association with anti-NMDAR encephalitis. Similarly, sleep dysfunction is an underrecognized feature in many AE subtypes, prominently anti-IgLON5 although the correlation of phenotype of sleep dysfunction with a particular antibody subtype in AE is unclear. Despite the recognition of both these features as part of an overreaching spectrum in any patient with AE, seldom are they the sole presenting manifestations. Additionally, the challenge is further compounded in a patient who has seronegative AE since neither sleep disturbances nor stereotypies have been well characterized with this condition yet, and the diagnosis is conditional to exhausting a list of ancillary supportive features. In this brief communication, we describe the case of a young man who presented with hypersomnolence and an unusual focal nose-pinching stereotypy of subacute onset who lacked the presence of other typical clinical characteristics such as cognitive/memory impairment and seizures and had negative autoimmune antibodies but responded to immune therapy dramatically. We propose that the presence of de novo hypersomnolence and stereotypy should inform a potential diagnosis of AE.

Striatal and cortical metabotropic glutamate 5 receptor expression and behavioral effects of the positive allosteric modulator CDPPB in a model of DYT1 dystonia

The metabotropic glutamate 5 (mGlu₅) receptor is critically involved in corticostriatal plasticity which is disturbed in various animal models of dystonia. Recently, the positive allosteric modulator 3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl)benzamide (CDPPB) exerted prodyskinetic effects in a phenotypic model of episodic dystonia. In the DYT1 knock-in (KI) mouse, a model for a persistent type of dystonia, previous ex vivo electrophysiological experiments indicated that mGlu₅ receptors are involved in abnormal striatal plasticity. Therefore, in the present study we examined the mGlu₅ receptor expression in the striatum and cortex of DYT1 KI mice in comparison with wildtype littermates. By immunohistochemistry (IHC) we found a lower expression of mGlu₅ receptors in the cortex (16%) and ventral striatum (10%) but not in the whole striatum of DYT1 KI mice, while mRNA levels were merely lower in the striatum of DYT1 KI mice (43%). However, mGlu₅ receptor protein levels measured by western blotting showed no significant differences in tissue of the whole striatum and in the cortex between both genotypes. Since DYT1 KI mice do not exhibit dystonic symptoms, we investigated if CDPPB provokes dystonia or dyskinesia. CDPPB (10, 20 and 30 mg/kg intraperitoneal, i.p.) did not induce abnormal movements and the locomotor activity did not differ between DYT1 KI and wildtype mice. The present data do not provide evidence for a crucial role of the mGlu₅ receptor in the pathophysiology of DYT1 dystonia, but corticostriatal changes are in line with the hypothesis of maladaptive plasticity in dystonia.