Objective clinical registration of tremor, bradykinesia, and rigidity during awake stereotactic neurosurgery: a scoping review.

Tremor, bradykinesia, and rigidity are incapacitating motor symptoms that can be suppressed with stereotactic neurosurgical treatment like deep brain stimulation (DBS) and ablative surgery (e.g., thalamotomy, pallidotomy). Traditionally, clinicians rely on clinical rating scales for intraoperative evaluation of these motor symptoms during awake stereotactic neurosurgery. However, these clinical scales have a relatively high inter-rater variability and rely on experienced raters. Therefore, objective registration (e.g., using movement sensors) is a reasonable extension for intraoperative assessment of tremor, bradykinesia, and rigidity. The main goal of this scoping review is to provide an overview of electronic motor measurements during awake stereotactic neurosurgery. The protocol was based on the PRISMA extension for scoping reviews. After a systematic database search (PubMed, Embase, and Web of Science), articles were screened for relevance. Hundred-and-three articles were subject to detailed screening. Key clinical and technical information was extracted. The inclusion criteria encompassed use of electronic motor measurements during stereotactic neurosurgery performed under local anesthesia. Twenty-three articles were included. These studies had various objectives, including correlating sensor-based outcome measures to clinical scores, identifying optimal DBS electrode positions, and translating clinical assessments to objective assessments. The studies were highly heterogeneous in device choice, sensor location, measurement protocol, design, outcome measures, and data analysis. This review shows that intraoperative quantification of motor symptoms is still limited by variable signal analysis techniques and lacking standardized measurement protocols. However, electronic motor measurements can complement visual evaluations and provide objective confirmation of correct placement of the DBS electrode and/or lesioning. On the long term, this might benefit patient outcomes and provide reliable outcome measures in scientific research.

Deep brain stimulation in dystonia: The added value of neuropsychological assessments.

Deep brain stimulation (DBS) of the internal globus pallidus (GPi) is a recognized treatment for medication-refractory dystonia. Problems in executive functions and social cognition can be part of dystonia phenotypes. The impact of pallidal DBS on cognition appears limited, but not all cognitive domains have been investigated yet. In the present study, we compare cognition before and after GPi DBS. Seventeen patients with dystonia of various aetiology completed pre- and post-DBS assessment (mean age 51 years; range 20-70 years). Neuropsychological assessment covered intelligence, verbal memory, attention and processing speed, executive functioning, social cognition, language and a depression questionnaire. Pre-DBS scores were compared with a healthy control group matched for age, gender and education, or with normative data. Patients were of average intelligence but performed significantly poorer than healthy peers on tests for planning and for information processing speed. Otherwise, they were cognitively unimpaired, including social cognition. DBS did not change the baseline neuropsychological scores. We confirmed previous reports of executive dysfunctions in adult dystonia patients with no significant influence of DBS on cognitive functioning in these patients. Pre-DBS neuropsychological assessments appear useful as they support clinicians in counselling their patients. Decisions about post-DBS neuropsychological evaluations should be made on a case-by-case basis.

New developments in diagnostics and treatment of adult-onset focal dystonia.

PURPOSE OF REVIEW: The aim of this review is to showcase the recent developments in the field of diagnosis and treatment of adult-onset focal dystonia. RECENT FINDINGS: Accurate phenotyping of focal dystonia is essential in the process of finding an underlying cause, including acquired, genetic, and idiopathic causes. Motor symptoms as well as the associated nonmotor symptoms and their detrimental impact on quality of life have received increased interest over the last years. The diagnostic process is complicated by the steadily increasing numbers of newly discovered genes associated with dystonia. Recent efforts have been aimed at further developing recommendations and algorithms to aid in diagnosis and in navigating the use of diagnostic tools. In terms of treatment, research on DBS is advancing towards a better understanding of the most effective stimulation locations within the globus pallidus. Moreover, with the introduction of the LFP-recording devices, the search continues for an accurate electrophysiological biomarker for dystonia. SUMMARY: Accurate phenotyping and (sub)classification of patients with dystonia is important for improving diagnosis, subsequent treatment effect and population-based study outcomes in research. Medical practitioners should be attentive to the presence of nonmotor symptoms in dystonia.

A Screening Tool to Quickly Identify Movement Disorders in Patients with Inborn Errors of Metabolism.

BACKGROUND: Movement disorders are frequent in patients with inborn errors of metabolism (IEMs) but poorly recognized, particularly by nonmovement disorder specialists. We propose an easy-to-use clinical screening tool to help recognize movement disorders. OBJECTIVE: The aim is to develop a user-friendly rapid screening tool for nonmovement disorder specialists to detect moderate and severe movement disorders in patients aged ≥4 years with IEMs. METHODS: Videos of 55 patients with different IEMs were scored by experienced movement disorder specialists (n = 12). Inter-rater agreements were determined on the presence and subtype of the movement disorder. Based on ranking and consensus, items were chosen to be incorporated into the screening tool. RESULTS: A movement disorder was rated as present in 80% of the patients, with a moderate inter-rater agreement (κ =0.420, P < 0.001) on the presence of a movement disorder. When considering only moderate and severe movement disorders, the inter-rater agreement increased to almost perfect (κ = 0.900, P < 0.001). Dystonia was most frequently scored (27.3%) as the dominant phenotype. Treatment was mainly suggested for patients with moderate or severe movement disorders. Walking, observations of the arms, and drawing a spiral were found to be the most informative tasks and were included in the screening tool. CONCLUSIONS: We designed a screening tool to recognize movement disorders in patients with IEMs. We propose that this screening tool can contribute to select patients who should be referred to a movement disorder specialist for further evaluation and, if necessary, treatment of the movement disorder. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Dystonia management across Europe within ERN-RND: current state and future challenges.

BACKGROUND: Since the first European-wide evaluation of dystonia management in 2016, several efforts have been made to improve dystonia-care. One of these was the development of the Dystonia Disease Group as a part of the European Reference Network for Rare Neurological Diseases (ERN-RND) that implemented several initiatives based on the recommendations made in 2016. AIM: To evaluate the current state of dystonia management across Europe. METHODS: Twenty-four countries were surveyed via 62 dystonia-experts from 44 ERN-RND-related centers. RESULTS: Dystonia-experts for adult patients were available in all surveyed countries. However, almost half of the countries evaluated accessibility as merely 'satisfactory'. Access to genetic and neurophysiological testing was challenging to varying degrees in over half of countries. Main oral medications and botulinum toxin were available in all countries. Deep brain stimulation (DBS) was easily accessible in one-third of the countries. Dystonia research was conducted in 20/24 countries. Trainings on dystonia for general practitioners (GPs) were available in 11/24 countries. However, lack of trainings for other professionals was almost general. For pediatric dystonia, experts and specific training were available in over half of the countries. CONCLUSIONS: In this overview, we present the current state of dystonia management within ERN-RND. Management has slightly improved since 2016 in several fields, including diagnostics, availability of DBS, and research. The results highlight that future challenges in dystonia management are accessibility of experts, and diagnostic tools and treatments, education on adult and childhood dystonia, and optimization of referral pathways. These findings are important for improving dystonia care across Europe.

A novel diagnostic approach for patients with adult-onset dystonia.

Adult-onset dystonia can be acquired, inherited or idiopathic. The dystonia is usually focal or segmental and for a limited number of cases causal treatment is available. In recent years, rapid developments in neuroimmunology have led to increased knowledge on autoantibody-related dystonias. At the same time, genetic diagnostics in sequencing technology have evolved and revealed several new genes associated with adult-onset dystonia. Furthermore, new phenotype-genotype correlations have been elucidated. Consequently, clinicians face the dilemma of which additional investigations should be performed and whether to perform genetic testing or not. To ensure early diagnosis and to prevent unnecessary investigations, integration of new diagnostic strategies is needed.We designed a new five-step diagnostic approach for adult-onset dystonia. The first four steps are based on a broad literature search and expert opinion, the fifth step, on when to perform genetic testing, is based on a detailed systematic literature review up to 1 December 2021.The basic principle of the algorithm is that genetic testing is unlikely to lead to changes in management in three groups: (1) patients with an acquired form of adult-onset dystonia; (2) patients with neurodegenerative disorders, presenting with a combined movement disorder including dystonic symptoms and (3) patients with adult-onset isolated focal or segmental dystonia. Throughout the approach, focus lies on early identification of treatable forms of dystonia, either acquired or genetic.This novel diagnostic approach for adult-onset dystonia can help clinicians to decide when to perform additional tests, including genetic testing and facilitates early aetiological diagnosis, to enable timely treatment.

[Dystonia in cerebral palsy; what are the treatment options?] / Dystonie bij cerebrale parese.

Cerebral palsy (CP) is the most common cause of motor disability in children. The largest group of children with CP present with spasticity. Dystonia is estimated to be present in approximately 15% of children with CP, referred to as dyskinetic CP. Still, dystonia in CP remains underdiagnosed. Dystonia and spasticity can occur together in a subgroup of children with CP as well. Dystonia is characterized by fluctuating hypertonia and involuntary movement and postures. Dystonia in children with CP can interfere with motor function, caregiving and comfort. It is important to recognize dystonia in children with CP as specific treatment is indicated. In this paper we describe three cases of children with dystonia in CP and we review the pharmacological treatment options for dystonia in CP and the surgical options including intrathecal baclofen pump and deep brain stimulation.

Are we on the right track in DBS surgery for dystonic head tremor? Polymyography is a promising answer.

The clinical benefit of Deep Brain Stimulation (DBS) is associated with electrode positioning accuracy. Intraoperative assessment of clinical effect is therefore key. Evaluating this clinical effect in patients with dystonic head tremor, as opposed to limb tremor, is challenging because the head is fixed in a stereotactic frame. To clinically assess head tremor during surgery, surface electromyography (EMG) electrodes were bilaterally applied to the sternocleidomastoid and cervical paraspinal muscles. This case shows that intraoperative polymyography is an easy and useful tool to assess the clinical effect of DBS electrode positioning.

Bilateral Pallidotomy for Dystonia: A Systematic Review.

Stereotactic lesioning of the bilateral globus pallidus (GPi) was one of the first surgical treatments for medication-refractory dystonia but has largely been abandoned in clinical practice after the introduction of deep brain stimulation (DBS). However, some patients with dystonia are not eligible for DBS. Therefore, we reviewed the efficacy, safety, and sustainability of bilateral pallidotomy by conducting a systematic review of individual patient data (IPD). Guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and IPD were followed. In May 2020, Medline, Embase, Web of Science, and Cochrane Library were searched for studies reporting on outcome of bilateral pallidotomy for dystonia. If available, IPD were collected. In this systematic review, 100 patients from 33 articles were evaluated. Adverse events were reported in 20 patients (20%), of which 8 were permanent (8%). Pre-and postoperative Burke-Fahn-Marsden Dystonia Rating Movement Scale scores were available for 53 patients. A clinically relevant improvement (>20%) of this score was found in 42 of 53 patients (79%). Twenty-five patients with status dystonicus (SD) were described. In all but 2 the SD resolved after bilateral pallidotomy. Seven patients experienced a relapse of SD. Median-reported follow-up was 12 months (n = 83; range: 2-180 months). Based on the current literature, bilateral pallidotomy is an effective and relatively safe procedure for certain types of dystonia, particularly in medication-refractory SD. Although due to publication bias the underreporting of negative outcomes is very likely, bilateral pallidotomy is a reasonable alternative to DBS in selected dystonia patients. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Diagnostic approach to paediatric movement disorders: a clinical practice guide.

Paediatric movement disorders (PMDs) comprise a large group of disorders (tics, myoclonus, tremor, dystonia, chorea, Parkinsonism, ataxia), often with mixed phenotypes. Determination of the underlying aetiology can be difficult given the broad differential diagnosis and the complexity of the genotype-phenotype relationships. This can make the diagnostic process time-consuming and difficult. In this overview, we present a diagnostic approach for PMDs, with emphasis on genetic causes. This approach can serve as a framework to lead the clinician through the diagnostic process in eight consecutive steps, including recognition of the different movement disorders, identification of a clinical syndrome, consideration of acquired causes, genetic testing including next-generation sequencing, post-sequencing phenotyping, and interpretation of test results. The aim of this approach is to increase the recognition and diagnostic yield in PMDs. WHAT THIS PAPER ADDS: An up-to-date description and diagnostic framework for testing of paediatric movement disorders is presented. The framework helps to determine which patients will benefit from next-generation sequencing.

Loss-of-Function Variants in HOPS Complex Genes VPS16 and VPS41 Cause Early Onset Dystonia Associated with Lysosomal Abnormalities.

OBJECTIVES: The majority of people with suspected genetic dystonia remain undiagnosed after maximal investigation, implying that a number of causative genes have not yet been recognized. We aimed to investigate this paucity of diagnoses. METHODS: We undertook weighted burden analysis of whole-exome sequencing (WES) data from 138 individuals with unresolved generalized dystonia of suspected genetic etiology, followed by additional case-finding from international databases, first for the gene implicated by the burden analysis (VPS16), and then for other functionally related genes. Electron microscopy was performed on patient-derived cells. RESULTS: Analysis revealed a significant burden for VPS16 (Fisher's exact test p value, 6.9 × 109 ). VPS16 encodes a subunit of the homotypic fusion and vacuole protein sorting (HOPS) complex, which plays a key role in autophagosome-lysosome fusion. A total of 18 individuals harboring heterozygous loss-of-function VPS16 variants, and one with a microdeletion, were identified. These individuals experienced early onset progressive dystonia with predominant cervical, bulbar, orofacial, and upper limb involvement. Some patients had a more complex phenotype with additional neuropsychiatric and/or developmental comorbidities. We also identified biallelic loss-of-function variants in VPS41, another HOPS-complex encoding gene, in an individual with infantile-onset generalized dystonia. Electron microscopy of patient-derived lymphocytes and fibroblasts from both patients with VPS16 and VPS41 showed vacuolar abnormalities suggestive of impaired lysosomal function. INTERPRETATION: Our study strongly supports a role for HOPS complex dysfunction in the pathogenesis of dystonia, although variants in different subunits display different phenotypic and inheritance characteristics. ANN NEUROL 2020;88:867-877.

The Effectiveness of Deep Brain Stimulation in Dystonia: A Patient-Centered Approach.

Background: To systematically evaluate the effectiveness of deep brain stimulation of the globus pallidus internus (GPi-DBS) in dystonia on pre-operatively set functional priorities in daily living. Methods: Fifteen pediatric and adult dystonia patients (8 male; median age 32y, range 8-65) receiving GPi-DBS were recruited. All patients underwent a multidisciplinary evaluation before and 1-year post DBS implantation. The Canadian Occupational Performance Measure (COPM) first identified and then measured changes in functional priorities. The Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) was used to evaluate dystonia severity. Results: Priorities in daily functioning substantially varied between patients but showed significant improvements on performance and satisfaction after DBS. Clinically significant COPM-score improvements were present in 7/8 motor responders, but also in 4/7 motor non-responders. Discussion: The use of a patient-oriented approach to measure GPi-DBS effectiveness in dystonia provides an unique insight in patients' priorities and demonstrates that tangible improvements can be achieved irrespective of motor response. Highlights: Functional priorities in life of dystonia patients and their caregivers vary greatlyThe effect of DBS on functional priorities did not correlate with motor outcomeHalf of the motor 'non-responder' patients reported important changes in their prioritiesThe effect of DBS in dystonia should not be measured by motor outcome alone.

A detailed description of the phenotypic spectrum of North Sea Progressive Myoclonus Epilepsy in a large cohort of seventeen patients.

INTRODUCTION: In 2011, a homozygous mutation in GOSR2 (c.430G > T; p. Gly144Trp) was reported as a novel cause of Progressive Myoclonus Epilepsy (PME) with early-onset ataxia. Interestingly, the ancestors of patients originate from countries bound to the North Sea, hence the condition was termed North Sea PME (NSPME). Until now, only 20 patients have been reported in literature. Here, we provide a detailed description of clinical and neurophysiological data of seventeen patients. METHODS: We collected clinical and neurophysiological data from the medical records of seventeen NSPME patients (5-46 years). In addition, we conducted an interview focused on factors influencing myoclonus severity. RESULTS: The core clinical features of NSPME are early-onset ataxia, myoclonus and seizures, with additionally areflexia and scoliosis. Factors such as fever, illness, heat, emotions, stress, noise and light (flashes) all exacerbated myoclonic jerks. Epilepsy severity ranged from the absence of or incidental clinical seizures to frequent daily seizures and status epilepticus. Some patients made use of a wheelchair during their first decade, whereas others still walked independently during their third decade. Neurophysiological features suggesting neuromuscular involvement in NSPME were variable, with findings ranging from indicative of sensory neuronopathy and anterior horn cell involvement to an isolated absent H-reflex. CONCLUSION: Although the sequence of symptoms is rather homogeneous, the severity of symptoms and rate of progression varied considerably among individual patients. Common triggers for myoclonus can be identified and myoclonus is difficult to treat; to what extent neuromuscular involvement contributes to the phenotype remains to be further elucidated.

[Deep brain stimulation for movement disorders]. / Diepe hersenstimulatie voor bewegingsstoornissen.

Deep brain stimulation (DBS) is a treatment which uses high-frequency electric stimulation to suppress pathological brain activity. DBS has been applied for over 30 years now, particularly in patients with severe movement disorders, such as Parkinson's disease, dystonia and tremor. Although there is clearly scientific evidence for the effectiveness of DBS in these three movement disorders, the effect size of the treatment remains limited. Furthermore, DBS is not curative and can only be applied in a select subset of patients. In this article, we discuss the key indications and contraindications for DBS, and the outcomes achieved when it is applied in the aforementioned movement disorders. We discuss the most notable controversies and new developments in the field of deep brain stimulation, in order to offer referrers and fellow healthcare professionals an accessible introduction to this mode of therapy.

Toward adaptive deep brain stimulation for dystonia.

The presence of abnormal neural oscillations within the cortico-basal ganglia-thalamo-cortical (CBGTC) network has emerged as one of the current principal theories to explain the pathophysiology of movement disorders. In theory, these oscillations can be used as biomarkers and thereby serve as a feedback signal to control the delivery of deep brain stimulation (DBS). This new form of DBS, dependent on different characteristics of pathological oscillations, is called adaptive DBS (aDBS), and it has already been applied in patients with Parkinson's disease. In this review, the authors summarize the scientific research to date on pathological oscillations in dystonia and address potential biomarkers that might be used as a feedback signal for controlling aDBS in patients with dystonia.

Non-motor effects of deep brain stimulation in dystonia: A systematic review.

INTRODUCTION: Deep brain stimulation (DBS) has emerged as an effective treatment in medically intractable dystonia, with the globus pallidus internus (GPi) being most frequently targeted. Non-motor symptoms, including pain and psychiatric, cognitive and sleep disturbances, are increasingly recognized as important determinants of disease burden in dystonia patients. We reviewed non-motor outcomes of DBS in dystonia, focusing on GPi-DBS. METHODS: A systematic literature search of Pubmed and Embase was performed according to the PRISMA guidelines. RESULTS: Fifty-two studies were included. GPi-DBS reduced pain related to dystonia. No major effects on anxiety, mood, and cognition were found. In contrast to motor outcome, non-motor outcome seems more independent of the etiology of dystonia. However, the impact of potential confounders (e.g. patient factors, changes in pharmacological treatment) is unclear. CONCLUSION: Despite the growing interest in non-motor symptoms in dystonia, DBS studies still focus primarily on motor outcome. We recommend systematic evaluation of both non-motor and motor features before and after DBS interventions to improve quality of life and management of patients with dystonia.

Crossing barriers: a multidisciplinary approach to children and adults with young-onset movement disorders.

BACKGROUND: Diagnosis of less common young-onset movement disorders is often challenging, requiring a broad spectrum of skills of clinicians regarding phenotyping, normal and abnormal development and the wide range of possible acquired and genetic etiologies. This complexity often leads to considerable diagnostic delays, paralleled by uncertainty for patients and their families. Therefore, we hypothesized that these patients might benefit from a multidisciplinary approach. We report on the first 100 young-onset movement disorders patients who visited our multidisciplinary outpatient clinic. METHODS: Clinical data were obtained from the medical records of patients with disease-onset before age 18 years. We investigated whether the multidisciplinary team, consisting of a movement disorder specialist, pediatric neurologist, pediatrician for inborn errors of metabolism and clinical geneticist, revised the movement disorder classification, etiological diagnosis, and/or treatment. RESULTS: The 100 referred patients (56 males) had a mean age of 12.5 ± 6.3 years and mean disease duration of 9.2 ± 6.3 years. Movement disorder classification was revised in 58/100 patients. Particularly dystonia and myoclonus were recognized frequently and supported by neurophysiological testing in 24/29 patients. Etiological diagnoses were made in 24/71 (34%) formerly undiagnosed patients, predominantly in the genetic domain. Treatment strategy was adjusted in 60 patients, of whom 43 (72%) reported a subjective positive effect. CONCLUSIONS: This exploratory study demonstrates that a dedicated tertiary multidisciplinary approach to complex young-onset movement disorders may facilitate phenotyping and improve recognition of rare disorders, with a high diagnostic yield and minimal diagnostic delay. Future studies are needed to investigate the cost-benefit ratio of a multidisciplinary approach in comparison to regular subspecialty care.

Reversal of Status Dystonicus after Relocation of Pallidal Electrodes in DYT6 Generalized Dystonia.

Background: DYT6 dystonia can have an unpredictable clinical course and the result of deep brain stimulation (DBS) of the internal part of the globus pallidus (GPi) is known to be less robust than in other forms of autosomal dominant dystonia. Patients who had previous stereotactic surgery with insufficient clinical benefit form a particular challenge with very limited other treatment options available. Case Report: A pediatric DYT6 patient unexpectedly deteriorated to status dystonicus 1 year after GPi DBS implantation with good initial clinical response. After repositioning the DBS electrodes the status dystonicus resolved. Discussion: This case study demonstrates that medication-resistant status dystonicus in DYT6 dystonia can be reversed by relocation of pallidal electrodes. This case highlights that repositioning of DBS electrodes may be considered in patients with status dystonicus, especially when the electrode position is not optimal, even after an initial clinical response to DBS.

The efficacy of the modified Atkins diet in North Sea Progressive Myoclonus Epilepsy: an observational prospective open-label study.

BACKGROUND: North Sea Progressive Myoclonus Epilepsy is a rare and severe disorder caused by mutations in the GOSR2 gene. It is clinically characterized by progressive myoclonus, seizures, early-onset ataxia and areflexia. As in other progressive myoclonus epilepsies, the efficacy of antiepileptic drugs is disappointingly limited in North Sea Progressive Myoclonus Epilepsy. The ketogenic diet and the less restrictive modified Atkins diet have been proven to be effective in other drug-resistant epilepsy syndromes, including those with myoclonic seizures. Our aim was to evaluate the efficacy of the modified Atkins diet in patients with North Sea Progressive Myoclonus Epilepsy. RESULTS: Four North Sea Progressive Myoclonus Epilepsy patients (aged 7-20 years) participated in an observational, prospective, open-label study on the efficacy of the modified Atkins diet. Several clinical parameters were assessed at baseline and again after participants had been on the diet for 3 months. The primary outcome measure was health-related quality of life, with seizure frequency and blinded rated myoclonus severity as secondary outcome measures. Ketosis was achieved within 2 weeks and all patients completed the 3 months on the modified Atkins diet. The diet was well tolerated by all four patients. Health-related quality of life improved considerably in one patient and showed sustained improvement during long-term follow-up, despite the progressive nature of the disorder. Health-related quality of life remained broadly unchanged in the other three patients and they did not continue the diet. Seizure frequency remained stable and blinded rating of their myoclonus showed improvement, albeit modest, in all patients. CONCLUSIONS: This observational, prospective study shows that some North Sea Progressive Myoclonus Epilepsy patients may benefit from the modified Atkins diet with sustained health-related quality of life improvement. Not all our patients continued on the diet, but nonetheless we show that the modified Atkins diet might be considered as a possible treatment in this devastating disorder.