Genetic Update and Treatment for Dystonia.

A neurological condition called dystonia results in abnormal, uncontrollable postures or movements because of sporadic or continuous muscular spasms. Several varieties of dystonia can impact people of all ages, leading to severe impairment and a decreased standard of living. The discovery of genes causing variations of single or mixed dystonia has improved our understanding of the disease's etiology. Genetic dystonias are linked to several genes, including pathogenic variations of VPS16, TOR1A, THAP1, GNAL, and ANO3. Diagnosis of dystonia is primarily based on clinical symptoms, which can be challenging due to overlapping symptoms with other neurological conditions, such as Parkinson's disease. This review aims to summarize recent advances in the genetic origins and management of focal dystonia.

The role of genetics in the treatment of dystonia with deep brain stimulation: Systematic review and Meta-analysis.

BACKGROUND: Dystonia is a movement disorder characterized by sustained or intermittent muscle contractions that lead to involuntary postures or repetitive movements. Genetic mutations are being increasingly recognized as a cause of dystonia. Deep brain stimulation (DBS) is one of the limited treatment options available. However, there are varying reports on its efficacy in genetic dystonias. This systematic review of the characteristics of genetic dystonias treated with DBS and their outcomes aims to aid in the evaluation of eligibility for such treatment. METHODS: We performed a PUBMED search of all papers related to genetic dystonias and DBS up until April 2022. In addition to performing a systematic review, we also performed a meta-analysis to assess the role of the mutation on DBS response. We included cases that had a confirmed genetic mutation and DBS along with pre-and post-operative BFMDRS. RESULTS: Ninety-one reports met our inclusion criteria and from them, 235 cases were analyzed. Based on our analysis DYT-TOR1A dystonia had the best evidence for DBS response and Rapid-Onset Dystonia Parkinsonism was among the least responsive to DBS. CONCLUSION: While our report supports the role of genetics in DBS selection and response, it is limited by the rarity of the individual genetic conditions, the reliance on case reports and case series, and the limited ability to obtain genetic testing on a large scale in real-time as opposed to retrospectively as in many cases.

Electrophysiological variability as marker of dystonia worsening under deep brain stimulation successive withdrawal and renewal effects.

DBS has been shown to be an effective intervention for neurological disorders. However, the intervention is complex and many aspects have not been understood. Various clinical situations have no solution and follow trial and error approaches. Dystonia is a movement disorder characterized by involuntary muscle contractions, which gives rise to abnormal movements and postures. Status dystonicus (SD) represents a life-threatening condition that requires urgent assessment and management. Electrophysiological markers for risk of symptom worsening and SD related patterns of evolution in patients treated with long-term deep brain stimulation (DBS), and specially under the effect of withdrawal and renewals of simulation are needed. To this end, we study the variability of neural synchronization as a mechanism for symptom generation under successive perturbations to a system, i.e. withdrawals and renewals of neuromodulation, through computational simulation of clinical profiles under different plasticity conditions. The simulation shows that the neuroplasticity makeup influences the variability of oscillation synchronization patterns in virtual "patients". The difference between the effect of different electrophysiological signatures is remarkable and under a certain condition (equal medium long term potentiation and long term depression) the situation resembles that of a stable equilibrium, putatively making the sudden worsening or change less likely. Stability of variability can only be observed in this condition and is clearly distinct from other scenarios. CONCLUSION: Our results demonstrate that the neuroplasticity makeup affects the variability of the oscillatory synchrony. This i) informs the shaping of the electrophysiological makeup and ii) might serve as a marker for clinical behavior.

Brain Shift during Staged Deep Brain Stimulation for Movement Disorders.

INTRODUCTION: Deep brain stimulation (DBS) is a routine neurosurgical procedure utilized to treat various movement disorders including Parkinson's disease (PD), essential tremor (ET), and dystonia. Treatment efficacy is dependent on stereotactic accuracy of lead placement into the deep brain target of interest. However, brain shift attributed to pneumocephalus can introduce unpredictable inaccuracies during DBS lead placement. This study aimed to determine whether intracranial air is associated with brain shift in patients undergoing staged DBS surgery. METHODS: We retrospectively evaluated 46 patients who underwent staged DBS surgery for PD, ET, and dystonia. Due to the staged nature of DBS surgery at our institution, the first electrode placement is used as a concrete fiducial marker for movement in the target location. Postoperative computed tomography (CT) images after the first electrode implantation, as well as preoperative, and postoperative CT images after the second electrode implantation were collected. Images were analyzed in stereotactic targeting software (BrainLab); intracranial air was manually segmented, and electrode shift was measured in the x, y, and z plane, as well as a Euclidian distance on each set of merged CT scans. A Pearson correlation analysis was used to determine the relationship between intracranial air and brain shift, and student's t test was used to compare means between patients with and without radiographic evidence of intracranial air. RESULTS: Thirty-six patients had pneumocephalus after the first electrode implantation, while 35 had pneumocephalus after the second electrode implantation. Accumulation of intracranial air following the first electrode implantation (4.49 ± 6.05 cm3) was significantly correlated with brain shift along the y axis (0.04 ± 0.35 mm; r (34) = 0.36; p = 0.03), as well as the Euclidean distance of deviation (0.57 ± 0.33 mm; r (34) = 0.33; p = 0.05) indicating statistically significant shift on the ipsilateral side. However, there was no significant correlation between intracranial air and brain shift following the second electrode implantation, suggesting contralateral shift is minimal. Furthermore, there was no significant difference in brain shift between patients with and without radiographic evidence of intracranial air following both electrode implantation surgeries. CONCLUSION: Despite observing volumes as high as 22.0 cm3 in patients with radiographic evidence of pneumocephalus, there was no significant difference in brain shift when compared to patients without pneumocephalus. Furthermore, the mean magnitude of brain shift was <1.0 mm regardless of whether pneumocephalus was presenting, suggesting that intracranial air accumulation may not produce clinical significant brain shift in our patients.

Short-term stimulations of the entopeduncular nucleus induce cerebellar changes of c-Fos expression in an animal model of paroxysmal dystonia.

Deep brain stimulation (DBS) of the globus pallidus internus (entopeduncular nucleus, EPN, in rodents) is important for the treatment of drug-refractory dystonia. The pathophysiology of this movement disorder and the mechanisms of DBS are largely unknown. Insights into the mechanisms of DBS in animal models of dystonia can be helpful for optimization of DBS and add-on therapeutics. We recently found that short-term EPN-DBS with 130 Hz (50 µA, 60 µs) for 3 h improved dystonia in dtsz hamsters and reduced spontaneous excitatory cortico-striatal activity in brain slices of this model, indicating fast effects on synaptic plasticity. Therefore, in the present study, we examined if these effects are related to changes of c-Fos, a marker of neuronal activity, in brains derived from dtsz hamsters after these short-term DBS or sham stimulations. After DBS vs. sham, c-Fos intensity was increased around the electrode, but the number of c-Fos+ cells was not altered within the whole EPN and projection areas (habenula, thalamus). DBS did not induce changes in striatal and cortical c-Fos+ cells as GABAergic (GAD67+ and parvalbumin-reactive) neurons in motor cortex and striatum. Unexpectedly, c-Fos+ cells were decreased in deep cerebellar nuclei (DCN) after DBS, suggesting that cerebellar changes may be involved in antidystonic effects already during short-term DBS. However, the present results do not exclude functional changes within the basal ganglia-thalamo-cortical network, which will be further investigated by long-term EPN stimulations. The present study indicates that the cerebellum deserves attention in ongoing examinations on the mechanisms of DBS in dystonia.

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.

Chronic Pallidal Local Field Potentials Are Associated With Dystonic Symptoms in Children.

BACKGROUND: Novel deep brain stimulation devices can record local field potentials (LFPs), which represent the synchronous synaptic activity of neuronal populations. The clinical relevance of LFPs in patients with dystonia remains unclear. OBJECTIVES: We sought to determine whether chronic LFPs recorded from the globus pallidus internus (GPi) were associated with symptoms of dystonia in children. MATERIALS AND METHODS: Ten patients with heterogeneous forms of dystonia (genetic and acquired) were implanted with neurostimulators that recorded LFP spectral snapshots. Spectra were compared across parent-reported asymptomatic and symptomatic periods, with daily narrowband data superimposed in 24 one-hour bins. RESULTS: Spectral power increased during periods of registered dystonic symptoms: mean increase = 102%, CI: (76.7, 132). Circadian rhythms within the LFP narrowband time series correlated with dystonic symptoms: for delta/theta-waves, correlation = 0.33, CI: (0.18, 0.47) and for alpha waves, correlation = 0.27, CI: (0.14, 0.40). CONCLUSIONS: LFP spectra recorded in the GPi indicate a circadian pattern and are associated with the manifestation of dystonic symptoms.

Deep brain stimulation in pediatric dystonia: calls for therapeutic realism over nihilism.

PURPOSE: Pediatric dystonia (PD) has a significant negative impact on the growth and development of the child. This study was done retrospectively to analyze functional outcomes in pediatric patients with dystonia who underwent deep brain stimulation. METHODS: In this retrospective analytical study, all the patients of age less than 18 years undergoing deep brain stimulation (DBS) for dystonia between 2012 and 2020 in a single center were analyzed and their functional outcomes were measured by the Burke-Fahn-Marsden-dystonia-rating-scale (BFMDRS). RESULTS: A total of 10 pediatric patients were included with a mean age of onset, duration of disease, and age at surgery being 5.75 years, 7.36 years, and 13.11 years, respectively, with a mean follow-up of 23.22 months. The mean pre-DBS motor score was 75.44 ± 23.53 which improved significantly at 6-month and 12-month follow-up to 57.27 (p value 0.004) and 50.38 (p value < 0.001), respectively. Limbs sub-scores improved significantly at both the scheduled intervals. There was a significant improvement in disability at 1-year follow-up with significant improvement in feeding, dressing, and walking components. There was a 27.34% and 36.64% improvement in dystonia with a 17.37% and 28.86% reduction in disability at 6 months and 12 months, respectively. There was a positive correlation between the absolute reduction of the motor score and improvement in disability of the patients at 6 months (rho = 0.865, p value 0.003). CONCLUSIONS: DBS in PD has an enormous role in reducing disease burden and achieving a sustainable therapeutic goal.

Quality of life outcomes after deep brain stimulation in acquired dystonia: a systematic review and meta-analysis.

BACKGROUND: Dystonia is a condition that affects the ability to control the movement and function of the body's muscles. It can cause not only physical problems, but also mental problems, resulting in impaired health-related quality of life (HRQoL). However, the effect of deep brain stimulation on quality of life in acquired dystonia remains unclear. METHODS: We conducted a systematic literature review from January 2000 to October 2022，determined the eligible studies, and performed a meta-analysis of HRQoL outcomes based on the Short-Form Health Survey-36 (SF-36) after DBS to evaluate the effects of DBS on physical and mental QoL. RESULTS: A total of 14 studies met the inclusion criteria and were systematically reviewed. A comprehensive meta-analysis was performed for 9 studies that reported physical and psychological data or physical component summary (PCS), or mental component summary (MCS) for SF-36. The mean (SD) age at DBS implantation was 34.29 (10.3) years, and the follow-up period after implantation was 2.21 (2.80) years. The random effects model meta-analysis revealed that both physical and mental domains of the SF-36 improved following DBS. There was no statistically significant difference between the physical domains (effect size=1.34; p<0.0001) and the mental domains (effect size=1.38; p<0.0001). CONCLUSION: This is the first meta-analysis that demonstrates significant benefits in HRQoL following DBS in patients with acquired dystonia. There were significant improvements in both physical QoL and mental QoL.

Deep Brain Stimulation for GNAO1-Associated Dystonia: A Systematic Review and Meta-Analysis.

OBJECTIVES: Guanine nucleotide-binding protein alpha-activating activity polypeptide O (GNAO1) syndrome, a rare congenital monogenetic disorder, is characterized by a neurodevelopmental syndrome and the presence of dystonia. Dystonia can be very pronounced and even lead to a life-threatening status dystonicus. In a small number of pharmaco-refractory cases, deep brain stimulation (DBS) has been attempted to reduce dystonia. In this study, we summarize the current literature on outcome, safety, and outcome predictors of DBS for GNAO1-associated dystonia. MATERIALS AND METHODS: We conducted a systematic review and meta-analysis on individual patient data. We included 18 studies describing 28 unique patients. RESULTS: The mean age of onset of symptoms was 2.4 years (SD 3.8); 16 of 28 patients were male, and dystonia was nearly always generalized (20/22 patients). Symptoms were present before DBS for a median duration of 19.5 months, although highly variable, occurring between 3 and 168 months. The exact phenotype, genotype, and radiologic abnormalities varied and seemed to be of little importance in terms of DBS outcome. All studies described an improvement in dystonia. Our meta-analysis focused on pallidal DBS and found an absolute and relative improvement in Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) of 32.5 points (37.9%; motor part; p = 0.001) and 5.8 points (21.5%; disability part; p = 0.043) at last follow-up compared with preoperative state; 80% of patients were considered responders (BFMDRS-M reduction by ≥25%). Although worsening over time does occur, an improvement was still observed in patients after >10 years. All reported cases of status dystonicus resolved after DBS surgery. Skin erosion and infection were observed in 18% of patients. CONCLUSION: Pallidal DBS can be efficacious and safe in GNAO1-associated dystonia.

Subthalamic nucleus deep brain stimulation in primary Meige syndrome: motor and non-motor outcomes.

BACKGROUND AND PURPOSE: Deep brain stimulation (DBS) has emerged as a promising treatment for movement disorders. This prospective study aims to evaluate the effects of bilateral subthalamic nucleus DBS (STN-DBS) on motor and non-motor symptoms in patients with primary Meige syndrome. METHODS: Thirty patients who underwent bilateral STN-DBS between April 2017 and June 2020 were included. Standardized and validated scales were utilized to assess the severity of dystonia, health-related quality of life, sleep, cognitive function and mental status at baseline and at 1 year and 3 years after neurostimulation. RESULTS: The Burke-Fahn-Marsden Dystonia Rating Scale movement scores showed a mean improvement of 63.0% and 66.8% at 1 year and 3 years, respectively, after neurostimulation. Similarly, the Burke-Fahn-Marsden Dystonia Rating Scale disability scores improved by 60.8% and 63.3% at the same time points. Postoperative quality of life demonstrated a significant and sustained improvement throughout the follow-up period. However, cognitive function, mental status, sleep quality and other neuropsychological functions did not change after 3 years of neurostimulation. Eight adverse events occurred in six patients, but no deaths or permanent sequelae were reported. CONCLUSIONS: Bilateral STN-DBS is a safe and effective alternative treatment for primary Meige syndrome, leading to improvements in motor function and quality of life. Nevertheless, it did not yield significant amelioration in cognitive, mental, sleep status and other neuropsychological functions after 3 years of neurostimulation.

The history of deep brain stimulation.

Deep brain stimulation (DBS) surgery is an established and effective treatment for several movement disorders (tremor, Parkinson's disease, and dystonia), and is under investigation in numerous other neurological and psychiatric disorders. However, the origins and development of this neurofunctional technique are not always well understood and recognized. In this mini-review, we review the history of DBS, highlighting important milestones and the most remarkable protagonists (neurosurgeons, neurologists, and neurophysiologists) who pioneered and fostered this therapy throughout the 20th and early 21st century. Alongside DBS historical markers, we also briefly discuss newer developments in the field, and the future challenges which accompany such progress.

Femur Fractures in 5 Individuals With Pantothenate Kinase-associated Neurodegeneration: The Role of Dystonia and Suggested Management.

BACKGROUND: Pantothenate kinase-associated neurodegeneration (PKAN) is a rare, neurodegenerative disorder that manifests with progressive loss of ambulation and refractory dystonia, especially in the early-onset classic form. This leads to osteopenia and stress on long bones, which pose an increased risk of atraumatic femur fractures. The purpose of this study is to describe the unique challenges in managing femur fractures in PKAN and the effect of disease manifestations on surgical outcomes. METHODS: A retrospective case review was conducted on 5 patients (ages 10 to 20 y) with PKAN with a femur fracture requiring surgical intervention. Data regarding initial presentation, surgical treatment, complications, and outcomes were obtained. RESULTS: All patients were non-ambulatory, with 4 of 5 patients sustaining an atraumatic femur fracture in the setting of dystonia episode. One patient had an additional contralateral acetabular fracture. Postoperatively, 4 of the 5 patients sustained orthopaedic complications requiring surgical revision, with 3 of these secondary to dystonia. Overall, 4 required prolonged hospitalization in the setting of refractory dystonia. CONCLUSION: Femur fractures in PKAN present distinct challenges for successful outcomes. A rigid intramedullary rod with proximal and distal interlocking screws is most protective against surgical complications associated with refractory dystonia occurring during the postoperative period. Multidisciplinary planning for postoperative care is essential and may include aggressive sedation and pain management to decrease the risk of subsequent injuries or complications. LEVEL OF EVIDENCE: Level IV.

Deep Brain Stimulation for an Unusual Presentation of Myoclonus Dystonia Associated with Russell-Silver Syndrome.

Background: Myoclonus dystonia syndrome typically results from autosomal dominant mutations in the epsilon-sarcoglycan gene (SGCE) via the paternally expressed allele on chromosome 7q21. There is evidence that deep brain stimulation (DBS) is beneficial for this genotype, however, there are few prior case reports on DBS for myoclonus dystonia syndrome secondary to other confirmed genetic etiologies. Case Report: A 20-year-old female with concomitant Russell-Silver syndrome and myoclonus dystonia syndrome secondary to maternal uniparental disomy of chromosome 7 (mUPD7) presented for medically refractory symptoms. She underwent DBS surgery targeting the bilateral globus pallidus interna with positive effects that persisted 16 months post-procedure. Discussion: We present a patient with the mUPD7 genotype for myoclonus dystonia syndrome who exhibited a similar, if not superior, response to DBS when compared to patients with other genotypes. Highlights: This report outlines the first described case of successful deep brain stimulation treatment for a rare genetic variant of myoclonus dystonia syndrome caused by uniparental disomy at chromosome 7. These findings may expand treatment options for patients with similar conditions.