Segmental Dystonia Research Articles

Brueghel Syndrome or Meige Syndrome? Two Sides of a Same Disease.

Different eponyms such as "Wood syndrome," Meige syndrome, "Brueghel syndrome," "Blepharospasm plus syndrome" have been used to describe segmental craniocervical dystonias. These facial and/or oromandibular movement disorders are characterized by muscle contractions and spasms involving eyes, facial region, and sometimes pharynx, jaw, floor of the mouth, and tongue. The pathophysiology of craniocervical dystonia is poorly understood, but abnormal plasticity and impaired inhibition are suspected. Injection of botulinum toxin appears to be the best therapeutic option for treating segmental craniocervical dystonia. The objective of this chapter is to depict the history of segmental craniocervical dystonia in order to delineate the phenotypic spectrum of the disorders and to distinguish this entity from other facial and/or oromandibular movement disorders.

Sensory Alterations in Patients with Isolated Idiopathic Dystonia: An Exploratory Quantitative Sensory Testing Analysis.

Abnormalities in the somatosensory system are increasingly being recognized in patients with dystonia. The aim of this study was to investigate whether sensory abnormalities are confined to the dystonic body segments or whether there is a wider involvement in patients with idiopathic dystonia. For this purpose, we recruited 20 patients, 8 had generalized, 5 had segmental dystonia with upper extremity involvement, and 7 had cervical dystonia. In total, there were 13 patients with upper extremity involvement. We used Quantitative Sensory Testing (QST) at the back of the hand in all patients and at the shoulder in patients with cervical dystonia. The main finding on the hand QST was impaired cold detection threshold (CDT), dynamic mechanical allodynia (DMA), and thermal sensory limen (TSL). The alterations were present on both hands, but more pronounced on the side more affected with dystonia. Patients with cervical dystonia showed a reduced CDT and hot detection threshold (HDT), enhanced TSL and DMA at the back of the hand, whereas the shoulder QST only revealed increased cold pain threshold and DMA. In summary, QST clearly shows distinct sensory abnormalities in patients with idiopathic dystonia, which may also manifest in body regions without evident dystonia. Further studies with larger groups of dystonia patients are needed to prove the consistency of these findings.

Tremor in Dystonia: A Cross-sectional Study from India.

Tremor is an important phenotypic motor feature in dystonia, but there is limited literature regarding its prevalence and phenomenology. This cross-sectional study included 90 patients with adult-onset, isolated dystonia from a tertiary care movement disorder center in India. Patients were assessed for tremor in the head and in different body parts. Surface electromyography studies of tremor were recorded of the involved limb in different positions. Tremor was present in 41 patients (45.55%) who had dystonia, including 21 of 41 patients (51.21%) with cervical dystonia, 15 of 34 (44.11%) with limb dystonia, and 5 of 15 (33.33%) with cranial dystonia. Significantly later age at presentation (47.19±14.55years vs. 40.39±13.74years; P=0.012) and longer disease duration (5.11±5.85years vs. 2.60±2.57years; P=0.004) were observed in patients with versus without tremor. Upper limb tremor was present in 33 patients, head tremor was present in 14, and leg tremor was present in 2. Tremor was present in 17 of 25 patients (68%) with segmental dystonia and in 6 of 9 (66.66%) with multifocal dystonia. Tremor was least frequent in patients with focal dystonia (18 of 56 patients; 32.14%). Tremor was common (>45%) in patients with primary adult-onset dystonia. Patients who had tremor were older and had a longer duration of symptoms. Patients with segmental and multifocal dystonia had more tremor than those with focal dystonia. In contrast to some other studies, the current patients had more upper limb tremor than head tremor, and a combination of dystonic tremor and tremor associated with dystonia was more common than isolated dystonic tremor.

Dystonia: Then and now

IntroductionDystonia is a rare disorder that has undergone extensive scientific investigation leading to a transformation of understanding over the past century. MethodsThis manuscript was prepared through a review of relevant literature for each topic. ResultsHistorically dystonia was considered the manifestation of psychiatric disorders. Subsequently, investigations have firmly established this as a neurological disorder. Though electrophysiological and imaging, dystonia is thought to arise from a loss inhibition of motor programs, defective sensorimotor integration and abnormal plasticity. The genetic studies in dystonia have revealed the hereditary nature of many forms of familial dystonia. Treatment of dystonia has focused primarily on botulinum toxin for focal and segmental dystonia and deep brain stimulation of the globus pallidus interna for generalized and medically refractory focal dystonia. ConclusionThe progress in dystonia in the past century has revised the concepts of this disorder, increased knowledge of genetics and underlying pathophysiology, and provides new therapeutic targets. To promote future research the development of diagnostic criteria, biomarkers and validated rating scales for each form of dystonia is essential.

Pharyngeal Dystonia Mimicking Spasmodic Dysphonia

The aim of this study was to describe the presentation of pharyngeal dystonia (PD), which can occur as a focal or segmental dystonia with a primarily pharyngeal involvement for the discussion of treatment methods for controlling consequent symptoms. PD is specific to speech-related tasks. A retrospective medical record review of four patients with PD was performed. All patients were initially misdiagnosed with adductor spasmodic dysphonia and failed standard treatment with botulinum toxin type A (BTX). On laryngoscopy, the patients were discovered to have segmental or focal dystonia primarily affecting the pharyngeal musculature contributing to their vocal manifestations. A novel treatment regimen was designed, which involved directing BTX injections into the muscles involved in spasmodic valving at the oropharyngeal level. After titrating to an optimal dose, all patients showed improvement in their voice and speech with only mild dysphagia. These patients have maintained favorable results with repeat injections at 6- to 12-week intervals. PD, or dystonia with predominant pharyngeal involvement, is a rare entity with vocal manifestations that are not well described. It can be easily mistaken for spasmodic dysphonia. PD is specific to speech-related tasks. A novel method of BTX injections into the involved muscles results in a significant improvement in voice without significant dysphagia.

Clozapine efficiency in tardive syndromes induced by anti-psychotic treatment

IntroductionTardive syndromes (TS) resulting from prolonged exposure to dopamine receptor blocking agents are frequent. Clozapine is considered to have a low risk of causing new onset TS and accounts therefore as an interesting option in patients with invalidating TS.ObjectivesOur study aims to describe clozapine indications in patients experiencing TS.MethodsPresentation of the clinical cases of five patients, who experienced different kinds of TS secondary to 1st and 2nd generation anti-psychotic treatment.ResultsWe present the cases of AB aged 41, MJ aged 40, HM aged 31 and AS aged 30, diagnosed with schizophrenia; and FB aged 24,diagnosed with schizoaffective disorder. Adverse side effects to conventional anti-psychotics such as limb and trunk tremors were described for AB, choreic limb movements, axial and segmental dystonia for MJ, AS, FB and oculogyration for FB. All patients were switched to atypical anti-psychotics without improvement of the TS. The switch to clozapine, associated with abotulinum injection for MJ, led to regression of the TS and improvement of clinical signs. In fact, according to several studies, clozapine seems to be an interesting option when invalidating TS occurs. The low prevalence of TS under clozapine can be explained by its low affinity for striatal-D2 receptors, its anti-serotonin and anti-cholinergic effects.ConclusionsClozapine should be considered in symptomatic patients who develop TS while receiving other anti-psychotics. Further research on mechanism of TS and clozapine effect on TS is needed.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Constant-Current Deep Brain Stimulation of the Globus Pallidus Internus in the Treatment of Primary Dystonia by a Novel 8-Contact (Octrode) Lead.

To evaluate bilateral constant-current globus pallidus internus (GPi) deep brain stimulation using an 8-contact lead. This prospective, open-label, single-center pilot study of 10 patients assessed the feasibility ofdelivering bilaterally constant-current GPi deep brain stimulation with a novel 8-channel lead to treat primary dystonia using standard scales as outcome measures. Patients included 4 men and 6 women with a mean age of 35.8 years ± 9.2 (range, 27-49 years). Mean age of onset was 18.5 years ± 9.1 (range, 8-35 years), and mean disease duration was 17.3 years (range, 7-27 years). All had primary dystonia (8 generalized dystonia, 1 segmental dystonia, 1 focal dystonia). The primary variable was determined as 50% reduction in dystonia symptoms from baseline to the 6-month follow-up, as defined by the Burke-Fahn-Marsden Dystonia Rating Scale. Six patients (60.0%) achieved >50% reduction in Burke-Fahn-Marsden Dystonia Rating Scale score and were classified as responders at the 6-month follow-up. Five of these 6 responders (83.3%) sustained that response through the assessment at the end of the first year. Constant-current stimulation was associated with significant improvement in pain and quality of life in all patients. Nearly 84% of the overall improvement occurred by the end of first month after stimulation onset, documenting an early response to treatment. Axial symptoms responded the best. Constant-current GPi deep brain stimulation proved safe and efficacious for treatment of primary dystonia. Motor scores improved by 54%, mostly within the first month. No phenotype-specific stimulation could be achieved, despite the capability of the new lead to stimulate specific loci within the GPi.

Headache Attributed to Craniocervical Dystonia - A Little Known Headache.

Craniocervical dystonia is a focal or segmental dystonia in its distribution, classically known as spasmodic torticollis when in its pure cervical presentation. Although craniocervical dystonia has been recognized as a possible cause of headache since the publication of the second version of International Classification of Headache Disorders, there are few studies about this entity. This was a narrative review. Craniocervical dystonia was associated with muscle pain in 67-89% of the cases. Headaches of any kind affected approximately 60% of patients with craniocervical dystonia, and were located mainly in the occipital and cervical regions. Headache attributed to craniocervical dystonia specifically was rarely found, and it was described in only one patient out of 80 in one study. Treatment with botulinum neurotoxin is considered to be the first-line treatment for focal dystonias, including craniocervical dystonia, and besides reducing clinical severity, impairment, and pain scores among the patients with craniocervical dystonia, there were also descriptions of improvements in headaches attributed to craniocervical dystonia and other headaches associated with this dystonia. Headache attributed to craniocervical dystonia has been poorly studied. There is a need for more studies to evaluate its characteristics and treatment.

Management of segmental dystonia associated with knee replacement surgery: A case report

Management of segmental dystonia associated with knee replacement surgery: A case report

Clinical and demographic characteristics related to onset site and spread of cervical dystonia.

Clinical characteristics of isolated idiopathic cervical dystonia such as onset site and spread to and from additional body regions have been addressed in single-site studies with limited data and incomplete or variable dissociation of focal and segmental subtypes. The objectives of this study were to characterize the clinical characteristics and demographics of isolated idiopathic cervical dystonia in the largest standardized multicenter cohort. The Dystonia Coalition, through a consortium of 37 recruiting sites in North America, Europe, and Australia, recruited 1477 participants with focal (60.7%) or segmental (39.3%) cervical dystonia on examination. Clinical and demographic characteristics were evaluated in terms of the body region of dystonia onset and spread. Site of dystonia onset was: (1) focal neck only (78.5%), (2) focal onset elsewhere with later segmental spread to neck (13.3%), and (3) segmental onset with initial neck involvement (8.2%). Frequency of spread from focal cervical to segmental dystonia (22.8%) was consistent with prior reports, but frequency of segmental onset with initial neck involvement was substantially higher than the 3% previously reported. Cervical dystonia with focal neck onset, more than other subtypes, was associated with spread and tremor of any type. Sensory tricks were less frequent in cervical dystonia with segmental components, and segmental cervical onset occurred at an older age. Subgroups had modest but significant differences in the clinical characteristics that may represent different clinical entities or pathophysiologic subtypes. These findings are critical for design and implementation of studies to describe, treat, or modify disease progression in idiopathic isolated cervical dystonia. © 2016 International Parkinson and Movement Disorder Society.

Influence of cognitive-motor interference on gait spatiotemporal parameters in children and adolescents with cerebral palsy: A preliminary study

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) has been established as an effective and safe treatment for dystonia. In general, side effects are rare, but there is increasing evidence that GPi DBS in dystonia can induce hypokinetic symptoms like micrographia or freezing of gait. We aimed to evaluate and quantify possible changes of gait following bilateral chronic GPi DBS for dystonia by computerized gait analyses.We prospectively performed computerized gait analysis in ten consecutive patients (mean age 57.8+/−14.3 years) with segmental dystonia but without involvement of lower trunk or legs who were treated with bilateral GPi DBS. Using pressure sensitive insoles, several parameters were measured preoperatively (pre-OP) and at a median of 7 months postoperatively.The mean step length significantly decreased from 60.0+/−6.9 cm pre-OP to 54.3+/−6.4 cm with GPi DBS (p < 0.01). Due to only small changes of walking distance and gait velocity, the cadence correspondingly increased from 105.6+/−9.2 steps/min to 111.3+/−11.4 steps/min (p < 0.05). More importantly, the variance of several gait parameters significantly decreased postoperatively.In patients with segmental dystonia, chronic DBS of the posteroventral lateral GPi is associated with only mild hypokinesia of gait, but with a relevant decrease in gait variability. Given other recently reported hypokinetic effects of GPi DBS for dystonia and recent results of electrophysiological coherence studies, these findings support the hypothesis of a general alteration of neuronal activity in striato-pallido-thalamo-cortical motor pathways following chronic stimulation of the posteroventral lateral GPi.

EP 56. Cerebellar learning and its modifiability by alcohol in myoclonus-dystonia

Objectives To investigate cerebellar learning and its modifiability by alcohol in SGCE mutation-positive myoclonus-dystonia and healthy controls using eyeblink conditioning. Background Myoclonus-dystonia is an inherited neurological movement disorder characterized predominantly by generalized myoclonic jerks and focal or segmental dystonia with a remarkable decrease of symptoms due to alcohol. This effect has raised the question whether the cerebellum could play an important role in the generation of motor symptoms. Methods Delay eyeblink conditioning was assessed in 12 SGCE mutation-positive myoclonus-dystonia patients and 16 control subjects on day 1 before (OFF_C2 state) and on day 2 after a single oral ethanol dose (ON_C2 state), calculated according to the Widmark formula to reach a breath alcohol content of 0.8 ‰ (±0.1 ‰ ). For the conditioning paradigm, an air puff applied to the outer canthus of the eye was preceded by a 540 ms tone, the conditioned stimulus, in 10 learning blocks each including 10 paired stimuli (LT1-LT10). The learning paradigm was followed by three extinction blocks (10 stimuli each), in which the single tone was given only (ET1-ET3). To test for differential effects, a multifactorial repeated measures ANOVA was used with the factors STATE (OFF_C2 and ON_C2), BLOCK (LT1-10 and ET1-3) and the in-between subject factor GROUP (patient and controls). Results The ANOVA showed a significant main effect of the factor GROUP (F1;26) = 7.162, p = 0.013) and BLOCK (F12;312) = 20.181, p p = 0.01) ( Fig. 1 ) indicating that ethanol has a differential effect in myoclonus dystonia compared to controls. Without the influence of alcohol, compared to healthy controls, myoclonus-dystonia patients revealed a significantly lower learning effect (GROUP (F1;26) = 13.255, p = 0.001) and BLOCK (F9;234) = 12.23, p p = 0.013) ( Fig. 1 A LT1-10) and an altered extinction rate (LT 10 to ET 1, patients 41%–22% and controls 79%–32%). Although conditioning rates under the influence of alcohol did not significantly differ when comparing patients and control subjects, both groups showed a reverse effect comparing the learning effect before and after alcohol administration. While the control group had lower conditioning rates under alcohol, myoclonus-dystonia patients showed an increased eye blink conditioning rate under alcohol influence with a main effect of the factor STATE when assessing cerebellar learning before and after alcohol consumption (F1;11) = 7.921, p = 0.017). Conclusion Cerebellar learning is impaired in patients with SGCE mutation-positive myoclonus-dystonia and alcohol administration is able to this improves learning effects. This goes along with the clinically evident improvement of motors symptoms after alcohol intake. This study supports the idea of a crucial role of the cerebellum in generating motor symptoms in myoclonus dystonia.

Hypokinetic gait changes induced by bilateral pallidal deep brain stimulation for segmental dystonia

BackgroundDeep brain stimulation (DBS) of the globus pallidus internus (GPi) has been established as an effective and safe treatment for dystonia. In general, side effects are rare, but there is increasing evidence that GPi DBS in dystonia can induce hypokinetic symptoms like micrographia or freezing of gait. We aimed to evaluate and quantify possible changes of gait following bilateral chronic GPi DBS for dystonia by computerized gait analyses. MethodsWe prospectively performed computerized gait analysis in ten consecutive patients (mean age 57.8+/−14.3 years) with segmental dystonia but without involvement of lower trunk or legs who were treated with bilateral GPi DBS. Using pressure sensitive insoles, several parameters were measured preoperatively (pre-OP) and at a median of 7 months postoperatively. ResultsThe mean step length significantly decreased from 60.0+/−6.9cm pre-OP to 54.3+/−6.4cm with GPi DBS (p<0.01). Due to only small changes of walking distance and gait velocity, the cadence correspondingly increased from 105.6+/−9.2 steps/min to 111.3+/−11.4 steps/min (p<0.05). More importantly, the variance of several gait parameters significantly decreased postoperatively. ConclusionsIn patients with segmental dystonia, chronic DBS of the posteroventral lateral GPi is associated with only mild hypokinesia of gait, but with a relevant decrease in gait variability. Given other recently reported hypokinetic effects of GPi DBS for dystonia and recent results of electrophysiological coherence studies, these findings support the hypothesis of a general alteration of neuronal activity in striato-pallido-thalamo-cortical motor pathways following chronic stimulation of the posteroventral lateral GPi.

A Short Commentary on Globus Pallidus Internus Deep Brain Stimulation in Primary Meige Syndrome

Meige syndrome is a type of segmental dystonia that manifests a combination of blepharospasm and oromandibular dystonia and is often associated with other types of craniocervical dystonia. Although the precise pathogenesis of primary Meige syndrome remains to be elucidated, it has been suggested that this movement disorder might be a basal ganglia disorder. Multiple single case reports and open-labelled small case series have shown that globus pallidus internus deep brain stimulation (GPi-DBS) could result in therapeutic benefits in patients with severe Meige syndrome. However, randomized and controlled trials are necessary to accurately assess the safety and therapeutic efficacy of GPi-DBS in treating patients with Meige syndrome. This short commentary introduces the current use of GPi-DBS in the treatment of medically refractory Meige syndrome.

Long-term effect on dystonia after pallidal deep brain stimulation (DBS) in three members of a family with a THAP1 mutation

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is an established treatment in patients with severe dystonia. However, factors predicting outcome are largely unknown and motor improvement in DYT6 patients after DBS has been reported to be poorer as compared to, e.g., DYT1 patients. Here, we report the course of clinical improvement for up to 11 years of pallidal DBS in three male patients belonging to the same family with early-onset generalized or segmental dystonia due to a heterozygous THAP1 gene mutation (DYT6). All patients showed an initial effective response to pallidal DBS with a mean of 56.9 ± 11.7% improvement in the Burke-Fahn-Marsden Dystonia motor and 45.5 ± 22.4% in the disability score at 1-year follow-up. The long-term outcome of pallidal DBS was favorable in two patients (39, 67% motor improvement, respectively). Our findings demonstrate that motor improvement is variable and may depend on disease severity, disease duration, and clinical presentation. Overall, our observation supports pallidal DBS as an important treatment option in patients with DYT6 dystonia.

Comparison of clinical characteristics of patients with adductor laryngeal dystonia in the focal and segmental types

AbstractDystonia is a central motor processing neurological disorder characterized by abnormal, often action-induced, involuntary movements or uncontrolled spasms. AimTo compare patients with the diagnoses of focal and segmental adductor laryngeal dystonia at the Neurolarynx Outpatient Clinic of the Federal University of São Paulo. Materials and methodsA clinical retrospective study of data collected from patient registries from 2003 to 2009. ResultsOf 34 patients, 25 presented focal dystonia and 9 presented segmental dystonia. There were 30 females (88.2%) and 4 males (11.8%). A relation with a traumatic event was reported in 11 cases (32.4%). Vocal tremor was observed in 21 patients (61.8%). The mean age at onset, the age at diagnosis, and time between the onset and the diagnosis were respectively 55, 61.3 and 6.3 years. There was no statistical difference between patients with focal laryngeal adductor dystonia and segmental dystonia in the study data. ConclusionThere were no statistical differences among patients with focal adductor laryngeal dystonia and segmental dystonia relating to age of onset, age of diagnosis, gender, time between onset and diagnosis, presence of associated tremor, and relation to trauma.

High rates of fatigue and sleep disturbances in dystonia

Background: Nonmotor symptoms in dystonia are increasingly recognized to impair the quality of life. The primary objective of this study was to determine the prevalence of fatigue and sleep disturbances in dystonia and to ascertain their impact on quality of life using standardized questionnaires. Methods: Dystonia patients presenting to a Botulinum toxin clinic were prospectively administered Fatigue Severity Scale (FSS), Multidimensional Fatigue Inventory (MFI), Epworth Sleepiness Scale (ESS) and Parkinson's Disease Sleep Scale (PDSS) for assessment of fatigue and sleep disturbances. Health-related Quality of life (HRQOL) was determined using MOS SF-36 scale and depressive symptoms were assessed using the Beck Depression Inventory II. Results: Ninety-one patients with dystonia participated (66 women, 25 men, mean age 60 ± 17 years). Nine subjects had generalized dystonia, 18 segmental dystonia and 64 had focal dystonia. Moderate to severe fatigue was present in 43% of the cohort (FSS), excessive daytime somnolence in 27% (ESS) and other sleep disturbances in 26% (PDSS). FSS and MFI scores correlated significantly with HRQOL even when controlled for depression and sleep disturbances. Excessive daytime somnolence and nocturnal sleep disturbances correlated significantly with the HRQOL; however, these effects were not seen for daytime somnolence when controlled for depression. Psychometric testing found adequate reliabilities and convergent validities for both fatigue and sleep scales. Conclusion: Fatigue and sleep disturbances revealed high prevalence rates in this large, first of its dystonia study. They negatively impacted the quality of life even when controlled for comorbid depression.

Body weight gain in patients with bilateral deep brain stimulation for dystonia.

In patients with Parkinson's disease, significant weight gain following chronic deep brain stimulation (DBS) has been reported. Recently, relevant weight gain could be demonstrated also following subthalamic nucleus DBS in patients with primary cervical dystonia. Prospective analyses of body weight changes following DBS in patients with dystonia, however, have not been published so far. We aimed to analyse the changes of body weight following DBS in patients with dystonia. The body mass index (BMI) of 17 consecutive patients with segmental or generalised dystonia (mean age 54.6±16.1years) treated with bilateral DBS of the globus pallidus internus (GPi) (n=14) or the thalamic ventral intermediate nucleus (n=3) was measured preoperatively (pre-OP) and at three follow-up (FU) time points post-DBS surgery (FU1=7months, FU2=17months, FU3=72months). All patients benefited from marked improvement in their dystonia. The mean BMI pre-OP (SD) was 22.5 (±3.7)kg/m(2) and increased stepwise to 24.0 (±3.3)kg/m(2) at FU1, 24.4 (±3.7)kg/m(2) at FU2 and 24.9 (±3.7)kg/m(2) at FU3 (p<0.05 at all three FUs compared to pre-OP). Relative BMI increase and improvement of dystonia were correlated (p=0.025). Chronic bilateral GPi DBS in patients with dystonia is associated with significant body weight gain, in particular during the first 6months post-OP. This probably is a result of improvement of dystonic motor symptoms and recovery of eating dysfunction rather than a target-specific phenomenon.

V21. Electrophysiological correlates of auditory change detection: A simultaneous depth and scalp EEG study

Introduction Attentive monitoring of the environment is fundamental for efficient detection of relevant stimuli and is well investigated for cortical regions. However, subcortical network circuitry and the involvement of these structures in the context of detection of relevant stimuli, involuntary attention and distractibility is not well understood. The P300 component is frequently used in electroencephalographic (EEG) studies as a measure for attentional and cognitive functions and is supposed to give further insight into context-specific processes of subcortical structures. Methods In this ongoing study, simultaneous recordings of local field potentials (LFPs) and event-related potentials (ERPs) from scalp EEG were obtained in 14 patients (mean age = 51.6 ± 21.7 years) undergoing deep brain stimulation (DBS). These patients were implanted bilaterally with quadripolar electrodes in the subthalamic nucleus (STN; n = 5; Parkinson disease), the thalamic ventral intermediate nucleus (VIM; n = 5; essential tremor and cervical dystonia), or the globus pallidus internus (GPi; n = 4; segmental dystonia, Parkinson disease and Tourette syndrome). Within five days after surgery, patients performed an auditory three-class oddball paradigm with externalized DBS electrodes. ERPs from scalp and DBS electrodes were analyzed upon presentation of one frequent standard stimulus (900 Hz; 72%) and two infrequent stimuli, either being a relevant (1200 Hz; 14%) or a distractor (600 Hz; 14%) stimulus. Stimuli were presented for 62 ms with an interstimulus interval of 800–1200 ms. The patients were asked to press a button to the relevant stimulus. Results Analysis reveals high accuracy in all patients (84.25%±15.14). Preliminary EEG results show a P300 component over parietal regions that was largest upon presentation of target stimuli compared with distractor and standard stimuli. A similar P300-like component was also found in depth recordings, suggesting stimulus-specific responses of subcortical structures. Here, STN showed shorter latencies and larger amplitudes compared to GPi or Vim. Discussion The P300 reflects attentional processes that require stimulus detection and discrimination. The present results suggest that, in particular, the STN may play a pivotal role in context-specific processes.

Deep brain stimulation for movement disorders: update on recent discoveries and outlook on future developments.

Modern deep brain stimulation (DBS) has become a routine therapy for patients with movement disorders such as Parkinson's disease, generalized or segmental dystonia and for multiple forms of tremor. Growing numbers of publications also report beneficial effects in other movement disorders such as Tourette's syndrome, various forms of chorea and DBS is even being studied for Parkinson's-related dementia. While exerting remarkable effects on many motor symptoms, DBS does not restore normal neurophysiology and therefore may also have undesirable side effects including speech and gait deterioration. Furthermore, its efficacy might be compromised in the long term, due to progression of the underlying disease. Various programming strategies have been studied to try and address these issues, e.g., the use of low-frequency rather than high-frequency stimulation or the targeting of alternative brain structures such as the pedunculopontine nucleus. In addition, further technical developments will soon provide clinicians with an expanded choice of hardware such as segmented electrodes allowing for a steering of the current to optimize beneficial effects and reduce side effects as well as the possibility of adaptive stimulation systems based on closed-loop concepts with or without accompanying advances in programming and imaging software. In the present article, we will provide an update on the most recent achievements and discoveries relevant to the application of DBS in the treatment of movement disorder patients and give an outlook on future clinical and technical developments.