Bilateral Pallidal Deep Brain Stimulation Research Articles

Bilateral Pallidal Deep Brain Stimulation in Meige Syndrome: Effects on Motor Function, Neuropsychological Status, and Mood.

Bilateral pallidal deep brain stimulation (DBS) has been broadly accepted as a feasible surgical procedure for treating various forms of dystonia, but its effects on motor function, neuropsychological status, and mood in patients with Meige syndrome have rarely been examined. To evaluate the effects of bilateral globus pallidus internus DBS (GPi-DBS) on the motor performance, quality of life, neuropsychological status, and mood of patients with primary Meige syndrome. Between January 2015 and April 2019, the database of 35 patients with Meige syndrome who underwent bilateral GPi-DBS in our institution was retrospectively reviewed. The severity of dystonia, health-related quality of life, cognitive function, and mood were assessed using standardized and validated rating scales at baseline. Repeat assessment of the same domains was performed at 1 year and 3 years after neurostimulation in a similar manner. One year and 3 years after bilateral GPi-DBS, Burke-Fahn-Marsden Dystonia Rating Scale movement scores were improved by 65% and 72% and Burke-Fahn-Marsden Dystonia Rating Scale disability scores were improved by 49% and 57%, respectively. The significant improvement in health-related quality of life observed at 1 year was sustained at 3 years. Relative to baseline and to the 1-year assessment, cognitive functions and mood remained stable after 3 years of neurostimulation. No deaths or life-threatening events were reported over the study period. Bilateral GPi-DBS is a safe and effective approach for medically refractory Meige syndrome that can improve motor function and quality of life without cognitive and mood side effects.

HP08: Deep Brain Stimulation Evoked Potentials in Children with dystonia

Pallidal Deep Brain Stimulation (DBS) is an established therapy for dystonia. Stimulation parameters are currently determined empirically. Recording the cortical response to the pallidal stimulus, known as Deep Brain Stimulation Evoked Potentials (DBSEPs) could provide a more objective measure of optimal contact selection (Tisch et al, MovDisord 2008;23:265-73; Bhanpuri et al, BrainStim 2014;7:718-26). Methods: Fifteen children with dystonia participated (age 7-19years), all with bilateral pallidal DBS implanted at least 6 months previously. Scalp EEG (10-20 system) was sampled at 5KHz. Contacts from each stimulating electrode were tested separately, using 6Hz bipolar stimulation. Pairs of electrode contacts were tested sequentially using combinations of cathodal stimulation (2 volts) with an adjacent anode, and pulse width at the patient’s therapeutic level. Each combination was recorded for 3 minutes, giving >1000 stimuli per contact pair. Therapeutic settings were restored on study completion. Offline, the DBS stimulus artefact was used to segment EEG data into epochs (10ms pre-stimulus, 150ms post-stimulus). After artefact rejection, 900-1100 epochs were averaged to obtain the DBSEP for each contact pair. Results: Clear DBSEPs were obtained in 12/15 patients on one or both sides, with peak latency of 20ms, and largest amplitude over the ipsilateral central/centro-parietal region, concordant with adult literature. In 3/15 patients no convincing DBSEP was obtained. Conclusion: To our knowledge this is the largest study of DBSEPs in dystonia and confirms the feasibility and tolerability of this technique in children. Future work will investigate potential clinical applications of DBSEPs to inform an individualised approach to DBS parameter selection.

Marie Vidailhet: recognising the importance of teamwork

The city of Toulouse in southern France is filled with a rich history of heroes, adventure, and challenges; where Concorde made its first test flight and the French National Centre for Space Studies obtained stunning satellite images of Earth. It is also the birthplace of Marie Vidailhet, professor of neurology and head of the Movement Disorders and Parkinson's Disease department at the Salpêtrière Hospital—the “cradle of neurology” in France (Sorbonne University, Paris). Bilateral, pallidal, deep-brain stimulation in primary generalised dystonia: a prospective 3 year follow-up studyBilateral pallidal stimulation provides sustained motor benefit after 3 years. Mild long-term improvements in quality of life and attention were also observed. Full-Text PDF Bilateral pallidal deep brain stimulation for the treatment of patients with dystonia-choreoathetosis cerebral palsy: a prospective pilot studyBilateral pallidal neurostimulation could be an effective treatment option for patients with dystonia-choreoathetosis CP. However, given the heterogeneity of motor outcomes and the small sample size, results should be interpreted with caution. The optimum placement of the leads seemed to be a crucial, but not exclusive, factor that could affect a good outcome. Full-Text PDF

Tardive Blepharospasm May Respond to Bilateral Pallidal Deep Brain Stimulation

Background:To date, there have been no reports of tardive blepharospasm being treated with deep brain stimulation (DBS), though there have been two reports of focal blepharospasm responding favorably to bilateral pallidal DBS.Case:A 34 year old man with tardive blepharospasm that was refractory to oral medications as well as botulinum toxin types A and B underwent bilateral pallidal DBS under general anesthesia. He had significant improvement of his severe blepharospasm by one and half months post-DBS which was sustained at last follow-up 30 months post-DBS. The best programming parameters included pulse widths of 90–100 µsec, frequencies of 140–150 Hz, and stimulating the ventral contacts in each side.Conclusion:Our case represents the first report of medically refractory tardive blepharospasm responding favorably to bilateral pallidal DBS.

Case Report: Globus Pallidus Internus (GPi) Deep Brain Stimulation Induced Keyboard Typing Dysfunction.

Introduction:Typing on a keyboard requires complex collaboration between visuospatial/procedural memory, language, and motor function. The impaired ability to type, independent of motor deficits, apraxia, or aphasia has been coined “dystypia.”Case Presentation: A 68-year-old woman with a history of blepharospasm, oromandibular, and segmental dystonia underwent bilateral pallidal deep brain stimulation (DBS) because of a waning response to botulinum toxin therapy. Following DBS, she discovered she no longer “remembered” how to type fluidly and had to “hunt and peck” for letters on the keyboard. This issue persisted at a 2-year follow-up. The patient underwent serial typing tests with the DBS ON vs. OFF. Post-operative lead reconstruction was performed using Lead-DBS. The volume of tissue activation (VTA) modeling was combined with whole-brain tractography.Results: Typing improved when the device was switched to the DBS OFF state. Cortical mapping revealed strong modulation of the right angular gyrus, left calcarine fissure, and left cuneus. There was also activation of bilateral supplemental motor areas and superior parietal gyri.Discussion: Shared lesion topography analysis of dystypia cases in the literature has suggested the involvement of the superior longitudinal fasciculus (SLF). The SLF involves the superior parietal lobe, angular gyrus, supramarginal gyrus, and arcuate fasciculus. Our patient’s connectivity pattern suggested SLF involvement. The improvement in OFF state typing and her imaging together suggested that the dystypia in her case was a stimulation-induced side effect.Conclusion: Dystypia is a rare side effect of Globus Pallidus Internus (GPi) DBS therapy and may be associated with SLF involvement.

Deep brain stimulation reduces (nocturnal) dyskinetic exacerbations in patients with ADCY5 mutation: a case series

Mutations in the ADCY5 gene can cause a complex hyperkinetic movement disorder. Episodic exacerbations of dyskinesia are a particularly disturbing symptom as they occur predominantly during night and interrupt sleep. We present the clinical short- and long-term effects of pallidal deep brain stimulation (DBS) in three patients with a confirmed pathogenic ADCY5 mutation. Patients were implanted with bilateral pallidal DBS at the age of 34, 20 and 13 years. Medical records were reviewed for clinical history. Pre- and postoperative video files were assessed using the “Abnormal Involuntary Movement Scale” (AIMS) as well as the motor part of the “Burke Fahn Marsden Dystonia Rating Scale” (BFMDRS). All patients reported subjective general improvement ranging from 40 to 60%, especially the reduction of nocturnal episodic dyskinesias (80–90%). Objective scales revealed only a mild decrease of involuntary movements in all and reduced dystonia in one patient. DBS-induced effects were sustained up to 13 years after implantation. We demonstrate that treatment with pallidal DBS was effective in reducing nocturnal dyskinetic exacerbations in patients with ADCY5-related movement disorder, which was sustained over the long term.

Long-term effects of bilateral pallidal deep brain stimulation in dystonia: a follow-up between 8 and 16\xa0years

ObjectiveObservational study to evaluate the long-term motor and non-motor effects of deep brain stimulation (DBS) of the globus pallidus internus (GPi) on medically refractory dystonia.BackgroundDystonia is a chronic disease affecting mainly young patients with a regular life expectancy and lifelong need for therapy. Pallidal DBS is an established treatment for severe isolated dystonia but long-term data are sparse.MethodsWe considered 36 consecutive patients with isolated generalized (n = 14) and cervical/segmental (n = 22) dystonia operated at Charité-University Hospital between 2000 and 2007 in a retrospective analysis for long-term outcome of pallidal DBS. In 19 of these patients, we could analyze dystonic symptoms and disability rated by the Burke–Fahn–Marsden Dystonia Rating scale (BFMDRS) at baseline, short-term (ST-FU, range 3–36 months) and long-term follow-up (LT-FU, range 93–197 months). Quality of life and mood were evaluated using the SF36 and Beck Depression Index (BDI) questionnaires.ResultsPatients reached an improvement in motor symptoms of 63.8 ± 5.7% (mean ± SE) at ST-FU and 67.9 ± 6.1% at LT-FU. Moreover, a significant and stable reduction in disability was shown following DBS (54.2 ± 9.4% at ST-FU and 53.8 ± 9.2% at LT-FU). BDI and SF36 had improved by 40% and 23%, respectively, at LT-FU (n = 14). Stimulation-induced adverse events included swallowing difficulties, dysarthria, and bradykinesia. Pulse generator (n = 3) and electrodes (n = 5) were revised in seven patients due to infection.ConclusionsPallidal DBS is a safe and efficacious long-term treatment for dystonia with sustained effects on motor impairment and disability, accompanied by a robust improvement in mood and quality of life.

Interleaving stimulation mode can improve better the health-related quality of life in primary generalized or segmental dystonia than standard bilateral pallidal deep brain stimulation

For the treatment of drug-refractory dystonia, bilateral pallidal deep brain stimulation (GPi-DBS) is proven to be an efficient option. However, a considerable portion (10–25%) of patients experience minimal alleviation despite good electrode placement. These patients can be regarded as non-responders to GPi-DBS. In cases series, the interleaving stimulation mode (ILSM) could improve dystonia in patients not responding to standard stimulation techniques. T In this prospective, randomized, double-blind and cross-over study, 34 patients with primary generalized or segmental dystonia were enrolled. Patients underwent four visits: (1) preoperative, (2) prestimulation (4 weeks after electrode implantation BUT before turning on the stimulation), (3) 3 months and (4) 6 months stimulation. Based on electrode location, the best two contacts were activated with submaximal amplitude, 120 μs, and 130 Hz. Patients were randomly assigned to either DMSM-ILSM or ILSM-DMSM sequence. Changes in Burke-Fahn-Marsden DRS, health-related quality of life (SF-36) and side-effects were compared Thirty patients completed the study protocol. A linear mixed model analysis was used to compare the efficacy of the two stimulation modes. The dystonia severity (DRS) significantly improved from the preoperative 33 points (median) to 10 points (median) after 6 months of stimulation (p = .001). There was a trend that ILSM was more efficient (p = .094). The SF-36 improved significantly from the preoperative 49 (median) to 74 (median) after 6 months stimulation (p = .001). The ILSM was superior to the DMSM (p = .010). Although the interleaving stimulation was only tendentiously better at reducing dystonia severity, it was associated with better health-related quality of life.

P.012 Bilateral pallidal deep brain stimulation in a patient with chorea-acanthocytosis

Background: Chorea-acanthocytosis (ChAc) is a rare autosomal recessive neurodegenerative disease due to mutation of the VPS13A gene encoding the protein chorein. ChAc is a slowly progressive disorder that typically presents in early adulthood, and whose clinical features include chorea and dystonia with involuntary lip, cheek and tongue biting. Some patients also have seizures. Treatment for ChAc is symptomatic. A small number of ChAc patients have been treated with bilateral deep brain stimulation (DBS) of the globus pallidus interna (GPi), and we now present an additional case. Methods: Patient chart, functional measures, and laboratory findings were reviewed from the time of ChAc diagnosis until 6 months after deep brain stimulation (DBS) surgery. Results: Here we present a case of ChAc in a 31 year old male positive for VPS13A gene muations who presented with chorea, tongue biting, dysarthria, weight loss, and mild cognitive dysfunction. GPi-DBS using monopolar stimulation was associated with significant improvement in chorea and dysarthria. Conclusions: This case adds to the current state of knowledge regarding the efficacy and safety of bilateral GPi-DBS for symptomatic control of drug-resistant hyperkinetic movements seen in ChAc. Controlled trials are needed to better assess the impact of DBS in ChAc.

Amelioration of Dystonic Opisthotonus in Pantothenate Kinase-Associated Neurodegeneration Syndrome with Absent "Eye-of-the-Tiger" Sign Following Bilateral Pallidal Deep Brain Stimulation.

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Long-Term Outcomes of Bilateral Pallidal Deep Brain Stimulation for X-Linked Dystonia and Parkinsonism

Background: X-linked dystonia parkinsonism (XDP) causes adult-onset progressive dystonia and parkinsonism, which may not respond to pharmacotherapy. Objective: Previous case reports have reported beneficial effects from bilateral pallidal (GPi) deep brain stimulation (DBS). Here, we report the long-term clinical outcomes of 3 patients treated at our center. Methods: All patients presented with medication refractory dystonia and parkinsonism. They were followed prospectively. Clinical evaluations included the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and the Unified Parkinson’s Disease Rating Scale (UPDRS). Adverse events were recorded. Results: The average length of follow-up was 45.7 months. No serious adverse events occurred. All patients experienced an immediate and sustained improvement in dystonia. Mean percentage improvement in motor subscores of BFMDRS was 63.5% at the last follow-up visit. Parkinsonism was less responsive to neuromodulation, with a mean improvement in UPDRS-III of 39.5%. Standard pallidal stimulation parameters were used. Freezing of gait developed after DBS therapy in 2 patients, stimulation-induced in one and due to disease progression in the other. Conclusion: Bilateral pallidal DBS resulted in significant and sustained improvement in dystonia and moderate improvement in parkinsonism. Pallidal DBS represents an important treatment option for XPD for the management of motor symptoms.

Pallidal and thalamic neural oscillatory patterns in tourette's syndrome.

Aberrant oscillatory activity has been hypothesized to play a role in the pathophysiology of Tourette's syndrome (TS). Deep brain stimulation (DBS) has recently been established as an effective treatment for severe TS. Modulation of symptom-specific oscillations may underlie the mechanism of action of DBS and could be used for adaptive neuromodulation to improve therapeutic efficacy. The objective of this study was to demonstrate a pathophysiological association of pallidal and thalamic local field potentials (LFPs) with TS. Nine medication-refractory TS patients were included in the study. Intracerebral LFPs were recorded simultaneously from bilateral pallidal and thalamic DBS electrodes. Spectral and temporal dynamics of pallidal and thalamic oscillations were characterized and correlated with preoperative Yale Global Tic Severity Scale (YGTSS) scores. Peaks of activity in the theta (3-12Hz) and beta (13-35Hz) were present in pallidal and thalamic recordings from all patients (3 women/6 men; mean age, 29.8 years) and coupled through coherence across targets. Presence of prolonged theta bursts in both targets was associated with preoperative motor tic severity. Total preoperative YGTSS scores (mean, 38.1) were correlated with pallidal and thalamic LFP activity using multivariable linear regression (R² = 0.96; p = 0.02). Our findings suggest that pallidothalamic oscillations may be implicated in the pathophysiology of TS. Furthermore, our results highlight the utility of multisite and -spectral oscillatory features in severely affected patients for future identification and clinical use of oscillatory physiomarkers for adaptive stimulation in TS. Ann Neurol 2018;84:505-514.

Long-term outcomes of pallidal deep brain stimulation in X-linked dystonia parkinsonism (XDP): Up to 84 months follow-up and review of literature

IntroductionX-linked dystonia-parkinsonism (XDP/DYT3/Lubag) patients had improved dystonia and parkinsonism with bilateral pallidal deep brain stimulation (DBS) in the literature. MethodWe reviewed eleven XDP patients who underwent bilateral pallidal DBS from October 2009 to September 2018. The Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and Unified Parkinson's Disease Rating Scale (UPDRS)-III scores were reviewed from baseline up to the longest follow-up together with the demographic and clinical data. The published case reports on DBS in XDP were also reviewed. ResultsThe mean age was 39 ± 9.2 years with a mean disease duration of 3 years (range 1–9 years). An immediate response for dystonia post-DBS (1 month) was seen in all cases, with a mean BFMDRS score of 23.3 ± 12.12 [from a mean baseline of 36.3 ± 12.1] and a small change in the mean UPDRS-III score of 20 ± 10.39 [from a mean baseline of 24.04 ± 8.74]. At 12 months (n = 10), the mean BFMDRS score was 13.7 ± 10.63 and the mean UPDRS-III score was 19 ± 13.19. There was improvement in the clinical and functional stage of the patients, with majority in Stage 1 (n = 3) and Stage 2 (n = 5) at their last follow-up. ConclusionBilateral pallidal DBS should be considered as a treatment option for XDP. It is effective in the first 12 months in controlling dystonia with variable response in controlling parkinsonism. It may be effective in up to 72–84 months, as seen in three patients.

Phenotype variability and allelic heterogeneity in KMT2B-Associated disease

BackgroundMutations in Lysine-Specific Histone Methyltransferase 2B gene (KMT2B) have been reported to be associated with complex early-onset dystonia. Almost all reported KMT2B mutations occurred de novo in the paternal germline or in the early development of the patient. We describe clinico-genetic features on four Japanese patients with novel de novo mutations and demonstrate the phenotypic spectrum of KMT2B mutations. MethodsWe performed genetic studies, including trio-based whole exome sequencing (WES), in a cohort of Japanese patients with a seemingly sporadic early-onset generalized combined dystonia. Potential effects by the identified nucleotide variations were evaluated biologically. Genotype-phenotype correlations were also investigated. ResultsFour patients had de novo heterozygous mutations in KMT2B, c.309delG, c.1656dupC, c.3325_3326insC, and c.5636delG. Biological analysis of KMT2B mRNA levels showed a reduced expression of mutant transcript frame. All patients presented with motor milestone delay, microcephaly, mild psychomotor impairment, childhood-onset generalized dystonia and superimposed choreoathetosis or myoclonus. One patient cannot stand due to axial hypotonia associated with cerebellar dysfunction. Three patients had bilateral globus pallidal deep brain stimulation (DBS) with excellent or partial response. ConclusionsWe further demonstrate the allelic heterogeneity and phenotypic variations of KMT2B-associated disease. Haploinsufficiency is one of molecular pathomechanisms underlying the disease. Cardinal clinical features include combined dystonia accompanying mild psychomotor disability. Cerebellum would be affected in KMT2B-associated disease.

Excellent outcome after bilateral pallidal deep brain stimulation in generalized dystonia due to amphetamine-induced bilateral basal ganglia necrosis

Excellent outcome after bilateral pallidal deep brain stimulation in generalized dystonia due to amphetamine-induced bilateral basal ganglia necrosis

Effects of bilateral pallidal deep brain stimulation on chorea after pulmonary thromboendarterectomy with deep hypothermia and circulatory arrest: a case report

A 41-year-old man was diagnosed with chronic pulmonary thromboembolism and underwent pulmonary thromboendarterectomy (PTE) with deep hypothermia and circulatory arrest. Five days after the operation, chorea emerged in the lower extremities. The patient was referred to our hospital for disabling chorea 16years after PTE. Neurological examination revealed choreatic movements in the four extremities. Brain magnetic resonance images indicated atrophy in the bilateral head of the caudate nuclei. The patient underwent deep brain stimulation (DBS) of the bilateral globus pallidus interna (GPi). Continuous GPi-DBS diminished the choreatic movements. GPi-DBS may be a treatment option for sustained choreatic movements after PTE.

Assessment of speech and swallowing functions in pediatric dystonia and monitoring under deep brain stimulation

Objective: Speech impairment and dysphagia are common in movement disorders such as Parkinson's disease; however, both are major features in different forms of dystonia. Despite the frequent cranial involvement in childhood onset dystonias, the assessment of specific symptoms such as dysarthria, dysphonia and dysphagia and the impact of therapeutics, has been only exceptionally addressed Our objective is to assess, in a group of pediatric dystonia patients recruited for deep brain stimulation (DBS), the proportion of patients presenting with dysphagia and speech impairment, relationship with underlying etiology and response to DBS. Methods: We retrospectively studied all pediatric cases under 17 who underwent DBS for generalized dystonia with cranio-cervical involvement, responsible for dysarthria, dysphagia and dysphonia. Clinical examination included the Burke-Fahn Marsden dystonia rating scale for assessment of speech and swallowing impairment. Water test and fiber optic endoscopic evaluation (FEES) of swallowing was available for several patients. The outcome of DBS effect on these three symptoms has been monitored. Results: Out of 120 pediatric generalized dystonia cases followed for bilateral pallidal DBS, 81 presented (67,5%) with cranio-cervical dystonia exhibiting dysphagia and or speech impairment. Major documented etiologies were Pantothenate kinase associated neurodegeneration (11 patients), mitochondiral enkephalopathy (8) and dyskinetic cerebral palsy secondary to hypoxic- ischemic enkephalopathy (19 patients). Both, dysphagia and speech impairment were more frequently associated in progressive disorders. Dysphagia was more frequently improved compared to speech impairment. In six patients, improvement of swallowing was sufficient enough to allow PEG suppression. Conclusion: When compared to Parkinson's disease, despite comparable speech and swallowing impairment in childhood dystonia (80% versus 67,5%) little is known about the impact of DBS. Our study document symptoms characteristics, severity and evolution under DBS therapy and provide arguments in favour of positive outcome in axial and limb dystonia but also in cranial involvement in a subgroup of patients.

Improvement of Post-hypoxic Myoclonus with Bilateral Pallidal Deep Brain Stimulation: A Case Report and Review of the Literature.

BackgroundPost-hypoxic myoclonus (PHM) is a syndrome that occurs when a patient has suffered hypoxic brain injury. The myoclonus is usually multifocal and generalized, often stemming from both cortical and subcortical origins. In severe cases, pharmacological treatments with antiepileptic medications may not satisfactorily control the myoclonus.MethodsWe present a case of a 23-year-old male with chronic medication refractory PHM following a cardiopulmonary arrest related to an asthmatic attack who improved with bilateral globus pallidus internus (GPi) deep brain stimulation (DBS). We review the clinical features of PHM, as well as the preoperative and postoperative Unified Myoclonus Rating Scale scores and DBS programming parameters in this patient and compare them with the three other published PHM-DBS cases in the literature.ResultsThis patient experienced an alleviation of myoclonic jerks at rest and a 39% reduction in action myoclonus with improvement in both positive and negative myoclonus with bilateral GPi-DBS. High frequency stimulation (130 Hz) with amplitudes >2.5 V were needed for the therapeutic response.DiscussionWe demonstrate a robust improvement in a medication refractory PHM patient with bilateral GPi-DBS, and suggest that it is a viable therapeutic option for debilitating post-hypoxic myoclonus.

Improvement of Post Anoxic Myoclonus with Valproic Acid and Add on Levetiracetam Therapy

Myoclonus may be defined as sudden muscle contractions that are brief, involuntary, and shock-like. There are many conditions that can lead to myoclonus including spinal cord injury, stroke and as a side effect of certain drugs. Post hypoxic myoclonus is a recognized entity that develops post successful resuscitation of cardiac arrest and this is known in the literature as Lance Adams Syndrome. Often myoclonus is confused with an underlying seizure disorder. Myoclonic status epilepticus at any time after return of spontaneous circulation (ROSC) is even considered to reliably indicate a poor prognosis. Different treatments have been attempted to manage post hypoxic myoclonus including valproic acid and clonazepam and even Bilateral Pallidal Deep Brain Stimulation. The authors would like to present a case report of a 59-years-old male with chronic post hypoxic myoclonus who was successful treated with a combination medication regime of valproic acid and levetiracetam.

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.