Intraputaminal Gene Delivery in Two Patients with Aromatic L-Amino Acid Decarboxylase Deficiency

BACKGROUND

Aromatic l-amino acid decarboxylase deficiency (AADCD) is a rare, early-onset, dyskinetic encephalopathy mostly reflecting a defective synthesis of brain dopamine and serotonin. Intracerebral gene delivery (GD) provided a significant improvement among AADCD patients (mean age, ≤6 years).

OBJECTIVE

We describe the clinical, biological, and imaging evolution of two AADCD patients ages >10 years after GD.

METHODS

Eladocagene exuparvovec, a recombinant adeno-associated virus containing the human complimentary DNA encoding the AADC enzyme, was administered into bilateral putamen by stereotactic surgery.

RESULTS

Eighteen months after GD, patients showed improvement in motor, cognitive and behavioral function, and in quality of life. Cerebral l-6-[18F] fluoro-3, 4-dihydroxyphenylalanine uptake was increased at 1 month, persisting at 1 year compared to baseline.

CONCLUSION

Two patients with a severe form of AADCD had an objective motor and non-motor benefit from eladocagene exuparvovec injection even when treated after the age of 10 years, as in the seminal study.

Deep brain stimulation effect in genetic dyskinetic cerebral palsy: The case of ADCY5- related disease

BACKGROUND

Cerebral Palsy (CP) represents a frequent cause of disability in childhood. Early in life, genetic disorders may present with motor dysfunction and diagnosed as CP. Establishing the primary, genetic etiology allows more accurate prognosis, genetic counselling, and planning for symptomatic interventions in homogeneous etiological groups. Deep brain stimulation (DBS) is recommended in refractory movement disorders, including isolated pediatric dystonias. For dystonia evolving in more complex associations in genetic CP, the effect of DBS is still understudied and currently only sporadically described.

OBJECTIVES

To report the effect of DBS applied to the globus pallidus pars interna (GPi) in children with complex movement disorders caused by pathogenic ADCY5 variants, diagnosed as dyskinetic CP previous to genetic diagnostic.

METHODS

We conducted a retrospective study on evolution of treatment with DBS in ADCY5-related disease. A standardized proforma including the different type of movement disorders and associated neurological signs was completed at each follow-up time, based on video recordings, as well as functional assessments used in children with CP.

RESULTS

Four children (mean of age, 13 ± 2.9 years) received GPi-DBS. The same de novo pathogenic missense variant (c.1252C > T, p.R418W) was identified in three out of four and a splice site variant (c.2088 + 2G > T) in one subject. Developmental delay and overlapping features including axial hypotonia, chorea, dystonic attacks, myoclonus, and cranial dyskinesia were present. The median age at DBS was 9 years and follow-up with DBS, 2.6 years. We identified a pattern of clinical response with early suppression of dystonic attacks, followed by improvement of myoclonus and facial dyskinesia. Effect on chorea was delayed and more limited. Two patients gained notable functional benefit related to sitting, standing, gait, use of upper limbs and speech.

CONCLUSION

ADCY5-related disease may benefit from GPi-DBS. The most significant clinical response relates to the early and sustained benefit on dystonic attacks and a variable but still positive response on the other hyperkinetic features. Genetic etiology of CP will contribute to further elucidate genotype-phenotype correlations and to refine DBS indication as network-related symptomatic interventions.

Submammary Implantation of Internal Pulse Generators for Deep Brain Stimulation: Long-Term Follow-up of Device Acceptance and Quality of Life in Women

BACKGROUND

A submammary approach to implanting pulse generators is innovative and has yielded good aesthetic results in the current literature. It was our aim to make a comparison of patient device acceptance, tolerance, and complications between submammary and abdominal device locations in deep brain stimulation.

METHODS

Twenty-five and 28 patients were included in the submammary and abdominal groups, respectively. Our primary criterion was patient acceptance that was calculated using total Florida Patient Acceptance Survey (FPAS) scores in each group. Secondarily, tolerance was assessed in the submammary group by means of a specific questionnaire.

RESULTS

Total FPAS scores from the submammary group [total FPAS: 77.1 versus 74.7, P = 0.29] revealed no significant difference when compared with the abdominal group. The same similarities were observed regarding the 4 subscales: return to function [16.3 versus 15.8, P = 0.53], device-related distress [22.0 versus 21.3, P = 0.31], body image concerns [9.2 versus 8.6, P = 0.14], and positive appraisal [17.8 versus 17.4, P = 0.58]. Tolerance was reported as good by the majority of the women from the submammary group. There was no evidence of higher infection rates in the submammary implantation (SMI) group.

CONCLUSIONS

SMI is a satisfactory alternative to other deep brain stimulation locations. SMI is a feasible option for any young woman who is eligible for deep brain stimulation.

Microendoscopic transventricular deep brain stimulation of the anterior nucleus of the thalamus as a safe treatment in intractable epilepsy: A feasibility study

INTRODUCTION

Deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) is proposed in patients with severe intractable epilepsy. When used, the transventricular approach increases the risk of bleeding due the anatomy around the entry point in the thalamus. To avoid such a complication, we used a transventricular microendoscopic technique.

METHODS

We performed a retrospective study of nine adult patients who were surgically treated for refractory epilepsy between 2010 and 2019 by DBS of the anterior thalamic nucleus.

RESULTS

Endoscopy provides a direct visual control of the entry point of the lead in the thalamus through the ventricle by avoiding ependymal vessels. No hemorrhage was recorded and accuracy was systematically checked by intraoperative stereotactic MRI. We reported a responder rate improvement in 88.9% of patients at 1 year and in 87.5% at 2 years. We showed a significant decrease in global seizure count per month one year after DBS (68.1%; P=0.013) leading to an overall improvement in quality of life. No major adverse effect was recorded during the follow-up. ANT DBS showed a prominent significant effect with a decrease of the number of generalized seizures.

CONCLUSION

We aimed at a better ANT/lead collimation using a vertical transventricular approach under microendoscopic monitoring. This technique permitted to demonstrate the safety and the accuracy of the procedure.

Transcutaneous ventriculo-peritoneal shunt catheter extrusion with silent bowel perforation following digestive surgery: a case report

This case report provides an account of transcutaneous ventriculo-peritoneal (VP) shunt extrusion with silent bowel perforation occurring 2 years post digestive surgery. A 22-year-old man treated since childhood for post-infectious hydrocephalus was referred to our neurosurgery department for an inflammatory wound to the right hypochondrium caused by an abandoned calcified VP shunt. This VP shunt was surgically removed without complications. The perforated bowel required no direct repair. Progress is favorable at 1 year follow-up.

KMT2B-related disorders: expansion of the phenotypic spectrum and long-term efficacy of deep brain stimulation

Heterozygous mutations in KMT2B are associated with an early-onset, progressive and often complex dystonia (DYT28). Key characteristics of typical disease include focal motor features at disease presentation, evolving through a caudocranial pattern into generalized dystonia, with prominent oromandibular, laryngeal and cervical involvement. Although KMT2B-related disease is emerging as one of the most common causes of early-onset genetic dystonia, much remains to be understood about the full spectrum of the disease. We describe a cohort of 53 patients with KMT2B mutations, with detailed delineation of their clinical phenotype and molecular genetic features. We report new disease presentations, including atypical patterns of dystonia evolution and a subgroup of patients with a non-dystonic neurodevelopmental phenotype. In addition to the previously reported systemic features, our study has identified co-morbidities, including the risk of status dystonicus, intrauterine growth retardation, and endocrinopathies. Analysis of this study cohort (n = 53) in tandem with published cases (n = 80) revealed that patients with chromosomal deletions and protein truncating variants had a significantly higher burden of systemic disease (with earlier onset of dystonia) than those with missense variants. Eighteen individuals had detailed longitudinal data available after insertion of deep brain stimulation for medically refractory dystonia. Median age at deep brain stimulation was 11.5 years (range: 4.5-37.0 years). Follow-up after deep brain stimulation ranged from 0.25 to 22 years. Significant improvement of motor function and disability (as assessed by the Burke Fahn Marsden's Dystonia Rating Scales, BFMDRS-M and BFMDRS-D) was evident at 6 months, 1 year and last follow-up (motor, P = 0.001, P = 0.004, and P = 0.012; disability, P = 0.009, P = 0.002 and P = 0.012). At 1 year post-deep brain stimulation, >50% of subjects showed BFMDRS-M and BFMDRS-D improvements of >30%. In the long-term deep brain stimulation cohort (deep brain stimulation inserted for >5 years, n = 8), improvement of >30% was maintained in 5/8 and 3/8 subjects for the BFMDRS-M and BFMDRS-D, respectively. The greatest BFMDRS-M improvements were observed for trunk (53.2%) and cervical (50.5%) dystonia, with less clinical impact on laryngeal dystonia. Improvements in gait dystonia decreased from 20.9% at 1 year to 16.2% at last assessment; no patient maintained a fully independent gait. Reduction of BFMDRS-D was maintained for swallowing (52.9%). Five patients developed mild parkinsonism following deep brain stimulation. KMT2B-related disease comprises an expanding continuum from infancy to adulthood, with early evidence of genotype-phenotype correlations. Except for laryngeal dysphonia, deep brain stimulation provides a significant improvement in quality of life and function with sustained clinical benefit depending on symptoms distribution.

Task- and Rest-based Functional Brain Connectivity in Food-related Reward Processes among Healthy Adolescents

It is known that the nucleus accumbens, orbitofrontal cortex and insula play a role in food-related reward processes. Although their interconnectedness would be an ideal topic for understanding food intake mechanisms, it nevertheless remains unclear especially in adolescent. Therefore, this study aims to investigate the effect of hunger on functional connectivity in healthy adolescents using task- and rest-based imaging. Fifteen participants underwent two MRI sessions, pre-lunch (hunger) and post-lunch (satiety), including food cue task and resting-state. During task- and rest-based imaging, functional connectivity was greater when hungry as opposed to satiated between the right posterior insula/nucleus accumbens, suggesting involvement of salient interoceptive stimuli signals. During task-based imaging, an increase was observed in functional connectivity when hungry as opposed to satiated between the medial and lateral orbitofrontal cortex which contributes to the perception of food deprivation as a frustration. A decrease was identified when hungry as opposed to satiated in functional connectivity in the right anterior orbitofrontal/accumbens and posterior insula/medial orbitofrontal cortices reflecting suppression of the affective and sensorial information. Conversely, functional connectivity was increased during aversive stimuli between the right medial orbitofrontal cortex and right posterior insula when hungry as opposed to satiated. This suggests that the value of valence could occur in the shift in connectivity between these two regions. In addition, during rest-based imaging, a left-sided lateralization was reported (accumbens/lateral orbitofrontal and accumbens/posterior insula) when hungry as opposed to satiated which may represent changes in internal state due to focus on the benefit of an upcoming meal.

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.

Dentate nucleus as target for deep brain stimulation in dystono-dyskinetic syndromes

PURPOSE

To discuss the potential of deep brain stimulation (DBS) of the dentate nucleus as a treatment for dystono-dyskinetic syndromes.

METHODS

An extensive literature review covered the anatomy and physiology of the dentate nucleus and the experimental evidence for its involvement in the pathophysiology of dystonia and dyskinesia.

RESULTS

Evidence from animal models and from functional imaging in humans is strongly in favor of involvement of the dentate nucleus in dystono-dyskinetic syndromes. Results from previous surgical series of dentate nucleus stimulation were promising but precise description of movement disorders being treated were lacking and outcome measures were generally not well defined.

CONCLUSIONS

In the light of new evidence regarding the involvement of the dentate nucleus in dystono-dyskinetic syndromes, we present a review of the current literature and discuss why the question of dentate nucleus stimulation deserves to be revisited.

Secondary Worsening Following DYT1 Dystonia Deep Brain Stimulation: A Multi-country Cohort

Objective: To reveal clinical characteristics of suboptimal responses to deep brain stimulation (DBS) in a multi-country DYT1 dystonia cohort. Methods: In this multi-country multi-center retrospective study, we analyzed the clinical data of DYT1 patients who experienced suboptimal responses to DBS defined as <30% improvement in dystonia scales at the last follow-up compared with baseline. We used a literature-driven historical cohort of 112 DYT1 patients for comparison. Results: Approximately 8% of our study cohort (11 out of 132) experienced suboptimal responses to DBS. Compared with the historical cohort, the multi-country cohort with suboptimal responses had a significantly younger age at onset (mean, 7.0 vs. 8.4 years; p = 0.025) and younger age at DBS (mean, 12.0 vs. 18.6 years; p = 0.019). Additionally, cranial involvement was more common in the multi-country cohort (before DBS, 64% vs. 45%, p = 0.074; before or after DBS, 91% vs. 47%, p = 0.001). Mean motor improvement at the last follow-up from baseline were 0% and 66% for the multi-country and historical cohorts, respectively. All 11 patients of the multi-country cohort had generalization of dystonia within 2.5 years after disease onset. All patients experienced dystonia improvement of >30% postoperatively; however, secondary worsening of dystonia commenced between 6 months and 3 years following DBS. The improvement at the last follow-up was less than 30% despite optimally-placed leads, a trial of multiple programming settings, and additional DBS surgeries in all patients. The on-/off-stimulation comparison at the long-term follow-up demonstrated beneficial effects of DBS despite missing the threshold of 30% improvement over baseline. Conclusion: Approximately 8% of patients represent a more aggressive phenotype of DYT1 dystonia characterized by younger age at onset, faster disease progression, and cranial involvement, which seems to be associated with long-term suboptimal responses to DBS (e.g., secondary worsening). This information could be useful for both clinicians and patients in clinical decision making and patient counseling before and following DBS implantations. Patients with this phenotype may have different neuroplasticity, neurogenetics, or possibly distinct neurophysiology.

Pallidal Deep Brain Stimulation in DYT6 Dystonia: Clinical Outcome and Predictive Factors for Motor Improvement

Pallidal deep brain stimulation is an established treatment in dystonia. Available data on the effect in DYT-THAP1 dystonia (also known as DYT6 dystonia) are scarce and long-term follow-up studies are lacking. In this retrospective, multicenter follow-up case series of medical records of such patients, the clinical outcome of pallidal deep brain stimulation in DYT-THAP1 dystonia, was evaluated. The Burke Fahn Marsden Dystonia Rating Scale served as an outcome measure. Nine females and 5 males were enrolled, with a median follow-up of 4 years and 10 months after implant. All benefited from surgery: dystonia severity was reduced by a median of 58% (IQR 31-62, p = 0.001) at last follow-up, as assessed by the Burke Fahn Marsden movement subscale. In the majority of individuals, there was no improvement of speech or swallowing, and overall, the effect was greater in the trunk and limbs as compared to the cranio-cervical and orolaryngeal regions. No correlation was found between disease duration before surgery, age at surgery, or preoperative disease burden and the outcome of deep brain stimulation. Device- and therapy-related side-effects were few. Accordingly, pallidal deep brain stimulation should be considered in clinically impairing and pharmaco-resistant DYT-THAP1 dystonia. The method is safe and effective, both short- and long-term.

Deep brain stimulation treated dystonia-trajectory via status dystonicus

BACKGROUND

Status dystonicus (SD) is a life-threatening condition.

OBJECTIVE AND METHODS

In a dystonia cohort who developed status dystonicus, we analyzed demographics, background dystonia phenomenology and complexity, trajectory previous to-, via status dystonicus episodes, and evolution following them.

RESULTS

Over 20 years, 40 of 328 dystonia patients who were receiving DBS developed 58 status dystonicus episodes. Dystonia was of pediatric onset (95%), frequently complex, and had additional cognitive and pyramidal impairment (62%) and MRI alterations (82.5%); 40% of episodes occured in adults. Mean disease duration preceding status dystonicus was 10.3 ± 8 years. Evolution time to status dystonicus varied from days to weeks; however, 37.5% of patients exhibited progressive worsening over years. Overall, DBS was efficient in resolving 90% of episodes.

CONCLUSION

Status dystonicus is potentially reversible and a result of heterogeneous conditions with nonuniform underlying physiology. Recognition of the complex phenomenology, morphological alterations, and distinct patterns of evolution, before and after status dystonicus, will help our understanding of these conditions. © 2018 International Parkinson and Movement Disorder Society.

Rechargeable or Nonrechargeable Deep Brain Stimulation in Dystonia: A Cost Analysis

OBJECTIVE

Deep brain stimulation of the internal Globus Pallidus (GPi DBS) delivered by an implantable neurostimulator (INS) is an established, effective, and safe treatment option for patients with medically refractory primary dystonia. Compared to other DBS targets, the battery life of the INS is substantially shorter due to the higher energy demands required to penetrate the GPi resulting in faster battery depletion and more frequent hospitalizations for INS replacement. We, therefore, performed a cost analysis to compare a rechargeable DBS system, Activa®RC, with nonrechargeable systems, from the perspective of the French public health insurer.

MATERIALS AND METHODS

To estimate the cost of INS replacement in the nonrechargeable cohort, and costs potentially avoided in the hypothetical Activa^® RC cohort, the medical records of patients who had undergone GPi DBS with a nonrechargeable INS between 1996 and 2010 at a center in France were accessed. Replacement rates were estimated for up to nine years.

RESULTS

With Activa^® RC, a total of 315 hospitalizations for replacement procedures would have been avoided over nine years compared with a nonrechargeable INS, resulting in a discounted mean direct medical cost per patient over nine years of €50,119 with a nonrechargeable INS and €33,306 with Activa^® RC, a reduction of 34%.

CONCLUSIONS

The adoption of a rechargeable instead of a nonrechargeable INS for eligible patients with dystonia may provide substantial savings to the public health insurer in France.

Long-term follow-up of pallidal Deep Brain Stimulation in teenagers with refractory Tourette syndrome and comorbid psychiatric disorders: About three cases

OBJECTIVES

Tourette syndrome (TS) is a complex neuropsychiatric disorder associated with comorbid psychiatric disorders. Peak of tic severity typically occurs in early adolescence and impacts quality of life. Since 1999, promising therapeutic effects of Deep Brain Stimulation (DBS) have been reported in tic reduction for adults with refractory TS. The aim of the study was to assess the long-term risk-benefit ratio of pallidal DBS for young patients with refractory TS and severe comorbid psychiatric disorders.

METHODS

We retrospectively assessed the long-term clinical outcomes of three adolescents who underwent pallidal DBS for the treatment of refractory TS.

RESULTS

The mean duration of follow-up was 52 months in our case series. We observed that motor tics decreased with posteroventral GPi DBS in all patients, without reaching a continuous significance over the long-term follow-up. Self-reported social inclusion was globally improved, despite lack of efficacy of DBS on comorbid conditions.

CONCLUSIONS

These findings suggest a long-term therapeutic benefit of early DBS intervention for highly socially impaired young patients suffering from intractable TS with severe comorbid psychiatric conditions. Further studies are needed to determine the most effective targets of DBS on both tics and comorbid psychiatric profile of TS.

Historical developments in children's deep brain stimulation

BACKGROUND

Heterogeneous by the underlying pathobiology and clinical presentation, childhood onset dystonia is most frequently progressive, with related disability and limitations in functions of daily living. Consequently, there is an obvious need for efficient symptomatic therapies.

METHODS AND RESULTS

Following lesional surgery to basal ganglia (BG) and thalamus, deep brain stimulation (DBS) is a more conservative and adjustable intervention to and validated for internal segment of the globus pallidus (GPi), highly efficient in treating isolated "primary" dystonia and associated symptoms such as subcortical myoclonus. The role of DBS in acquired, neurometabolic and degenerative disorders with dystonia deserves further exploration to confirm as an efficient and lasting therapy. However, the pathobiological background with distribution of the sequellae over the central nervous system and related clinical features, will limit DBS efficacy in these conditions. Cumulative arguments propose DBS in severe life threatening dystonic conditions called status dystonicus as first line therapy, irrespective of the underlying cause. There are no currently available validated selection criteria for DBS in pediatric dystonia. Concurrent targets such as subthalamic nucleus (STN) and several motor nuclei of the thalamus are under exploration and only little information is available in children. DBS programming in paediatric population was adopted from experience in adults. The choice of neuromodulatory DBS parameters could influence not only the initial therapeutic outcome of dystonic symptoms but also its maintenance over time and potentially the occurrence of DBS related side effects.

CONCLUSION

DBS allows efficient symptomatic treatment of severe dystonia in children and advances pathophysiological knowledge about local and distributed abnormal neural activity over the motor cortical-subcortical networks in dystonia and other movement disorders.

A Case of Vertebrovertebral Arteriovenous Fistula Presenting with Subarachnoid Haemorrhage

A rare paediatric case of vertebrovertebral arteriovenous fistula presented with a subarachnoid haemorrhage.

A 12 year-old boy, who fell on his back at school, presented with a one week history of headache, vomiting, and double vision. Computed tomography (CT) scan revealed subarachnoid haemorrhage.

Magnetic resonance imaging (MRI) demonstrated a tortuous vessel on the anterior surface of the spinal cord. Selective angiography showed an arteriovenous fistula of the left vertebral artery at the level of C1.

The venous drainage of the fistula refluxed into the medullary vein at the level of C6-7, and drained upwards into the posterior fossa veins. An endovascular detachable balloon technique was employed and complete occlusion of the fistula was achieved.

Psychiatric comorbidity in temporal DNET and improvement after surgery

BACKGROUND

"Alien tissue" may be responsible for a higher frequency of psychiatric disorders in patients with temporal lobe epilepsy (TLE). Also, ganglioglioma and dysembryoplastic neuroepithelial tumors (DNET) could represent a risk-factor for the development of post-surgical psychoses. Classically, severe psychiatric disorders contra-indicate epilepsy surgery.

OBJECTIVES

Assessment of inter-ictal psychiatric disorders in 10 consecutive patients with temporal DNET, before and after epilepsy surgery with a minimum of a 2-year follow-up evaluation.

METHODS

DNETs were confirmed on histological examination. Psychiatric disorders were classified according to the DSM-IV-TR.

RESULTS

Five patients presented inter-ictal psychiatric disorders with, according to the DSM-IV-TR, undifferentiated schizophrenia (one case), "borderline" personality (two cases), intermittent explosive disorder with slight mental retardation (one case), and personality disorders not otherwise specified but with some traits of dependent personality and with mythomania (one case). The condition of these five patients dramatically improved after surgery. No psychiatric behavior or "de novo" psychosis was observed after surgery in any of the patients.

CONCLUSION

The prevalence of inter-ictal psychiatric disorders appears to be high in epileptic patients with a temporal lobe DNET primarily in relation to personality and behavioral problems with some degree of impulsivity and verbal aggressiveness. The improvements after surgery suggest that this therapy could be performed in these patients and severe psychiatric disorders do not contra-indicate this procedure.

Can emotional stress trigger the onset of epilepsy?

OBJECTIVE

The aim of this study was to investigate the potential role of an acute adverse stress as "trigger" for the onset of epilepsy.

METHODS

Among 4618 consecutive patients, twenty-two reported a major life event within three months before the onset of epilepsy.

RESULTS

All patients had focal epilepsy except one with idiopathic generalized epilepsy. The temporal lobe was involved in 90% of patients with focal epilepsy. More precisely, 13 patients (62% of patients with focal epilepsy) had medial temporal lobe epilepsy (MTLE), two had lateral temporal lobe epilepsy, four had temporoparietooccipital junction epilepsy, and two patients had central lobe epilepsy. The mean age and the median age at onset of epilepsy for patients with MTLE were both 38 years (range: 9.5-65 years). Ten patients had right and three had left MTLE. Among patients with focal epilepsy, MRI was abnormal in 7 (33%) with hippocampal sclerosis in four, periventricular nodular heterotopia in two, and complex cortical dysgenesis in one. The mean age at onset of epilepsy for patients with brain lesions was 26 years (range: 9.5-49). Twelve patients (54%) reported a death as a triggering factor for the onset of their epilepsy. Seven patients (32%) reported that a relationship of trust had been broken. Three patients (14%) had been subjects of violence. No patient reported sexual abuse as a triggering factor.

CONCLUSION

This study provides evidence that some patients (5/1000 patients) began their seizures in the wake of significant life events. The average age at onset of epilepsy is quite late, around age 30, even in the presence of brain lesions. These patients are emotionally and affectively more prone to have consequences of a stressful life event. The recognition and management of such situations may bring significant relief with improvement of the control of epilepsy.

Longterm deep brain stimulation withdrawal: clinical stability despite electrophysiological instability

Deep brain stimulation (DBS) is a powerful treatment option for movement disorders, including severe generalised dystonia. After several years of treatment, cases have been reported in which DBS has been stopped without any deterioration in clinical benefit. This might indicate that DBS can restore function in some cases. The mechanism of DBS induced clinical retention effects has been addressed before. Here, the question we asked was if such clinical stability is reflected at the underlying physiology level or whether there is indication to believe that a stand-still of symptoms might be at risk because of neurophysiological instability. We recorded patients with pre-intervention life-threatening or severe genetic dystonia with long lasting clinical benefit when turned off DBS. Despite clinical stability, our physiological studies revealed large changes in the excitability of excitatory and inhibitory motor circuits in the cortex, which exceed normal fluctuation. This discrepancy between instability in the motor network physiology caused by removal of DBS and clinical stability alerts as it potentially indicates a risk to fail and cause symptoms to return.

Deep brain stimulation for Huntington's disease: long-term results of a prospective open-label study

OBJECT.: To date, experience of globus pallidus internus (GPi) deep brain stimulation (DBS) in the treatment of Huntington's disease (HD) has been limited to a small number of case reports. The aim of this study was to analyze long-term motor outcome of a cohort of HD patients treated with GPi DBS.

METHODS

Seven patients with pharmacologically resistant chorea and functional impairment were included in a prospective open-label study from 2008 to 2011. The main outcome measure was the motor section of the Unified Huntington's Disease Rating Scale. The primary end point was reduction of chorea.

RESULTS

Patients underwent MRI-guided bilateral GPi implantation. The median duration of follow-up was 3 years. A significant reduction of chorea was observed in all patients, with sustained therapeutic effect; the mean improvement on the chorea subscore was 58.34% at the 12-month follow-up visit (p = 0.018) and 59.8% at the 3-year visit (p = 0.040). Bradykinesia and dystonia showed a nonsignificant trend toward progressive worsening related to disease evolution and partly to DBS. The frequency of stimulation was 130 Hz for all patients. DBS-induced bradykinesia was managed by pulse-width reduction or bipolar settings. Levodopa mildly improved bradykinesia in 4 patients. Regular off-stimulation tests confirmed a persistent therapeutic effect of DBS on chorea.

CONCLUSIONS

GPi DBS may provide sustained chorea improvement in selected HD patients with pharmacologically resistant chorea, with transient benefit in physical aspects of quality of life before progression of behavioral and cognitive disorders. DBS therapy did not improve dystonia or bradykinesia. Further studies including quality of life measures are needed to evaluate the impact of DBS in the long-term outcome of HD.

The influence of deep brain stimulation intensity and duration on symptoms evolution in an OFF stimulation dystonia study

BACKGROUND

Deep brain stimulation (DBS) of the internal globus pallidus (GPi) is an established therapy for primary generalized dystonia. However, the evolution of dystonia symptoms after DBS discontinuation after years of therapy has only rarely been reported. We therefore longitudinally studied the main physiological measurements known to be impaired in dystonia, with DBS ON and then again after termination of DBS, after at least five years of continuous DBS.

OBJECTIVE

We studied whether dystonia evolution after DBS discontinuation in patients benefiting from long-term GPi DBS is different from that observed in earlier stages of the therapy.

METHODS

In eleven DYT1 patients treated with bilateral GPi DBS for at least 5 years, dystonia was assessed ON-DBS, immediately after switch-off (OFF-DBS1) and 48 h after DBS termination (OFF-DBS2). We studied the influence of DBS intensity on dystonia when DBS was discontinued.

RESULTS

On average a significant difference in symptoms was measured only between ON-DBS and OFF-DBS1 conditions. Importantly, none of the patients returned to their preoperative dystonia severity, even 48 h after discontinuation. The amount of clinical deterioration in the OFF conditions positively correlated with higher stimulation current in the chronic ON-DBS condition.

CONCLUSIONS

The duration of DBS application influences symptom evolution after DBS termination. DBS intensity seems to have a prominent role on evolution of dystonic symptoms when DBS is discontinued. In conclusion, DBS induces changing modulation of the motor network with less worsening of symptoms after long term stimulation, when DBS is stopped.

Evolution of brain impedance in dystonic patients treated by GPI electrical stimulation

Deep Brain Stimulation is an effective treatment of generalized dystonia. Optimal stimulation parameters vary between patients. This article investigates the influence of electrical brain impedance and delivered current on the brain response to stimulation. Twenty-four patients were bilaterally stimulated in the globus pallidus internus through two implanted four-contact electrodes. The variation of brain impedance and current measurements was correlated with stimulation parameters, time course, and clinical outcome. When a contact was activated, a statistically significant and reversible decrease of brain impedance was found. Impedance and current values and their variations with time significantly differed between patients. The absolute impedance did not significantly correlate with the final outcome. We conclude that the reversible decrease of impedance reflects an adaptive long-term mechanism, which could be due to a plasticity phenomenon, but has no prognostic value. Impedance and current measurements give new complementary information for parameter adjustment and trouble shooting and should therefore be included in all patients' follow-up.

Staged implantation of multiple electrodes in the internal globus pallidus in the treatment of primary generalized dystonia

Object

Deep brain stimulation (DBS) is used for treating various types of dystonia. Multiple electrodes could be proposed to improve the therapeutic outcome enabling the targeting of specific neuronal populations not reached by the electrical field generated by the initially implanted electrode. The authors address the question of the feasibility and safety of staged multiple lead implantations in the sensorimotor internal globus pallidus (GPi) in primary generalized dystonia (PGD). Criteria for patient selection, surgical technique, target selection, electrical settings management, and clinical outcome are presented.

Methods

Sixteen patients (8 harbored the DYT1 gene mutation) presented with PGD and were enrolled in this study. Patients underwent clinical assessment using the Burke-Fahn-Marsden Dystonia Rating Scale preoperatively and during follow-up with DBS. Prior to the addition of electrodes, the authors confirmed, by turning off stimulation, that the patient was still benefiting from DBS and that DBS settings adjustment did not provide further improvement. The second target was defined according to the position of the first electrode, to the residual volume within the sensorimotor GPi, and according to residual symptoms. The second surgery followed the same protocol as the first and the new electrode were inserted using the same bur hole as the first electrode.

Results

The addition of a new pair of electrodes was followed by significant improvement in the whole population (p = 0.005), as well as in the DYT1-negative subgroup (p = 0.012) but not in the DYT1 subgroup (p = not significant). Nevertheless, some patients did not exhibit significant additional benefit. Seven hardware-related complications occurred during the entire follow-up, 3 prior to it, and 4 after the addition of the second pair of electrodes.

Conclusions

The addition of a second pair of electrodes in the GPi in patients with PGD with suboptimal or decaying benefit following the first surgery seems to be a safe procedure and is not followed by an increase in surgery-related complications. This staged procedure may provide further clinical improvement in patients with PGD in whom DBS effect is initially incomplete or when disease progression occurs over time. The position of the additional electrode within the GPi is determined by the available volume within the posteroventral GPi and by the distribution of the dystonic symptoms that need to be controlled.

Deep brain stimulation of the globus pallidus internus and Gilles de la Tourette syndrome: Toward multiple networks modulation

Background:

Gilles de la Tourette's syndrome (GTS) is a complex neuropsychiatric disorder characterized by disabling motor and vocal tics. The pathophysiology of GTS remains poorly understood. Conventional treatment consists in pharmacological and behavioral treatment. For patients suffering severe adverse effects or not responding to pharmacological treatment, deep brain stimulation (DBS) presents an alternative treatment. However, the optimal target choice in DBS for GTS remains a divisive issue.

Methods:

A PubMed search from 1999 to 2012 was conducted. Thirty-three research articles reporting on DBS in patients with GTS were selected and analyzed.

Results:

Eighty-eight patients with Tourette's syndrome were treated since 1999 with DBS. The majority of patients received thalamic stimulation. Significantly fewer patients were treated with globus pallidus internus stimulation. Occasionally, the anterior limb of the internal capsule and the nucleus accumbens were implanted. The subthalamic nucleus was selected once. All targets were reported with positive results, but of variable extent. Only 14 patients exhibited level 1 evidence.

Conclusion:

In light of the wide spectrum of associated behavioral co-morbidities in GTS, multiple networks modulation may result in the most efficacious treatment strategy. The optimal locations for DBS within the cortico-basal ganglia-thalamocortical circuits remain to be established. However, at the current stage, comparison between targets should be done with great caution. Significant disparity between number of patients treated per target, methodological variability, and quality of reporting renders a meaningful comparison between targets difficult. Randomized controlled trials with larger cohorts and standardization of procedures are urgently needed.

Shaping reversibility? Long-term deep brain stimulation in dystonia: the relationship between effects on electrophysiology and clinical symptoms

Long-term results show that benefits from chronic deep brain stimulation in dystonia are maintained for many years. Despite this, the neurophysiological long-term consequences of treatment and their relationship to clinical effects are not well understood. Previous studies have shown that transcranial magnetic stimulation measures of abnormal long-term potentiation-like plasticity (paired associative stimulation) and GABAa-ergic inhibition (short-interval intracortical inhibition), which are seen in dystonia, normalize after several months of deep brain stimulation. In the present study, we examine the same measures in a homogenous group of 10 DYT1 gene-positive patients after long-term deep brain stimulation treatment for at least 4.5 years. Recordings were made 'on' deep brain stimulation and after stopping deep brain stimulation for 2 days. The results show that: (i) on average, prior to discontinuing deep brain stimulation, the paired associative stimulation response was almost absent and short-interval intracortical inhibition was reduced compared with normal. This pattern differs from that in both healthy volunteers and from the typical pattern of enhanced plasticity and reduced inhibition seen in deep brain stimulation-naïve dystonia. It is similar to that seen in untreated Parkinson's disease and may relate to thus far unexplained clinical phenomena like parkinsonian symptoms that have sometimes been observed in patients treated with deep brain stimulation. (ii) Overall, there was no change in average physiological or clinical status when deep brain stimulation was turned off for 2 days, suggesting that deep brain stimulation had produced long-term neural reorganization in the motor system. (iii) However, there was considerable variation between patients. Those who had higher levels of plasticity when deep brain stimulation was 'on', had the best retention of clinical benefit when deep brain stimulation was stopped and vice versa. This may indicate that better plasticity is required for longer term retention of normal movement when deep brain stimulation is off. (iv) Patients with the highest plasticity 'on' deep brain stimulation were those who had been receiving stimulation with the least current drain. This suggests that it might be possible to 'shape' deep brain stimulation of an individual patient to maximize beneficial neurophysiological patterns that have an impact on clinical status. The results are relevant for understanding long-term consequences and management of deep brain stimulation in dystonia.

A target-specific electrode and lead design for internal globus pallidus deep brain stimulation

In nearly all deep brain stimulation (DBS) applications, the same quadripolar electrode design is used for different anatomical targets even if shape and volume differences exist between nuclei. Taking into account the electrode location within the internal globus pallidus (GPi) and the size of the GPi, 2 electrodes were designed in order to improve the therapeutic benefit, to minimize side effects from DBS and to obtain a more homogeneous electric field distribution. The electrodes were evaluated numerically by using a stereotactic model measuring the correlation between the electric field and the GPi. The model was applied to 26 dystonodyskinetic patients who underwent surgery for a bilateral lead implantation into the posteroventral part of the GPi. The designed electrodes produced a more homogeneous distribution of the electric field than the quadripolar electrode.

Factors predicting improvement in primary generalized dystonia treated by pallidal deep brain stimulation

Despite the beneficial effects of Globus Pallidus internus (GPi) deep brain stimulation (DBS) in patients with primary generalized dystonia (PGD), the degree of improvement varies from one patient to another. The objective of this study was to examine the effects of clinical, anatomical (volume of the GPi), and electrical variables on the postoperative Burke-Fahn-Marsden Dystonia rating scale (BFMDRS) motor score to identify which factors may be predictive of the degree of improvement. We reviewed retrospectively the clinical records of 40 steady-state patients with PGD who had been treated by bilateral GPi lead implantation. The follow-up period was 2 to 8 years. The correlation between the electrical parameters (voltage, impedance, and current) and the clinical outcome was studied. An analysis of covariance was performed to identify factors predictive of the magnitude of improvement. The most influential factors according to the model are as follows: the preoperative BFMDRS score (P < 0.0001); age at surgery (P < 0.0001); the right GPi volume (P = 0.002); the left stimulated GPi volume (P = 0.005). No significant correlation was found between the electrical parameters used and the mean motor scores in steady state.

Prognostic value of globus pallidus internus volume in primary dystonia treated by deep brain stimulation

Object

Given that improvement is variable from one patient to another, the authors analyzed the impact of globus pallidus internus (GPi) volume on the result of deep brain stimulation (DBS) by comparing highly and less improved patients with primary dystonodyskinetic syndromes.

Methods

A stereotactic model was developed to visualize and quantify the relationship between the isofield lines generated by the DBS lead and GPi target. The model was used in 30 right-handed selected patients with primary dystonodyskinetic syndromes who had been treated using bilateral stimulation of the sensorimotor GPi. Ten healthy control individuals were also included in the study. First, the authors compared the GPi volumes between patients and healthy controls. Second, the stimulated GPi volumes, that is, the intersection between the volume of each isofield value and the GPi volumes, were compared between less improved and highly improved patients.

Results

Improvement in the Burke-Fahn-Marsden Dystonia Rating Scale's motor score was rated > 90% in 20 patients (97 ± 4.6%) and < 60% in 10 patients (56.9 ± 6%). The mean volume of the right (461.8 ± 81.8 mm3) and left (406.6 ± 113.2 mm3) GPi in patients showing less response to DBS was significantly smaller than the GPi volume of patients who responded well (right 539.9 ± 86.6 mm3, left 510.6 ± 88.7 mm3) and healthy controls (right 557.8 ± 109.1 mm3, left 525.1 ± 40.8 mm3).

Conclusions

On the left side, the mean stimulated volumes (isofield line range 0.2–1 V/mm) were significantly larger in highly improved than in less improved patients. In this model, the threshold for functional effect was calculated at 0.2 V/mm.