Surgical treatment of dyskinesia in Parkinson's disease

Fundamentals of deep brain stimulation for Parkinson's disease in clinical practice: part 2

The field of neuromodulation has evolved significantly over the past decade. Developments include novel indications and innovations of hardware, software, and stimulation techniques leading to an expansion in scope and role of these techniques as powerful therapeutic interventions. In this review, which is the second part of an effort to document and integrate the basic fundamentals and recent successful developments in the field, we will focus on classic paradigms for electrode placement as well as new exploratory targets, mechanisms of neuromodulation using this technique and new developments, including focused ultrasound driven ablative procedures.

Clinical and Economic Insights into Parkinson's Disease Hospitalization: A Comprehensive Study of 19,719 Inpatient Cases in Hubei Province, China

OBJECTIVE

Parkinson's disease (PD) is a profoundly incapacitating neurodegenerative disorder, which presents a substantial challenge to the economic sustainability of the global healthcare system. The present study seeks to clarify the factors that contribute to the costs associated with PD hospitalization and analyze the economic burden it imposes.

METHODS

We examined data of 19,719 patients with a primary diagnosis of PD who were admitted to hospitals in Hubei Province, China, during the study period. Healthcare data were obtained from the database of electronic medical records. The study presents a comprehensive analysis of the demographic characteristics and investigates the factors that affect their healthcare expenditure.

RESULTS

The cohort consisted of 10,442 (53.0%) males and 9,277 (47.0%) females. The age-group of 66-70 years experienced the highest incidence of hospitalization among PD patients, with a mortality rate of 0.76‰. The average length of stay for patients was 9.9 ± 8.6 days and the average cost per patient was USD 1,759.9 ± 4,787.7. Surgical interventions were conducted on a mere 2.0% of the total inpatient population. The primary cost component for these interventions was material expenses, accounting for 70.1% of the total. Non-surgical patients primarily incurred expenses related to diagnosis and medication. Notably, surgical patients faced a substantial out-of-pocket rate, reaching up to 90.6%. Surgery was identified as the most influential factor that negatively affected both length of stay and hospitalization costs. Inpatients exhibited significant associations with prolonged length of stay and increased medical expenditure as age increased. Male patients had significantly longer hospital stays and higher medical costs than did females. Additionally, patient's occupation and type of medical insurance exerted significant effects on both length of stay and medical expense.

CONCLUSION

Age significantly affects PD hospitalization costs. Given the prevailing demographic shift toward an aging population, the government's medical insurance burden related to PD will continue to escalate. Meanwhile, high treatment expenses and out-of-pocket rates impose substantial financial burdens on patients, limiting surgical intervention access to a small fraction of patients. Addressing these issues is of utmost importance in order to ensure comprehensive disease management for the majority of individuals affected by PD.

Rescue subthalamic stimulation after unsatisfactory outcome of pallidal stimulation in Parkinson's disease: a case series and review

Background

Subthalamic nucleus (STN) and globus pallidus interna (GPi) are two main structures primarily targeted by deep brain stimulation (DBS) to treat advanced Parkinson's disease (PD). A subset of cases with unsatisfactory outcomes may benefit from rescue DBS surgery targeting another structure, while these patients' characteristics have not been well described and this phenomenon has not been well reviewed.

Methods

This monocentric retrospective study included patients with PD, who underwent rescue STN DBS following an unsatisfactory outcome of the initial bilateral GPi DBS in a retrospective manner. A short review of the current literature was conducted to report the clinical outcome of rescue DBS surgeries.

Results

Eight patients were identified, and six of them were included in this study. The rescue STN DBS was performed 19.8 months after the initial GPi DBS. After 8.8 months from the rescue STN DBS, patients showed a significant off-medication improvement by 29.2% in motor symptoms compared to initial GPi DBS. Non-motor symptoms and the health-related quality of life were also significantly improved.

Conclusion

Our findings suggest that the rescue STN DBS may improve off-medication motor and non-motor symptoms and quality of life in patients with failure of initial GPi DBS. The short review of the current literature showed that the target switching from GPi to STN was mainly due to poor initial outcomes and was performed by target substitution, whereas the switching from STN to GPi was mainly due to a gradual waning of benefits, long-term axial symptoms, dyskinesia, and dystonia and was performed by target addition.

Efecto del compuesto N-2,6-dicloro-aralquil-2-Aminoindano en la conducta estereotipada de ratas. Acción dopaminérgica selectiva central sobre los ganglios basales más que en las estructuras límbicas

Dopamine 1 is involved in neurodegenerative disorders affect-ing the central nervous system (CNS), such as Parkinson’s disease. Despite the absence of some available drugs capable of preventing, stopping or curing the progression of such diseases, there are numerous compounds designed, synthesized, and pharmacologically tested which give rise to pharmacophoric generalizations about the dopaminergic receptor required for the search of a drug able to improve or cure those pathologies. N-aralkyl-2-aminoindane de-rivatives have shown selective activity in the central dopaminergic system. Both the N-[(2,4-dichlorophenyl)-1-methyl-ethyl]-2-aminoindane hydrochloride 2and N-[(3,4-dichlorophenyl)-1-methyl-ethyl]-2-aminoindane hydrochloride 3 showed an agonistic activity mediated by central dopaminergic mechanisms. To contribute to the search of new drugs able to re-establish homeostasis in the dopaminergic transmission in Parkinson’s disease, the compound N-2,6-dichloro-aralkyl-2-aminoindane 4 was designed through medicinal chemistry strategies that contain pharmacophoric approximations of prodrugs. The phar-macological evaluation of compound 4 in the stereotyped behavior of male Sprague Dawley rats showed agonistic activity through the activation of central dopaminergic mechanisms and a higher selectivity in the responses of stereo-typed behavior characteristic of the basal ganglia over the typical responses from limbic structures.

Deep brain stimulation in Parkinson's disease: state of the art and future perspectives

For more than 30 years, Deep Brain Stimulation (DBS) has been a therapeutic option for Parkinson's disease (PD) treatment. However, this therapy is still underutilized mainly due to misinformation regarding risks and clinical outcomes. DBS can ameliorate several motor and non-motor symptoms, improving patients' quality of life. Furthermore, most of the improvement after DBS is long-lasting and present even in advanced PD. Adequate patient selection, precise electric leads placement, and correct DBS programming are paramount for good surgical outcomes. Nonetheless, DBS still has many limitations: axial symptoms and signs, such as speech, balance and gait, do not improve to the same extent as appendicular symptoms and can even be worsened as a direct or indirect consequence of surgery and stimulation. In addition, there are still unanswered questions regarding patient's selection, surgical planning and programming techniques, such as the role of surgicogenomics, more precise imaging-based lead placement, new brain targets, advanced programming strategies and hardware features. The net effect of these innovations should not only be to refine the beneficial effect we currently observe on selected symptoms and signs but also to improve treatment resistant facets of PD, such as axial and non-motor features. In this review, we discuss the current state of the art regarding DBS selection, implant, and programming, and explore new advances in the DBS field.

Molecular Mechanisms and Therapeutic Strategies for Levodopa-Induced Dyskinesia in Parkinson's Disease: A Perspective Through Preclinical and Clinical Evidence

Parkinson's disease (PD) is the second leading neurodegenerative disease that is characterized by severe locomotor abnormalities. Levodopa (L-DOPA) treatment has been considered a mainstay for the management of PD; however, its prolonged treatment is often associated with abnormal involuntary movements and results in L-DOPA-induced dyskinesia (LID). Although LID is encountered after chronic administration of L-DOPA, the appearance of dyskinesia after weeks or months of the L-DOPA treatment has complicated our understanding of its pathogenesis. Pathophysiology of LID is mainly associated with alteration of direct and indirect pathways of the cortico-basal ganglia-thalamic loop, which regulates normal fine motor movements. Hypersensitivity of dopamine receptors has been involved in the development of LID; moreover, these symptoms are worsened by concurrent non-dopaminergic innervations including glutamatergic, serotonergic, and peptidergic neurotransmission. The present study is focused on discussing the recent updates in molecular mechanisms and therapeutic approaches for the effective management of LID in PD patients.

Brain MRI-guided focused ultrasound conceptualised as a tool for brain network intervention

Magnetic resonance imaging guided high intensity focused ultrasound (HIFU) has emerged as a tool offering incisionless intervention on brain tissue. The low risk and rapid recovery from this procedure, in addition to the ability to assess for clinical benefit and adverse events intraprocedurally, makes it an ideal tool for intervention upon brain networks both for clinical and research applications. This review article proposes that conceptualising brain focused ultrasound as a tool for brain network intervention and adoption of methodology to complement this approach may result in better clinical outcomes, fewer adverse events and may unveil or allow treatment opportunities not otherwise possible. A brief introduction to network neuroscience is discussed before a description of pathological brain networks is provided for a number of conditions for which MRI-guided brain HIFU intervention has been implemented. Essential Tremor is discussed as the most advanced example of MRI-guided brain HIFU intervention adoption along with the issues that present with this treatment modality compared to alternatives. The brain network intervention paradigm is proposed to overcome these issues and a number of examples of implementation of this are discussed. The ability of low intensity MRI guided focussed ultrasound to neuromoduate brain tissue without lesioning is introduced. This tool is discussed with regards to its potential clinical application as well as its potential to further our understanding of network neuroscience via its ability to interrogate brain networks without damaging tissue. Finally, a number of current clinical trials utilising brain focused ultrasound are discussed, along with the additional applications available from the utilisation of low intensity focused ultrasound.

Suicidality Associated With Deep Brain Stimulation in Extrapyramidal Diseases: A Critical Review and Hypotheses on Neuroanatomical and Neuroimmune Mechanisms

Deep brain stimulation (DBS) is a very well-established and effective treatment for patients with extrapyramidal diseases. Despite its generally favorable clinical efficacy, some undesirable outcomes associated with DBS have been reported. Among such complications are incidences of suicidal ideation (SI) and behavior (SB) in patients undergoing this neurosurgical procedure. However, causal associations between DBS and increased suicide risk are not demonstrated and they constitute a debated issue. In light of these observations, the main objective of this work is to provide a comprehensive and unbiased overview of the literature on suicide risk in patients who received subthalamic nucleus (STN) and internal part of globus pallidum (GPi) DBS treatment. Additionally, putative mechanisms that might be involved in the development of SI and SB in these patients as well as caveats associated with these hypotheses are introduced. Finally, we briefly propose some clinical implications, including therapeutic strategies addressing these potential disease mechanisms. While a mechanistic connection between DBS and suicidality remains a controversial topic that requires further investigation, it is of critical importance to consider suicide risk as an integral component of candidate selection and post-operative care in DBS.

Medical management after subthalamic stimulation in Parkinson's disease: a phenotype perspective

Subthalamic nucleus deep brain stimulation (STN DBS) is an established treatment that improves motor fluctuations, dyskinesia, and tremor in Parkinson's disease (PD). After the surgery, a careful electrode programming strategy and medical management are crucial, because an imbalance between them can compromise the quality of life over time. Clinical management is not straightforward and depends on several perioperative motor and non-motor symptoms. In this study, we review the literature data on acute medical management after STN DBS in PD and propose a clinical algorithm on medical management focused on the patient's phenotypic profile at the perioperative period. Overall, across the trials, the levodopa equivalent daily dose is reduced by 30 to 50% one year after surgery. In patients taking high doses of dopaminergic drugs or with high risk of impulse control disorders, an initial reduction in dopamine agonists after STN DBS is recommended to avoid the hyperdopaminergic syndrome, particularly hypomania. On the other hand, a rapid reduction of dopaminergic agonists of more than 70% during the first months can lead to dopaminergic agonist withdrawal syndrome, characterized by apathy, pain, and autonomic features. In a subset of patients with severe dyskinesia before surgery, an initial reduction in levodopa seems to be a more reasonable approach. Finally, when the patient's phenotype before the surgery is the severe parkinsonism (wearing-off) with or without tremor, reduction of the medication after surgery can be more conservative. Individualized medical management following DBS contributes to the ultimate therapy success.

Analysis of factors associated with brittle response in patients with Parkinson's disease

INTRODUCTION

The brittle response (BR) in patients with Parkinson's disease (PD) refers to a special type of levodopa-induced dyskinesia (LID). This study aimed to describe the clinical characteristics of BR patients and to analyze the associated risk factors.

METHODS

A retrospective study was conducted to analyze the data of 97 patients with PD. Patients were divided into a BR group and a non-brittle response (NBR) group. Demographic and clinical data, motor symptoms, and non-motor symptoms of the two groups were assessed.

RESULTS

Among 97 PD patients, 11 were in the BR group and 86 were in the NBR group. The proportion of female patients was 72.7% and 38.3%, respectively, in the BR and NBR groups (P < 0.05). Compared to NBR patients, BR patients had relatively low body weight, low BMI, long disease duration, high levodopa equivalent daily dosage (LEDD), and high levodopa dose per weight (P < 0.05). The BR group had significantly higher scores of UPDRS (II, III, and IV) (P < 0.05). But no difference was found in the UPDRS I, emotional state, cognitive status, and accompanied by REM sleep behavior disorder (RBD) (P> 0.05). Multivariate logistic regression analysis showed that BR patients had lower body weight and higher levodopa dose per weight.

CONCLUSION

BR is associated with being female, low body weight, low BMI, long disease duration, high LEDD, and high levodopa dose per weight. Body weight and levodopa dose per body weight are independent risk factors for BR.

Basal ganglia role in learning rewarded actions and executing previously learned choices: Healthy and diseased states

The basal ganglia (BG) is a collection of nuclei located deep beneath the cerebral cortex that is involved in learning and selection of rewarded actions. Here, we analyzed BG mechanisms that enable these functions. We implemented a rate model of a BG-thalamo-cortical loop and simulated its performance in a standard action selection task. We have shown that potentiation of corticostriatal synapses enables learning of a rewarded option. However, these synapses became redundant later as direct connections between prefrontal and premotor cortices (PFC-PMC) were potentiated by Hebbian learning. After we switched the reward to the previously unrewarded option (reversal), the BG was again responsible for switching to the new option. Due to the potentiated direct cortical connections, the system was biased to the previously rewarded choice, and establishing the new choice required a greater number of trials. Guided by physiological research, we then modified our model to reproduce pathological states of mild Parkinson's and Huntington's diseases. We found that in the Parkinsonian state PMC activity levels become extremely variable, which is caused by oscillations arising in the BG-thalamo-cortical loop. The model reproduced severe impairment of learning and predicted that this is caused by these oscillations as well as a reduced reward prediction signal. In the Huntington state, the potentiation of the PFC-PMC connections produced better learning, but altered BG output disrupted expression of the rewarded choices. This resulted in random switching between rewarded and unrewarded choices resembling an exploratory phase that never ended. Along with other computational studies, our results further reconcile the apparent contradiction between the critical involvement of the BG in execution of previously learned actions and yet no impairment of these actions after BG output is ablated by lesions or deep brain stimulation. We predict that the cortico-BG-thalamo-cortical loop conforms to previously learned choice in healthy conditions, but impedes those choices in disease states.

Pallidal versus subthalamic nucleus deep brain stimulation for levodopa-induced dyskinesia

OBJECTIVE

To compare the efficacy of subthalamic nucleus (STN) and globus pallidus internus (GPi) deep brain stimulation (DBS) on reducing levodopa-induced dyskinesia (LID) in Parkinson's disease, and to explore the potential underlying mechanisms.

METHODS

We retrospectively assessed clinical outcomes in 43 patients with preoperative LID who underwent DBS targeting the STN (20/43) or GPi (23/43). The primary clinical outcome was the change from baseline in the Unified Dyskinesia Rating Scale (UDysRS) and secondary outcomes included changes in the total daily levodopa equivalent dose, the drug-off Unified Parkinson Disease Rating Scale Part Ⅲ at the last follow-up (median, 18 months), adverse effects, and programming settings. Correlation analysis was used to find potential associated factors that could be used to predict the efficacy of DBS for dyskinesia management.

RESULTS

Compared to baseline, both the STN group and the GPi group showed significant improvement in LID with 60.73 ± 40.29% (mean ± standard deviation) and 93.78 ± 14.15% improvement, respectively, according to the UDysRS score. Furthermore, GPi-DBS provided greater clinical benefit in the improvement of dyskinesia (P < 0.05) compared to the STN. Compared to the GPi group, the levodopa equivalent dose reduction was greater in the STN group at the last follow-up (43.81% vs. 13.29%, P < 0.05). For the correlation analysis, the improvement in the UDysRS outcomes were significantly associated with a reduction in levodopa equivalent dose in the STN group (r = 0.543, P = 0.013), but not in the GPi group (r = -0.056, P = 0.801).

INTERPRETATION

Both STN and GPi-DBS have a beneficial effect on LID but GPi-DBS provided greater anti-dyskinetic effects. Dyskinesia suppression for STN-DBS may depend on the reduction of levodopa equivalent dose. Unlike the STN, GPi-DBS might exert a direct and independent anti-dyskinesia effect.

[Deep brain stimulation effect on postural instability and gait disorders in Parkinson's disease]

An effect of deep brain stimulation on postural instability and gait disorders in Parkinson's disease S.G. Sultanova, N.V. Fedorova, E.V. Bril, A.A. Gamaleya, A.A. Tomskiy During the last time, surgical treatment of patients with Parkinson's disease has firmly taken its place in the general algorithm for managing patients with this pathology. Deep brain electrostimulation is the most advanced and promising method, which allows the reduction in the severity of main clinical manifestations of the disease, including axial symptoms. It is noted that certain temporal aspects of parkinsonian gait disorder remain therapeutically resistant. Subthalamic nucleus stimulation was also reported to improve levodopa-responsive freezing of gait. In this review, the authors summarize the effects of deep brain stimulation on gait and postural symptoms.

Comparison Between Levodopa-Carbidopa Intestinal Gel Infusion and Subthalamic Nucleus Deep-Brain Stimulation for Advanced Parkinson's Disease: A Systematic Review and Meta-Analysis

Background: Currently, some advanced treatments such as Levodopa-Carbidopa intestinal gel infusion (LCIG), deep-brain stimulation (DBS), and subcutaneous apomorphine infusion have become alternative strategies for advanced Parkinson's disease (PD). However, which treatment is better for individual patients remains unclear. This review aims to compare therapeutic effects of motor and/or non-motor symptoms of advanced PD patients between LCIG and DBS.

Methods: We manually searched electronic databases (PubMed, Embase, Cochrane Library) and reference lists of included articles published until April 04, 2019 using related terms, without language restriction. We included case-controlled cohort studies and randomized-controlled trials, which directly compared differences between LCIG and DBS. The Newcastle-Ottawa scale (NOS), proposed by the Cochrane Collaboration, was utilized to assess the quality of the included studies. Two investigators independently extracted data from each trial. Pooled standard-mean differences (SMDs) and relative risks (RRs) with 95% confidence intervals (CIs) were calculated by meta-analysis. Outcomes were grouped according to the part III and part IV of the Unified Parkinson Disease Rating Scale (UPDRS) and adverse events. We also descriptively reviewed some data, which were unavailable for statistical analysis.

Results: This review included five cohort trials of 257 patients for meta-analysis. There were no significant differences between LCIG and subthalamic nucleus deep-brain stimulation (STN-DBS) on UPDRS-III and adverse events comparisons: UPDRS-III (pooled SMDs = 0.200, 95% CI: −0.126–0.527, P = 0.230), total adverse events (pooled RRs = 1.279, 95% CI: 0.983–1.664, P = 0.067), serious adverse events (pooled RRs = 1.539, 95% CI: 0.664–3.566, P = 0.315). Notably, the improvement of UPDRS-IV was more significant in STN-DBS groups: pooled SMDs = 0.857, 95% CI: 0.130–1.584, P = 0.021. However, the heterogeneity was moderate for UPDRS-IV (I² = 73.8%).

Conclusion: LCIG has comparable effects to STN-DBS on motor function for advanced PD, with acceptable tolerability. More large, well-designed trials are needed to assess the comparability of LCIG and STN-DBS in the future.

The efficacy and limits of magnetic resonance-guided focused ultrasound pallidotomy for Parkinson's disease: a Phase I clinical trial

OBJECTIVE

Recently, MR-guided focused ultrasound (MRgFUS) has emerged as an innovative treatment for numerous neurological disorders, including essential tremor, Parkinson's disease (PD), and some psychiatric disorders. Thus, clinical applications with this modality have been tried using various targets. The purpose of this study was to determine the feasibility, initial effectiveness, and potential side effects of unilateral MRgFUS pallidotomy for the treatment of parkinsonian dyskinesia.

METHODS

A prospective, nonrandomized, single-arm clinical trial was conducted between December 2013 and May 2016 at a single tertiary medical center. Ten patients with medication-refractory, dyskinesia-dominant PD were enrolled. Participants underwent unilateral MRgFUS pallidotomy using the Exablate 4000 device (InSightec) after providing written informed consent. Patients were serially evaluated for motor improvement, neuropsychological effects, and adverse events according to the 1-year follow-up protocol. Primary measures included the changes in the Unified Parkinson's Disease Rating Scale (UPDRS) and Unified Dyskinesia Rating Scale (UDysRS) scores from baseline to 1 week, 1 month, 3 months, 6 months, and 1 year. Secondary measures consisted of neuropsychological batteries and quality of life questionnaire (SF-36). Technical failure and safety issues were also carefully assessed by monitoring all events during the study period.

RESULTS

Unilateral MRgFUS pallidotomy was successfully performed in 8 of 10 patients (80%), and patients were followed up for more than 6 months. Clinical outcomes showed significant improvements of 32.2% in the "medication-off" UPDRS part III score (p = 0.018) and 52.7% in UDysRS (p = 0.017) at the 6-month follow-up, as well as 39.1% (p = 0.046) and 42.7% (p = 0.046) at the 1-year follow-up, respectively. These results were accompanied by improvement in quality of life. Among 8 cases, 1 patient suffered an unusual side effect of sonication; however, no patient experienced persistent aftereffects.

CONCLUSIONS

In the present study, which marks the first Phase I pilot study of unilateral MRgFUS pallidotomy for parkinsonian dyskinesia, the authors demonstrated the efficacy of pallidal lesioning using MRgFUS and certain limitations that are unavoidably associated with incomplete thermal lesioning due to technical issues. Further investigation and long-term follow-up are necessary to validate the use of MRgFUS in clinical practice.Clinical trial registration no.: NCT02003248 (clinicaltrials.gov).

A review of basal ganglia circuits and physiology: Application to deep brain stimulation

INTRODUCTION

Drawing on the seminal work of DeLong, Albin, and Young, we have now entered an era of basal ganglia neuromodulation. Understanding, re-evaluating, and leveraging the lessons learned from neuromodulation will be crucial to facilitate an increased and improved application of neuromodulation in human disease.

METHODS

We will focus on deep brain stimulation (DBS) - the most common form of basal ganglia neuromodulation - however, similar principles can apply to other neuromodulation modalities. We start with a brief review of DBS for Parkinson's disease, essential tremor, dystonia, and Tourette syndrome. We then review hallmark studies on basal ganglia circuits and electrophysiology resulting from decades of experience in neuromodulation. The organization and content of this paper follow Dr. Okun's Lecture from the 2018 Parkinsonism and Related Disorders World Congress.

RESULTS

Information gained from neuromodulation has led to an expansion of the basal ganglia rate model, an enhanced understanding of nuclei dynamics, an emerging focus on pathological oscillations, a revision of the tripartite division of the basal ganglia, and a redirected focus toward individualized symptom-specific stimulation. Though there have been many limitations of the basal ganglia "box model," the construct provided the necessary foundation to advance the field. We now understand that information in the basal ganglia is encoded through complex neural responses that can be reliably measured and used to infer disease states for clinical translation.

CONCLUSIONS

Our deepened understanding of basal ganglia physiology will drive new neuromodulation strategies such as adaptive DBS or cell-specific neuromodulation through the use of optogenetics.

Stem cell-based therapy for Parkinson's disease with a focus on human endometrium-derived mesenchymal stem cells

Parkinson's disease (PD) as an increasing clinical syndrome is a multifunctional impairment with systemic involvement. At present, therapeutic approaches such as l-3,4-dihydroxy-phenylalanine replacement therapy, dopaminergic agonist administration, and neurosurgical treatment intend to relieve PD symptoms which are palliative and incompetent in counteracting PD progression. These mentioned therapies have not been able to replace the lost cells and they could not effectively slow down the relentless neurodegenerative process. Till now, there is a lack of eligible treatment for PD, and stem cells therapy recently has been considered for PD treatment. In this review, we demonstrate how human stem cell technology especially human endometrium-derived stem cells have made advancement as a therapeutic source for PD compared with other treatments.

Chinese expert consensus on programming deep brain stimulation for patients with Parkinson's disease

Background

Deep Brain Stimulation (DBS) therapy for the treatment of Parkinson’s Disease (PD) is now a well-established option for some patients. Postoperative standardized programming processes can improve the level of postoperative management and programming, relieve symptoms and improve quality of life.

Main body

In order to improve the quality of the programming, the experts on DBS and PD in neurology and neurosurgery in China reviewed the relevant literatures and combined their own experiences and developed this expert consensus on the programming of deep brain stimulation in patients with PD in China.

Conclusion

This Chinese expert consensus on postoperative programming can standardize and improve postoperative management and programming of DBS for PD.

[Unilateral posteroventral pallidotomy in the treatment of drug-induced dyskinesia in Parkinson's disease]

OBJECTIVE

to determine the efficacy of unilateral posteroventral pallidotomy (PVP) in the treatment of drug-induced dyskinesia (DID) in Parkinson's disease (PD).

MATERIAL AND METHODS

We analyzed surgical treatment of 14 patients with PD complicated by DID who underwent unilateral PVP at the Research Center of Neurology in the period between 2012 and 2015. The clinical type of DID was mainly represented by peak-dose choreoathetoid dyskinesia, more pronounced in the distal limbs, and predominantly unilateral. The severity of drug-induced dyskinesia was assessed on the UPDRS scale (part IV-A) before surgery and at 1 week and 6 months after surgery.

RESULTS

One week after pallidotomy, all of the 14 patients had a regression of contralateral dyskinesia by 68.3±9.7%; 50% of patients had a regression of ipsilateral dyskinesias by 43%, on average. In 50% of cases, the dose of levodopa was reduced by 15%, on average. On examination at 6 months after surgery, regression of contralateral dyskinesia was 55.7±8.8%, and the severity of ipsilateral DID returned to the preoperative level. The use of pallidotomy significantly improved the indicators of daily activity and quality of life of patients. There were no significant postoperative complications. Three patients had mild speech disorders in the form of dysarthria, which regressed 2-3 weeks after surgery.

Treatment of Movement Disorders With Focused Ultrasound

Although the use of ultrasound as a potential therapeutic modality in the brain has been under study for several decades, relatively few neuroscientists or neurologists are familiar with this technology. Stereotactic brain lesioning had been widely used as a treatment for medically refractory patients with essential tremor (ET), Parkinson disease (PD), and dystonia but has been largely replaced by deep brain stimulation (DBS) surgery, with advantages both in safety and efficacy. However, DBS is associated with complications including intracerebral hemorrhage, infection, and hardware malfunction. The occurrence of these complications has spurred interest in less invasive stereotactic brain lesioning methods including magnetic resonance imaging–guided high intensity–focused ultrasound (FUS) surgery. Engineering advances now allow sound waves to be targeted noninvasively through the skull to a brain target. High intensities of sonic energy can create a coagulation lesion similar to that of older radiofrequency stereotactic methods, but without opening the skull, recent Food and Drug Administration approval of unilateral thalamotomy for treatment of ET. Clinical studies of stereotactic FUS for aspects of PD are underway. Moderate intensity, pulsed FUS has also demonstrated the potential to safely open the blood-brain barrier for localized delivery of therapeutics including proteins, genes, and cell-based therapy for PD and related disorders. The goal of this review is to provide basic and clinical neuroscientists with a level of understanding to interact with medical physicists, biomedical engineers, and radiologists to accelerate the application of this powerful technology to brain disease

Current Experimental Studies of Gene Therapy in Parkinson's Disease

Parkinson's disease (PD) was characterized by late-onset, progressive dopamine neuron loss and movement disorders. The progresses of PD affected the neural function and integrity. To date, most researches had largely addressed the dopamine replacement therapies, but the appearance of L-dopa-induced dyskinesia hampered the use of the drug. And the mechanism of PD is so complicated that it's hard to solve the problem by just add drugs. Researchers began to focus on the genetic underpinnings of Parkinson's disease, searching for new method that may affect the neurodegeneration processes in it. In this paper, we reviewed current delivery methods used in gene therapies for PD, we also summarized the primary target of the gene therapy in the treatment of PD, such like neurotrophic factor (for regeneration), the synthesis of neurotransmitter (for prolong the duration of L-dopa), and the potential proteins that might be a target to modulate via gene therapy. Finally, we discussed RNA interference therapies used in Parkinson's disease, it might act as a new class of drug. We mainly focus on the efficiency and tooling features of different gene therapies in the treatment of PD.

Focused Ultrasound: An Emerging Therapeutic Modality for Neurologic Disease

Therapeutic ultrasound is only beginning to be applied to neurologic conditions, but the potential of this modality for a wide spectrum of brain applications is high. Engineering advances now allow sound waves to be targeted through the skull to a brain region selected with real time magnetic resonance imaging and thermography, using a commercial array of focused emitters. High intensities of sonic energy can create a coagulation lesion similar to that of older radiofrequency stereotactic methods, but without opening the skull. This has led to the recent Food and Drug Administration approval of focused ultrasound (FUS) thalamotomy for unilateral treatment of essential tremor. Clinical studies of stereotactic FUS for aspects of Parkinson's disease, chronic pain, and refractory psychiatric indications are underway, with promising results. Moderate-intensity FUS has the potential to safely open the blood-brain barrier for localized delivery of therapeutics, while low levels of sonic energy can be used as a form of neuromodulation.

Surgical Treatment of Levodopa-induced Dyskinesia in Parkinson's Disease

The treatment of motor manifestations of Parkinson's disease (PD) is essentially a trade-off between adequate relief of motor symptoms and prevention and control of motor complications, particularly levodopa-induced dyskinesia (LID). Progression of PD is paralleled by a progressive difficulty in achieving the balance. Functional neurosurgical procedures provide sustained relief of LID in carefully selected patients when further tailoring of medical therapy fails to achieve this goal. Though deep brain stimulation (DBS) has superseded lesioning surgeries, pallidotomy still has a role in those patients in whom DBS is not feasible for financial or other reasons.

A Direct Cortico-Nigral Pathway as Revealed by Constrained Spherical Deconvolution Tractography in Humans

Substantia nigra is an important neuronal structure, located in the ventral midbrain, that exerts a regulatory function within the basal ganglia circuitry through the nigro-striatal pathway. Although its subcortical connections are relatively well-known in human brain, little is known about its cortical connections. The existence of a direct cortico-nigral pathway has been demonstrated in rodents and primates but only hypothesized in humans. In this study, we aimed at evaluating cortical connections of substantia nigra in vivo in human brain by using probabilistic constrained spherical deconvolution (CSD) tractography on magnetic resonance diffusion weighted imaging data. We found that substantia nigra is connected with cerebral cortex as a whole, with the most representative connections involving prefrontal cortex, precentral and postcentral gyri and superior parietal lobule. These results may be relevant for the comprehension of the pathophysiology of several neurological disorders involving substantia nigra, such as parkinson's disease, schizophrenia, and pathological addictions.

The recommendations of Chinese Parkinson's disease and movement disorder society consensus on therapeutic management of Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a chronic, progressive and debilitating disease, which affects over 2.5 million people in China. PD is characterized clinically by resting tremor, muscular rigidity, bradykinesia and postural instability. As the disease progresses, additional complications can arise such as non-motor and neurobehavioral symptoms. Pharmacological treatment and surgical intervention for PD have been implemented in China. Until 10 years ago, there was lack of standardization for the management of PD in different regions and among different physicians, leading to different treatment levels in different regions and different physicians. Since then, the Chinese Parkinson's Disease and Movement Disorder Society have published three versions of guidelines for the management of PD in China, in 2006, 2009 and 2014, respectively. Correspondingly, the overall level of treatment for PD in China improved.

OBJECTIVES

To update the treatment guidelines based on current foreign and domestic practice guidelines and clinical evidence, and to improve the treatment options available to physicians in the management of PD.

SUMMARY

A variety of treatment recommendations in the treatment guidelines have been proposed, including physical activity and disease-modifying medication, which should be initiated at the early-stage of the disease. The principles of dosage titration should be followed to avoid acute adverse reactions to the drugs, to achieve a satisfactory clinical effect with a low dose and to reduce the incidence of long-term motor complications. Moreover, different treatment strategies should be considered at different stages of the disease. Importantly, treatment guidelines and personalized treatments should be valued equally. A set of treatment recommendations has been developed to assist physicians to improve and optimize clinical outcomes for patients with PD in China.

Eligibility Criteria for Deep Brain Stimulation in Parkinson’s Disease, Tremor, and Dystonia

In this review, the available evidence to guide clinicians regarding eligibility for deep brain stimulation (DBS) in the main conditions in which these forms of therapy are generally indicated—Parkinson’s disease (PD), tremor, and dystonia—is presented. In general, the literature shows that DBS is effective for PD, essential tremor, and idiopathic dystonia. In these cases, key points in patient selection must include the level of disability and inability to manage symptoms using the best available medical therapy. Results are, however, still not optimal when dealing with other aetiologies, such as secondary tremors and symptomatic dystonia. Also, in PD, issues such as age and neuropsychiatric profile are still debatable parameters. Overall, currently available literature is able to guide physicians on basic aspects of patient selection and indications for DBS; however, a few points are still debatable and controversial. These issues should be refined and clarified in future studies.

The globus pallidus pars interna in goal-oriented and routine behaviors: Resolving a long-standing paradox

BACKGROUND

There is an apparent contradiction between experimental data showing that the basal ganglia are involved in goal-oriented and routine behaviors and clinical observations. Lesion or disruption by deep brain stimulation of the globus pallidus interna has been used for various therapeutic purposes ranging from the improvement of dystonia to the treatment of Tourette's syndrome. None of these approaches has reported any severe impairment in goal-oriented or automatic movement.

METHOD

To solve this conundrum, we trained 2 monkeys to perform a variant of a 2-armed bandit-task (with different reward contingencies). In the latter we alternated blocks of trials with choices between familiar rewarded targets that elicit routine behavior and blocks with novel pairs of targets that require an intentional learning process.

RESULTS

Bilateral inactivation of the globus pallidus interna, by injection of muscimol, prevents animals from learning new contingencies while performance remains intact, although slower for the familiar stimuli. We replicate in silico these data by adding lateral competition and Hebbian learning in the cortical layer of the theoretical model of the cortex-basal ganglia loop that provided the framework of our experimental approach.

CONCLUSION

The basal ganglia play a critical role in the deliberative process that underlies learning but are not necessary for the expression of routine movements. Our approach predicts that after pallidotomy or during stimulation, patients should have difficulty with complex decision-making processes or learning new goal-oriented behaviors. © 2016 Movement Disorder Society.