Core assessment program for surgical interventional therapies in Parkinson's disease (CAPSIT-PD)

Pallidal Stimulation Modulates Pedunculopontine Nuclei in Parkinson's Disease

Background: In advanced Parkinson’s disease, the pedunculopontine nucleus region is thought to be abnormally inhibited by gamma-aminobutyric acid (GABA) ergic inputs from the over-active globus pallidus internus. Recent attempts to boost pedunculopontine nucleus function through deep brain stimulation are promising, but suffer from the incomplete understanding of the physiology of the pedunculopontine nucleus region. Methods: Local field potentials of the pedunculopontine nucleus region and the globus pallidus internus were recorded and quantitatively analyzed in a patient with Parkinson’s disease. In particular, we compared the local field potentials from the pedunculopontine nucleus region at rest and during deep brain stimulation of the globus pallidus internus. Results: At rest, the spectrum of local field potentials in the globus pallidus internus was mainly characterized by delta-theta and beta frequency activity whereas the spectrum of the pedunculopontine nucleus region was dominated by activity only in the delta and theta band. High-frequency deep brain stimulation of the globus pallidus internus led to increased theta activity in the pedunculopontine nucleus region and enabled information exchange between the left and right pedunculopontine nuclei. Therefore, Conclusions: When applying deep brain stimulation in the globus pallidus internus, its modulatory effect on pedunculopontine nucleus physiology should be taken into account.

Subthalamic deep brain stimulation and levodopa in Parkinson's disease: a meta-analysis of combined effects

INTRODUCTION

While subthalamic nucleus deep brain stimulation (STN-DBS) and levodopa improve motor symptoms in Parkinson disease (PD) to a similar magnitude, their combined effect remains unclear. We sought to evaluate whether STN-DBS and levodopa yield differential effects on motor outcomes, dyskinesia, and activities of daily living (ADL) when combined compared to when administered alone.

METHODS

We conducted a meta-analysis of all studies reporting motor, dyskinesia, and ADL outcomes after bilateral STN-DBS in PD with presurgical Unified Parkinson's Disease Rating Scale (UPDRS-III) in Medication-OFF and Medication-ON states and postsurgical assessments in four conditions: Stimulation-ON/Medication-ON, Stimulation-ON/Medication-OFF, Stimulation-OFF/Medication-ON, and Stimulation-OFF/Medication-OFF. Dyskinesia duration (UPDRS item 32) and ADL (UPDRS-II) were compared between high and low postsurgical levodopa equivalent daily dose (LEDD) reduction. Random-effects meta-analyses using generic-inverse variance were conducted. Confidence in outcomes effect sizes was assessed.

RESULTS

Twelve studies were included (n = 401 patients). Stimulation-ON/Medication-ON was associated with an UPDRS-III improvement of - 35.7 points [95% confidence interval, - 40.4, - 31.0] compared with Stimulation-OFF/Medication-OFF, - 11.2 points [- 14.0, - 8.4] compared with Stimulation-OFF/Medication-ON, and - 9.5 points [- 11.0, - 8.0] compared to Stimulation-ON/Medication-OFF within 5 years. The difference was maintained beyond 5 years by - 28.6 [- 32.8, - 24.4], - 8.1 [- 10.2, - 5.9], and - 8.0 [- 10.3, - 5.6], respectively. No difference was observed between Stimulation-ON/Medication-OFF and Stimulation-OFF/Medication-ON within and beyond 5 years. Dyskinesia duration and ADL outcomes were similar in high vs. low postsurgical LEDD reduction.

CONCLUSION

Subthalamic nucleus deep brain stimulation and levodopa independently lessened motor severity in PD to a similar magnitude, but their combined effect was greater than either treatment alone, suggesting therapeutic synergism.

Opening the debate on deep brain stimulation for Alzheimer disease - a critical evaluation of rationale, shortcomings, and ethical justification

BACKGROUND

Deep brain stimulation (DBS) as investigational intervention for symptomatic relief from Alzheimer disease (AD) has generated big expectations. Our aim is to discuss the ethical justification of this research agenda by examining the underlying research rationale as well as potential methodological pitfalls. The shortcomings we address are of high ethical importance because only scientifically valid research has the potential to be ethical.

METHOD

We performed a systematic search on MEDLINE and EMBASE. We included 166 publications about DBS for AD into the analysis of research rationale, risks and ethical aspects. Fifty-eight patients were reported in peer-reviewed journals with very mixed results. A grey literature search revealed hints for 75 yet to be published, potentially enrolled patients.

RESULTS

The results of our systematic review indicate methodological shortcomings in the literature that are both scientific and ethical in nature. According to our analysis, research with human subjects was performed before decisive preclinical research was published examining the specific research question at stake. We also raise the concern that conclusions on the potential safety and efficacy have been reported in the literature that seem premature given the design of the feasibility studies from which they were drawn. In addition, some publications report that DBS for AD was performed without written informed consent from some patients, but from surrogates only. Furthermore, registered ongoing trials plan to enroll severely demented patients. We provide reasons that this would violate Art. 28 of the Declaration of Helsinki, because DBS for AD involves more than minimal risks and burdens, and because its efficacy and safety are not yet empirically established to be likely.

CONCLUSION

Based on our empirical analysis, we argue that clinical research on interventions of risk class III (Food and Drug Administration and European Medicines Agency) should not be exploratory but grounded on sound, preclinically tested, and disease-specific a posteriori hypotheses. This also applies to DBS for dementia as long as therapeutic benefits are uncertain, and especially when research subjects with cognitive deficits are involved, who may foreseeably progress to full incapacity to provide informed consent during the required follow-up period.

MR-Guided Functional Neurosurgery: Laser Ablation and Deep Brain Stimulation

Intraoperative magnetic resonance imaging (iMRI) is increasingly implemented for image-guided procedures in functional neurosurgery. iMRI facilitates accurate electrode implantation for deep brain stimulation (DBS) and is currently an alternative method for DBS electrode targeting. The application of iMRI also allows for greater accuracy and precision in laser-induced thermal therapy (LITT). The expanding use of functional neurosurgical procedures makes safety and feasibility of iMRI important considerations, particularly in patients with comorbidities or complex medical histories. We review here the applications of iMRI and discuss its safety, feasibility, and limitations in functional neurosurgery.To motivate discussion of this topic, we also present a 52-year-old patient with an implanted cardioverter-defibrillator (ICD) who successfully underwent iMRI-guided DBS electrode implantation for advanced Parkinson disease (PD). Neither iMRI nor the passage of electrical current through the implanted DBS electrodes demonstrated detectable interference in ICD function. This case demonstrates that, even in complex clinical contexts, iMRI is a promising tool that merits further exploration for procedures requiring highly accurate and precise identification of target structures.

Machine Learning for Neurodegenerative Disorder Diagnosis — Survey of Practices and Launch of Benchmark Dataset

Neurodegenerative disorders, such as Alzheimer’s and Parkinson’s, constitute a major factor in long-term disability and are becoming more and more a serious concern in developed countries. As there are, at present, no effective therapies, early diagnosis along with avoidance of misdiagnosis seem to be critical in ensuring a good quality of life for patients. In this sense, the adoption of computer-aided-diagnosis tools can offer significant assistance to clinicians. In the present paper, we provide in the first place a comprehensive recording of medical examinations relevant to those disorders. Then, a review is conducted concerning the use of Machine Learning techniques in supporting diagnosis of neurodegenerative diseases, with reference to at times used medical datasets. Special attention has been given to the field of Deep Learning. In addition to that, we communicate the launch of a newly created dataset for Parkinson’s disease, containing epidemiological, clinical and imaging data, which will be publicly available to researchers for benchmarking purposes. To assess the potential of the new dataset, an experimental study in Parkinson’s diagnosis is carried out, based on state-of-the-art Deep Neural Network architectures and yielding very promising accuracy results.

Method of Levodopa Response Calculation Determines Strength of Association With Clinical Factors in Parkinson Disease

Background

The levodopa challenge test is routinely used in Parkinson disease (PD) to determine a patient’s motor improvement following levodopa administration [levodopa response (LR)]. LR is most commonly reported as a percent OFF to ON change in the Unified Parkinson Disease Rating Scale (UPDRS) part III score, and occasionally as an absolute difference in score. This inconsistency in LR determination alters how clinical factors such as patient age and disease duration are understood in relation to LR in PD.

Objective

The aim of this study was to compare the calculation of the LR as either a percent change or difference in UPDRS-III motor score between OFF and ON medication. These two scores were then used to correlate to disease duration, patient age, levodopa duration, levodopa equivalent dose (LED), OFF score, cognition, mood, gait, and quality of life (QOL).

Methods

70 PD patients underwent the levodopa challenge test. The UPDRS-III motor examination was performed in the defined OFF and ON medication states to determine LR. Each patient was assessed after 12–14 h without anti-parkinsonian medication and then given three 100/25 mg levodopa/carbidopa tablets. LR was reported as both a difference in score [OFF − ON; absolute LR (aLR)] and as a percent change in score [(OFF − ON)/OFF*100%; %LR]. Patients completed the following non-motor symptom assessment scales: Montreal Cognitive Assessment, Freezing of Gait Questionnaire, Activities-specific Balance Confidence Scale, Parkinson’s Disease Questionnaire, and Geriatric Depression Scale. The effect of the LR calculation method was correlated to the clinical measures.

Results

The aLR was significantly associated with disease duration (r = 0.40), levodopa duration (r = 0.47), OFF motor score (r = 0.58), and LED (r = 0.31), but not age. The aLR was also found to have a significant relationship with clinical scales assessing cognition (r = 0.41), freezing of gait (r = 0.35), QOL (r = 0.40), and depression (r = 0.30). By contrast, the more commonly used %LR demonstrated no significant relationships with any of the variables tested.

Conclusion

Although the %LR is more commonly employed in clinical protocols and research studies, the aLR is the superior method for reporting motor response to levodopa in PD given its significant associations with the clinical factors evaluated.

Dopamine transporter imaging predicts motor responsiveness to levodopa challenge in patients with Parkinson's disease: A pilot study of DATSCAN for subthalamic deep brain stimulation

Imaging studies are necessary prior to subthalamic deep brain stimulation (STN-DBS). Dopamine transporter (DAT) imaging is a powerful tool for visualizing dopamine terminals in the striatum, but its usefulness in STN-DBS is unclear. Here, we retrospectively investigated the relationship between motor symptoms and the specific binding ratio (SBR) on DAT imaging in patients with Parkinson's disease (PD). We included 23 consecutive patients (9 female; 14 male) who were evaluated for DBS eligibility between October 2013 and October 2014 and subsequently received bilateral STN-DBS. Correlation and simple regression analyses were performed on SBR values and clinical parameters before and after surgery. SBR value was negatively correlated with Unified Parkinson's Disease Rating Scale (UPDRS) motor score in the "ON" state before surgery (r_s=-0.637, p=0.001) and positively correlated with the reduction of the levodopa equivalent daily dose by surgery (r=0.422, p=0.045). A simple regression analysis revealed that SBR value was positively correlated with UPDRS motor score improvement after levodopa challenge before surgery (p=0.001, R²=0.423). DAT imaging may be useful in STN-DBS candidate selection and the identification of the therapeutic mechanism of STN-DBS in patients with advanced PD and motor symptom fluctuations.

Voltage adjustment improves rigidity and tremor in Parkinson's disease patients receiving deep brain stimulation

Deep brain stimulation of the subthalamic nucleus is recognized as the most effective treatment for moderate and advanced Parkinson's disease. Programming of the stimulation parameters is important for maintaining the efficacy of deep brain stimulation. Voltage is considered to be the most effective programming parameter. The present study is a retrospective analysis of six patients with Parkinson's disease (four men and two women, aged 37–65 years), who underwent bilateral deep brain stimulation of the subthalamic nucleus at the First Affiliated Hospital of Sun Yat-sen University, China, and who subsequently adjusted only the stimulation voltage. We evaluated motor symptom severity using the Unified Parkinson's Disease Rating Scale Part III, symptom progression using the Hoehn and Yahr scale, and the levodopa equivalent daily dose, before surgery and 1 and 2 years after surgery. The 2-year follow-up results show that rigidity and tremor improved, and clinical symptoms were reduced, while pulse width was maintained at 60 μs and frequency at 130 Hz. Voltage adjustment alone is particularly suitable for patients who cannot tolerate multiparameter program adjustment. Levodopa equivalent daily dose was markedly reduced 1 and 2 years after surgery compared with baseline. Our results confirm that rigidity, tremor and bradykinesia can be best alleviated by voltage adjustment. The trial was registered at ClinicalTrials.gov (identifier: NCT01934881).

Assessing the Efficacy of Cell Transplantation for Parkinson's Disease: A Patient-Centered Approach

BACKGROUND

Evidence from a growing number of preclinical studies indicate that recently discovered stem cell lines may be translated into viable cellular therapies for people with Parkinson's disease.

OBJECTIVES

In a brief but critical review, we examine the use of primary and secondary outcome measures currently used to evaluate the efficacy of cellular therapies.

METHODS

The current practice of relying on a single primary outcome measure does not appear to provide the evidence required for demonstrating the robust, life-changing recovery anticipated with the successful implementation of cellular therapies.

RESULTS

We propose a 360-degree assessment protocol, which includes co-primary and composite outcome measures to provide accurate and comprehensive evidence of treatment efficacy, from the perspectives of both the researchers and the patients.

Role of clinical neuropsychology in deep brain stimulation: Review of the literature and considerations for clinicians

Deep Brain Stimulation (DBS) is an effective surgical therapy for several neurological movement disorders. The clinical neuropsychologist has a well-established role in the neuropsychological evaluation and selection of surgical candidates. In this article, we argue that the clinical neuropsychologist's role is much broader, when considered in relation to applied psychologists' core competencies. We consider the role of the clinical neuropsychologist in DBS in relation to: assessment, formulation, evaluation and research, intervention or implementation, and communication. For each competence the relevant evidence-base was reviewed. Clinical neuropsychology has a vital role in presurgical assessment of cognitive functioning and psychological, and emotional and behavioral difficulties. Formulation is central to the selection of surgical candidates and crucial to intervention planning. Clinical neuropsychology has a well-established role in postsurgical assessment of cognitive functioning and psychological, emotional, and behavioral outcomes, which is fundamental to evaluation on an individual and service level. The unique contribution clinical neuropsychology makes to pre- and postsurgical interventions is also highlighted. Finally, we discuss how clinical neuropsychology can promote clear and effective communication with patients and between professionals.

Dopaminergic polymorphisms associated with medication responsiveness of gait in Parkinson's disease

BACKGROUND

Gait dysfunction is a common symptom of Parkinson's disease that can cause significant disability and put patients at risk for falls. These symptoms show variable responsiveness to dopaminergic therapy.

OBJECTIVE

To determine whether dopaminergic (rs1076560 DRD2 G > T and rs4680 catechole-o-methyltranspherase (COMT) Val158Met) or brain derived neurotrophic factor (rs6265 BDNF Val66Met) genetic polymorphisms are associated with gait function and medication responsiveness in Parkinson's disease.

METHOD

Gait function was evaluated on two days for patients (ON and OFF medication in a counterbalanced fashion) and a single session for controls. Investigators were blinded to genotype during data collection. Associations between genotype and medication responsiveness were analyzed using mixed model ANOVAs. A priori hypotheses were tested using GAITRite^® electronic mat spatiotemporal gait parameters including step length, step width, velocity, portion of double and single support per gait cycle, and variability of these measures ON and OFF medication.

RESULTS

We found that the DRD2 polymorphism, but neither COMT nor BDNF, was consistently associated with gait function and medication responsiveness in the patients. Specifically, Parkinson's disease patients with reduced striatal D2 expression (DRD2 T allele carriers) had worse gait dysfunction and showed greater dopamine responsiveness of gait function compared to patients who were homozygous for the G allele. There was no effect of any of the genetic polymorphisms on gait for controls.

CONCLUSIONS AND RELEVANCE

The findings suggest that genetic subgrouping, in particular for DRD2, may be used to identify Parkinson's disease patient subgroups that are more dopamine responsive for gait function.

The changing landscape of surgery for Parkinson's Disease

Neurosurgical interventions have been used to treat PD for over a century. We examined the changing landscape of surgery for PD to appraise the value of various procedures in the context of advances in our understanding and technology. We assessed the number of articles published on neurosurgical procedures for PD over time as an albeit imprecise surrogate for their usage level. We identified over 8,000 publications associated with PD surgery. Over half the publications were on DBS. The field of DBS for PD showed a rapid rise in articles, but is now in a steady state. Thalamotomy and, to a lesser extent, pallidotomy follow a biphasic publication distribution with peaks approximately 30 years apart. Articles on gene therapy and transplantation experienced initial rapid rises and significant recent declines. Procedures using novel technologies, including gamma knife and focused ultrasound, are emerging, but are yet to have significant impact as measured by publication numbers. Pallidotomy and thalamotomy are prominent examples of procedures that were popular, declined, and re-emerged and redeclined. Transplantation and gene therapy have never broken into clinical practice. DBS overtook all procedures as the dominant surgical intervention and drove widespread use of surgery for PD. Notwithstanding, the number of DBS articles appears to have plateaued. As advances continue, emerging treatments may compete with DBS in the future. © 2017 International Parkinson and Movement Disorder Society.

Early versus Late Application of Subthalamic deep brain Stimulation to Parkinson's disease patients with motor complications (ELASS): protocol of a multicentre, prospective and observational study

INTRODUCTION

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a well-established surgical treatment for Parkinson's disease (PD). However, there is currently no consensus on the best timing for this surgery. The aim of our study is to compare the therapeutic efficacy of bilateral STN DBS in patients with PD with early and late motor complications.

METHODS AND ANALYSIS

200 patients with PD will be enrolled in this multicentre, prospective, observational study, and will be followed up for 4 years. Patients with PD who meet the criteria for STN DBS surgery will be allocated to either the early stimulation group or the late stimulation group based on the duration of their motor complications. The primary outcome will be changes in quality of life from baseline to 4 years, measured using the 39-item Parkinson's Disease Questionnaire Summary Index. The secondary outcomes include changes in motor function measured using Movement Disorder Society-revised Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III, self-reported experiences of daily living measured using MDS-UPDRS Part I B and Part II, good 'on' time recorded by the patients using a diary and safety profile of both groups.

ETHICS AND DISSEMINATION

The study received ethical approval from the Medical Ethical Committee of the First Affiliated Hospital, Sun Yat-sen University. The results of this study will be published in peer-reviewed journals and presented at international conferences.

TRIAL REGISTRATION NUMBER

NCT01922388; Pre-results.

Clinical Ethics in the Context of Deep Brain Stimulation for Movement Disorders

OBJECTIVE

Discuss common clinical ethical challenges encountered in working with patients who are candidates for deep brain stimulation (DBS) for the treatment of motor symptoms of Parkinson's disease (PD).

METHOD

The relevant literature is reviewed and supplemented by descriptive, ethically challenging cases stemming from decades of combined experience working on DBS teams. We outline ethical arguments and provide pragmatic recommendations to assist neuropsychologists working in movement disorder teams.

RESULTS

The goals of the pre-operative neuropsychological DBS assessment include: (1) identification of potential cognitive risk factors; (2) identification of relevant neuropsychiatric or neurobehavioral factors; (3) assessment of level of family support; and (4) systematic assessment of patient's and family member's goals or expectations for DBS. The information gleaned from the pre-operative neuropsychological assessment is highly relevant to the most commonly studied clinical ethics challenges encountered in DBS: (1) assessment of risk/benefit; (2) determinations regarding inclusion/exclusion; (3) autonomy; and (4) patient's perception of benefit and quality of life.

CONCLUSIONS

Neuropsychologists are particularly well poised to provide unique and important insights to assist with developing the most ethically sound practices that take into account patient's values as well as fiduciary responsibilities to the patient, the team, the profession, and the broader community.

Abnormal intrinsic brain functional network dynamics in Parkinson's disease

See Nieuwhof and Helmich (doi:10.1093/brain/awx267 ) for a scientific commentary on this article .

Parkinson’s disease is a neurodegenerative disorder characterized by nigrostriatal dopamine depletion. Previous studies measuring spontaneous brain activity using resting state functional magnetic resonance imaging have reported abnormal changes in broadly distributed whole-brain networks. Although resting state functional connectivity, estimating temporal correlations between brain regions, is measured with the assumption that intrinsic fluctuations throughout the scan are stable, dynamic changes of functional connectivity have recently been suggested to reflect aspects of functional capacity of neural systems, and thus may serve as biomarkers of disease. The present work is the first study to investigate the dynamic functional connectivity in patients with Parkinson’s disease, with a focus on the temporal properties of functional connectivity states as well as the variability of network topological organization using resting state functional magnetic resonance imaging. Thirty-one Parkinson’s disease patients and 23 healthy controls were studied using group spatial independent component analysis, a sliding windows approach, and graph-theory methods. The dynamic functional connectivity analyses suggested two discrete connectivity configurations: a more frequent, sparsely connected within-network state (State I) and a less frequent, more strongly interconnected between-network state (State II). In patients with Parkinson’s disease, the occurrence of the sparsely connected State I dropped by 12.62%, while the expression of the more strongly interconnected State II increased by the same amount. This was consistent with the altered temporal properties of the dynamic functional connectivity characterized by a shortening of the dwell time of State I and by a proportional increase of the dwell time pattern in State II. These changes are suggestive of a reduction in functional segregation among networks and are correlated with the clinical severity of Parkinson’s disease symptoms. Additionally, there was a higher variability in the network global efficiency, suggesting an abnormal global integration of the brain networks. The altered functional segregation and abnormal global integration in brain networks confirmed the vulnerability of functional connectivity networks in Parkinson’s disease.

Validation of a Smartphone Application Measuring Motor Function in Parkinson's Disease

BACKGROUND

Measurement of motor function is critical to the assessment and management of Parkinson's disease. Ambulatory motor assessment has the potential to provide a glimpse of the patient's clinical state beyond the consultation. We custom-designed a smartphone application that quantitatively measures hand dexterity and hypothesized that this can give an indication of a patient's overall motor function.

OBJECTIVE

The aims of this study were to (i) validate this smartphone application against MDS-UPDRS motor assessment (MDS-UPDRS-III) and the two-target tapping test; (ii) generate a prediction model for MDS-UPDRS-III; (iii) assess repeatability of our smartphone application and (iv) examine compliance and user-satisfaction of this application.

METHODS

103 patients with Parkinson's disease were recruited from two movement disorders clinics. After initial assessment, a group of patients underwent repeat assessment within two weeks. Patients were invited to use the smartphone application at home over three days, followed by a survey to assess their experience.

RESULTS

Significant correlation between key smartphone application test parameters and MDS-UPDRS-III (r = 0.281-0.608, p < 0.0001) was demonstrated. A prediction model based on these parameters accounted for 52.3% of variation in MDS-UPDRS-III (R2 = 0.523, F(4,93) = 25.48, p < 0.0001). Forty-eight patients underwent repeat assessment under identical clinical conditions. Repeatability of key smartphone application tests parameters and predicted MDS-UPDRS-III was moderate to strong (intraclass correlation coefficient 0.584-0.763, p < 0.0001). The follow-up survey identified that our patients were very comfortable with the smartphone application and mobile technology.

CONCLUSIONS

Our smartphone application demonstrated satisfactory repeatability and validity when measured against MDS-UPDRS-III. Its performance is acceptable considering our smartphone application measures hand dexterity only.

High-dose transdermal nicotine in Parkinson's disease patients: a randomized, open-label, blinded-endpoint evaluation phase 2 study

BACKGROUND AND PURPOSE

Studies of the effects of nicotine on motor symptoms in Parkinson's disease (PD) brought out discordant results. The aim of the present study was to evaluate the efficacy and safety of high doses of transdermal nicotine on motor symptoms in PD.

METHODS

Forty PD patients were randomly assigned to a treated and untreated arm in an open-label study. Treated patients received increasing doses of nicotine to reach 90 mg/day by 11 weeks. This dosage was maintained for 28 weeks (W39) and then reduced over 6 weeks. Final evaluation was performed 6 weeks after washout. The main outcome measure was the OFF-DOPA Unified Parkinson's Disease Rating Scale (UPDRS) motor score measured on video recordings by raters blinded to the medication status of the patients.

RESULTS

There was no significant difference in OFF-DOPA UPDRS motor scores between the nicotine-treated and non-treated groups, neither at W39 (19.4 ± 9.3 vs. 21.5 ± 14.2) nor considering W39 differences from baseline (-1.5 ± 12.1 vs. +0.9 ± 12.1). The 39-item Parkinson's disease questionnaire scores decreased in nicotine-treated patients and increased in non-treated patients, but the difference was not significant. Overall tolerability was acceptable, and 12/20 treated patients reached the maximal dosage.

CONCLUSIONS

High doses of transdermal nicotine were tolerated, but our study failed to demonstrate significant improvement in UPDRS motor scores. Improvement in unblinded secondary outcomes (UPDRS-II, UPDRS-IV, doses of l-DOPA equivalents) suggest a possible benefit for patients treated with nicotine, which should be confirmed in larger double blind, placebo-controlled studies.

Micro lesion effect of the globus pallidus internus with deep brain stimulation in Parkinson's disease patients

BACKGROUND

The micro-lesion effect (MLE) has been observed in many Parkinson's disease (PD) patients after deep brain stimulation (DBS) surgery. For subthalamic nucleus (STN) stimulation, the MLE has been reported as a predictor of the long-term efficacy of DBS. However, the research on the MLE in the globus pallidus internus (GPi) is insufficient. In this report, we conducted a study of the correlation between the MLE and improvement of GPi DBS.

METHODS

From July 2014 to November 2015, 36 PD patients underwent GPi DBS in our hospital. The patients were evaluated before DBS and postoperatively at 24 h, 1 week, 2 weeks, 3 weeks, 6 months and 1 year. The evaluated items included the following: the UPDRSIII score with and without medication, off time per day and severe dyskinesia time per day. The dose of L-dopa, magnitude and duration of MLE were also recorded.

RESULTS

There were 32 patients with a postoperative MLE. In these 32 cases, the dose of L-dopa decreased from 960.5 ± 257.8 mg (range, 550-1550) to 910.4 ± 207.5 mg (range, 550-1250). There is a correlation between the magnitude of the MLE in UPDRSIII and the improvement degree of DBS at 6 and 12 months compared with the preoperative findings when off medication. The duration of the MLE is also an indication of the improvement of DBS in the long term when off medication. However, there was no correlation with on medication. Compared with the preoperative state, the UPDRSIII score, off time and severe dyskinesia time had improved postoperatively.

CONCLUSIONS

The MLE of GPi is a predictor of PD patients who would benefit from DBS in the long term. Medication may have some conflicting effects on the MLE. The exact mechanism of the MLE requires further exploration.

Stratifying Parkinson's Patients With STN-DBS Into High-Frequency or 60 Hz-Frequency Modulation Using a Computational Model

OBJECTIVE

High frequency stimulation (HFS) of the subthalamic nucleus (STN) is a well-established therapy for Parkinson's disease (PD), particularly the cardinal motor symptoms and levodopa induced motor complications. Recent studies have suggested the possible role of 60 Hz stimulation in STN-deep brain stimulation (DBS) for patients with gait disorder. The objective of this study was to develop a computational model, which stratifies patients a priori based on symptomatology into different frequency settings (i.e., high frequency or 60 Hz).

METHODS

We retrospectively analyzed preoperative MDS-Unified Parkinson's Disease Rating Scale III scores (32 indicators) collected from 20 PD patients implanted with STN-DBS at Mount Sinai Medical Center on either 60 Hz stimulation (ten patients) or HFS (130-185 Hz) (ten patients) for an average of 12 months. Predictive models using the Random Forest classification algorithm were built to associate patient/disease characteristics at surgery to the stimulation frequency. These models were evaluated objectively using leave-one-out cross-validation approach.

RESULTS

The computational models produced, stratified patients into 60 Hz or HFS (130-185 Hz) with 95% accuracy. The best models relied on two or three predictors out of the 32 analyzed for classification. Across all predictors, gait and rest tremor of the right hand were consistently the most important.

CONCLUSIONS

Computational models were developed using preoperative clinical indicators in PD patients treated with STN-DBS. These models were able to accurately stratify PD patients into 60 Hz stimulation or HFS (130-185 Hz) groups a priori, offering a unique potential to enhance the utilization of this therapy based on clinical subtypes.

Weight gain after STN-DBS: The role of reward sensitivity and impulsivity

Weight gain has been reported after deep brain stimulation of the subthalamic nucleus (STN-DBS), a widely used treatment for Parkinson's disease (PD). This nucleus has been repeatedly found to be linked both to reward and to inhibitory control, two key aspects in the control of food intake. In this study, we assessed whether weight gain experienced by patients with PD after STN-DBS, might be due to an alteration of reward and inhibitory functions. Eighteen patients with PD were compared to eighteen healthy controls and tested three times: before surgery, in ON medication and after surgery, respectively five days after the implantation in ON medication/OFF stimulation and at least three months after surgery in ON medication/ON stimulation. All participants were assessed for depression (Beck Depression Inventory), anhedonia (Snaith-Hamilton Pleasure Scale) and impulsiveness (Barratt Impulsiveness Scale). They performed a battery of tests assessing food reward sensitivity (Liking, Wanting and Preference) and a food go/no-go task. Results showed that body weight significantly increased after STN-DBS. A few days after surgery, patients were slower and more impulsive in the go/no-go task, showed a higher preference for high calorie (HC) foods and rated foods as less tasty. Months after subthalamic stimulation, the performance on the go/no-go task improved while no differences were observed in reward sensitivity. Interestingly, weight gain resulted greater in patients with higher levels of attentional impulsiveness pre-surgery, higher wanting for low calorie (LC) foods and impulsivity in the go/no-go task in ON medication/ON stimulation. However, only wanting and attentional impulsivity significantly predicted weight change. Furthermore, weight gain resulted associated with the reduction of l-Dopa after surgery and disease's duration. In conclusion, our findings are consistent with the view that weight gain in PD after STN-DBS has a multifactorial nature, which reflects the complex functional organization of the STN.

Medical Management of Parkinson's Disease after Initiation of Deep Brain Stimulation

In this review, we have gathered all the available evidence to guide medication management after deep brain stimulation (DBS) in Parkinson's disease (PD). Surprisingly, we found that almost no study addressed drug-based management in the postoperative period. Dopaminergic medications are usually reduced, but whether the levodopa or dopamine agonist is to be reduced is left to the personal preference of the treating physician. We have summarized the pros and cons of both approaches. No study on the management of cognitive problems after DBS has been done, and only a few studies have explored the pharmacological management of such DBS-resistant symptoms as voice (amantadine), balance (donepezil) or gait disorders (amantadine, methylphenidate). As for the psychiatric problems so frequently reported in PD patients, researchers have directed their attention to the complex interplay between stimulation and reduction of dopaminergic drugs only recently. In conclusion, studies addressing medical management following DBS are still needed and will certainly contribute to the ultimate success of DBS procedures.

Dual Anchor Internal Pulse Generator Technique May Lower Risk of Twiddler's Syndrome: A Case Series and Literature Review

BACKGROUND

Twiddler's syndrome (TS) is described as a spontaneous rotation or intentional external manipulation of implanted internal pulse generator (IPG) for neurological or cardiac disorders. There have been identified some predisposing factors of the development of TS such as: loose subcutaneous tissue, older age of individuals undergoing deep brain stimulation (DBS) procedures, creation of too large pockets for IPG. Apart from these factors, the construction of IPG itself may predispose to the development of TS.

OBJECTIVE

To report the clinical course of three patients with TS. Moreover, the purpose of this study is to present the change in fixation technique of IPG that can prevent the occurrence of TS in patients after DBS procedure.

METHODS

A prospectively collected database of all hardware related complications for patients operated on for various movement disorders was analyzed. In a total number of 347 DBS systems implanted since 1999 we have identified three patients diagnosed with TS. All three patients with TS in our series were implanted with the IPG harboring a single anchoring hole. This complication has never occurred in patients with the IPG harboring two anchoring holes in our center.

RESULTS

All three patients underwent revision surgery. During reoperations all connection cables were replaced and IPG sutured with one additional silk stich through the plastic housing to immobilize it properly in subcutaneous pocket. There were no recurrences of TS in our patients.

CONCLUSIONS

Our case series suggests that a predisposing factor of TS may also be the construction of IPG itself (a single anchoring hole intended for fixation), which naturally represents less fixation of the IPG to the fascia or muscle in the subcutaneous pocket. In this preliminary report we present suggestions to lower the risk of TS, including using dual anchor capable IPGs, reducing pocket volume and using nonabsorbable suture.

Improvement of Advanced Parkinson's Disease Manifestations with Deep Brain Stimulation of the Subthalamic Nucleus: A Single Institution Experience

We present our experience at the University of Illinois at Chicago (UIC) in deep brain stimulation (DBS) of the subthalamic nucleus (STN), describing our surgical technique, and reporting our clinical results, and morbidities. Twenty patients with advanced Parkinson’s disease (PD) who underwent bilateral STN-DBS were studied. Patients were assessed preoperatively and followed up for one year using the Unified Parkinson’s Disease Rating Scale (UPDRS) in “on” and “off” medication and “on” and “off” stimulation conditions. At one-year follow-up, we calculated significant improvement in all the motor aspects of PD (UPDRS III) and in activities of daily living (UPDRS II) in the “off” medication state. The “off” medication UPDRS improved by 49.3%, tremors improved by 81.6%, rigidity improved by 50.0%, and bradykinesia improved by 39.3%. The “off” medication UPDRS II scores improved by 73.8%. The Levodopa equivalent daily dose was reduced by 54.1%. The UPDRS IVa score (dyskinesia) was reduced by 65.1%. The UPDRS IVb score (motor fluctuation) was reduced by 48.6%. Deep brain stimulation of the STN improves the cardinal motor manifestations of the idiopathic PD. It also improves activities of daily living, and reduces medication-induced complications.

Establishing a Standard of Care for Deep Brain Stimulation Centers in Canada

During the “DBS Canada Day” symposium held in Toronto July 4-5, 2014, the scientific committee invited experts to share their knowledge regarding deep brain stimulation (DBS) management of movement disorders in three domains: (1) the programming algorithms, (2) the necessary team to run a neurosurgery program, and (3) the appropriate scales to better define in a more comprehensive fashion the effect of the brain surgery. Each presentation was followed by an open discussion, and this article reports on the conclusions of this meeting on these three questions. Concerning programming, the role of the pulse width and the switching off of the stimulation at night for thalamic stimulation for the control of tremor have been discussed. The algorithms proposed in the literature for programming in Parkinson’s disease (PD) need validation. In dystonia, the use of monopolar vs bipolar parameters, the use of low vs high frequencies and the use of smaller versus larger pulse widths all need to be examined properly. Concerning the necessary team to run a neurosurgical program, recommendations will follow the suggestions for standardized outcome measures. Regarding the outcome measures for DBS in PD, investigations need to focus on the non-motor aspects of PD. Identifying which nonmotor symptoms respond to DBS would allow a better screening before and satisfaction postoperatively. There is an important need for more data to determine the optimal programming protocol and the standard measures that should be performed routinely by all centers.

Fatigue in Parkinson's disease: The contribution of cerebral metabolic changes

Fatigue is a common and disabling non-motor symptom in Parkinson's disease associated with a feeling of overwhelming lack of energy. The aim of this study was to identify the neural substrates that may contribute to the development of fatigue in Parkinson's disease. Twenty-three Parkinson's disease patients meeting UK Brain Bank criteria for the diagnosis of idiopathic Parkinson's disease were recruited and completed the 2-[¹⁸ F]fluoro-2-deoxy-D-glucose (FDG)-PET scan. The metabolic activities of Parkinson's disease patients with fatigue were compared to those without fatigue using statistical parametric mapping analysis. The Parkinson's disease group exhibiting higher level of fatigue showed anti-correlated metabolic changes in cortical regions associated with the salience (i.e., right insular region) and default (i.e., bilateral posterior cingulate cortex) networks. The metabolic abnormalities detected in these brain regions displayed a significant correlation with level of fatigue and were associated with a disruption of the functional correlations with different cortical areas. These observations suggest that fatigue in Parkinson's disease may be the expression of metabolic abnormalities and impaired functional interactions between brain regions linked to the salience network and other neural networks. Hum Brain Mapp 38:283-292, 2017. © 2016 Wiley Periodicals, Inc.

Quantification of neural reflex and muscular intrinsic contributions to parkinsonian rigidity

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by rigidity, bradykinesia, resting tremor, and postural instability. Rigidity, defined as an increased resistance to passive movement of a joint, progresses faster than other motor signs in PD. Rigidity is attributable to both exaggerated neural reflex and altered muscle mechanical properties. However, little is known about the contributions of individual components to rigidity. Further, there is no evidence regarding the effects of dopaminergic medication on individual components. Objectives of this study were to quantify the contributions of neural reflexes and intrinsic muscle properties to rigidity and investigate the effects of medication on each contributing component. Joint torque and muscle activities of the wrist in 14 patients and 14 controls were measured during externally induced movements. Each subject with PD was tested in Off- and On-medication states. A system identification technique was applied to differentiate and quantify the neural reflex and intrinsic mechanical components. A mixed model of ANOVA was performed to compare the differences between the two components of rigidity for both groups, and to compare between the Off- and On-medication states for patients. The results showed that reflex and intrinsic components are comparable (p > 0.05), and both are enhanced in subjects with PD than in the controls (p < 0.05). Medication decreased the reflex component of rigidity (p < 0.01). It is concluded that both reflex and intrinsic factors are responsible for rigidity. Present findings are clinically significant as they may provide guidance in development of effective therapeutic interventions.

Effect of subthalamic stimulation on distal and proximal upper limb movements in Parkinson's disease

INTRODUCTION

A different innervation pattern of proximal and distal muscles from the contra- and ipsilateral motor circuits raises the question as to whether bilateral, contra- and ipsilateral subthalamic stimulation may have different effects on the distal and proximal movements of the upper limb. To answer this question, we performed kinematic analyzes in patients with Parkinson's disease.

METHODS

Twenty-eight Parkinsonian patients treated by bilateral subthalamic stimulation were examined with an age-matched control group of 28 healthy subjects. They performed 14s of finger tapping, hand grasping and pronation-supination. The patient group performed these sessions in four conditions (BOTH ON, BOTH OFF, CONTRA ON, IPSI ON) after withdrawal of dopaminergic medication for 12h and a fifth condition after taking medication (BOTH ON-MED ON). A motion sensor with a three-dimensional gyroscope was worn on the index finger. Speed, amplitude, rhythm and decrement of movements were calculated and compared across these conditions.

RESULTS

Speed and amplitude of the more distal movements were improved similarly by contra- and bilateral stimulation. Bilateral stimulation was more effective than contralateral stimulation for the more proximal movements. Contra- and bilateral stimulation ameliorated the rhythm similarly in each movement task. Decrement of distal and proximal movements was not affected by the stimulation conditions.

CONCLUSION

This is the first study to show that the outcome of bi- and unilateral subthalamic stimulation on proximal and distal upper limb movements should be evaluated separately postulating the different somatotopic organization of subloops in the cortico-basal ganglia motor circuits.

Benefits of subthalamic stimulation for elderly parkinsonian patients aged 70 years or older

OBJECTIVES

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an accepted treatment for advanced Parkinson disease (PD). However, there is general reluctance in considering this therapy for PD patients over age 70 years with limited supporting evidence. Present study investigates age impacts in STN-DBS outcomes, focusing particularly on the elderly patients.

PATIENTS AND METHODS

Seventy-two consecutive patients were divided into younger and elderly (n=16, cutoff age=70years) groups. Both groups were comparable in preoperative clinical severity, except the elderly exhibited a levodopa (LD) response (P<0.05) inferior to that of the younger. Improvements in drug-off/DBS-on Unified PD Rating Scale (UPDRS) scores and reduction in daily LD-equivalent dose (LED) after 6 months were evaluated relative to the presurgical drug-off baseline. Preoperative factors predictive of favorable surgical outcomes were analyzed using a multivariate linear regression model.

RESULTS

After DBS therapy, elderly patients exhibited clinical improvements particularly in the tremor (56%) and LD-induced dyskinesia (78%). Improvement of axial dysfunction (24%) and reduction of daily LED (24%) showed no intergroup difference. Adverse events, particularly dysarthria, occurred frequently in elderly group. The overall improvements in UPDRS scores were suboptimal in elderly group, correlating with their preoperative inferior LD responses. Elderly patients who presented predominantly with akinesia before surgery achieved superior surgical outcomes (adjusted R(2)=0.657, P<0.001).

CONCLUSION

STN-DBS therapy is beneficial to some elderly PD patients aged 70 years or older. Tremor, axial dysfunctions and drug-induced dyskinesia are the main indications for the elderly; however, their clinical benefits are inferior to those of younger patients.

A Validation Study of a Smartphone-Based Finger Tapping Application for Quantitative Assessment of Bradykinesia in Parkinson's Disease

Background

Most studies of smartphone-based assessments of motor symptoms in Parkinson’s disease (PD) focused on gait, tremor or speech. Studies evaluating bradykinesia using wearable sensors are limited by a small cohort size and study design. We developed an application named smartphone tapper (SmT) to determine its applicability for clinical purposes and compared SmT parameters to current standard methods in a larger cohort.

Methods

A total of 57 PD patients and 87 controls examined with motor UPDRS underwent timed tapping tests (TT) using SmT and mechanical tappers (MeT) according to CAPSIT-PD. Subjects were asked to alternately tap each side of two rectangles with an index finger at maximum speed for ten seconds. Kinematic measurements were compared between the two groups.

Results

The mean number of correct tapping (MCoT), mean total distance of finger movement (T-Dist), mean inter-tap distance, and mean inter-tap dwelling time (IT-DwT) were significantly different between PD patients and controls. MCoT, as assessed using SmT, significantly correlated with motor UPDRS scores, bradykinesia subscores and MCoT using MeT. Multivariate analysis using the SmT parameters, such as T-Dist or IT-DwT, as predictive variables and age and gender as covariates demonstrated that PD patients were discriminated from controls. ROC curve analysis of a regression model demonstrated that the AUC for T-Dist was 0.92 (95% CI 0.88–0.96).

Conclusion

Our results suggest that a smartphone tapping application is comparable to conventional methods for the assessment of motor dysfunction in PD and may be useful in clinical practice.

Infusion treatments and deep brain stimulation in Parkinson's Disease: The role of nursing

Parkinson's Disease (PD) represents one of the most common neurodegenerative disorders in the elderly. PD is caused by a loss of dopaminergic cells in the substantia nigra pars compacta. The motor cardinal signs include a resting tremor, bradykinesia, rigidity and postural reflex impairment. Although levodopa represents the gold standard also in the advanced stage of the disease, over the years most patients develop disabling motor fluctuations, dyskinesias, and non-motor complications, which are difficult to manage. At this stage, more complex treatment approaches, such as infusion therapies (subcutaneous apomorphine and intraduodenal levodopa) and deep brain stimulation of the subthalamic nucleus or the globus pallidus internus should be considered. All three procedures require careful selection and good compliance of candidate patients. In particular, infusional therapies need adequate training both of caregivers and nursing staff in order to assist clinicians in the management of patients in the complicated stages of disease.

Quantitative gait analysis in parkin disease: Possible role of dystonia

INTRODUCTION

Parkin disease (PARK2, OMIM 602544) is an autosomal-recessive early-onset parkinsonism characterized by an early occurrence of lower limb dystonia. The aim of this study was to analyze spatiotemporal, kinematic, and kinetic gait parameters in patients with parkin disease in the OFF and ON conditions compared to healthy age-matched controls.

METHODS

Fifteen patients with parkin disease and 15 healthy age-matched controls were studied in a gait analysis laboratory with an integrated optoelectronic system. Spatiotemporal, kinematic, and kinetic gait parameters at a self-selected speed were recorded in the OFF and ON conditions. A jerk index was computed to quantify the possible reduction of smoothness of joint movements.

RESULTS

Compared to controls, parkin patients had, either in the OFF or in the ON conditions, significant reduction of walking velocity, increased step width, and decreased percentage of double support. Kinematic analysis in both conditions showed: increased ankle dorsiflexion and knee flexion at the initial contact; maximal flexion and increased range of motion in mid stance; increased hip flexion and max extension in stance at pelvis; and increased mean tilt antiversion. Kinetics showed increased hip and knee power generation in stance in either condition. The jerk index was increased at all joints both in OFF and ON. There were no correlations between individual gait parameters and clinical ratings.

CONCLUSION

Parkin patients have an abnormal gait pattern that does not vary between the OFF and the ON conditions. Variations recorded with instrumented analysis are more evident for kinematic than kinetic parameters at lower limbs. Severity of dystonia does not correlate with any individual kinematic parameter. © 2016 International Parkinson and Movement Disorder Society.

Split-belt locomotion in Parkinson's disease links asymmetry, dyscoordination and sequence effect

BACKGROUND

The pathophysiology behind gait impairments seen in Parkinson's disease (PD), in particular freezing of gait (FOG), is not fully understood. Here we study the interplay between several gait features related to FOG during different split-belt treadmill (SBTM) conditions.

METHODS

We investigated the spatiotemporal properties, the phenomenon of sequence effect and the inter-limb symmetry and temporal coordination of gait during different split-belt conditions in 20 patients with advanced Parkinson's disease and different severities of freezing. Subjects were tested in four belt configurations: tied, split while reducing the velocity of leg with the shorter (worst side reduction, WSR) and longer (best side reduction, BSR) step length, and tied again to measure the after-effect.

RESULTS

We found that in spite of an improvement of spatial symmetry, the BSR led to a worsening of coordination (i.e. the left-right anti-phased stepping) and an increased sequence effect (i.e. progressive shortening of the step length). By contrast, in spite of a worsened spatial symmetry, WSR improved inter-limbs coordination and reduced the sequence effect. After prolonged split-belt walking gait was differently modulated according to the reduction of the best or worst leg velocity: BSR led to positive after effects in symmetry, bilateral coordination and sequence effect.

CONCLUSIONS

These findings support the hypothesis that the irregularity of inter-limb coordination and defective amplitude generation leading to sequence effect might be coupled and result from the same maladaptive motor behavior. Furthermore, our results show that SBTM can be an effective tool to improve parkinsonian gait.

Effect of Age and Disease Duration on the Levodopa Response in Patients with Advanced Parkinson's Disease for Deep Brain Stimulation of the Subthalamic Nucleus

Background

Deep brain stimulation (DBS) has become a preferred option for the treatment of motor symptoms in patients with advanced Parkinson’s disease (PD). A good levodopa response (LR) is considered the most important criterion in determining the suitability of a patient for DBS. However, the effect of age and disease duration (DD) on the LR is still a subject of discussion.

Objective

Here, we investigated the effect of age and DD on the preoperative LR in PD patients to be selected for DBS.

Methods

From August 2011 to May 2015, 54 consecutive patients (29 men and 25 women) with advanced PD were evaluated for DBS of the STN and included in this retrospective study.

Results

Thirty-seven patients were found suitable for DBS of the STN and 29 of them underwent bilateral surgery. We found no significant correlation between DD and the LR. However, there was a significant negative correlation between the patients’ age and the LR.

Conclusion

The results indicate that the patients’ age, rather than DD, has a negative effect on the LR. The study, therefore, indicates that PD patients with an advanced age and with a poor LR are not good candidates for DBS of the STN.

Advanced therapies in Parkinson's disease: Long-term retrospective study

BACKGROUND

Levodopa/carbidopa intestinal gel infusion (LCIG) and subthalamic nucleus deep brain stimulation (STN-DBS) are approved therapies for advanced Parkinson's disease (PD) whose long-term comparability remains unclear.

METHODS

We reviewed the 5-year data on activities of daily living (ADL) and motor complications (OFF time, dyskinesia duration, and dyskinesia severity), as measured by the Unified Parkinson Disease Rating Scale (UPDRS) section-II and section-IV (items 39, 32, and 33, respectively) in 60 PD patients exposed to STN-DBS (n = 20), LCIG (n = 20), and oral medical therapy (OMT) (n = 20) at similar baseline disability and cognitive state.

RESULTS

STN-DBS and LCIG showed a similar magnitude of deterioration in ADL (+6.1 vs. +5.7 UPDRS-II; p = 0.709), but lesser than with OMT (+13.7 UPDRS-II; p = 0.005). OFF time also improved to the same extent in STN-DBS and LCIG (-62% vs. -54.5%; p = 0.830), while worsened with OMT (+78.6%; p < 0.001). STN-DBS and LCIG yielded greater improvement on dyskinesia compared to OMT (dyskinesia duration: -66.1% vs. -9.0% vs. +24.2% [p = 0.001]; dyskinesia severity: -68.8% vs. -18.0% vs. +16.2% [p = 0.002]), with relative superiority of STN-DBS over LCIG (p = 0.004 for duration; p = 0.014 for severity). The annualized rate of complication was lower in STN-DBS vs. LCIG (0.13 vs. 0.68; p < 0.001) but not different between STN-DBS and OMT (0.13 vs. 0.10; p = 0.795).

CONCLUSIONS

STN-DBS and LCIG showed comparable efficacy in ADL and OFF time, superior to OMT. STN-DBS yielded greater improvement in dyskinesia and lower long-term rate of complications than LCIG.

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.

Low-frequency Subthalamic Stimulation in Parkinson's Disease: Long-term Outcome and Predictors

BACKGROUND

Parkinson's disease patients undergoing subthalamic nucleus deep brain stimulation (STN DBS) at standard frequency (>100 Hz) often develop gait impairment, postural instability and speech difficulties. Low frequency stimulation (<100 Hz, LFS) can improve such axial symptoms, but there are concerns that improvement may be transient.

OBJECTIVE

To identify long-term outcome and predictors of low-frequency subthalamic stimulation in Parkinson's disease.

METHODS

Through a chart review we identified 85 out of 324 STN DBS patients who received a trial of LFS and describe their characteristics and outcome predictors.

RESULTS

Patients were switched to LFS (<100 Hz) 3.8 ± 3.3 years after surgery. Most patients (64%) attained a subjective improvement of gait, speech or balance for 2.0 ± 1.9 years. Motor scores improved within the first year after the stimulation change and showed a slower progression over time when compared to patients switched back to high frequency stimulation. UPDRS III axial score on medication before surgery and the y-axis coordinate of the active contact were independent predictors of LFS retention.

CONCLUSIONS

This report provides evidence that the use of LFS yields an enduring benefit in a considerable percentage of patients who develop axial motor symptoms during conventional stimulation.