Long-Term Follow-Up of the LEAP Study: Early Versus Delayed Levodopa in Early Parkinson's Disease

BACKGROUND AND OBJECTIVE

The Levodopa in EArly Parkinson's disease study showed no effect of earlier versus later levodopa initiation on Parkinson's disease (PD) progression over 80 weeks. We now report the effects over 5 years.

METHODS

The Levodopa in EArly Parkinson's disease study randomly assigned patients to levodopa/carbidopa 300/75 mg daily for 80 weeks (early start) or to placebo for 40 weeks followed by levodopa/carbidopa 300/75 mg daily for 40 weeks (delayed start). Follow-up visits were performed 3 and 5 years after baseline. We assessed the between-group differences in terms of square root transformed total Unified Parkinson's Disease Rating Scale score at 3 and 5 years with linear regression. We compared the prevalence of dyskinesia, prevalence of wearing off, and the levodopa equivalent daily dose.

RESULTS

A total of 321 patients completed the 5-year visit. The adjusted square root transformed total Unified Parkinson's Disease Rating Scale did not differ between treatment groups at 3 (estimated difference, 0.17; standard error, 0.13; P = 0.18) and 5 years (estimated difference, 0.24; standard error, 0.13; P = 0.07). At 5 years, 46 of 160 patients in the early-start group and 62 of 161 patients in the delayed-start group experienced dyskinesia (P = 0.06). The prevalence of wearing off and the levodopa equivalent daily dose were not significantly different between groups.

CONCLUSIONS

We did not find a difference in disease progression or in prevalence of motor complications between patients with early PD starting treatment with a low dose of levodopa 40 weeks earlier versus 40 weeks later over the subsequent 5 years. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Deep Brain Stimulation for Orthostatic Tremor: An Observational Study

BACKGROUND

Primary orthostatic tremor (OT) can affect patients' life. Treatment of OT with deep brain stimulation (DBS) of the thalamic ventral intermediate nucleus (Vim) is described in a limited number of patients. The Vim and posterior subthalamic area (PSA) can be targeted in a single trajectory, allowing both stimulation of the Vim and/or dentatorubrothalamic tract (DRT). In essential tremor this is currently often used with positive effects.

OBJECTIVE

To evaluate the efficacy of Vim/DRT-DBS in OT-patients, based on standing time and Quality of Life (QoL), also on the long-term. Furthermore, to relate stimulation of the Vim and DRT, medial lemniscus (ML) and pyramidal tract (PT) to beneficial clinical and side-effects.

METHODS

Nine severely affected OT-patients received bilateral Vim/DRT-DBS. Primary outcome measure was standing time; secondary measures included self-reported measures, neurophysiological measures, structural analyses, surgical complications, stimulation-induced side-effects, and QoL up to 56 months. Stimulation of volume of tissue activated (VTA) were related to outcome measures.

RESULTS

Average maximum standing time increased from 41.0 s ± 51.0 s to 109.3 s ± 65.0 s after 18 months, with improvements measured in seven of nine patients. VTA (n = 7) overlapped with the DRT in six patients and with the ML and/or PT in six patients. All patients experienced side-effects and QoL worsened during the first year after surgery, which improved again during long-term follow-up, although remaining below age-related normal values. Most patients reported a positive effect of DBS.

CONCLUSION

Vim/DRT-DBS improved standing time in patients with severe OT. Observed side-effects are possibly related to stimulation of the ML and PT.

Programming Algorithm for the Management of Speech Impairment in Subthalamic Nucleus Deep Brain Stimulation for Parkinson's Disease

OBJECTIVES

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) for Parkinson's disease (PD) has an ambiguous relation to speech. Speech impairment can be a stimulation-induced side effect, and parkinsonian dysarthria can improve with STN-DBS. Owing to the lack of an up-to-date and evidence-based approach, DBS reprogramming for speech impairment is largely blind and greatly relies on the physician's experience. In this study, we aimed to establish an evidence- and experience-based algorithm for managing speech impairment in patients with PD treated with STN-DBS.

MATERIALS AND METHODS

We performed a single-center retrospective study to identify patients with STN-DBS and speech impairment. Onset of speech impairment, lead localization, and assessment of DBS-induced nature of speech impairment were collected. When DBS settings were adjusted for improving speech, the magnitude and duration of effect were collected. We also performed a systematic literature review to identify studies describing the effects of parameter adjustments aimed at improving speech impairment in patients with PD receiving STN-DBS.

RESULTS

In the retrospective study, 245 of 631 patients (38.8%) with STN-DBS had significant speech impairment. The probability of sustained marked improvement upon reprogramming was generally low (27.9%). In the systematic review, 23 of 662 identified studies were included. Only two randomized controlled trials have been performed, providing evidence for interleaving-interlink stimulation only. Considerable methodologic heterogeneity precluded the conduction of a meta-analysis.

CONCLUSIONS

Speech impairment in STN-DBS for PD is frequent, but high-quality evidence regarding DBS parameter adjustments is scarce, and the probability of sustained improvement is low. To improve this outcome, we propose an evidence- and experience-based approach to address speech impairment in STN-DBS that can be used in clinical practice.

Bidirectional Interplay between Deep Brain Stimulation and Cognition in Parkinson's Disease: A Systematic Review

BACKGROUND

Deep brain stimulation (DBS) is efficacious for treating motor symptoms in Parkinson's disease (PD).

OBJECTIVES

The aim is to evaluate the evidence regarding DBS effectiveness after postoperative cognitive deterioration, the impact of preoperative cognition on DBS effectiveness, and the impact of DBS on cognition.

METHODS

Literature searches were performed on MEDLINE, EMBASE, and CENTRAL (Cochrane library). Primary outcomes were OFF-drug Unified Parkinson Disease Rating Scale Part III score and cognitive test scores.

RESULTS

DBS effectiveness did not differ in patients with postoperative declining compared to stable cognition (n = 5 studies). Preoperative cognition did not influence DBS effectiveness (n = 1 study). DBS moderately decreased verbal fluency compared to the best medical treatment (n = 24 studies), which may be transient.

CONCLUSION

DBS motor effectiveness in PD does not appear to be influenced by cognition. DBS in PD seems cognitively safe, except for a moderate decline in verbal fluency. Further research is warranted. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Changes in neurologists' treatment preferences for Parkinson's disease in the Netherlands

•Data about treatment preferences for Parkinson's disease (PD) are scarce.•A survey was sent to neurologists in the Netherlands in 2010 and 2021.•In 2021, levodopa was increasingly prescribed for PD.•In 2021, levodopa was increasingly prescribed for younger PD patients.•In 2021, Deep Brain Stimulation became the treatment choice for advanced PD.

The Fast Gray Matter Acquisition T1 Inversion Recovery Sequence in Deep Brain Stimulation: Introducing the Rubral Wing for Dentato-Rubro-Thalamic Tract Depiction and Tremor Control

BACKGROUND

The dentato-rubro-thalamic tract (DRT) is currently considered as a potential target in deep brain stimulation (DBS) for various types of tremor. However, tractography depiction can vary depending on the included brain regions. The fast gray matter acquisition T1 inversion recovery (FGATIR) sequence, with excellent delineation of gray and white matter, possibly provides anatomical identification of rubro-thalamic DRT fibers.

OBJECTIVE

This study aimed to evaluate the FGATIR sequence by comparison with DRT depiction, electrode localization, and effectiveness of DBS therapy.

MATERIALS AND METHODS

In patients with DBS therapy because of medication-refractory tremor, the FGATIR sequence was evaluated for depiction of the thalamus, red nucleus (RN), and rubro-thalamic connections. Deterministic tractography of the DRT, electrode localization, and tremor control were compared. The essential tremor rating scale was used to assess (hand) tremor. Tremor control was considered successful when complete tremor suppression (grade 0) or almost complete suppression (grade 1) was observed.

RESULTS

In the postoperative phase, we evaluated 14 patients who underwent DRT-guided DBS: 12 patients with essential tremor, one with tremor-dominant Parkinson disease, and one with multiple sclerosis, representing 24 trajectories. Mean follow-up was 11.3 months (range 6-19 months). The FGATIR sequence provided a clear delineation of a hypointense white matter tract within the hyperintense thalamus. In coronal plane, this tract was most readily recognizable as a "rubral wing," with the round RN as base and lateral triangular convergence. The deterministic DRT depiction was consistently situated within the rubral wing. The number of active contacts located within the DRT (and rubral wing) was 22 (92%), of which 16 (73%) showed successful tremor control.

CONCLUSIONS

The FGATIR sequence offers visualization of the rubro-thalamic connections that form the DRT, most readily recognizable as a "rubral wing" in coronal plane. This sequence contributes to tractographic depiction of DRT and provides a direct anatomical DBS target area for tremor control.

Dorsal subthalamic nucleus targeting in deep brain stimulation: microelectrode recording versus 7-Tesla connectivity

Connectivity-derived 7-Tesla MRI segmentation and intraoperative microelectrode recording can both assist subthalamic nucleus targeting for deep brain stimulation in Parkinson's disease. It remains unclear whether deep brain stimulation electrodes placed in the 7-Tesla MRI segmented subdivision with predominant projections to cortical motor areas (hyperdirect pathway) achieve superior motor improvement and whether microelectrode recording can accurately distinguish the motor subdivision. In 25 patients with Parkinson's disease, deep brain stimulation electrodes were evaluated for being inside or outside the predominantly motor-connected subthalamic nucleus (motor-connected subthalamic nucleus or non-motor-connected subthalamic nucleus, respectively) based on 7-Tesla MRI connectivity segmentation. Hemi-body motor improvement (Movement Disorder Society Unified Parkinson's Disease Rating Scale, Part III) and microelectrode recording characteristics of multi- and single-unit activities were compared between groups. Deep brain stimulation electrodes placed in the motor-connected subthalamic nucleus resulted in higher hemi-body motor improvement, compared with electrodes placed in the non-motor-connected subthalamic nucleus (80% versus 52%, P < 0.0001). Multi-unit activity was found slightly higher in the motor-connected subthalamic nucleus versus the non-motor-connected subthalamic nucleus (P < 0.001, receiver operating characteristic 0.63); single-unit activity did not differ between groups. Deep brain stimulation in the connectivity-derived 7-Tesla MRI subthalamic nucleus motor segment produced a superior clinical outcome; however, microelectrode recording did not accurately distinguish this subdivision within the subthalamic nucleus.

Directional versus ring-mode deep brain stimulation for Parkinson's disease: protocol of a multi-centre double-blind randomised crossover trial

BACKGROUND

The effectiveness of Deep Brain Stimulation (DBS) therapy for Parkinson's disease can be limited by side-effects caused by electrical current spillover into structures adjacent to the target area. The objective of the STEEred versus RING-mode DBS for Parkinson's disease (STEERING) study is to investigate if directional DBS for Parkinson's disease results in a better clinical outcome when compared to ring-mode DBS.

METHODS

The STEERING study is a prospective multi-centre double-blind randomised crossover trial. Inclusion criteria are Parkinson's disease, subthalamic nucleus DBS in a 'classic' ring-mode setting for a minimum of six months, and optimal ring-mode settings have been established. Participants are categorised into one of two subgroups according to their clinical response to the ring-mode settings as 'responders' (i.e., patient with a satisfactory effect of ring-mode DBS) or 'non-responder' (i.e., patient with a non-satisfactory effect of ring-mode DBS). A total of 64 responders and 38 non-responders will be included (total 102 patients). After an optimisation period in which an optimal directional setting is found, participants are randomised to first receive ring-mode DBS for 56 days (range 28-66) followed by directional DBS for 56 days (28-66) or vice-versa. The primary outcome is the difference between ring-mode DBS and directional DBS settings on the Movement Disorders Society Unified Parkinson's Disease Rating Scale - Motor Evaluation (MDS-UPDRS-ME) in the off-medication state. Secondary outcome measures consist of MDS-UPDRS-ME in the on-medication state, MDS-UPDRS Activities of Daily Living, MDS-UPDRS Motor Complications-Dyskinesia, disease related quality of life measured with the Parkinson's Disease Questionnaire 39, stimulation-induced side-effects, antiparkinsonian medication use, and DBS-parameters. Participants' therapy preference is measured at the end of the study. Outcomes will be analysed for both responder and non-responder groups, as well as for both groups pooled together.

DISCUSSION

The STEERING trial will provide insights into whether or not directional DBS should be standardly used in all Parkinson's disease DBS patients or if directional DBS should only be used in a case-based approach.

TRIAL REGISTRATION

This trial was registered on the Netherlands Trial Register, as trial NL6508 ( NTR6696 ) on June 23, 2017.

Magnetoencephalography to measure the effect of contact point-specific deep brain stimulation in Parkinson's disease: A proof of concept study

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for disabling fluctuations in motor symptoms in Parkinson's disease (PD) patients. However, iterative exploration of all individual contact points (four in each STN) by the clinician for optimal clinical effects may take months.

OBJECTIVE

In this proof of concept study we explored whether magnetoencephalography (MEG) has the potential to noninvasively measure the effects of changing the active contact point of STN-DBS on spectral power and functional connectivity in PD patients, with the ultimate aim to aid in the process of selecting the optimal contact point, and perhaps reduce the time to achieve optimal stimulation settings.

METHODS

The study included 30 PD patients who had undergone bilateral DBS of the STN. MEG was recorded during stimulation of each of the eight contact points separately (four on each side). Each stimulation position was projected on a vector running through the longitudinal axis of the STN, leading to one scalar value indicating a more dorsolateral or ventromedial contact point position. Using linear mixed models, the stimulation positions were correlated with band-specific absolute spectral power and functional connectivity of i) the motor cortex ipsilateral tot the stimulated side, ii) the whole brain.

RESULTS

At group level, more dorsolateral stimulation was associated with lower low-beta absolute band power in the ipsilateral motor cortex (p = .019). More ventromedial stimulation was associated with higher whole-brain absolute delta (p = .001) and theta (p = .005) power, as well as higher whole-brain theta band functional connectivity (p = .040). At the level of the individual patient, switching the active contact point caused significant changes in spectral power, but the results were highly variable.

CONCLUSIONS

We demonstrate for the first time that stimulation of the dorsolateral (motor) STN in PD patients is associated with lower low-beta power values in the motor cortex. Furthermore, our group-level data show that the location of the active contact point correlates with whole-brain brain activity and connectivity. As results in individual patients were quite variable, it remains unclear if MEG is useful in the selection of the optimal DBS contact point.

Utilizing 7-Tesla Subthalamic Nucleus Connectivity in Deep Brain Stimulation for Parkinson Disease

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a highly effective surgical treatment for patients with advanced Parkinson disease (PD). Combining 7.0-Tesla (7T) T2- and diffusion-weighted imaging (DWI) sequences allows for selective segmenting of the motor part of the STN and, thus, for possible optimization of DBS.

MATERIALS AND METHODS

7T T2 and DWI sequences were obtained, and probabilistic segmentation of motor, associative, and limbic STN segments was performed. Left- and right-sided motor outcome (Movement Disorders Society Unified Parkinson's Disease Rating Scale) scores were used for evaluating the correspondence between the active electrode contacts in selectively segmented STN and the clinical DBS effect. The Bejjani line was reviewed for crossing of segments.

RESULTS

A total of 50 STNs were segmented in 25 patients and proved highly feasible. Although the highest density of motor connections was situated in the dorsolateral STN for all patients, the exact partitioning of segments differed considerably. For all the active electrode contacts situated within the predominantly motor-connected segment of the STN, the average hemi-body Unified Parkinson's Disease Rating Scale motor improvement was 80%; outside this segment, it was 52% (p < 0.01). The Bejjani line was situated in the motor segment for 32 STNs.

CONCLUSION

The implementation of 7T T2 and DWI segmentation of the STN in DBS for PD is feasible and offers insight into the location of the motor segment. Segmentation-guided electrode placement is likely to further improve motor response in DBS for PD. However, commercially available DBS software for postprocessing imaging would greatly facilitate widespread implementation.

Levodopa Response in Patients With Early Parkinson Disease: Further Observations of the LEAP Study

BACKGROUND AND OBJECTIVES

The Levodopa in EArly Parkinson's Disease (LEAP) study enabled us to conduct post hoc analyses concerning the effects of levodopa in patients with early Parkinson disease.

METHODS

The LEAP study was a double-blind, placebo-controlled, randomized, delayed-start trial in which patients with early Parkinson disease were randomized to receive levodopa/carbidopa 300/75 mg daily for 80 weeks (early-start group) or to placebo for 40 weeks followed by levodopa/carbidopa 300/75 mg daily for 40 weeks (delayed-start group). We analyzed the effect of levodopa with the Unified Parkinson's Disease Rating Scale on bradykinesia, rigidity, and tremor. At week 80, participants answered 3 questions regarding motor response fluctuations.

RESULTS

A total of 222 patients were randomized to the early-start group (mean ± SD age at baseline 64.8 ± 8.7 years; 71% male) and 223 to the delayed-start group (mean ± SD age at baseline 65.5 ± 8.8 years; 69% male). The difference between the early- and delayed-start groups in mean change from baseline to week 4, expressed as Hedges g effect size, was -0.33 for bradykinesia, -0.29 for rigidity, and -0.25 for tremor (for all symptoms indicating a small effect in favor of the early-start group); from baseline to week 22, respectively, -0.49, -0.36, and -0.44 (small to medium effect); and from baseline to week 40, respectively, -0.32, -0.19, and -0.27 (small effect). At 80 weeks, fewer patients in the early-start group (46 of 205 patients, 23%) experienced motor response fluctuations than patients in the delayed-start group (81 of 211, 38%; p < 0.01).

DISCUSSION

In patients with early Parkinson disease, levodopa improves bradykinesia, rigidity, and tremor to the same order of magnitude. For all 3 symptoms, effects were larger at 22 weeks compared with 4 weeks. At 80 weeks, there were fewer patients with motor response fluctuations in the group that had started levodopa earlier.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that the effect of levodopa on bradykinesia, rigidity, and tremor is larger after 22 weeks compared with 4 weeks of treatment.

TRIAL REGISTRATION INFORMATION

ISRCTN30518857, EudraCT number 2011-000678-72.

Trial of Deferiprone in Parkinson's Disease

BACKGROUND

Iron content is increased in the substantia nigra of persons with Parkinson's disease and may contribute to the pathophysiology of the disorder. Early research suggests that the iron chelator deferiprone can reduce nigrostriatal iron content in persons with Parkinson's disease, but its effects on disease progression are unclear.

METHODS

We conducted a multicenter, phase 2, randomized, double-blind trial involving participants with newly diagnosed Parkinson's disease who had never received levodopa. Participants were assigned (in a 1:1 ratio) to receive oral deferiprone at a dose of 15 mg per kilogram of body weight twice daily or matched placebo for 36 weeks. Dopaminergic therapy was withheld unless deemed necessary for symptom control. The primary outcome was the change in the total score on the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS; range, 0 to 260, with higher scores indicating more severe impairment) at 36 weeks. Secondary and exploratory clinical outcomes at up to 40 weeks included measures of motor and nonmotor disability. Brain iron content measured with the use of magnetic resonance imaging was also an exploratory outcome.

RESULTS

A total of 372 participants were enrolled; 186 were assigned to receive deferiprone and 186 to receive placebo. Progression of symptoms led to the initiation of dopaminergic therapy in 22.0% of the participants in the deferiprone group and 2.7% of those in the placebo group. The mean MDS-UPDRS total score at baseline was 34.3 in the deferiprone group and 33.2 in the placebo group and increased (worsened) by 15.6 points and 6.3 points, respectively (difference, 9.3 points; 95% confidence interval, 6.3 to 12.2; P<0.001). Nigrostriatal iron content decreased more in the deferiprone group than in the placebo group. The main serious adverse events with deferiprone were agranulocytosis in 2 participants and neutropenia in 3 participants.

CONCLUSIONS

In participants with early Parkinson's disease who had never received levodopa and in whom treatment with dopaminergic medications was not planned, deferiprone was associated with worse scores in measures of parkinsonism than those with placebo over a period of 36 weeks. (Funded by the European Union Horizon 2020 program; FAIRPARK-II ClinicalTrials.gov number, NCT02655315.).

Imaging Dopaminergic Neurotransmission in Neurodegenerative Disorders

Imaging of dopaminergic transmission in neurodegenerative disorders such as Parkinson disease (PD) or dementia with Lewy bodies plays a major role in clinical practice and in clinical research. We here review the role of imaging of the nigrostriatal pathway, as well as of striatal receptors and dopamine release, in common neurodegenerative disorders in clinical practice and research. Imaging of the nigrostriatal pathway has a high diagnostic accuracy to detect nigrostriatal degeneration in disorders characterized by nigrostriatal degeneration, such as PD and dementia with Lewy bodies, and disorders of more clinical importance, namely in patients with clinically uncertain parkinsonism. Imaging of striatal dopamine D2/3 receptors is not recommended for the differential diagnosis of parkinsonian disorders in clinical practice anymore. Regarding research, recently the European Medicines Agency has qualified dopamine transporter imaging as an enrichment biomarker for clinical trials in early PD, which underlines the high diagnostic accuracy of this imaging tool and will be implemented in future trials. Also, imaging of the presynaptic dopaminergic system plays a major role in, for example, examining the extent of nigrostriatal degeneration in preclinical and premotor phases of neurodegenerative disorders and to examine subtypes of PD. Also, imaging of postsynaptic dopamine D2/3 receptors plays a role in studying, for example, the neuronal substrate of impulse control disorders in PD, as well as in measuring endogenous dopamine release to examine, for example, motor complications in the treatment of PD. Finally, novel MRI sequences as neuromelanin-sensitive MRI are promising new tools to study nigrostriatal degeneration in vivo.

Dutch injection versus surgery trial in patients with carpal tunnel syndrome (DISTRICTS): protocol of a randomised controlled trial comparing two treatment strategies

INTRODUCTION

Carpal tunnel syndrome (CTS) is the most common peripheral neuropathy. The optimal treatment strategy is still unknown. The objective of the Dutch Injection versus Surgery TRIal in patients with CTS (DISTRICTS) is to investigate if initial surgery of CTS results in a better clinical outcome and is more cost-effective when compared with initial treatment with corticosteroid injection.

METHODS AND ANALYSIS

The DISTRICTS is an ongoing multicenter, open-label randomised controlled trial. Participants with CTS are randomised to treatment with surgery or with a corticosteroid injection. If needed, any additional treatments after this first treatment are allowed and these are not dictated by the study protocol. The primary outcome is the difference between the groups in the proportion of participants recovered at 18 months. Recovery is defined as having no or mild symptoms as measured with the 6-item carpal tunnel symptoms scale. Secondary outcome measurements are among others: time to recovery, hand function, patient satisfaction, quality of life, additional treatments, adverse events, and use of care and health-related costs.

ETHICS AND DISSEMINATION

The study was approved by the Medical Ethical Committee of the Amsterdam University Medical Centers (study number 2017-171). Study results will be disseminated in peer-reviewed journals and conferences.

TRIAL REGISTRATION NUMBER

ISRCTN Registry: 13164336.

Diving into the Subcortex: The Potential of Chronic Subcortical Sensing for Unravelling Basal Ganglia Function and Optimization of Deep Brain STIMULATION

Subcortical structures are a relative neurophysiological 'terra incognita' owing to their location within the skull. While perioperative subcortical sensing has been performed for more than 20 years, the neurophysiology of the basal ganglia in the home setting has remained almost unexplored. However, with the recent advent of implantable pulse generators (IPG) that are able to record neural activity, the opportunity to chronically record local field potentials (LFPs) directly from electrodes implanted for deep brain stimulation opens up. This allows for a breakthrough of chronic subcortical sensing into fundamental research and clinical practice. In this review an extensive overview of the current state of subcortical sensing is provided. The widespread potential of chronic subcortical sensing for investigational and clinical use is discussed. Finally, status and future perspectives of the most promising application of chronic subcortical sensing -i.e., adaptive deep brain stimulation (aDBS)- are discussed in the context of movement disorders. The development of aDBS based on both chronic subcortical and cortical sensing has the potential to dramatically change clinical practice and the life of patients with movement disorders. However, several barriers still stand in the way of clinical implementation. Advancements regarding IPG and lead technology, physiomarkers, and aDBS algorithms as well as harnessing artificial intelligence, multimodality and sensing in the naturalistic setting are needed to bring aDBS to clinical practice.

Serendipitous Stimulation of Nucleus Basalis of Meynert-The Effect of Unintentional, Long-Term High-Frequency Stimulation on Cognition in Parkinson's Disease

There is a growing interest in deep brain stimulation (DBS) of the nucleus basalis of Meynert (NBM) as a potential therapeutic modality for Parkinson’s disease dementia (PDD). Low-frequency stimulation has yielded encouraging results in individual patients; however, these are not yet sustained in larger studies. With the aim to expand the understanding of NBM-DBS, we share our experience with serendipitous NBM-DBS in patients treated with DBS of the internal Globus pallidus (GPi) for Parkinson’s disease. Since NBM is anatomically located ventral to GPi, several GPi-treated patients appeared to have the distal contact of DBS-electrode(s) positioned in the NBM. We hypothesized that unintentional high-frequency NBM-DBS over a period of one year would result in the opposite effect of low-frequency NBM-stimulation and cause cognitive decline. We studied a cohort of 33 patients with bilateral high-frequency DBS in the GPi for Parkinson’s disease, of which twelve were unintentionally co-stimulated in NBM. The subgroups of unintentional unilateral (N = 7) and bilateral NBM-DBS (N = 5) were compared to the control group of bilateral GPi-DBS (N = 11). Here, we show that unintentional high-frequency NBM-DBS did not cause a significantly faster decline in cognitive function. Further research is warranted for characterizing the therapeutic role of NBM-DBS.

Dopaminergic Therapy for Motor Symptoms in Early Parkinson Disease Practice Guideline Summary: A Report of the AAN Guideline Subcommittee

BACKGROUND AND OBJECTIVES

To review the current evidence on the options available for initiating dopaminergic treatment of motor symptoms in early-stage Parkinson disease and provide recommendations to clinicians.

METHODS

A multidisciplinary panel developed practice recommendations, integrating findings from a systematic review and following an Institute of Medicine-compliant process to ensure transparency and patient engagement. Recommendations were supported by structured rationales, integrating evidence from the systematic review, related evidence, principles of care, and inferences from evidence.

RESULTS

Initial treatment with levodopa provides superior motor benefit compared to treatment with dopamine agonists, whereas levodopa is more likely than dopamine agonists to cause dyskinesia. The comparison of different formulations of dopamine agonists yielded little evidence that any one formulation or method of administration is superior. Long-acting forms of levodopa and levodopa with entacapone do not appear to differ in efficacy from immediate-release levodopa for motor symptoms in early disease. There is a higher risk of impulse control disorders associated with the use of dopamine agonists than levodopa. Recommendations on initial therapy for motor symptoms are provided to assist the clinician and patient in choosing between treatment options and to guide counseling, prescribing, and monitoring of efficacy and safety.

Evaluating and Optimizing Dentato-Rubro-Thalamic-Tract Deterministic Tractography in Deep Brain Stimulation for Essential Tremor

BACKGROUND

Dentato-rubro-thalamic tract (DRT) deep brain stimulation (DBS) suppresses tremor in essential tremor (ET) patients. However, DRT depiction through tractography can vary depending on the included brain regions. Moreover, it is unclear which section of the DRT is optimal for DBS.

OBJECTIVE

To evaluate deterministic DRT tractography and tremor control in DBS for ET.

METHODS

After DBS surgery, DRT tractography was conducted in 37 trajectories (20 ET patients). Per trajectory, 5 different DRT depictions with various regions of interest (ROI) were constructed. Comparison resulted in a DRT depiction with highest correspondence to intraoperative tremor control. This DRT depiction was subsequently used for evaluation of short-term postoperative adverse and beneficial effects.

RESULTS

Postoperative optimized DRT tractography employing the ROI motor cortex, posterior subthalamic area (PSA), and ipsilateral superior cerebellar peduncle and dentate nucleus best corresponded with intraoperative trajectories (92%) and active DBS contacts (93%) showing optimal tremor control. DRT tractography employing a red nucleus or ventral intermediate nucleus of the thalamus (VIM) ROI often resulted in a more medial course. Optimal stimulation was located in the section between VIM and PSA.

CONCLUSION

This optimized deterministic DRT tractography strongly correlates with optimal tremor control. This technique is readily implementable for prospective evaluation in DBS target planning for ET.

General Anesthesia vs Local Anesthesia in Microelectrode Recording-Guided Deep-Brain Stimulation for Parkinson Disease: The GALAXY Randomized Clinical Trial

Importance

It is unknown if there is a difference in outcome in asleep vs awake deep brain stimulation (DBS) of the subthalamic nucleus for advanced Parkinson disease.

Objective

To determine the difference in adverse effects concerning cognition, mood, and behavior between awake and asleep DBS favoring the asleep arm of the study.

Design, Setting, and Participants

This study was a single-center prospective randomized open-label blinded end point clinical trial. A total of 187 persons with Parkinson disease were referred for DBS between May 2015 to March 2019. Analysis took place from January 2016 to January 2020. The primary outcome follow-up visit was conducted 6 months after DBS.

Interventions

Bilateral subthalamic nucleus DBS was performed while the patient was asleep (under general anesthesia) in 1 study arm and awake in the other study arm. Both arms of the study used a frame-based intraoperative microelectrode recording technique to refine final target placement of the DBS lead.

Main Outcomes and Measures

The primary outcome variable was the between-group difference in cognitive, mood, and behavioral adverse effects as measured by a composite score. The secondary outcomes included the Movement Disorders Society Unified Parkinson's Disease Rating Scale, the patient assessment of surgical burden and operative time.

Results

A total of 110 patients were randomized to awake (local anesthesia; n = 56; mean [SD] age, 60.0 (7.4) years; 40 [71%] male) or to asleep (general anesthesia; n = 54; mean [SD] age, 61.3 [7.9] years; 38 [70%] male) DBS surgery. The 6-month follow-up visit was completed by 103 participants. The proportion of patients with adverse cognitive, mood, and behavioral effects on the composite score was 15 of 52 (29%) after awake and 11 of 51 (22%) after asleep DBS (odds ratio, 0.7 [95% CI, 0.3-1.7]). There was no difference in improvement in the off-medication Movement Disorders Society Unified Parkinson's Disease Rating Scale Motor Examination scores between groups (awake group: mean [SD], -27.3 [17.5] points; asleep group: mean [SD], -25.3 [14.3] points; mean difference, -2.0 [95% CI, -8.1 to 4.2]). Asleep surgery was experienced as less burdensome by patients and was 26 minutes shorter than awake surgery.

Conclusions and Relevance

There was no difference in the primary outcome of asleep vs awake DBS. Future large randomized clinical trials should examine some of the newer asleep based DBS technologies because this study was limited to frame-based microelectrode-guided procedures.

Trial Registration

trialregister.nl Identifier: NTR5809.

[Orthostatic tremor]

BACKGROUND

Orthostatic tremor is a rare disease characterized by difficulty with standing still. Patients often undergo a long diagnostic search and often feel underrecognized, partly due to unfamiliarity of physicians with the disease.

CASE DESCRIPTION

We report a 72-year-old male experiencing difficulty in standing still, accompanied by a tingling, trembling and painful sensation in the legs, over the last ten years. Several orthopedic and neurological causes had been suspected until neurological examination revealed a 'helicopter sign' upon auscultation of the leg muscles. Tremor registration showed a 14 Hz tremor in the legs upon standing, confirming the diagnosis of orthostatic tremor. There was moderate improvement with pharmacological treatment.

CONCLUSION

Orthostatic tremor should be suspected in patients with instability or atypical symptoms upon standing. A neurological referral including tremor registration is recommended in these cases.

Value of Clinical Signs in Identifying Patients with Scans without Evidence of Dopaminergic Deficit (SWEDD)

BACKGROUND

In clinical trials that recruited patients with early Parkinson's disease (PD), 4-15% of the participants with a clinical diagnosis of PD had normal dopamine transporter single photon emission computed tomography (DAT SPECT) scans, also called "scans without evidence of dopaminergic deficit" (SWEDD).

OBJECTIVE

To investigate in patients with a clinical diagnosis of PD, if specific clinical features are useful to distinguish patients with nigrostriatal degeneration from those that have no nigrostriatal degeneration.

METHODS

We performed a diagnostic test accuracy study. Patients that participated in the Levodopa in Early Parkinson's disease trial, a clinical trial in patients with early PD, were asked to participate if they had not undergone DAT SPECT imaging earlier. The index tests were specific clinical features that were videotaped. A panel of six neurologists in training (NT), six general neurologists (GN), and six movement disorders experts (MDE) received a batch of ten videos consisting of all SWEDD subjects and a random sample of patients with abnormal DAT SPECT scans. The raters analyzed the videos for presence of specific signs and if they suspected the patient to have SWEDD. The reference test was visually assessed DAT SPECT imaging.

RESULTS

Of a total of 87 participants, three subjects were SWEDDs (3.4%). The overall intraclass correlation coefficient (ICC) of the Parkinsonian signs was poor to moderate with ICCs ranging from 0.14 to 0.67. NT correctly identified 50.0% of the SWEDD subjects, GN 33.3%, and MDE 66.7%.

CONCLUSION

Our study suggests that the selected videotaped clinical features cannot reliably distinguish patients with a clinical diagnosis of PD and an abnormal DAT SPECT from patients with clinical PD and a SWEDD.

Subthalamic and pallidal deep brain stimulation: are we modulating the same network?

The subthalamic nucleus and internal pallidum are main target sites for deep brain stimulation in Parkinson's disease. Multiple trials that investigated subthalamic versus pallidal stimulation were unable to settle on a definitive optimal target between the two. One reason could be that the effect is mediated via a common functional network. To test this hypothesis, we calculated connectivity profiles seeding from deep brain stimulation electrodes in 94 patients that underwent subthalamic and 28 patients with pallidal treatment based on a normative connectome atlas calculated from 1,000 healthy subjects. In each cohort, we calculated connectivity profiles that were associated with optimal clinical improvements. The two maps showed striking similarity and were able to cross-predict outcomes in the respective other cohort (R = 0.37 at p < 0.001; R = 0.34 at p = 0.032). Next, we calculated an agreement map which retained regions common to both target sites. Crucially, this map was able to explain an additional amount of variance in clinical improvements of either cohort when compared to the maps calculated on the two cohorts alone. Finally, we tested profiles and predictive utility of connectivity maps calculated from different motor symptom subscores with a specific focus on bradykinesia and rigidity. While our study is based on retrospective data and indirect connectivity metrics, it may deliver empirical data to support the hypothesis of a largely overlapping network associated with effective deep brain stimulation in Parkinson's disease irrespective of the specific target.

Rivastigmine for minor visual hallucinations in Parkinson's disease: A randomized controlled trial with 24 months follow-up

BACKGROUND

Visual hallucinations are common in patients with Parkinson's disease and represent probably the major independent predictor for cognitive deterioration and nursing home placement.

OBJECTIVE

To investigate if treatment of minor visual hallucinations in Parkinson's disease with rivastigmine delays the progression to psychosis.

METHODS

A multicenter, randomized, double-blind, placebo-controlled trial was conducted which aimed to recruit 168 patients with Parkinson's disease reporting minor visual hallucinations 4 weeks before it. Important exclusion criteria were Parkinson's disease dementia, current delirium, and treatment with antipsychotics or drugs that have significant anti-cholinergic side effects. Subjects were randomized to rivastigmine capsules, 3-6 mg twice a day, or placebo for 24 months. The primary outcome was the time to Parkinson's disease psychosis, which was defined as the need to start with antipsychotics.

RESULTS

The trial was stopped prematurely because of slow recruitment. Ninety-one patients were randomized: 46 patients were assigned to rivastigmine and 45 patients to placebo. No effect of rivastigmine could be demonstrated on the transition time to psychosis or dementia during the 24-month follow-up period. After 6 months of study treatment, cognition, mood, motor performance, and non-motor performance did not differ significantly between the rivastigmine-group and the placebo-group.

CONCLUSIONS

Because the study was terminated early, it was insufficiently powered to properly evaluate the primary outcome. The limited data of the study favor a wait and see approach instead of early treatment with rivastigmine in PD patients with minor VH.

Advanced Care Planning in Parkinson's Disease: In-depth Interviews With Patients on Experiences and Needs

Introduction: Advance care planning (ACP) is an iterative process of discussing the needs, wishes, and preferences of patients regarding disease-specific and end-of-life issues. There is ample evidence that ACP improves the quality of life and promotes the autonomy of patients with cancer and motor neuron disease who have a high disease burden and shortened life expectancy. In Parkinson's disease (PD) though, knowledge about the experiences and preferences of patients regarding ACP is scarce, despite the major disease burden associated with PD.

Aim: This study aims to explore the experiences, needs, and preferences of PD patients regarding the content and timing of ACP.

Methods: In-depth interviews were conducted with a purposively selected sample of patients diagnosed with PD. Using a semi-structured topic list, the participants were asked about their prospects for a future living with PD and with whom they wanted to discuss this. Qualitative analysis was performed in parallel with data collection using a data-driven constant comparative approach. The transcribed interviews were coded and analyzed by two researchers using MAXQDA software.

Results: Of all 20 patients (13 males; age 47–82; disease duration 1–27 years), most expressed a wish to talk about ACP with a healthcare provider, enabling them to anticipate the uncertain future. The majority of patients preferred their healthcare provider to initiate the discussion on ACP, preferably at an early stage of the disease. Nearly all patients expressed the wish to receive more information regarding the long-term impact of PD, although, the preferred timing varied between patients. They also perceived that their neurologist was primarily focused on medication and had little time to address their need for a more holistic approach toward living with PD.

Conclusion: Our results suggest that PD patients are in need of discussing ACP with their healthcare provider (HCP), even in the early stages of the disease. In addition, PD patients perceive a lack of information on their disease course and miss guidance on available supportive care. We recommend HCPs to inquire the information requirements and preferences of patients regarding ACP regularly, starting soon after diagnosis.

International Multicenter Analysis of Brain Structure Across Clinical Stages of Parkinson's Disease

BACKGROUND

Brain structure abnormalities throughout the course of Parkinson's disease have yet to be fully elucidated.

OBJECTIVE

Using a multicenter approach and harmonized analysis methods, we aimed to shed light on Parkinson's disease stage-specific profiles of pathology, as suggested by in vivo neuroimaging.

METHODS

Individual brain MRI and clinical data from 2357 Parkinson's disease patients and 1182 healthy controls were collected from 19 sources. We analyzed regional cortical thickness, cortical surface area, and subcortical volume using mixed-effects models. Patients grouped according to Hoehn and Yahr stage were compared with age- and sex-matched controls. Within the patient sample, we investigated associations with Montreal Cognitive Assessment score.

RESULTS

Overall, patients showed a thinner cortex in 38 of 68 regions compared with controls (d_max  = -0.20, d_min  = -0.09). The bilateral putamen (d_left  = -0.14, d_right  = -0.14) and left amygdala (d = -0.13) were smaller in patients, whereas the left thalamus was larger (d = 0.13). Analysis of staging demonstrated an initial presentation of thinner occipital, parietal, and temporal cortices, extending toward rostrally located cortical regions with increased disease severity. From stage 2 and onward, the bilateral putamen and amygdala were consistently smaller with larger differences denoting each increment. Poorer cognition was associated with widespread cortical thinning and lower volumes of core limbic structures.

CONCLUSIONS

Our findings offer robust and novel imaging signatures that are generally incremental across but in certain regions specific to disease stages. Our findings highlight the importance of adequately powered multicenter collaborations.

Translating Evidence to Advanced Parkinson's Disease Patients: A Systematic Review and Meta-Analysis

In the advanced stages of Parkinson's disease (PD), patients frequently experience disabling motor complications. Treatment options include deep brain stimulation (DBS), levodopa‐carbidopa intestinal gel (LCIG), and continuous subcutaneous apomorphine infusion (CSAI). Choosing among these treatments is influenced by scientific evidence, clinical expertise, and patient preferences. To foster patient engagement in decision‐making among the options, scientific evidence should be adjusted to their information needs. We conducted a systematic review from the patient perspective. First, patients selected outcomes for a treatment choice: quality of life, activities of daily living, ON and OFF time, and adverse events. Second, we conducted a systematic review and meta‐analysis for each treatment versus best medical treatment using Grading of Recommendations, Assessment, Development, and Evaluation (GRADE). Finally, the evidence was transformed into comprehensible and comparable information. We converted the meta‐analysis results into the number of patients (per 100) who benefit clinically from an advanced treatment per outcome, based on the minimal clinically important difference and the cumulative distribution function. Although this approach allows for a comparison of outcomes across the three device‐aided therapies, they have never been compared directly. The interpretation is hindered by the relatively short follow‐up time in the included studies, usually less than 12 months. These limitations should be clarified to patients during the decision‐making process. This review can help patients integrate the evidence with their own preferences, and with their clinician's expertise, to reach an informed decision. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Metabolomics of sebum reveals lipid dysregulation in Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder, which is characterised by degeneration of distinct neuronal populations, including dopaminergic neurons of the substantia nigra. Here, we use a metabolomics profiling approach to identify changes to lipids in PD observed in sebum, a non-invasively available biofluid. We used liquid chromatography-mass spectrometry (LC-MS) to analyse 274 samples from participants (80 drug naïve PD, 138 medicated PD and 56 well matched control subjects) and detected metabolites that could predict PD phenotype. Pathway enrichment analysis shows alterations in lipid metabolism related to the carnitine shuttle, sphingolipid metabolism, arachidonic acid metabolism and fatty acid biosynthesis. This study shows sebum can be used to identify potential biomarkers for PD.

Validating Differential Volatilome Profiles in Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder that does not currently have a robust clinical diagnostic test. Nonmotor symptoms such as skin disorders have long since been associated with the disease, and more recently a characteristic odor emanating from the skin of people with Parkinson's has been identified. Here, dynamic head space (DHS) thermal desorption (TD) gas chromatography-mass spectrometry (GC-MS) is implemented to directly measure the volatile components of sebum on swabs sampled from people with Parkinson's-both drug naïve and those on PD medications (n = 100) and control subjects (n = 29). Supervised multivariate analyses of data showed 84.4% correct classification of PD cases using all detected volatile compounds. Variable importance in projection (VIP) scores were generated from these data, which revealed eight features with VIP > 1 and p < 0.05 which all presented a downregulation within the control cohorts. Purified standards based on previously annotated analytes of interest eicosane and octadecanal did not match to patient sample data, although multiple metabolite features are annotated with these compounds all with high spectral matches indicating the presence of a series of similar structured species. DHS-TD-GC-MS analysis of a range of lipid standards has revealed the presence of common hydrocarbon species rather than differentiated intact compounds which are hypothesized to be breakdown products of lipids. This replication study validates that a differential volatile profile between control and PD cohorts can be measured using an analytical method that measures volatile compounds directly from skin swabs.

Structural and functional correlates of subthalamic deep brain stimulation-induced apathy in Parkinson's disease

BACKGROUND

Notwithstanding the large improvement in motor function in Parkinson's disease (PD) patients treated with deep brain stimulation (DBS), apathy may increase. Postoperative apathy cannot always be related to a dose reduction of dopaminergic medication and stimulation itself may play a role.

OBJECTIVE

We studied whether apathy in DBS-treated PD patients could be a stimulation effect.

METHODS

In 26 PD patients we acquired apathy scores before and >6 months after DBS of the subthalamic nucleus (STN). Magnetoencephalography recordings (ON and OFF stimulation) were performed ≥6 months after DBS placement. Change in apathy severity was correlated with (i) improvement in motor function and dose reduction of dopaminergic medication, (ii) stimulation location (merged MRI and CT-scans) and (iii) stimulation-related changes in functional connectivity of brain regions that have an alleged role in apathy.

RESULTS

Average apathy severity significantly increased after DBS (p < 0.001) and the number of patients considered apathetic increased from two to nine. Change in apathy severity did not correlate with improvement in motor function or dose reduction of dopaminergic medication. For the left hemisphere, increase in apathy was associated with a more dorsolateral stimulation location (p = 0.010). The increase in apathy severity correlated with a decrease in alpha1 functional connectivity of the dorsolateral prefrontal cortex (p = 0.006), but not with changes of the medial orbitofrontal or the anterior cingulate cortex.

CONCLUSIONS

The present observations suggest that apathy after STN-DBS is not necessarily related to dose reductions of dopaminergic medication, but may be an effect of the stimulation itself. This highlights the importance of determining optimal DBS settings based on both motor and non-motor symptoms.

The Choice Between Advanced Therapies for Parkinson's Disease Patients: Why, What, and When?

When oral dopaminergic medication falls short in the treatment of Parkinson’s disease, patients are left with motor response fluctuations and dyskinesias that may have a large impact on functioning in daily life. They may benefit from one of the currently available advanced treatments, namely deep brain stimulation, continuous levodopa-carbidopa intestinal gel, and continuous subcutaneous apomorphine infusion. The indication, choice between the separate advanced treatments and the timing can be challenging and will be discussed against the background of the progressive nature of the disease, the heterogeneity of disease manifestation and variable patient characteristics.

The cerebral tremor circuit in a patient with Holmes tremor

The cerebral network associated with Holmes tremor has never been determined directly. A previous study reported a brain network that is functionally connected, in healthy individuals, to different lesions that cause Holmes tremor (lesion connectome). We report a 71-year-old man with severe left-sided tremor caused by a microbleed near the right red nucleus. Using accelerometry-fMRI, we show tremor-related activity in contralateral sensorimotor cortex and cerebellar vermis. This network was distinct from, but functionally coupled to, the Holmes lesion connectome. We propose that Holmes tremor involves three distinct cerebral mechanisms: a structural lesion, an intermediate lesion connectome, and symptom-related activity.

Overall and Disease Related Mortality in Parkinson's Disease - a Longitudinal Cohort Study

Background:

Earlier research showed that Parkinson’s disease is related to increased overall mortality, but it remains unclear which patient level factors are predictive of increased mortality in Parkinson’s disease.

Objective:

To jointly evaluate potential risk factors for overall and Parkinson’s disease (PD) related mortality, we collected detailed information from a cohort of newly diagnosed PD patients which was consequently followed for over a decade.

Methods:

A total of 133 consecutive patients with newly diagnosed PD were followed for at least 13 years. Survival analysis of observed mortality was used to evaluate risk factors for overall mortality, whereas survival analysis of mortality as corrected for the general population was used to evaluate risk factors for PD-related mortality.

Results:

Overall mortality increased with age, male sex, higher levodopa equivalent dose, and presence of mild cognitive impairment. PD-related mortality increased with earlier onset of Parkinson’s disease, higher levodopa equivalent dose, and mild cognitive impairment.

Conclusions:

Our findings provide confirmation and extension of risk factors for overall mortality and generate new insights into PD-related mortality.

Initiation of pharmacological therapy in Parkinson's disease: when, why, and how

Debate is ongoing regarding when, why, and how to initiate pharmacotherapy for Parkinson's disease. Early initiation of dopaminergic therapies does not convey disease-modifying effects but does reduce disability. Concerns about the development of motor complications arising from the early initiation of levodopa, which led to misconceived levodopa-sparing strategies, have been largely mitigated by the outcomes of the PD MED and Levodopa in Early Parkinson's Disease (LEAP) studies. The LEAP study also showed the potential for early improvement in quality of life, even when disability is negligible. Until more effective methods of providing stable dopamine concentrations are developed, current evidence supports the use of levodopa as initial symptomatic treatment in most patients with Parkinson's disease, starting with low doses and titrating to therapeutic threshold. Monoamine oxidase-B inhibitors and dopamine agonists can be reserved as potential adjunct treatments later in the disease course. Future research will need to establish effective disease-modifying treatments, address whether patients' quality of life is substantially improved with early initiation of treatment rather than a wait and watch strategy, and establish whether new levodopa formulations will delay onset of dyskinesia.

Relative Contribution of Magnetic Resonance Imaging, Microelectrode Recordings, and Awake Test Stimulation in Final Lead Placement during Deep Brain Stimulation Surgery of the Subthalamic Nucleus in Parkinson's Disease

INTRODUCTION

For deep brain stimulation (DBS) surgery of the subthalamic nucleus (STN) in Parkinson's disease (PD), many centers employ visualization of the nucleus on magnetic resonance imaging (MRI), intraoperative microelectrode recordings (MER), and test stimulation in awake patients. The value of these steps is a subject for ongoing debate. In the current study, we determined the relative contribution of MRI targeting, multitrack MER, and awake test stimulation in final lead placement during STN DBS surgery for PD.

METHODS

Data on PD patients undergoing MRI-targeted STN DBS surgery with three-channel MER and awake test stimulation between February 2010 and January 2014 were analyzed to determine in which MER trajectory final leads were implanted and why this tract was chosen.

RESULTS

Seventy-six patients underwent implantation of 146 DBS leads. In 92% of the STN, the final leads were implanted in one of the three planned channels. In 6%, additional channels were needed. In 2%, surgery was aborted before final lead implantation due to anxiety or fatigue. The final leads were implanted in the channels with the longest STN MER signal trajectory in 60% of the STN (38% of the bilaterally implanted patients). This was the central channel containing the MRI target in 39% of the STN (18% bilaterally). The most frequently noted reasons why another channel than the central channel was chosen for final lead placement were (1) a lower threshold for side effects (54%) and (2) no or a too short trajectory of the STN MER signal (40%) in the central channel. The latter reason correlated with larger 2D (x and y) errors in our stereotactic method.

CONCLUSIONS

STN DBS leads were often not implanted in the MRI-planned trajectory or in the trajectory with the longest STN MER signal. Thresholds for side effects during awake test stimulation were decisive for final target selection in the majority of patients.

Motor effects of deep brain stimulation correlate with increased functional connectivity in Parkinson's disease: An MEG study

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an established symptomatic treatment in Parkinson's disease, yet its mechanism of action is not fully understood. Locally in the STN, stimulation lowers beta band power, in parallel with symptom relief. Therefore, beta band oscillations are sometimes referred to as "anti-kinetic". However, in recent studies functional interactions have been observed beyond the STN, which we hypothesized to reflect clinical effects of DBS. Resting-state, whole-brain magnetoencephalography (MEG) recordings and assessments on motor function were obtained in 18 Parkinson's disease patients with bilateral STN-DBS, on and off stimulation. For each brain region, we estimated source-space spectral power and functional connectivity with the rest of the brain. Stimulation led to an increase in average peak frequency and a suppression of absolute band power (delta to low-beta band) in the sensorimotor cortices. Significant changes (decreases and increases) in low-beta band functional connectivity were observed upon stimulation. Improvement in bradykinesia/rigidity was significantly related to increases in alpha2 and low-beta band functional connectivity (of sensorimotor regions, the cortex as a whole, and subcortical regions). By contrast, tremor improvement did not correlate with changes in functional connectivity. Our results highlight the distributed effects of DBS on the resting-state brain and suggest that DBS-related improvements in rigidity and bradykinesia, but not tremor, may be mediated by an increase in alpha2 and low-beta functional connectivity. Beyond the local effects of DBS in and around the STN, functional connectivity changes in these frequency bands might therefore be considered as "pro-kinetic".

Defining the Dorsal STN Border Using 7.0-T MRI: A Comparison to Microelectrode Recordings and Lower Field Strength MRI

BACKGROUND

7.0-T T2-weighted MRI offers excellent visibility of the subthalamic nucleus (STN), which is used as a target for deep brain stimulation (DBS) in Parkinson's disease (PD). A comparison of 7.0-T MRI to microelectrode recordings (MER) for STN border identification has not been performed.

OBJECTIVE

To compare representation of STN borders on 7.0-T T2 MRI with the borders identified during MER in patients undergoing DBS for PD and to evaluate whether STN identification on 7.0-T T2 MRI leads to alterations in stereotactic target planning.

DESIGN/METHODS

STN border identification was done using volumetric 7.0-T T2 MRI acquisitions. This was compared to the STN borders identified by MER. STN target planning was independently performed by 3 DBS surgeons on T2 imaging using 1.5-, 3.0-, and 7.0-T MRI.

RESULTS

A total of 102 microelectrode tracks were evaluated in 19 patients. Identification of the dorsal STN border was well feasible on 7-T T2, whereas the ventral STN was un-distinguishable from the substantia nigra. The dorsal STN border on MRI was located more dorsal than MER in 73% of trajectories. The average distance from MRI to MER border was 0.9 mm (range -4.4 to +3.5 mm). STN target planning showed high correspondence between the 3 field strengths.

CONCLUSION

7.0-T T2 MRI offers the possibility of easy identification of the dorsal border of the STN. However, higher field strength MRI does not change the planning of the target. Compared to MER, the dorsal border on MRI was located more dorsal in the majority of cases, situating MER activity within STN representation.

Distance to white matter tracts is associated with deep brain stimulation motor outcome in Parkinson's disease

OBJECTIVE

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) alleviates motor symptoms in patients with Parkinson's disease (PD). However, the underlying mechanism of tremor suppression is not well understood. Stimulation of white matter tracts, such as the dentatorubrothalamic tract (DRT), might be involved. Also, side effects, including dysarthria, might result from (unwanted) stimulation of white matter tracts in proximity to the STN. The aim of this study was to establish an association between stimulation effect on tremor and dysarthria and stimulation location relative to relevant white matter tracts.

METHODS

In 35 PD patients in whom a bilateral STN DBS system was implanted, the authors established clinical outcome measures per electrode contact. The distance from each stimulation location to the center of the DRT, corticopontocerebellar tract, pyramidal tract (PT), and medial lemniscus was determined using diffusion-weighted MRI data. Clinical outcome measures were subsequently related to the distances to the white matter tracts.

RESULTS

Patients with activated contacts closer to the DRT showed increased tremor improvement. Proximity of activated contacts to the PT was associated with dysarthria.

CONCLUSIONS

Proximity to specific white matter tracts is associated with tremor outcome and side effects in DBS. This knowledge can help to optimize both electrode placement and postsurgical electrode contact selection. Presurgical white matter tract visualization may improve targeting and DBS outcome. These findings are of interest not only for treatment in PD, but potentially also for other (movement) disorders.

Reliability of visual assessment by non-expert nuclear medicine physicians and appropriateness of indications of [123I]FP-CIT SPECT imaging by neurologists in patients with early drug-naive Parkinson's disease

Purpose

To determine the reliability of visual assessment of [¹²³I]FP-CIT SPECT imaging by non-experts in dopamine transporter (DAT) SPECT imaging in patients with early drug-naive Parkinson’s disease (PD). Also, we explored the indications of DAT SPECT imaging in clinical practice by neurologists.

Methods

We collected [¹²³I]FP-CIT SPECT scans of the Levodopa in EArly Parkinson’s disease (LEAP) trial participants that were made prior to recruitment, as part of routine clinical work-up. All scans were reassessed by an expert in DAT imaging. A survey on the use of DAT SPECT imaging was sent to all referring neurologists.

Results

The concordance of the initial local assessment and the expert reassessment was 98.7%. The survey showed that neurologists requested DAT SPECT imaging in only 73.6% of patients to differentiate between a neurodegenerative disease and non-neurodegenerative parkinsonism.

Conclusions

Visual assessment of [¹²³I]FP-CIT SPECT imaging by community nuclear medicine physicians in patients with early PD is reliable. Neurologists who request DAT SPECT scans are not always aware that the high accuracy is limited only to the differentiation between neurodegenerative and non-neurodegenerative parkinsonism. A significant portion of neurologists who request DAT SPECT scans is not always aware that the high accuracy is limited to the differentiation between neurodegenerative and non-neurodegenerative parkinsonism as DAT SPECT cannot reliably distinguish the various Parkinsonian syndromes.

Electrode Location in a Microelectrode Recording-Based Model of the Subthalamic Nucleus Can Predict Motor Improvement After Deep Brain Stimulation for Parkinson's Disease

Motor improvement after deep brain stimulation (DBS) in the subthalamic nucleus (STN) may vary substantially between Parkinson’s disease (PD) patients. Research into the relation between improvement and active contact location requires a correction for anatomical variation. We studied the relation between active contact location relative to the neurophysiological STN, estimated by the intraoperative microelectrode recordings (MER-based STN), and contralateral motor improvement after one year. A generic STN shape was transformed to fit onto the stereotactically defined MER sites. The location of 43 electrodes (26 patients), derived from MRI-fused CT images, was expressed relative to this patient-specific MER-based STN. Using regression analyses, the relation between contact location and motor improvement was studied. The regression model that predicts motor improvement based on levodopa effect alone was significantly improved by adding the one-year active contact coordinates (R² change = 0.176, p = 0.014). In the combined prediction model (adjusted R² = 0.389, p < 0.001), the largest contribution was made by the mediolateral location of the active contact (standardized beta = 0.490, p = 0.002). With the MER-based STN as a reference, we were able to find a significant relation between active contact location and motor improvement. MER-based STN modeling can be used to complement imaging-based STN models in the application of DBS.

Randomized Delayed-Start Trial of Levodopa in Parkinson's Disease

BACKGROUND

Levodopa is the main treatment for symptoms of Parkinson's disease. Determining whether levodopa also has a disease-modifying effect could provide guidance as to when in the course of the disease the treatment with this drug should be initiated.

METHODS

In a multicenter, double-blind, placebo-controlled, delayed-start trial, we randomly assigned patients with early Parkinson's disease to receive levodopa (100 mg three times per day) in combination with carbidopa (25 mg three times per day) for 80 weeks (early-start group) or placebo for 40 weeks followed by levodopa in combination with carbidopa for 40 weeks (delayed-start group). The primary outcome was the between-group difference in the mean change from baseline to week 80 in the total score on the Unified Parkinson's Disease Rating Scale (UPDRS; scores range from 0 to 176, with higher scores signifying more severe disease). Secondary analyses included the progression of symptoms, as measured by the UPDRS score, between weeks 4 and 40 and the noninferiority of early initiation of treatment to delayed initiation between weeks 44 and 80, with a noninferiority margin of 0.055 points per week.

RESULTS

A total of 445 patients were randomly assigned: 222 to the early-start group and 223 to the delayed-start group. The mean (±SD) UPDRS score at baseline was 28.1±11.4 points in the early-start group and 29.3±12.1 points in the delayed-start group. The change in UPDRS score from baseline to week 80 was -1.0±13.1 points and -2.0±13.0 points, respectively (difference, 1.0 point; 95% confidence interval [CI], -1.5 to 3.5; P=0.44); this finding of no significant between-group difference at week 80 implies that levodopa had no disease-modifying effect. Between weeks 4 and 40, the rate of progression of symptoms, as measured in UPDRS points per week, was 0.04±0.23 in the early-start group and 0.06±0.34 in the delayed-start group (difference, -0.02; 95% CI, -0.07 to 0.03). The corresponding rates between weeks 44 and 80 were 0.10±0.25 and 0.03±0.28 (difference, 0.07; two-sided 90% CI, 0.03 to 0.10); the difference in the rate of progression between weeks 44 and 80 did not meet the criterion for noninferiority of early receipt of levodopa to delayed receipt. The rates of dyskinesia and levodopa-related fluctuations in motor response did not differ significantly between the two groups.

CONCLUSIONS

Among patients with early Parkinson's disease who were evaluated over the course of 80 weeks, treatment with levodopa in combination with carbidopa had no disease-modifying effect. (Funded by the Netherlands Organization for Health Research and Development and others; LEAP Current Controlled Trials number, ISRCTN30518857 .).

Risk of Parkinson's disease dementia related to level I MDS PD-MCI

BACKGROUND

The International Parkinson and Movement Disorders Society criteria for mild cognitive impairment in PD need validation. The objectives of this present study were to evaluate prognostic validity of level I (abbreviated) International Parkinson and Movement Disorders Society mild cognitive impairment in PD criteria for development of PD dementia and compared them with level II (comprehensive) criteria.

METHODS

We analyzed data from 8 international studies (1045 patients) from our consortium that included baseline data on demographics, motor signs, depression, detailed neuropsychological testing, and longitudinal follow-up for conversion to Parkinson's disease dementia. Survival analysis evaluated their contribution to the hazard of Parkinson's disease dementia.

RESULTS

Level I mild cognitive impairment in PD, increasing age, male sex, and severity of PD motor signs independently increased the hazard of Parkinson's disease dementia. Level I and level II mild cognitive impairment in PD classification had similar discriminative ability with respect to the time to Parkinson's disease dementia.

CONCLUSIONS

Level I mild cognitive impairment in PD classification independently contributes to the hazard of Parkinson's disease dementia. This finding supports the prognostic validity of the abbreviated mild cognitive impairment in PD criteria. © 2019 International Parkinson and Movement Disorder Society.

Detecting Mild Cognitive Deficits in Parkinson's Disease: Comparison of Neuropsychological Tests

BACKGROUND

Numerous neuropsychological tests and test versions are used in Parkinson's disease research, but their relative capacity to detect mild cognitive deficits and their comparability across studies are unknown. The objective of this study was to identify neuropsychological tests that consistently detect cognitive decline in PD across studies.

METHODS

Data from 30 normed neuropsychological tests across 20 international studies in up to 2908 nondemented PD patients were analyzed. A subset of 17 tests was administered to up to 1247 healthy controls. A 2-step meta-analytic approach using standardized scores compared performance in PD with normative data.

RESULTS

Pooled estimates of the differences between PD and site-specific healthy controls identified significant cognitive deficits in PD patients on 14 test scores across 5 commonly assessed cognitive domains (attention or working memory, executive, language, memory, and visuospatial abilities), but healthy control performance was statistically above average on 7 of these tests. Analyses based on published norms only, as opposed to direct assessment of healthy controls, showed high between-study variability that could not be accounted for and led to inconclusive results.

CONCLUSIONS

Normed neuropsychological tests across multiple cognitive domains consistently detect cognitive deficits in PD when compared with site-specific healthy control performance, but relative PD performance was significantly affected by the inclusion and type of healthy controls versus the use of published norms only. Additional research is needed to identify a cognitive battery that can be administered in multisite international studies and that is sensitive to cognitive decline, responsive to therapeutic interventions, and superior to individual cognitive tests. © 2018 International Parkinson and Movement Disorder Society.

Electrode Penetration of the Caudate Nucleus in Deep Brain Stimulation Surgery for Parkinson's Disease

OBJECTIVE

To evaluate the possible influence of electrode trajectories penetrating the caudate nucleus (CN) on cognitive outcomes in deep brain stimulation (DBS) surgery for Parkinson's disease (PD).

BACKGROUND

It is currently unclear how mandatory CN avoidance during trajectory planning is.

DESIGN/METHODS

Electrode trajectories were determined to be inside, outside, or in border region of the CN. Pre- and postoperative neuropsychological tests of each trajectory group were compared in order to evaluate possible differences in cognitive outcomes 12 months after bilateral STN DBS.

RESULTS

One hundred six electrode tracks in 53 patients were evaluated. Bilateral penetration of the CN occurred in 15 (28%) patients, while unilateral penetration occurred in 28 (53%). In 19 (36%) patients tracks were located in the border region of the CN. There was no electrode penetration of the CN in 10 (19%) patients. No difference in cognitive outcomes was found between the different groups.

CONCLUSION

Cognitive outcome was not influenced by DBS electrode tracks penetrating the CN. It is both feasible and sensible to avoid electrode tracks through the CN when possible, considering its function and anatomical position. However, penetration of the CN can be considered without major concerns regarding cognitive decline when this facilitates optimal trajectory planning due to specific individual anatomical variations.